JP7248296B2 - LENS ON-AXIS OFF-AXIS POINT IMAGE OBSERVATION METHOD, APPARATUS AND PROGRAM USING THE SAME METHOD - Google Patents

Description

TECHNICAL FIELD The present invention relates to an on-axis off-axis point image observation method, an apparatus for the same, and a program using the method. The present invention relates to a lens on-axis off-axis point image observation method, an apparatus for the same, and a program using the method.

In general, manufacturing errors such as eccentric errors and surface shape errors may occur on each lens surface when manufacturing a single lens or a lens group or an optical system composed of a plurality of lenses. Such manufacturing errors lead to deterioration of the imaging performance of the entire optical system. In recent years, ultra-compact lenses are used in optical systems (for example, cameras) mounted on smartphones. Against this background, axial aberration measurement of microlenses is commonly performed.

However, in recent years, as the optical system of smartphones has become even more precise, the need to measure not only axial wavefront aberration but also off-axis wavefront aberration has increased. Also, off-axis aberration includes information that cannot be obtained from on-axis wavefront aberration. By obtaining the off-axis aberration data, it becomes possible to collect data for analyzing the imaging performance and manufacturing error of the lens to be measured (optical system to be measured).

For example, in Japanese Patent Application Laid-Open No. 57-179638 (Patent Document 1), a position sensor (for example, CCD, image sensor, etc.) that measures the spot position of the light beam that has passed through the lens to be inspected detects the light receiving position. An aberrometer is disclosed for measuring the aberration of a lens under test by performing calculations along geometric optics based on the above.

In addition, in Japanese Patent Application Laid-Open No. 2004-325173 (Patent Document 2), an on-axis and off-axis image is obtained by photographing an image formed by a point image magnification observation system of transmitted light from a lens to be inspected with a CCD camera. Apparatus and methods for observing aberrations are disclosed.

JP-A-57-179638 Japanese Patent Application Laid-Open No. 2004-325173

The aberration measuring instrument described in Patent Document 1 easily measures aberrations by computer-processing an electrical signal indicating the spot position obtained using a position sensor. Observation and measurement cannot be performed by displaying all aberration spot images due to wavefront aberration on one screen.

Further, in the apparatus and method for observing aberrations described in Patent Document 2, an aberration spot image for measuring the distribution of on-axis and off-axis aberration spot shapes for a lens to be examined is used as an aberration spot distribution image. The function to display everything on the screen and the corresponding configuration are not included.

The present invention has been made in view of the above points, and an object of the present invention is to provide an aberration spot image for measuring the distribution of on-axis and off-axis aberration spot shapes with respect to a lens to be measured. By displaying all on one screen, the distribution data of each aberration spot image can be observed at once and the aberration can be measured, and all the aberration characteristics of the lens to be measured can be judged. It is to provide a program using the device and the method.

The object of the on-axis off-axis point image observation method according to the present invention is to provide a lens using a lens to be measured, an illumination optical section, a fixing section for the lens to be measured , a rotating stage, an imaging section, an inclined section, an image processing section, and a display section. In the on-axis off-axis point image observation method, the illumination optical unit irradiates the lens to be measured with diffused light, the lens to be measured is fixed to the lens-to-be-measured fixing unit, The optical axis of the illumination optical section , the optical axis of the imaging section, and the optical axis of the lens to be measured are relatively tilted by a predetermined tilt angle, and the imaging section detects parallel light emitted from the lens to be measured. is captured and converted into an image signal, and the image processing unit generates aberration spot image data using the image data converted based on the image signal , Via the measurement lens fixing portion, the rotation stage rotates the lens to be measured by a predetermined rotation angle about the optical axis of the lens to be measured, and the inclined portion passes through substantially the center of the lens to be measured. , by rotating the optical axis of the illumination optical unit, the optical axis of the imaging unit, and the optical axis of the lens to be measured about an axis orthogonal to each other, the optical axis is tilted by the predetermined tilt angle, By controlling the predetermined rotation angle and the predetermined tilt angle at predetermined intervals, the aberration spot image data is sequentially acquired, and the display unit displays the aberration spot image data at the predetermined rotation angle and the tilt angle . An aberration spot distribution image arranged corresponding to a predetermined tilt angle is displayed , and the display of the aberration spot distribution image is performed by setting orthogonal α-axis and β-axis on the screen of the display unit, A display based on the aberration spot image data of the axial aberration is performed at the intersection of the axis and the β axis, and the first quadrant formed by the α axis, the β axis, and the α axis and the β axis are displayed. This is achieved by providing a plurality of representations based on the aberration spot image data for off-axis aberrations in each of up to four quadrants .

Further, the object of the lens on-axis off-axis point image observation method according to the present invention is that the aberration spot distribution images of the off-axis aberration are four on the α-axis, four on the β-axis, and the first quadrant This is achieved more effectively by displaying three each in the regions from to the fourth quadrant .

Further, the above object of the lens on-axis off-axis point image observation apparatus according to the present invention includes : In the lens on-axis off-axis point image observation device, the illumination optical unit irradiates the lens to be measured with diffused light, the lens to be measured is fixed to the lens to be measured fixing unit, and the inclined section relatively tilts the optical axis of the illumination optical section , the optical axis of the imaging section, and the optical axis of the lens to be measured by a predetermined tilt angle, and the imaging section emits light from the lens to be measured. The focused spot of parallel light is photographed and converted into an image signal, and the image processing unit uses the image data converted based on the image signal to generate aberration spot image data, and the object to be measured The lens is rotated by a predetermined rotation angle about the optical axis of the lens to be measured by the rotation stage through the fixing portion of the lens to be measured, and the inclined portion is moved to the position of the lens to be measured. The predetermined tilt angle is obtained by rotating about an axis that passes through substantially the center and perpendicularly intersects the optical axis of the illumination optical unit, the optical axis of the imaging unit, and the optical axis of the lens to be measured. and controlling the predetermined rotation angle and the predetermined tilt angle by predetermined intervals to sequentially acquire the aberration spot image data, and the display unit displays the aberration spot image data at the predetermined The aberration spot distribution image arranged in correspondence with the rotation angle of and the predetermined tilt angle is displayed, and the aberration spot distribution image is displayed on the screen of the display unit by A display based on the aberration spot image data of the axial aberration is displayed at the intersection of the α axis and the β axis, and the α axis and the β axis are formed. This can be achieved more effectively by providing a plurality of displays based on the aberration spot image data of the off-axis aberration in each region from the first quadrant to the fourth quadrant.

