JP2881297B2 - Optical measuring device with optical stylus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical measuring device using an optical stylus, and more particularly to an optical device for measuring a wall surface to be measured at a position substantially parallel to and substantially coincident with the optical axis of an objective lens of the device. This is an invention related to improvement of a measuring device.

[0002]

[Prior art]

B) An optical measuring device using an optical stylus for detecting a minute area of a wall surface from a direction perpendicular to the wall surface to be measured (a method of optically non-contact detection like a contact type stylus) is known. I have.

[0003] These use an expensive objective lens with a large NA specially designed to make the size of the micro area as small as possible, and switch a plurality of objective lenses with a revolver or the like to respond to a wider range of measurement requirements. It was used.

B) On the other hand, as an optical measuring device using an optical stylus on a wall to be measured at a position parallel to the optical axis of the objective lens and at a distance from the optical axis, an object having optical axes of a plurality of optical systems or rotating There are known objects due to the optical axis.

[0005] For example, a projection optical system and an observation optical system are rotated on a plurality of wall surfaces by using an object described in Japanese Patent Publication No. 58135/1988 and Japanese Patent Publication No. There is an optical stylus such as providing a plurality of optical axes with a plurality of projection optical systems and a plurality of observation optical systems on an object to be measured or on a plurality of wall surfaces separated from the optical axis.

[0006] Since these are configured with reference to a rotating optical axis or a plurality of optical axes, their structures are complicated, and there is a limit in the manufacturing accuracy of the apparatus including stability, and it is difficult to sufficiently increase the measuring accuracy. Met.

Further, since the optical system is configured inside the hole, the measurement has been limited to the measurement of the inner diameter of a large hole.

(C) Further, as an optical measuring apparatus for detecting a wall surface to be measured at a position parallel to and coincident with the optical axis of the objective lens, a projection optical system and an observation optical system include a wall object to be measured ( An optical measuring device is known which has a structure provided on the same optical axis at an opposite position via a work (hereinafter referred to as a work) and measures the distance between a plurality of wall surfaces of the work.

For example, Japanese Patent Application Nos. 5-1174 and 6-1.
Since the device of 182549 has a simple configuration based on one optical axis, the manufacturing accuracy of the device can be maintained high, and the optical system can be configured outside the end face of the hole. In some cases, the distance between wall surfaces can be measured with high accuracy (1 μ or less) even in the measurement of 1).

In order to explain the present invention with the above-mentioned apparatus (c), the outline of the above-mentioned apparatus will be described first with reference to FIGS.

The projection optical system 7 includes a light source unit 3 for generating light having a small diameter and an objective lens 6 for projection (hereinafter referred to as a projection lens).
It consists of.

For example, a light source unit 3 illuminates a reticle 2 having a transparent part with a small diameter with a lamp 1 to generate a pattern light with a small diameter.

The projection lens 6 is configured to collect the pattern light having a small diameter and project a projection image P toward the wall surface of the work 8.

The observation optical system 11 is composed of an observation lens 9 (hereinafter referred to as an observation lens) and a CCD camera 10. The observation optical system 11 has a work 8 on the same optical axis (Z1-Z2) as the projection optical system 7. On the other side.

The wall surface of the work 8 is held so as to be parallel to the optical axis Z1-Z2.
It is movable in the -X2 direction.

When the wall surface of the work 8 coincides with the optical axis, FIG.
The reflected light RF reflected on the wall surface of the projected image P forms an image at the center of the screen of the CCD camera 10 by the observation lens 9 as shown in FIG.
With this configuration, the other wall surface of the work 8 is moved along the optical axis Z.
By moving so as to coincide with 1-Z2 so that the reflected image RF is at the center of the screen of the CCD camera 10 in the same manner as described above, it is confirmed that the other wall surface (not shown) coincides with the optical axis. it can.

Since the linear scale 4 is provided in the mechanism holding the work 8, the distance between the wall surfaces can be precisely known by reading the movement amount of the work 8.

