JP5383983B2 - Lens meter and lens measuring method - Google Patents

Description

  The present invention relates to a lens meter that measures the characteristics of a spectacle lens.

  The measurement of the lens characteristics includes a narrow area measurement for measuring a narrow range of the lens located at the center of the optical axis of the measurement light and a wide area measurement for measuring a wide range of the lens. In the wide-area measurement, it is necessary to acquire a measurement image formed by light that has passed through a pattern mask having openings regularly arranged in the vertical and horizontal directions, and to perform processing for specifying the coordinates of the light spot in the measurement image.

In the conventional lens meter, the light spot is searched by scanning in the XY directions from the origin of the corner of the measurement image. This search for the light spot is computationally intensive, and the conventional lens meter has a delay from the start of lens measurement until the measurement result is displayed.
Japanese Patent No. 3658886

  Therefore, an object of the present invention is to provide a lens meter and a lens measuring method capable of instantaneously measuring lens characteristics.

In order to solve the above-described problem, a lens meter according to the present invention includes a light projecting unit that projects measurement light onto a lens to be examined, and a concentric arrangement with the optical axis center of the measurement light, in the vicinity of the optical axis center. A pattern mask for narrow area measurement having an opening opening only in an annular shape, and pinholes arranged in a grid shape over a wide range of the measurement light, and one of the pinholes is an optical axis of the measurement light A wide area measurement pattern mask arranged in the center; imaging means for receiving the measurement light to generate image data; and arithmetic means for analyzing the image data and calculating characteristics of the test lens. The calculation means receives the measurement light that has passed through the narrow area measurement pattern mask and the test lens, and the center coordinates of an annular image corresponding to the opening in the narrow area image generated by the imaging means And times Calculates the point of coordinates wide measurement pattern mask and said receiving the measurement light that has passed through the test lens in the optical axis center of the measurement light in the large area image which the image pickup means has generated narrow the The coordinates of the eight light spots around the light spot in the center of the optical axis are determined as the pitch of the pinhole, the center coordinates of the opening, and the magnification. And based on the predicted coordinates, the coordinates of the light spot at the center of the optical axis and the coordinates of the eight surrounding light spots are respectively calculated from an image within a predetermined range centered on the predicted coordinates, and calculated first. The coordinates of the further light spots adjacent to the two adjacent light spots that are adjacent to each other are predicted to be aligned with the coordinates of the two light spots adjacent to each other that were calculated earlier, and the predicted coordinates Around Repeat to calculate the additional point coordinates from the image that are within the scope of the constant, and shall be calculated for all of the light spot of the coordinates corresponding to the pin holes of the wide area measurement pattern mask.

  According to this configuration, the position of the light spot in the central portion is predicted by narrow area measurement, the light spot coordinates in the central portion are calculated with the calculation range limited, and the calculation of the coordinates of the surrounding light spots is already performed. By limiting the calculation range by predicting the position based on the coordinates of the light spot, the image range used for the calculation of the light spot coordinates can be limited to a small size, and high-speed calculation is possible.

  Since the optical characteristics of the lens to be measured change continuously, the predicted coordinates and the actual coordinates can be greatly shifted by predicting in order from the light spot coordinates in the center to the surrounding light spot coordinates. In addition, the image range used for the calculation of the light spot coordinates can be limited to a small size, and high-speed calculation is possible.

In the lens meter according to the present invention, a coordinate obtained by adding the difference between the coordinates of the two adjacent light spots to the coordinates of the light spot adjacent to the further light spot is predicted as the coordinates of the further light spot. May be.