Further, the above object of the program for causing a computer to perform on-axis off-axis point image observation of the lens according to the present invention includes a lens to be measured, an illumination optical section, a fixing section for the lens to be measured, a rotating stage, an imaging section, an inclined section, A program for causing a computer to perform lens on-axis off-axis point image observation using an image processing unit and a display unit, the program comprising a step of irradiating the lens to be measured with diffused light by the illumination optical unit; a step of fixing the lens to be measured to a measurement lens fixing portion; a step of relatively inclining by an angle; a step of capturing a condensed spot of parallel light emitted from the lens to be measured by the imaging unit and converting it into an image signal; a step of generating aberration spot image data using image data converted based on a signal; While rotating by a predetermined rotation angle about the axis as a central axis, the inclined portion passes through substantially the center of the lens to be measured, and the optical axis of the illumination optical unit and the optical axis of the imaging unit and the optical axis of the lens to be measured. By rotating about an axis orthogonal to the optical axis of the measuring lens, the measuring lens is tilted by the predetermined tilt angle, and the predetermined rotation angle and the predetermined tilt angle are controlled by predetermined intervals. The step of sequentially acquiring the aberration spot image data, and the display unit displaying an aberration spot distribution image in which the aberration spot image data are arranged in correspondence with the predetermined rotation angle and the predetermined tilt angle. and the display of the aberration spot distribution image is performed by setting an α axis and a β axis that are orthogonal to each other on the screen of the display unit, and an axial aberration at the intersection of the α axis and the β axis. off-axis aberration on the α-axis and the β-axis, and on each region from the first quadrant to the fourth quadrant formed by the α-axis and the β-axis, and performing a plurality of displays based on the aberrated spot image data .

According to the lens on-axis and off-axis point image observation method of the present invention, the apparatus for the same, and the program using the method, the aberration spot image obtained by measuring the on-axis and off-axis aberration spot shapes of the lens to be measured is converted into the aberration spot distribution. By displaying all the aberration spot image data on one screen as an image, it is possible to observe and measure each aberration spot image data at a time, and it is possible to judge all the aberration characteristics of the lens to be measured.

FIG. 2 is a configuration diagram when performing axial aberration measurement in the on-lens off-axis point image observation device according to the first embodiment of the present invention. FIG. 2 is a configuration diagram when performing off-axis aberration measurement in the on-lens off-axis point image observation apparatus according to the first embodiment of the present invention. FIG. 2 is a schematic configuration diagram of an example of an inclined portion applied to an on-lens off-axis point image observation apparatus according to each embodiment of the present invention; It is an example of the aberration spot distribution image displayed in the on-lens off-axis point image observation device according to the first embodiment of the present invention. 6 is an example of a flow chart of processing details performed by the on-lens off-axis point image observation device according to the first embodiment of the present invention. FIG. 9 is a schematic diagram showing a state in which a set of an illumination light source unit and a plurality of imaging units is provided in an on-lens off-axis point image observation device according to a second embodiment of the present invention. FIG. 12 is a schematic diagram showing how and how the lens to be measured is positioned on the XY plane perpendicular to the optical axis in the on-lens off-axis point image observation apparatus according to the third embodiment of the present invention. FIG. 3 is a schematic diagram showing a configuration example of a rotary stage of the on-lens off-axis point image observation apparatus according to each embodiment of the present invention, and a relationship between the fixed part of the lens to be measured and the rotary stage.

Embodiments of the present invention will be described below with reference to the drawings. However, the embodiments described below are merely examples, and are not intended to exclude various modifications and application of techniques not explicitly described below. That is, the present invention can be implemented in various modifications (combining each embodiment, etc.) without departing from the scope of the invention. In addition, in the description of the drawings below, the same or similar parts are denoted by the same or similar reference numerals. The drawings are schematic and do not necessarily correspond to actual dimensions, proportions, and the like. Even between the drawings, there are cases where portions with different dimensional relationships and ratios are included.

<<First embodiment>>
First, a lens on-axis off-axis point image observation device 10 according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration diagram for performing axial aberration measurement in an on-lens off-axis point image observation apparatus according to a first embodiment of the present invention. As shown in FIG. 1, the optical axis of the lens 13 to be measured is AX, and the Z axis of the XYZ coordinate system is set parallel to the optical axis AX. Also, the lens 13 to be measured is arranged above the illumination optical unit 12 .

The X-axis, Y-axis and Z-axis are orthogonal to each other. Therefore, the XY plane is perpendicular to the Z axis. The illumination optical unit and imaging unit are hereinafter referred to as an aberration imaging unit. Note that the inclination around the X-axis is expressed as θx, and the inclination angle around the Y-axis is expressed as θy. In particular, let ψ be the rotation angle about the Z-axis, that is, the rotation angle about the optical axis AX of the lens 13 to be measured. Also, the angle at which the lens 13 to be measured and the imaging unit 15 are tilted about an axis (for example, the Y-axis) perpendicular to the optical axis AX is defined as a tilt angle φ. That is, when the optical axis of the illumination optical unit 12 and the optical axis of the imaging unit 15 are inclined around the Y-axis, the inclination angle φ is the optical axis of the illumination optical unit 12 or the optical axis of the imaging unit 15 It is an angle formed with AX (Z axis). Note that the tilt angle φ is used when measuring lens off-axis aberrations, which will be described later. When measuring the axial aberration of the lens 13 to be measured, the tilt angle φ is set to 0° as shown in FIG.