The distance between the wall surfaces is the same as that of the projected image P as shown in FIG.
Is moved in the optical axis direction within the entire length ZW of the work 8, the distance between the wall surfaces at an arbitrary wall position can be measured.

For the description of the position of the projected image P, abbreviations are defined as shown in FIG. 3 and used for the description. The end face of the work on the projection means side is BED, the end face on the observation means side is TOP, the distance of the projection image P from the BED side is ZB, and the distance from the TOP side is ZT.

The center position (ZB = ZT) of the work is set to MI
Abbreviated as D.

FIG. 4 shows the optical path of the direct image DF in which the projection image P passes through the work 8 and reaches the observation means 11.

As described above, in the above apparatus, all the optical systems are one.
Since the optical axis can be configured with reference to the optical axis, measurement can be performed with high accuracy in the measurement of a normal work.

[0023]

The CC of the apparatus shown in FIG.
The output image of the reflection image of the D camera 10 is observed as a waveform approximated to a Gaussian distribution in which the left and right are balanced.

Therefore, when the work 8 is correctly aligned with the optical axis Z1-Z2, the reflection image is observed at the image center position corresponding to the optical axis.

If the output waveform is deviated from the center of the image for some reason even though the wall surface of the work coincides with the optical axis, the measurer sets the work waveform at the center of the image so as to set the output waveform. 8, the measurement is performed, and an error is induced in the distance measurement between the plurality of wall surfaces.

In a detailed study of the factors causing such measurement errors, it was found that there was one factor in the behavior of the wall projection image.

As shown in FIG. 2, when the projected image P is given to the MID in order to measure the distance between the walls at the center MID position of the work 8, the projected image is widely projected from the BED to the TOP on the wall, as shown in FIG. Has been confirmed.

Since the pattern light having a small diameter from the light source section 2 also has a large size, the light is divided into three parts in consideration of this, and the optical path diagram is shown for easy understanding. Light passing through the outer periphery of the projection lens 6 of the light source unit 2 is collected near the MID on the wall surface.

Since the projected image on the wall surface is close to the image forming position, it is projected brightly and clearly.

On the other hand, the light passing near the center of the projection lens 2 spreads to the end faces of the TOP and BED and is projected and reflected. Therefore, since the projection position on the wall surface is farther from the imaging position, the image is projected on the wall surface as a dark dispersed image.

Since the projection images on the wall surface are synthesized, the projection image LV on the wall surface is projected as a shape having a peak (luminance) on the MID as shown in FIG.

The projection optical system 11 reflects this projection image LV as a reflection image.
The reflected image on the bright wall surface is formed on the CCD camera 10 through a portion near the periphery of the observation lens.

On the other hand, the reflected image of the dispersed image which is dark and dispersed at a position close to the end face of the TOP or BED is formed on the CCD camera 10 through the vicinity of the center of the observation lens 6.

With this configuration, the output waveform 12 of the reflected image of the CCD camera 10 is observed as a waveform symmetrical with respect to the image center (X = 0) corresponding to the optical axis as indicated by RF '.

On the other hand, the output waveform 13 of the direct image as shown in FIG.
As shown by DF ', the optical path is kicked by the wall that coincides with the optical axis, so the level is low, and the optical path can only pass through half the width, so half the width on one side of the image center corresponding to the optical axis Is observed as a waveform.

In the observation image of the observation optical system, such a reflected image output and a direct image output are combined, and the combined image is observed on a monitor (not shown) or the like.

Accordingly, at the position of the MID, the reflected image output (peak deviation = 0) and the level which are balanced to the left and right are low, but the observation image is formed by combining the direct image output having the deviation to the right (+) side. Will be gained.

Therefore, although slightly, the output of the observed image is +
Will be biased.

As a result, the measured value measures a plurality of walls with the + biased observation image aligned with the center of the image, so that a measurement error in the negative direction is induced in the measured value of the distance between the walls.

However, since this value was 0.5 μm or less, it could be corrected by a simple correction calculation or the like, and as a result, the distance between the wall surfaces could be measured with high accuracy.