Further, the lens meter measurement method according to the present invention includes a narrow area measurement pattern mask having an opening that is arranged concentrically with the center of the optical axis of the measurement light and that opens annularly only in the vicinity of the center of the optical axis. A narrow-band image formed through a lens to be examined is acquired, and the center coordinates and the narrow-band image located at the optical axis center of the measurement light based on the position and size of the image of the opening in the narrow-band image The measurement light has a pinhole arranged in a grid shape over a wide range of the measurement light, and one of the pinholes is arranged at the center of the optical axis of the measurement light. use pattern mask and the by imaging through the test lens acquires the global image including a plurality of light spots, the coordinate of the light spot on the optical axis of the measuring light in the wide area image in the narrow-area image open The coordinates of the eight light spots around the light spot at the center of the optical axis are predicted based on the pitch of the pinhole, the center coordinates of the opening, and the magnification. Then, the coordinates of the light spot at the center of the optical axis and the eight light spots around it are calculated from an image within a predetermined range centered on each predicted coordinate, and they are adjacent to each other. Predict that the coordinates of the further light spots adjacent to the two light spots are aligned with the previously calculated coordinates of the two light spots adjacent to each other, and that are centered on the predicted coordinates. The method of calculating the coordinates of all the light spots corresponding to the pinholes of the pattern mask for wide area measurement is repeated by repeatedly calculating the coordinates of the further light spots from the image within the range.

  The lens meter of the present invention predicts the position of the light spot coordinates of the wide area measurement by narrow area measurement, and narrows down the range of the image used for the calculation to calculate the light spot coordinates. The optical characteristics of the test lens can be calculated and displayed.

Embodiments of the present invention will now be described with reference to the drawings.
1 and 2 show a lens meter 1 according to an embodiment of the present invention. The lens meter 1 houses an optical system (light projecting means) for projecting measurement light on the upper part of the apparatus main body 2, and a light projecting unit 4 having a display device 3 on its surface is provided below the light projecting unit 4. A holding unit 6 for placing and holding the test lens 5 (mounted on the spectacle frame in FIG. 2) and a memory switch 7 for storing measurement data are provided, and the measurement light that has passed through the test lens 5 is received. A light receiving unit 8 that houses an optical system for receiving light is provided. Further, the lens meter 1 includes a contact plate 9 and a pressing member 10 that assist in positioning of the test lens 5 on the holding unit 6, and further, an optical center is set on the test lens 5 positioned on the holding unit 6. It has a marking device 11 for marking.

  FIG. 3 shows an optical configuration of the lens meter 1. The lens meter 1 includes a light emitting element 12 that is a point light source inside the light projecting unit 4, and a light projecting lens 13 that projects the diffused light emitted from the light emitting element 12 into parallel measurement light and projects it onto the lens 5 to be tested. And a measurement pattern mask 14 that allows measurement light to pass therethrough, a screen 15 on which the measurement light is projected, and an image projected on the screen 15 by an imaging lens 16 to form an electrical signal. And an image sensor 17 for generating image data by converting the image data.

  In the lens meter 1, the pattern mask 14 is configured such that the narrow area measurement pattern mask 14a shown in FIG. 4 and the wide area measurement pattern mask 14b shown in FIG. 5 are automatically replaced. The narrow area measurement pattern mask 14a is generally used when marking the optical center of the lens 5 to be measured, and a small annular opening 18a is formed in the vicinity of the optical axis center of the measurement light. Are arranged concentrically with the optical axis of the measuring light. The wide-area measurement pattern mask 14b is used to analyze a wide range of optical characteristics (such as sphericity and cylindricality) of the lens 5 to be mapped and displayed on the display device 3, and has a wide range of measurement light. A plurality of (for example, 9 × 9 = 81) pinholes 18b are regularly arranged in a vertical and horizontal grid. The central pinhole 18b of the wide-area measurement pattern mask 14b is arranged on the optical axis of the measurement light.

  When the narrow area measurement pattern mask 14a is arranged in the optical path, the measurement light projected through the lens 5 and the narrow area measurement pattern mask 14a and projected onto the screen 15 is shown in FIG. It is converted into such narrow-area image data. This narrow area image is a set of data indicating the color of each point of the resolution (for example, 640 × 480 pixels) of the image sensor. The narrow area image includes an annular high-brightness image corresponding to the portion on which the measurement light is projected. If the optical center of the test lens 5 is deviated from the optical axis of the measurement light, the annular image is narrowed. The position is shifted from the center of the area image, and the vertical and horizontal sizes (magnification) of the annular image differ depending on the power of the lens 5 to be examined.

  When the wide area measurement pattern mask 14b is arranged in the optical path, a wide area image as shown in FIG. 7 is obtained. In this wide-area image, the light spots due to the measurement light that has passed through the pinholes 18b are arranged vertically and horizontally. .