Also, the arrangement for measuring the aberration under the measurement conditions of the rotation angle .phi. and the tilt angle .phi. The spot image data captured at each beam spot measurement point BSP (ψ, φ) is represented as aberration spot image data SD (ψ, φ).

Then, the configuration of the lens on-axis off-axis point image observation device 10 according to the first embodiment of the present invention and the operation of each part and the optical path when performing on-axis aberration measurement will be described with reference to the drawings.

The first stage 11 includes a tilting stage (θy rotating stage) 11a that tilts the light source 12a around the Y axis with respect to the optical axis AX, a first XY stage 11b that moves the light source 12a in the plane direction along the XY plane, and an optical It is composed of a first Z-stage 11c that linearly moves in the Z-axis direction parallel to the axis AX.

The illumination optical section 12 is composed of a light source 12a and a first lens 12b. The illumination optical unit 12 is installed on the first stage 11 . The light source 12a is installed on the tilt stage 11a. Therefore, the position and tilt angle θy of the light source 12 a can be adjusted by the first stage 11 . By these adjustments, the optical axis AX and the optical axis of the illumination optical section 12 are substantially aligned.

The light emitted from the light source 12a is arranged so as to be condensed at a beam spot position BS0 at a predetermined distance from the first lens 12b after passing through the first lens 12b. The light emitted from the first lens 12b is condensed at the beam spot position BS0. Since the beam spot position BS0 is located at a position substantially the focal length away from the center of the lens to be measured, the diffused light from the beam spot position BS0 is converted into substantially parallel light by the lens 13 to be measured.

Next, the lens 13 to be measured is arranged above the illumination optical section 12 . The second stage 14 includes a lens-to-be-measured fixing portion 14a for fixing the lens-to-be-measured 13, a rotary stage 14b for rotating the lens-to-be-measured fixing portion 14a around the optical axis AX, and the rotary stage 14b on the XY plane. It is composed of a second XY stage 14c that moves in the planar direction along, and a second Z stage 14d that linearly moves the rotary stage 14b in the Z direction. As shown in FIG. 1, the rotary stage 14b supports the lens 13 to be tested rotatably around the optical axis AX.

The imaging unit 15 is composed of a second lens 15a and a camera 15b. The parallel light is condensed on the imaging surface of the camera 15b by the second lens 15a to form a condensed spot S on the imaging surface. The camera 15 b converts the focused spot S into an image signal and transmits the image signal to the image processing section 16 .

Next, the image processing unit 16 performs image processing on the image data converted from the image signal. Then, the image processing unit 16 generates aberration spot image data SD (ψ, φ) based on the image data.

Then, the display unit 17 displays the aberration spot image data SD (φ, φ) generated by the image processing unit 16 .

Next, FIG. 2 shows a configuration diagram for performing off-axis aberration measurement in the on-lens off-axis point image observation apparatus according to the first embodiment of the present invention. Further, in the on-lens off-axis point image observation apparatus according to the first embodiment of the present invention, the arrangement and operation of the illumination optical unit 12 and the photographing unit 15 when performing off-axis aberration measurement will be described with reference to FIG. explain. As shown in FIG. 2, the illumination optical unit 12 is held so that the optical axis of the imaging unit 15 substantially coincides with the optical axis of the imaging unit 15, and the lens to be measured 13 is arranged at an angle of inclination φ with respect to the optical axis AX. The image processing unit 16 records the aberration spot image data SD (φ, φ) observed in .

Here, an inclined portion capable of realizing the above arrangement will be described. For example, FIG. 3 shows a schematic configuration of an example of an inclined portion used in an on-axis off-axis point image observation device 10 to which the present invention is applied. As shown in FIG. 3, the inclined portion 19 is composed of a motor 19a and an arm 19b. An arm 19b is joined to the rotating shaft 191a of the motor 19a. The arm 19b has a U-shape in which an upper end portion 192b and a lower end portion 193b of a plate-like arm body 191b protrude in parallel.

Also, since the illumination optical unit 12 is placed or installed on the first stage 11 , the tilt of the optical axis of the illumination optical unit 12 rotates according to the tilt angle of the first stage 11 . The same applies to the tilt angle of the imaging section 15 . Therefore, the illumination optical unit 12 and the imaging unit 15 are supported by the arm 19b so as to be rotatable about the Y-axis direction.

With such a configuration, the optical axis of the illumination optical unit 12 and the optical axis of the imaging unit 15 can be held so as to substantially coincide with each other.

In addition, the control unit 18 (not shown) controls the optical axis of the illumination optical unit 12 mounted or installed on the first stage 11 and the entire imaging unit 15 to the on-axis off-axis point image observation device 10 . However, the motor 19a can be controlled to be rotatable around the Y-axis direction.

Then, the control unit 18 rotates and controls the rotation angle ψ of the illumination optical unit 12 and the imaging unit 15 by a predetermined interval (angle step Δψ), or changes the tilt angle φ of the illumination optical unit 12 and the imaging unit 15 by a predetermined interval. Rotation is controlled by (angle step Δφ). By controlling the tilt angle φ by the controller 18, the beam spot BS(ψ, φ) from the illumination optical unit 12 is separated from the optical axis AX.

Also, by controlling the rotation angle ψ by the control unit 18, the beam spot BS(ψ,φ) from the illumination optical unit 12 rotates concentrically around the optical axis AX.