However, as shown in FIG. 5, when measuring a special work in which the distance between the wall surfaces near the end surfaces of the BED and TOP (for example, ZB = small) is important, the left-right balance of the projected image LV is lost. When the distance (ZB or ZT) near the end face is relatively large, there is no lack of a projected image of a bright peak portion (for example, a half-value width portion), so that a bias as a reflected image output hardly occurs. Becomes smaller, such as 0.5 mm, one side of the bright peak is cut off, resulting in a biased reflected image output waveform, and the reflected image alone causes a large measurement error. (The BED side induces a measurement error in the + direction and the TOP side induces a measurement value error in the-direction.) Therefore, in the measurement on the TOP side, the-measurement error factor due to the bias of the reflected image and the-error factor due to the direct image. Are added in the composite image (observed image), causing a large -direction error.

In order to correct the measurement error by the correction operation as in the case of the MID measurement, the correction becomes complicated because the error value is large and the error changes according to the measurement position (ZB). The scale becomes large, which is not preferable.

Accordingly, there has been a demand for a basic improvement in which no measurement error occurs over the entire length (ZW) up to the vicinity of the end face.

On the other hand, when measuring the inside diameter of a hole of a work having a small overall length ZW, that is, a thin work such as a washer, the total length ZW of the wall surface is compared with the width of the projected image LV on the wall surface.
Becomes small, the slight difference (MID ± α) of the measurement position (projection position) and the finish of the end face may cause the projection image LV to vary.
Balance is lost, and a measurement error tends to occur.

Therefore, there is a further need for a method capable of stably measuring such a thin work without error and with high repeatability.

Further, by increasing the diameter of the projection lens to increase the optical path projected at an acute angle from the outer periphery of the projection lens,
There is a method of measuring a thin workpiece by raising the level of a bright and clear projection image to be higher than that of a dark dispersion projection image, thereby obtaining the same effect as a case where the width of the projection image is relatively narrowed.

This means that a lens having a large NA is used. However, it is difficult to manufacture a lens with a large working distance and a large NA, so using this method shortens the working distance. Even when a thin work can be measured, the measurement of a normal thick work is difficult due to lack of the working distance. There was a drawback that measurement could not be performed.

In order to be able to measure a wide variety of works by this method, it is necessary to provide a revolver as described at the beginning (a) in the projection optical system. Comes with complexity.

Further, since the thickness of the work wall parallel to the optical axis of a thin work is shorter than that of a thick work, the amount of a direct image passing through the wall is increased as compared with a thick work (observation of a composite image). There is a disadvantage that the measurement error is further increased (due to the bias of the output waveform), and the method using the lens having a large NA is not enough to solve this problem.

Similarly, in the measurement of a work having a convex curved surface such as a ball, the positional deviation in the Z1-Z2 direction is also more difficult than that of the thin work because the positional deviation is caused by the convex curved surface. In the measurement of a work having a small inner diameter with respect to the total length ZW, that is, a work having a high aspect ratio, the angle of incidence at which light from the projection means enters the hole becomes small (the output angle to the observation optical system is also small). Similarly, the apparent lens has the same NA as that of the lens having a reduced NA.
The projected image is projected on the wall surface of the work at an obtuse angle as shown in the figure, the level of the bright peak at the center is lowered, the difference from the diffused image spread on the end face is reduced, and the influence of the dispersed image is greatly reflected. It affects the image output.

Therefore, in such a work, when measuring the distance between the wall surfaces near the end face as shown in FIG. 5, the deviation of the output waveform of the reflected image further increases, and the error tends to be larger than that of the object having a small aspect ratio. was there.

As can be seen from FIGS. 2, 4 and 5, the output of the reflected image decreases in accordance with the aspect ratio.
Since the direct image passes through the work in the optical path near the optical axis, it does not decrease much even if the aspect ratio increases.

Therefore, as the aspect ratio increases, the ratio of the direct image used as the composite image as the observation image increases.

This further increases the deviation of the output waveform of the composite image in the vicinity of the end face, thereby increasing the measurement error.

As described above, when the projection optical system projects the projection image on the workpiece wall surface at a position parallel to and coincident with the optical axis, the projection image is widely diffused on the wall surface.
As described above, when the measurement conditions are variously changed, there is a disadvantage that a measurement error cannot be avoided.