FIG. 8 shows a procedure for analyzing the optical characteristics of the lens 5 to be examined in the lens meter 1. In the lens meter 1, when wide-area measurement for measuring a wide range of optical characteristics of the test lens 5 is started, first, in step S 1, a narrow area image is acquired using the narrow area pattern mask 14 a. In step S2, the narrow area image is analyzed by a built-in microcomputer (calculation means), and the center coordinates C (0,0) = (Cx ₀ , Cy ₀ ) of the annular image are calculated. The vertical and horizontal magnifications Rx and Ry of the image are calculated from the vertical and horizontal (x / y direction) diameters.

  Subsequently, in step S3, the lens meter 1 arranges the wide area measurement pattern mask 14b in the optical path, and acquires a wide area image.

The lens meter 1 uses the loop from step S4 to step S7 to obtain the centers of light spots corresponding to nine pinholes 18b in a total of three rows and three columns in the center of the wide area measurement pattern mask 14b from the acquired wide area image. The light spot coordinates are calculated. Here, the coordinates of the center of the light spot by the central pinhole 18b are the light spot coordinates G (0, 0) = (Gx ₀ , Gy ₀ ), and the coordinates of the light spot in the i-th column and the j-th row are G ( i, j). That is, in this loop, the light spot coordinates G (i, j) = (Gx _i , Gy _j ) are calculated for combinations of i = −1, 0, 1, j = −1, 0, 1.

  In the lens meter 1, the annular opening 18a of the narrow area measurement pattern mask 14a and the central pinhole 18b of the wide area measurement pattern mask 14b are arranged on the optical axis of the measurement light. If the position of the test lens 5 is not moved, the light spot coordinates G (0,0) of the light spot by the central pinhole 18b in the wide area image is the center coordinates C (0,0) of the annular image of the narrow area image. ) And substantially the same position.

  In step S6, as shown in FIG. 9, for example, a range of 15 pixels or less (15 × 15 = 225 pixels) at an 8-neighbor distance from the center coordinate C (0, 0) is set as the neighborhood range S (0, 0). By analyzing the image within this range, the light spot coordinate G (0, 0) of the light spot at the center of the wide area image is calculated.

Further, since the magnification of the light spot pitch at the center of the wide area image is substantially the same as the magnification of the annular image of the narrow area image, the positions C (8) of the eight light spots adjacent to the central light spot of the wide area image. i, j) can be predicted by the ratio between the diameter of the annular opening 18a of the wide area measurement pattern mask 14a and the pitch of the pinholes 18b of the wide area measurement pattern mask 14b. That is, in step S5, the nine light spots at the center of the wide area image are predicted to exist at the predicted coordinates C (i, j) = (Cx ₀ + i × A × Rx, Cy ₀ + i × A × Ry).

  In step S6, the light spot coordinates G (i, j) are, for example, each of the neighborhood range S (i, j) in the wide-area image, that is, the predicted coordinates C (i, j) and the surrounding predetermined range. It can be obtained as the center of gravity of the luminance of the pixel. At this time, the luminance distribution range (maximum value and minimum value) is examined, and the center of gravity may be calculated by excluding data in a predetermined range, for example, data of 20% or less from the minimum value to the maximum value.

  If the light spot coordinates G (i, j) (i = -1, 0, 1, j = -1, 0, 1), which are the centers of the center nine light spots, are calculated in the loop of steps S4 to S7. In the loop from step S8 to step S11, the light spot coordinates G (i, j) of the remaining light spots are calculated.

In step S9, as shown in FIG. 11, it is assumed that the light spots adjacent to the light spot for which the center coordinates have been calculated are aligned at equal intervals with the light spot for which the center coordinates have been previously calculated. i, j) = (Cx _i , Cy _j ) is predicted. If the light spot is adjacent to the x direction, the predicted coordinates C (i, j) = ((Gx _i-1 ) + (Gx _i-1 -Gx _i-2 ) (Gy _i-1 ) + (Gy _{i- 1−} Gy _i−2 )).

  In step S10, as in step S6, a predetermined range (for example, within 7 pixels at 8 neighboring distances) from the predicted coordinates C (i, j) is set as the neighboring range S (i, j), and the wide area image in this range The light spot coordinates G ((i, j) (for example, the center of gravity of the luminance) are calculated. The size of the neighborhood range S (i, j) is not necessarily the same as that in step S6.