Then, the image processing unit 16 uses the image data captured by the camera 15b at each beam spot measurement point BSP (φ, φ) to generate aberration spot image data SD (φ, φ).

Furthermore, the image processing unit 16 collects aberration spot image data SD (ψ, φ) observed at each beam spot measurement point BSP (ψ, φ) based on the aberration spot image data SD (ψ, φ). Generate a spot distribution image.

Finally, the monitor 17 displays the aberration spot distribution image. The lens on-axis and off-axis point image observation device 10 according to the first embodiment of the present invention uses the aberration spot image data SD (ψ, φ) to measure the on-axis and off-axis aberration spot shapes of the lens to be measured. By displaying all the aberration spot images as aberration spot distribution images on one screen, the inspector (user) can view the aberration spot distribution images under different conditions of off-axis aberrations at the rotation angle ψ and the tilt angle φ. Observation and aberration measurement can be performed at once, and all aberration characteristics of the lens 13 to be measured can be judged.

FIG. 4 shows an example of an aberration spot distribution image displayed. In the example of the aberration spot distribution image shown in FIG. 4, an arbitrary point A on the αβ plane with the α axis set in the horizontal direction and the β axis set in the vertical direction corresponds to the rotation angle ψ and the tilt angle φ on a one-to-one basis. represents the position where the aberration spot image data SD(φ, φ) is arranged. In FIG. 4, only one piece of aberration spot image data SD(0, 0) representing axial aberration is arranged at the origin on the αβ plane. On the other hand, the aberration spot image data SD (ψ, φ) (ψ≠0, φ≠0) representing off-axis aberrations are four along the α axis, four along the β axis, and Three pieces of aberration spot image data SD (φ, φ) are arranged in each quadrant.

The aberration spot distribution image shown in FIG. 4 is an example composed of a total of 21 pieces of aberration spot image data SD(φ, φ) representing one on-axis and twenty off-axis aberrations. It is preferable to display the light intensity in each aberration spot image data SD (φ, φ) as shown in FIG. 4 according to the order of gradation, for example.

In this way, all the aberration spot image data SD (ψ, φ) obtained by measuring the axial aberration and off-axis aberration spot shapes of the lens 13 to be measured are displayed on one screen as an aberration spot distribution image. The spot image data SD (φ, φ) can be observed and the aberration can be measured at the same time, and all the aberration characteristics of the lens 13 to be measured can be judged.

Next, the operation of the lens on-axis off-axis point image observation device 10 according to the first embodiment of the present invention will be described. FIG. 5 shows an example of a flow chart of processing contents performed by the on-lens off-axis point image observation device 10 according to the first embodiment of the present invention.

First, the lens to be measured 13 is installed on the lens to be measured fixing portion 14a (step S10).

Next, the rotation angle ψ and the tilt angle φ of the imaging unit 15 and the illumination optical unit 12 are initialized (step S20). For example, the rotation angle ψ and the tilt angle φ are set to 0° (zero). Subsequently, the light source 12a is turned on (step S30). Then, the imaging unit 15 measures the aberration spot image data SD (ψ, φ) of the lens 13 to be measured (step S40).

Next, the control unit 18 rotates the rotation angle ψ of the lens fixing unit 14a to be measured by a predetermined angle step Δψ (step S50).

At this time, the control unit 18 determines whether or not the rotation angle ψ is 360° (2π radians) or more, that is, whether or not the lens to be measured 13 has rotated once around the optical axis AX (step S60). .

If the determination result in step S60 is No, the process returns to step S40, and subsequently the imaging unit 15 measures the aberration spot image data SD (ψ, φ) of the lens 13 to be measured.

On the other hand, if the determination result in step S60 is Yes, the rotation angle ψ is 360° or more, that is, the control unit 18 determines that the lens-to-be-measured fixing unit 14a has rotated once around the optical axis AX, which will be described later. Proceed to step S70.

Then, the control unit 18 rotates the tilt angle φ by a predetermined angle step Δφ, holds the illumination optical unit 12 so that the optical axis of the imaging unit 15 substantially coincides with the optical axis of the imaging unit 15, and rotates the lens 13 to be measured. It is tilted by a relative tilt angle φ with respect to the optical axis AX, and the rotation angle ψ is set to an initial value (ψ=0°) (step S70).

Next, the control unit 18 determines whether or not the tilt angle ψ is greater than or equal to the maximum tilt angle ψmax (step S80). If the determination result in step S80 is No, the process returns to step S40, and the imaging unit 15 measures the aberration spot image data SD (ψ, φ) of the lens 13 to be measured.

On the other hand, if the determination result in step S80 is Yes, it is determined that the rotation angle ψ is greater than or equal to the maximum tilt angle ψmax, that is, the tilt has reached its limit, and the process proceeds to step S90, which will be described later.

Then, based on the aberration spot image data SD (ψ, φ) repeatedly photographed in step S40, the image processing unit 16 generates an aberration spot distribution image (step S90). Next, the light source 12a is turned off (step S100). Subsequently, the aberration spot distribution image is displayed on the monitor 17 (step S110).

Finally, the lens to be measured 13 is removed from the lens to be measured fixing portion 14b (step S120).

<<Second embodiment>>
Next, a lens on-axis off-axis point image observation device 20 according to a second embodiment of the present invention will be described with reference to FIG.

The lens on-axis off-axis point image observation device 20 according to the second embodiment of the present invention is provided with a plurality of sets of illumination light source units and imaging units, which is different from the on-axis point image observation apparatus 20 according to the first embodiment of the present invention. Unlike the off-axis point image observation device 10, the rest of the configuration is substantially the same. Therefore, constituent elements common to those of the first embodiment are denoted by the same reference numerals, and descriptions thereof are omitted.