Therefore, in order to basically solve the above-mentioned problem, a method for enabling an optical stylus even on a wall surface which is parallel to and coincident with the optical axis has been required.

Further, it has been required to reduce the influence of the direct image which always accompanies the synthesized image.

[0058]

The gist of the present invention will be described with reference to the accompanying drawings.

An optical axis blocking member for blocking the optical path near the optical axis of the projection optical system is provided near the objective lens for projection with the optical axis as the center, and the measurement is made substantially parallel to the optical axis and almost coincident with the optical axis. The present invention relates to an optical measuring device using an optical stylus, which projects projection light onto a minute area on a wall surface.

Further, an optical axis blocking member for blocking an optical path near the optical axis of the observation optical system is provided near the observation objective lens with the optical axis as the center, and is substantially parallel to the optical axis and substantially coincides with the optical axis. The present invention relates to an optical measuring device using an optical stylus, which observes a minute area on a measurement wall.

Further, an optical measuring device for providing a projection optical system and an observation optical system at opposite positions and on the same optical axis via a wall to be measured to measure a distance between a plurality of walls to be measured is provided. 2. The optical stylus according to claim 1, wherein an optical axis blocking member that blocks an optical path near an optical axis of the projection optical system is provided near a projection objective lens centered on the optical axis. According to the present invention.

Further, the projection optical system and the observation optical system are provided at opposite positions and on the same optical axis via the measured wall, and an optical measuring device for measuring the distance between the plurality of measured walls is provided. 3. The light according to claim 2, wherein an optical axis blocking member that blocks an optical path near an optical axis of the observation optical system is provided near an observation objective lens around the optical axis. The present invention relates to an optical measuring device using a stylus.

Further, the projection optical system and the observation optical system are provided on the same optical axis at opposite positions via the object to be measured, and the distance between the plurality of wall surfaces at the position coinciding with the optical axis of the object to be measured is determined. In an optical measuring device for measuring, an optical axis blocking member for blocking an optical path near an optical axis of the projection optical system is provided near an objective lens for projection with the optical axis as a center. The optical measuring device using an optical stylus according to claim 3 or 4, wherein an optical axis blocking member that blocks an optical path near the axis is provided near the objective lens for observation centering on the optical axis. It is related.

[0064]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention (how to implement the invention) will be briefly described with reference to the drawings, showing the operational effects thereof.

According to the present invention, the optical axis Z
A projection optical system having an optical axis blocking member S configured to block the optical path of 1-Z2 projects a projection image LVS onto a narrow area on the wall surface of the work 8 at a position parallel to and coincident with the optical axis. This is an optical measurement device using a light stylus.

That is, since the projected image near the optical axis is cut off near the light projecting lens 6, only a bright and clear projected image projected at an acute angle from the outer periphery of the projecting lens 6 is formed on the wall surface. A projection image is projected in a narrow area, and a reflection image in a narrow area on the wall surface is given to the observation optical system.

Further, since the direct image passes through the work along the periphery of the optical axis, most of the direct image is blocked by the optical axis blocking member in the present invention, so that the direct image mixed into the observed image is reduced. Benefits are also obtained.

Therefore, since the reflected image is an object based on the projected image of the narrow area on the wall surface, that is, optical palpation, measurement of a thin work, measurement over the entire length ZW including the vicinity of the end face,
Measurement of wall-to-wall distance at minute intervals, curved wall measurement, work with relatively high aspect ratio, etc. can be measured with high accuracy, and the same effect as increasing NA without reducing working distance Can be measured from a thin work to a thick work, and according to the present invention, not only a specially designed working distance long and high NA lens is not required, but also a specially designed lens A ring-shaped lens, a beam splitter, and the like are not required, and a general objective lens can be selected and used according to the application, and the apparatus can be configured at low cost.

Further, since the direct image is also excluded from the above-mentioned various works, the measurement and measurement can be performed with high accuracy without requiring any special correction operation.