  As shown in FIG. 12, when the light spot coordinates G (i, j) of the light spot adjacent in the x direction to the center coordinates of the center nine light spots are obtained, as shown in FIG. Based on the calculated light spot coordinates G (i, j-1) and light spot coordinates G (i, j-2), the light spot coordinates G (i, j) of light spots adjacent in the y direction are calculated. To do.

  In this way, in the loop from step S8 to step S11, the light spot coordinates G (i, j) that are the centers of the light spots corresponding to all the pinholes 18b of the wide area measurement pattern mask 14b are calculated.

  Under the conditions exemplified in the present embodiment, there are 15 × 15 = 225 pixel data in the vicinity range of 9 × 9 = 81 locations, respectively, and therefore a total of 18225 pixel data is confirmed. On the other hand, 640 × 480 = 307200 pixel data exists in the entire wide area image, and the amount of data to be actually confirmed is about 1/17 of the entire wide area image. For this reason, in this embodiment, the process which specifies each light spot coordinate G (i, j) is very high-speed.

  In the lens meter 1, if the light spot coordinates G (i, j) are specified, the optical characteristics of the lens 5 to be measured are calculated from the light spot coordinates G (i, j) in step S 12, and the display device 3 is used. Display mapping. The method for calculating the optical characteristics of the lens 5 to be examined from the light spot coordinates G (i, j) is the same as that of a conventional lens meter, and is well known, so that the description thereof is omitted.

  Furthermore, FIG. 14 shows an optical configuration of a lens meter according to the second embodiment of the present invention. In the lens meter 1 of the present embodiment, the light source 12 and the light projecting lens 13 project measurement light having a first wavelength that is used only for wide-area measurement, and have a second wavelength that is used only for narrow-area measurement. A second light source 19 and a second light projecting lens 20 are provided for projecting the measurement light, and the half mirror 21 superimposes the first measurement light and the second measurement light on the same axis. The light is projected to the analyzing lens 5.

  The narrow area measurement pattern mask 14 a is disposed between the second light source and the second light projecting lens 20. The wide-area measurement pattern mask 14b is made of a material that blocks the first measurement light for narrow-area measurement, and is made of a material that transmits the second measurement light. The first measurement light is transmitted only through the pinhole 18b.

  Since the other structure of this embodiment and the method for calculating the optical characteristics of the lens 5 to be examined are the same as those of the first embodiment, description thereof will be omitted.

  As in this embodiment, even if measurement light with different wavelengths is projected using different light sources 12 and 19, the optical axis of each measurement light is configured to be incident on the same position of the test lens 5. For example, only the optical characteristics of the test lens 5 determine the amount of eccentricity (shift amount) of the optical axis of each measurement light and the magnification near the optical axis. Thereby, it is possible to calculate the coordinates of the light spot by limiting the analysis range of the wide area image from the narrow area image.

  Even if the lens meter is provided with a dedicated light projecting means and imaging means for each of the narrow area measurement and wide area measurement, if the light beam used as a reference for each measurement light is incident on the same position of the lens under test, the narrow area The position of the light spot at the center of the wide area image can be predicted from the positional deviation and magnification of the center of the image, and such a configuration is also included in the present invention.

  In the above embodiment, the central pinhole of the wide-area measurement pattern mask is arranged on the optical axis of the measurement light. In the present invention, the optical axis of the measurement light is between the pinholes. For example, coordinates of four central light spots among the light spots of the wide area image may be predicted from the center coordinates and the magnification of the narrow area image.

  Further, if the neighborhood range for analyzing the light spot is increased, the coordinates of all the light spots in the wide area image may be predicted based on the center coordinates and the magnification of the narrow area image.