In the on-lens off-axis point image observation device 20 according to the second embodiment of the present invention, a first set of aberration photographing units consisting of the illumination light source section 12 and the imaging section 15; FIG. 6 shows how two sets of aberration-photographing units and a third set of aberration-photographing units consisting of the illumination light source section 32 and the imaging section 35 are arranged.

In FIG. 6, the approximate center of the lens 13 to be measured is located at the position OP on the optical axis AX, and the lens on-axis off-axis point image observation apparatus according to the first embodiment of the present invention shown in FIGS. 10, the lens-to-be-measured fixing portion 14a can be rotated around the optical axis AX by the rotation stage 14b.

As shown in FIG. 6, while the optical axis of the illumination optical unit 12 and the optical axis of the imaging unit 15 of the first set of aberration imaging units are held so as to substantially coincide with each other, the lens to be measured 13 is relative to the optical axis AX. The image processing unit 16 records the aberration spot image data (ψ, φ ₁ ) observed in an arrangement that can be tilted by a tilt angle φ1. In addition, in FIG. 6, the inclination angle is φ1.

Similarly, while holding the illumination optical unit 22 and the imaging unit 25 of the second set of aberration photographing units so that their optical axes are substantially aligned, the relative tilt angle φ of the lens 13 to be measured with respect to the optical axis AX The image processing unit 16 records the aberration spot image data SD(φ, φ ₂ ) observed in an arrangement tilted by ₂ .

Similarly, while the optical axis of the illumination optical unit 32 and the optical axis of the imaging unit 35 of the third aberration photographing unit are held so as to substantially coincide with each other, the relative tilt angle φ of the lens 13 to be measured with respect to the optical axis AX The image processing unit 16 records the aberration spot image data SD(φ, φ ₃ ) observed in an arrangement tilted by ₃ .

The on-lens off-axis point image observation device 20 according to the second embodiment of the present invention includes a first set of aberration imaging units, a second set of aberration imaging units, and a third set of aberration imaging units. Under the measurement conditions of the rotation angles ψ ₁ , ψ ₂ and ψ ₃ , the aberration spots can be photographed almost simultaneously, so it is possible to complete the photographing at approximately three times the speed (approximately 1/3 the measurement time). be.

For example, as a measurement condition, the first set of aberration-photographing units, the second set of aberration-photographing units, and the third set of aberration-photographing units are tilted by a common tilt angle ψ ₀ with respect to the optical axis AX of the lens to be measured. , the first set of aberration-photographing units, the second set of aberration-photographing units, and the third set of aberration-photographing units are rotated about the optical axis AX of the lens under measurement by rotation angles ψ ₁ and ψ ₂ (=ψ ₁ +120°) and ψ ₃ (=ψ ₂ +120°), the aberration spot image SD (ψ ₁ , φ), the aberration spot image SD (ψ ₂ , φ) and the aberration spot image SD ( ψ ₃ , φ) can be imaged. That is, the tilt angle φ ₀ is changed in the range of 0≦φ ₀ <φmax (maximum tilt angle) and is changed in the range of 0≦φ ₁ <120°, and the photographing of the aberration spot images (φ, φ) is omitted. It is possible to finish at three times the speed (approximately 1/3 the measurement time).

<<Third Embodiment>>
Next, an on-lens off-axis point image observation device 30 according to a third embodiment of the present invention will be described with reference to FIG.

In the lens on-axis off-axis point image observation device 30 according to the third embodiment of the present invention, the beam spot measurement point BSP (ψ, φ) at the rotation angle ψ and the tilt angle φ is perpendicular to the optical axis of the lens under test. , and positioned on the XY plane separated by the focal length from the lens under test. are substantially the same. Therefore, constituent elements common to those of the first embodiment are denoted by the same reference numerals, and descriptions thereof are omitted.

FIG. 7 shows how and how the lens on-axis off-axis point image observation device 30 according to the third embodiment of the present invention is controlled to be positioned on the XY plane perpendicular to the optical axis AX of the lens under test. . In FIG. 7, f ₀ is the focal length of the lens 13 under test, and φ is the tilt angle.

First, the beam spot position in the case of axial aberration measurement is BS (0, 0), and the off-axis aberration measurement beam spot position in the case of off-axis aberration measurement with an arbitrary rotation angle ψ and tilt angle φ is BS (ψ, φ ).

As shown in FIG. 7, in the lens on-axis off-axis point image observation device 30 according to the third embodiment of the present invention, the aberration spot image data SD (ψ, φ) is measured at an arbitrary rotation angle ψ and tilt angle φ. When the illumination optical unit 12 and the first stage 11 are tilted by the tilt angle φ, the first Z stage 11c is arranged such that the illumination optical unit 12 is shifted from the optical axis AX of the lens under test 13 to f ₀ ( 1/sin φ−1).

With this control method, the beam spot BS (ψ, φ) is placed on the XY plane perpendicular to the optical axis AX of the lens under test 13 and separated from the lens under test 13 by the focal length f ₀ of the lens under test 13. position can be controlled.

In general, there is an image height in off-axis aberration measurement of a lens. Therefore, when measuring the aberration of the aberration spot image data SD (ψ, φ) by controlling the first stage 11 in the lens on-axis off-axis point image observation device 30 according to the third embodiment of the present invention, has the special effect of suppressing the aberration due to the difference in image height and displaying the aberration of the aberration spot image data SD (ψ, φ) on one screen.

In the specification of the present application, the term "image height" refers to the distance (image height) from the optical axis (central axis) of the lens to be measured whose aberration is to be measured to the beam spot BS (ψ, φ) ( distance). In other words, the “image height” is an index indicating the height of the image (beam spot of incident light) from the central axis of the lens to be measured.