Further, by providing the optical axis blocking member in the observation optical system as in the projection optical system, an optical stylus can be formed on the wall surface of the work at a position parallel to and coincident with the optical axis. Similar effects can be obtained.

Therefore, as described above, the optical palpation apparatus of the present invention can not only meet a wider range of measurement requirements than the conventional apparatus, but can also configure a simple apparatus in which all components can be configured with one optical axis as a reference. Therefore, it is easy to maintain the manufacturing accuracy of the measuring device, and it is possible to provide an optical measuring device capable of measuring with high accuracy.

[0072]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 7, the apparatus according to the present invention has a light source unit 3 formed by a reticle 2 having a fine pattern (transparent portion) on the projection side, and a light projecting lens 6 and a light projecting near the light projecting lens 6. A projection optical system 7S based on an optical stylus provided with a shaft blocking member S is provided.

As shown in FIG. 8, the optical axis blocking member S is provided with a circular mask-shaped optical axis blocking member S made of an opaque member at the center of the transparent glass member SJ, the center of which coincides with the optical axis Z1-Z2. Provided.

On the observation side, the observation lens 9 and the CC
The observation optical system 11 including the D camera 10 is used for the projection optical system 7S.
Are provided so as to coincide with the optical axis Z1-Z2.

The work 8 coincides with the optical axis in the same manner as described above, and is set to a position at the time of measurement.

With this configuration, the light from the light source unit 2 is condensed by the projection lens 6 as shown in FIG. 9 to project the projection image P 'on the image forming position on the work wall surface.

However, the light in the optical path near the optical axis of the projection lens is blocked by the optical axis blocking member S and does not reach the direction of the work 8.

On the other hand, light passing near the outer periphery of the projection lens 6 travels at an acute angle toward the wall surface of the work 8 without being affected by the optical axis blocking member S, and projects a projection image.

Since the center of the optical axis blocking member S is provided so as to coincide with the optical axis, the passing projection light projects a projected image on the wall surface in an amount symmetrical with respect to the optical axis.

Therefore, there is no dark and unclear dispersed projection image projected at an obtuse angle on the wall surface of the work 8, and only a bright and clear projection image LVS projected at an acute angle is projected on a narrow area as shown in the figure. Will be.

In order to reduce the size of the region, the diameter of the pattern light of the light source unit 3 (for example, the diameter of the transparent portion of the reticle) is made as small as possible, and the diameter of the optical axis blocking member S is made large. Is preferred. This value may be a value within a range where sufficient luminance can be obtained and the S / N can withstand the measurement, and a value that reduces the measurement error may be experimentally obtained.

Here, an example in which the pattern is a single circular shape has been described, but the pattern may be formed by arranging two circular transparent portions in the X direction near the optical axis. In this case, it is the same as dividing the one pattern into two, and the circular diameter + pitch of the two transparent portions corresponds to the size of the pattern. It is also preferable in this case that it is as small as possible.

Although the light source 3 is shown and described using an example using incoherent light, the pattern diameter may be reduced by using coherent light generated by a laser or the like.

For example, in the embodiment, the reticle 2 of the light source unit 3
The size of the transparent part is 30 μm,
An optical axis blocking member S having a diameter of 1 to 2 mm is provided.

The lens 6 has the same magnification of 4 times as before and has
= 0.1 is used.

With such a simple configuration, in the measurement of a normal work (aspect ratio <10), the size of the projected image on the wall surface can be an optical stylus of φ0.1 or less.

Here, the optical axis blocking member S is the projection lens 6
Although the example in which the position is in the vicinity of is shown, the same effect can be obtained by providing in the vicinity of the work 8.

However, when the distance between the projection lens 6 and the optical axis blocking member S increases, the brightness loss increases unless the diameter of the blocking member S is reduced, and the center thereof coincides with the optical axis. It is difficult to perform the above operation, and the above-mentioned balance of the projected image is likely to be lost, which may cause a bias in the output waveform of the reflected image. Therefore, it is preferable that the projection image is provided as close to the lens 6 as possible for ease of manufacture.