The perspective view of the lens meter of 1st Embodiment of this invention. The side view of the lens meter of FIG. Schematic which shows the optical structure of the lens meter of FIG. The top view of the pattern mask for narrow region measurement of the lens meter of FIG. The top view of the pattern mask for wide area measurement of the lens meter of FIG. The figure which illustrates the narrow region image obtained using the pattern mask for narrow region measurement of FIG. The figure which illustrates the wide area image obtained using the pattern mask for wide area measurement of FIG. The flowchart which shows the optical characteristic calculation procedure of the to-be-tested lens of the lens meter of FIG. The figure which shows the calculation range of the center coordinate calculation of the center light spot of a wide area image. The figure which shows calculation of the center coordinate of nine light spots of the center of a wide area image. The figure which shows the calculation range of the center coordinate calculation of the light spot around a wide area image. The figure which shows calculation of the center coordinate of the light spot of the x direction around a wide area image. The figure which shows calculation of the center coordinate of the light spot of the y direction around a wide area image. Schematic which shows the optical structure of the lens meter of 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens meter 5 Test lens 12 Light emitting element 13 Projection lens 14a Pattern mask for narrow area measurement 14b Pattern mask for wide area measurement 17 Imaging element (imaging means)
C (i, j) Predicted coordinates S (i, j) Neighborhood range G (i, j) Center coordinates

Claims (3)

A light projecting means for projecting measurement light onto the test lens;
A narrow area measurement pattern mask having an opening that is concentrically arranged with the optical axis center of the measurement light and has an annular opening only in the vicinity of the optical axis center;
A pattern mask for wide area measurement having pinholes arranged in a grid over a wide range of the measurement light, and one of the pinholes being arranged at the center of the optical axis of the measurement light;
Imaging means for receiving the measurement light and generating image data;
An arithmetic means for analyzing the image data and calculating characteristics of the test lens,
The calculation means receives the measurement light that has passed through the narrow area measurement pattern mask and the test lens, and the center coordinates of an annular image corresponding to the opening in the narrow area image generated by the imaging means, and Calculate the magnification,
The coordinates of the light spot at the center of the optical axis of the measurement light in the wide-area image generated by the imaging means by receiving the measurement light that has passed through the wide-area measurement pattern mask and the test lens is the narrow-area image. Predicts that it matches the center coordinates of the opening, and predicts the coordinates of the eight light spots around the light spot at the center of the optical axis based on the pinhole pitch, the center coordinates of the opening, and the magnification. And calculating the coordinates of the light spot at the center of the optical axis and the eight light spots around the image from an image within a predetermined range centered on each predicted coordinate,
Predict that the coordinates of the further light spots adjacent to the two light spots adjacent to each other calculated earlier are aligned with the coordinates of the two light spots adjacent to each other calculated earlier, Calculate the coordinates of all the light spots corresponding to the pinholes of the pattern mask for wide area measurement by repeatedly calculating the coordinates of the further light spots from an image within a predetermined range centered on the predicted coordinates. A lens meter characterized by:   The coordinate obtained by adding the difference between the coordinates of the two adjacent light spots to the coordinates of the light spot adjacent to the further light spot is predicted as the coordinates of the further light spot. The lens meter described in 1. A narrow-band image in which measurement light is concentrically arranged with the center of the optical axis of the measurement light and is imaged through a narrow-area measurement pattern mask having an opening opening annularly only in the vicinity of the optical axis center and a test lens Get
Calculate the center coordinates and magnification of the annular image corresponding to the opening in the narrow area image ,
The measurement light has pinholes arranged in a grid shape over a wide range of the measurement light, and one of the pinholes is arranged at the center of the optical axis of the measurement light, and the measurement mask A wide-area image including multiple light spots is obtained by imaging through the lens.
It is predicted that the coordinates of the light spot at the center of the optical axis of the measurement light in the wide area image coincide with the center coordinates of the opening in the narrow area image, and eight light spots around the light spot at the center of the optical axis. Is estimated based on the pitch of the pinhole, the center coordinate of the opening, and the magnification, and is located in the center of the optical axis from an image within a predetermined range centered on each predicted coordinate. Calculate the coordinates of the light spot and the surrounding eight light spots,
Predict that the coordinates of the further light spots adjacent to the two light spots adjacent to each other calculated earlier are aligned with the coordinates of the two light spots adjacent to each other calculated earlier, Calculate the coordinates of all the light spots corresponding to the pinholes of the pattern mask for wide area measurement by repeatedly calculating the coordinates of the further light spots from an image within a predetermined range centered on the predicted coordinates. And a lens measuring method.

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