The embodiments of the present invention have been described above using examples, but each example shows a preferred example, and other structures or configurations having similar effects and characteristics are within the scope of the present invention. be. The present invention is by no means limited to the above embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

In the on-lens off-axis point image observation apparatus 10 according to the first embodiment of the present invention, as shown in FIG. 1, the rotation stage 14b rotatably supports the lens under test 13 with the optical axis AX as the rotation axis. However, appropriate modifications and detailed mechanisms can be added to implement it.

For example, when supplementing the detailed mechanism of the rotation stage 14b, it may include a stepping motor 141b, a gear 142b, and a shaft 143b. Note that the stepping motor 141b may be replaced with a DC motor or the like.

FIG. 8 shows an example of the arrangement of the stepping motor 141b, shaft 142b and gear 143b of the rotary stage 14b. FIG. 8 shows the position of the lens 13 to be measured, the positional relationship of the illumination optical unit 12, and how the gears 141a and 143b formed around the lens fixing unit 14a are engaged with each other.

As shown in FIG. 8, as the rotating shaft 142b of the stepping motor 141b rotates, the gear 142b transmits torque to the gear 141a. As a result, the lens-to-be-measured fixing portion 14a rotates around the optical axis AX while fixing the lens-to-be-measured 13 to the gear 141a. For such rotation control, by sending a control signal from the control unit 18 (not shown), the rotation angle ψ around the optical axis AX of the lens fixing unit 14a to be measured and the rotation speed of the rotation angle ψ It is preferable to control (Δψ/Δt).

Further, in the lens on-axis off-axis point image observation device 10 according to the first embodiment of the present invention, as shown in FIG. Although only the provision of a gripping ramp has been described, appropriate modifications and detailed mechanisms can be added to accomplish this.

Further, in the on-axis off-axis point image observation device according to each embodiment of the present invention, the camera 15b for photographing the focused spot S may be, for example, a CCD line sensor camera, a CCD area sensor camera, or a frame transfer type CCD image sensor. , a full frame transfer type CCD image sensor, or the like may be used.

Further, the light sources 12a, 22a, and 32a provided in the illumination optical units 12, 22, and 32 in the lens on-axis off-axis point image observation apparatus according to each embodiment of the present invention may be semiconductor lasers. Accordingly, an objective lens, a beam expander or an optical slit may be appropriately arranged on the exit side of the light source. Also, semiconductor lasers have been mentioned as examples of the light sources 12a, 22a, and 32a, but other light sources may be employed.

Further, in the lens on-axis off-axis point image observation device according to each embodiment of the present invention, the image processing unit 16 displays the aberration spot image data SD (φ, φ) according to the rotation angle φ and the tilt angle φ. Although it is shown that they are arranged on the screen of the unit 17, the display of the aberration spot image data SD (ψ, φ) is changed according to the aberration calculated based on the aberration spot image data SD (ψ, φ). You can do it. That is, the aberration spot distribution image may be changed by comparing each aberration with the set allowable range, upper limit value, or lower limit value for the aberration at the beam spot measurement point BSP (φ, φ). For example, when the aberration at the beam spot measurement point BSP (ψ, φ) exceeds the allowable value or exceeds the upper limit, the image processing unit 16 generates a warning image indicating that the aberration exceeds the upper limit, and the display unit 6 can also be displayed. When displaying such a warning image, the color, contrast, area, shape, etc. of the aberration spot image data SD (ψ, φ) are changed, or the numbers indicating the amount of aberration are highlighted. can also be performed and displayed on the display unit 17 . In other words, the image processing unit 16 can display a warning image on the display unit 17 in the aberration spot distribution image when the aberration of the lens under measurement is large. Conversely, the image processing unit 16 displays the aberration spot image data SD (ψ, φ) so as to indicate that the aberration at the beam spot measurement point BSP (ψ, φ) is within the allowable value or does not exceed the upper limit value. It is also possible to display on the display unit 17 by changing the color, contrast, area, and shape, or by emphasizing the number indicating the amount of aberration. With such a display method, an inspector (user) can observe and measure aberrations at once while viewing aberration spot images under different conditions of off-axis aberrations at the rotation angle ψ and the tilt angle φ. All 13 aberration characteristics can be judged more easily.

Further, with respect to the on-axis off-axis point image observation apparatus according to each embodiment of the present invention, each component shown in the figure is functionally conceptual, and does not necessarily need to be physically configured as shown in the figure. . For example, the processing functions provided in the image processing unit 16, the display unit 17, and the control unit 18 of the lens on-axis off-axis point image observation device according to each embodiment of the present invention, particularly the image processing unit 16 and the control unit 18 All or any part of each processing function to be performed may be realized by a CPU and a program interpreted and executed by the CPU. The program is recorded on a non-transitory computer-readable recording medium that includes programmed instructions for causing a computer to execute the method according to the present invention. It is read mechanically by the part 18 .

The image processing unit 16 and the control unit 18 may be configured as an information processing device such as a known personal computer, or may be configured by connecting any peripheral device to the information processing device. Further, the image processing unit 16 and the control unit 18 may be implemented by installing software (including programs, data, etc.) that causes the information processing apparatus to implement the method of the present invention.

Furthermore, the specific form of distribution/integration of the devices is not limited to the one shown in the figure, and all or part of them can be functionally or physically arranged in arbitrary units according to various additions or functional loads. It can be configured by distributing and integrating That is, the embodiments described above may be arbitrarily combined and implemented, or the embodiments may be selectively implemented.