Although the example in which the optical axis blocking member is provided in the optical path on the work 8 side has been described, it may be provided on the light source section 3 side.

Further, as shown in FIG. 10, the optical axis blocking member S can reduce the direct image included in the observation image.

A) shows the direct image light path when there is no work 8 in the conventional apparatus. All of the projection light is a direct image.

(B) shows the direct image light path when there is no work 8 in the apparatus of the present invention. The direct image near the optical axis disappears and the direct image decreases.

C) shows a direct image at the time of measurement in which the wall surface of the work 8 is set at a position coincident with the optical axis in the apparatus of the present invention. In this case, the light from the optical path around the lens is kicked by the wall surface (left on the projection side and right on the reflection side) that coincides with the optical axis of the work, and the direct image disappears. As described above, the projection optical system 7S using the optical stylus by the optical axis blocking member S has the effect of not only reducing the size of the projection image LVS on the wall surface but also reducing the direct image, and also reduces the error due to the direct image. It is possible to reduce it.

Therefore, in the apparatus according to the present invention, since the image is directly lost, the measurement accuracy can be improved without performing the calculation for correcting the measurement error.

In the device of the present invention, the projection is performed by the optical stylus, but the wall surface to be measured is parallel to the projection direction.
In addition to measuring the distance between a plurality of opposing walls at a precise predetermined distance (ZB), the distance between the walls in accordance with a minute positional change (ZB + ΔZ) from the position can be measured.

Further, the projection image position can be changed along the optical axis with reference to a predetermined position (ZB) on one side wall surface, and the unevenness of the wall surface can be measured by capturing a plurality of wall position positions on the one side wall surface.

Further, as shown in FIG. 11, even if the distance (ZB, ZT) from the end face of the work becomes small, the balance of the reflected image is not lost, so that the measurement can be performed without error.

In the embodiment, it is assumed that the measurement was not possible in the prior art.
Measurement at a position near the end face of 5 mm or less became possible.

Further, since it is an optical stylus, when measuring the distance between the wall surfaces of the center (MID) such as a hole of a thin work, even if the position is not correctly aligned with the center, the projected image (reflected image output waveform) is Since the balance is not lost, measurement errors are less induced and the measurement repeatability is improved.

For example, in the embodiment, even on the wall surface of the work at t = 0.1, ± 10 from the center position MID (0.05 mm).
Even if there was a deviation of%, the error was suppressed to a small value, and the repeatability of the measurement could be suppressed to 1 μ or less.

As described above, a thin work tends to have a higher direct image level than a normal work as described above. However, in the apparatus of the present invention, the direct image is blocked by the optical axis blocking member. However, the level of the direct image can be kept sufficiently low, and the measurement error due to the direct image can be reduced.

Also, the apparatus of the present invention enables optical stylus without using a lens having a high working distance and a high NA, so that a wide range of measurement from a special thin work to a thick normal work can be performed. .

In the measurement of a workpiece having a relatively high aspect ratio, the size of a bright projected image (optical stylus) of the minute area on the wall surface is slightly increased. The wall distance can be measured with less error than the conventional one over the entire length of the device.

In this case, since the optical path becomes narrow as the apparent NA decreases, the diameter of the optical axis blocking member S is set to the value of the normal work so that the luminance loss of the reflected image is minimized and the error is reduced. It is better to experimentally select a smaller value.

For example, when the aspect ratio is 30, the optical axis blocking member may be set to φ1 to 0.5 or may be set to a position close to the projection lens 6.

Further, it is necessary to increase the brightness of the light source by an amount corresponding to the decrease of the apparent NA. However, since there is no dispersed light, an optical stylus can be provided without the influence of masking due to light on unnecessary wall surfaces.

FIG. 12 is a block diagram of an apparatus in which the projection optical system 7S of the optical stylus and the observation optical system are the observation optical system 11S of the optical stylus. .

The optical axis blocking member SS is provided in the vicinity of the observation lens 9 with the optical axis as the center, so that a minute area on the wall surface to be measured at a position substantially parallel to and substantially coincident with the optical axis can be observed with the optical stylus. The observation optical system 11S is constituted.