10, 20, 30 lens on-axis off-axis point image observation device 11 first stage 11a tilt stage (θy rotation stage)
11b 1st XY stage 11c 1st Z stage 12, 22, 32 Illumination optical section 12a, 22a, 32a Light source 12b, 22b, 32b First lens 13 Lens to be measured 14 Second stage 14a Lens to be measured fixing section 14b Rotation stage (ψ rotation stage)
14c Second XY stage 14d Second Z stage 15, 25, 35 Imaging unit 15a, 25a, 35a Second lens 15b, 25b, 35b Camera 16 Image processing unit 17 Display unit (monitor)
18 Control unit 141a Gear 141b Stepping motor 142b Shaft 143b Gear AX Optical axis AX10 of the lens under measurement Optical axis AX20 of the first aberration imaging unit Optical axis AX30 of the second aberration imaging unit Optical axis AX30 of the third aberration imaging unit Optical axis L1 Locus of rotation about camera center L2 Locus of rotation of first stage OP Center position of lens under measurement ψ Rotation angle φ Tilt angle S Condensed spot BS0 Axial aberration measurement beam spot position BS (φ, φ) Axis External aberration measurement beam spot position BSP (ψ, φ) Beam spot measurement point SD (ψ, φ) Aberration spot image data

Claims (8)

An on-axis off-axis point image observation method using a lens to be measured, an illumination optical unit, a fixing unit for the lens to be measured , a rotating stage, an imaging unit, an inclined unit, an image processing unit, and a display unit,
The illumination optical unit irradiates the lens to be measured with diffused light,
The lens to be measured is fixed to the lens-to-be-measured fixing portion,
the tilting section relatively tilts the optical axis of the illumination optical section, the optical axis of the imaging section, and the optical axis of the lens to be measured by a predetermined tilt angle;
The imaging unit captures a condensed spot of parallel light emitted from the lens to be measured and converts it into an image signal,
Aberration spot image data is generated by the image processing unit using the image data converted based on the image signal,
The lens to be measured is rotated by a predetermined rotation angle about the optical axis of the lens to be measured by the rotation stage via the lens fixing portion to be measured, and
The inclined portion is rotated around an axis that passes through substantially the center of the lens to be measured and is perpendicular to the optical axis of the lens to be measured and the optical axis of the illumination optical unit and the optical axis of the imaging unit. By moving, it is tilted by the predetermined tilt angle,
sequentially acquiring the aberration spot image data by controlling the predetermined rotation angle and the predetermined tilt angle at predetermined intervals;
The display unit displays an aberration spot distribution image in which the aberration spot image data are arranged in association with the predetermined rotation angle and the predetermined tilt angle,
Display of the aberration spot distribution image includes:
setting an α-axis and a β-axis orthogonal to each other on the screen of the display unit;
performing display based on the aberration spot image data of the axial aberration at the intersection of the α axis and the β axis;
A plurality of displays based on the aberration spot image data of the off-axis aberration are displayed on the α-axis and the β-axis and in each region from the first quadrant to the fourth quadrant formed by the α-axis and the β-axis. conduct,
A lens on-axis off-axis point image observation method characterized by: 2. The aberration spot distribution image of the off-axis aberration according to claim 1, wherein four images are displayed on the α axis, four images on the β axis, and three images each in the first to fourth quadrants. on-axis off-axis point image observation method. An on-axis off-axis point image observation apparatus comprising a lens to be measured, an illumination optical section, a fixing section for the lens to be measured , a rotating stage, an imaging section, an inclined section, an image processing section, and a display section,
The illumination optical unit irradiates the lens to be measured with diffused light,
The lens to be measured is fixed to the lens to be measured fixing portion,
The tilting section relatively tilts the optical axis of the illumination optical section , the optical axis of the imaging section, and the optical axis of the lens to be measured by a predetermined tilt angle,
The imaging unit captures a condensed spot of parallel light emitted from the lens to be measured, converts it into an image signal,
The image processing unit generates aberration spot image data using image data converted based on the image signal,
The lens to be measured is rotated by a predetermined rotation angle about the optical axis of the lens to be measured by the rotation stage via the lens fixing portion to be measured, and
The inclined portion is rotated around an axis that passes through substantially the center of the lens to be measured and is perpendicular to the optical axis of the lens to be measured and the optical axis of the illumination optical unit and the optical axis of the imaging unit. By moving, it is tilted by the predetermined tilt angle,
sequentially acquiring the aberration spot image data by controlling the predetermined rotation angle and the predetermined tilt angle at predetermined intervals;
The display unit displays an aberration spot distribution image in which the aberration spot image data are arranged in association with the predetermined rotation angle and the predetermined tilt angle ,
Display of the aberration spot distribution image includes:
setting an α-axis and a β-axis orthogonal to each other on the screen of the display unit;
Display based on the aberration spot image data of the axial aberration at the intersection of the α axis and the β axis,
A plurality of displays based on the aberration spot image data of the off-axis aberration are displayed on the α-axis and the β-axis and in each region from the first quadrant to the fourth quadrant formed by the α-axis and the β-axis. to be
A lens on-axis off-axis point image observation device characterized by: A lens on-axis off-axis point image comprising a lens to be measured, a fixed part for the lens to be measured, a rotating stage, three sets of aberration imaging units, inclined parts for holding the three sets of aberration imaging units, an image processing part, and a display part An observation device,
each of the aberration imaging units includes an illumination optical section and an imaging section;
The illumination optical unit irradiates the lens to be measured with diffused light,
The lens to be measured is fixed to the lens to be measured fixing portion,
The tilting section relatively tilts the optical axis of the illumination optical section, the optical axis of the imaging section, and the optical axis of the lens to be measured by a predetermined tilt angle,
The imaging unit captures a condensed spot of parallel light emitted from the lens to be measured, converts it into an image signal,
The image processing unit generates aberration spot image data using image data converted based on the image signal,
The lens to be measured is rotated by the rotation stage via the lens-to-be-measured fixing portion about the optical axis of the lens-to-be-measured by a predetermined rotation angle in the range of 0 degrees or more and less than 120 degrees. Rotate and
The inclined portion is rotated around an axis that passes through substantially the center of the lens to be measured and is perpendicular to the optical axis of the lens to be measured and the optical axis of the illumination optical unit and the optical axis of the imaging unit. By moving, it tilts by the predetermined tilt angle in the range of 0 degrees or more and less than the maximum tilt angle,
sequentially acquiring the aberration spot image data by controlling the predetermined rotation angle and the predetermined tilt angle at predetermined intervals;
The display unit displays an aberration spot distribution image in which the aberration spot image data are arranged in association with the predetermined rotation angle and the predetermined tilt angle ,
The aberration spot distribution image is displayed by setting an α-axis and a β-axis orthogonal to each other on the screen of the display unit, and based on the aberration spot image data of the axial aberration at the intersection of the α-axis and the β-axis. is displayed, on the α-axis and the β-axis, and in each region from the first quadrant to the fourth quadrant formed by the α-axis and the β-axis, based on the aberration spot image data of the off-axis aberration multiple displays,
A lens on-axis off-axis point image observation device characterized by: An on-axis off-axis point image observation device comprising a lens to be measured, an illumination optical unit, a first stage, a fixing unit for the lens to be measured , a rotating stage, an imaging unit, an inclined unit, an image processing unit, and a display unit,
The illumination optical unit is installed on the first stage and is composed of a light source and a first lens. Irradiate with diffused light,
The first stage includes a tilting stage that tilts the illumination optical unit about an axis (Y-axis) perpendicular to the optical axis (Z-axis) of the lens to be measured, and an axis (X-axis) perpendicular to these two axes. A first XY stage that moves in the plane direction along a plane (XY plane) perpendicular to the Z-axis formed by the Y-axis and the Y-axis, and a first stage that moves linearly in the Z-axis direction parallel to the optical axis. and a Z stage of
The lens to be measured is fixed to the lens to be measured fixing portion,
The tilting section relatively tilts the optical axis of the illumination optical section , the optical axis of the imaging section, and the optical axis of the lens to be measured by a predetermined tilt angle,
The imaging unit captures a condensed spot of parallel light emitted from the lens to be measured, converts it into an image signal,
The image processing unit generates aberration spot image data using image data converted based on the image signal,
The lens to be measured is rotated by a predetermined rotation angle about the optical axis of the lens to be measured by the rotation stage via the lens fixing portion to be measured, and
The inclined portion is rotated around an axis that passes through substantially the center of the lens to be measured and is perpendicular to the optical axis of the lens to be measured and the optical axis of the illumination optical unit and the optical axis of the imaging unit. tilting by the predetermined tilt angle by moving,
When the inclined portion is inclined, the beam spot position is positioned perpendicular to the optical axis of the lens to be measured and separated from the lens to be measured by the focal length according to the predetermined inclination angle. , controlling the tilt stage, the first XY stage, and the first Z stage;
sequentially acquiring the aberration spot image data by controlling the predetermined rotation angle and the predetermined tilt angle at predetermined intervals;
The display unit displays an aberration spot distribution image in which the aberration spot image data are arranged in association with the predetermined rotation angle and the predetermined tilt angle ,
Display of the aberration spot distribution image includes:
setting an α-axis and a β-axis orthogonal to each other on the screen of the display unit;
Display based on the aberration spot image data of the axial aberration at the intersection of the α axis and the β axis,
A plurality of displays based on the aberration spot image data of the off-axis aberration are displayed on the α-axis and the β-axis and in each region from the first quadrant to the fourth quadrant formed by the α-axis and the β-axis. to be
A lens on-axis off-axis point image observation device characterized by: 6. The aberration spot distribution images of the off-axis aberration are displayed in four on the α-axis, four on the β-axis, and three each in the first to fourth quadrants. The lens on-axis off-axis point image observation device according to any one of the above. A program for causing a computer to perform lens on-axis off-axis point image observation using a lens to be measured, an illumination optical unit, a fixed unit for a lens to be measured , a rotating stage, an imaging unit, an inclined unit, an image processing unit, and a display unit, ,
a step of irradiating the lens to be measured with diffused light by the illumination optical unit;
a step of fixing the lens to be measured to the lens-to-be-measured fixing portion;
a step of relatively tilting the optical axis of the illumination optical section, the optical axis of the imaging section, and the optical axis of the lens to be measured by a predetermined tilt angle by the tilt section;
a step in which the imaging unit captures a condensed spot of parallel light emitted from the lens to be measured and converts it into an image signal;
generating aberration spot image data by the image processing unit using the image data converted based on the image signal;
The lens to be measured is rotated by a predetermined rotation angle about the optical axis of the lens to be measured by the rotation stage via the lens fixing portion to be measured, and
The inclined portion is rotated around an axis that passes through substantially the center of the lens to be measured and is perpendicular to the optical axis of the lens to be measured and the optical axis of the illumination optical unit and the optical axis of the imaging unit. By moving, it is tilted by the predetermined tilt angle,
a step of sequentially acquiring the aberration spot image data by controlling the predetermined rotation angle and the predetermined tilt angle by predetermined intervals;
displaying an aberration spot distribution image obtained by arranging the aberration spot image data in association with the predetermined rotation angle and the predetermined tilt angle by the display unit;
Display of the aberration spot distribution image includes:
setting an α-axis and a β-axis orthogonal to each other on the screen of the display unit;
performing display based on the aberration spot image data of the axial aberration at the intersection of the α axis and the β axis;
A plurality of displays based on the aberration spot image data of the off-axis aberration are displayed on the α-axis and the β-axis and in each region from the first quadrant to the fourth quadrant formed by the α-axis and the β-axis. conduct,
A program for performing lens on-axis off-axis point image observation, characterized by : 8. The aberration spot distribution image of the off-axis aberration according to claim 7, wherein four images are displayed on the α axis, four images on the β axis, and three images each in the first to fourth quadrants. A program for performing lens on-axis off-axis point image observation.

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