In this case, the projected image LV of the minute area on the wall surface
S passes through the periphery of the observation lens 9 and forms an image on the CCD camera 10, but the other part of the wall surface (near the end face in the figure) passes through the optical path near the optical axis of the observation lens 9, so that it is shielded by the optical axis blocking member SS. Therefore, no image is formed on the CCD camera 10.

Therefore, the above wall surface can be observed with the optical stylus.

In the case of FIG. 12, since the optical stylus is used on both the projection side and the observation side, the above-mentioned effect can be doubled.

Even if only the observation optical system is used as the observation optical system 11S of the optical stylus as in the fourth aspect, an effect similar to that obtained when only the above-described projection optical system 7S is used can be expected. (The illustration and description are omitted to avoid duplication.) Also, as described above, the observation optical system 11S is not affected by disturbance light on a portion other than the optical stylus on the wall surface, so that the S / N ratio is improved. Can be expected.

The optical axis blocking member S (SS) has been described as a circular mask centered on the optical axis as shown in FIG.
Although the performance is reduced, the optical axis blocking member SB may be simply configured as a band along the Y1-Y2 axis as shown in FIG.

The peripheral optical paths of the objective lens are Z1-Z2 and X1
On a plane including the -X2 axis, the same effect as the above-described circular mask can be obtained.

In the distance measurement between a plurality of opposing wall surfaces of the work, one of the wall surfaces is first aligned with the optical axis as shown in FIG. 9, and the measurement is performed on the other wall surface. The wall surface will be aligned with the optical axis from the opposite direction like '.

Therefore, the optical path is reversed with respect to the optical axis.

Even in such a case, the optical axis blocking member S (S
Since the center of S) is configured to coincide with the optical axis, the same operation can be performed only by reversing the optical paths for measurement of a plurality of wall surfaces.

Therefore, the measurement with the optical stylus can be easily performed without worrying about the direction of the wall surface with respect to the optical axis in the measurement of a plurality of wall surfaces.

[0120]

【The invention's effect】

"A" In the present invention, the optical stylus can be placed on the workpiece wall at a position where the projected image is parallel to the optical axis and coincident with the optical axis.

1) The position specified over the entire length of the work can be accurately grasped and the distance between the wall surfaces at that position can be measured.

2) In particular, measurement can be performed up to a minute distance near the end face of the work.

3) It is possible to measure a change in the distance between the wall surfaces in accordance with a minute positional change (ΔZ) on the wall surface. 4) Thin workpieces can be measured with high accuracy, and repetition accuracy can be improved.

5) Measurement of a work having an aspect ratio higher than that of a normal work is also possible.

5) Since the same effect as a lens having a high NA can be obtained without shortening the working distance, a wide range of work measurement can be performed from a thin work to a thick work. 6) Measurement of a convex curved surface or a convex spherical surface becomes possible.

[B] In a device in which the projection optical system and the observation optical system are configured on the same optical axis, the direct image is shielded by the optical axis blocking member, so that the bias of the observation image waveform output due to the direct image is reduced. The secondary effect of eliminating the measurement error is great.

"C" 1) Therefore, the effects of "A" and "B" eliminate the necessity of correction calculation, simplify the construction, facilitate the fabrication, and basically improve the accuracy.

2) The apparatus of the present invention can be manufactured with a simple structure because the setting of an important optical system and an object to be measured is based on only one optical axis. Since the system can be configured outside the object to be measured, a minute distance between wall surfaces can be measured.

3) Since it is not necessary to use a ring-shaped special lens for the objective lens to be used, a general high-performance objective lens composed of a plurality of lenses can be arbitrarily used, so that the apparatus can be constructed at low cost.

4) In the measurement of a plurality of wall surfaces, the measurement on the wall surface on the same side and the measurement on the opposite wall surface can be easily performed without switching the configuration of the apparatus.

As described above, it is possible to provide an optical measuring device which can satisfy a wide variety of work measurement requirements and can measure with high accuracy.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a conventional device.

FIG. 2 is an optical path diagram of a reflected image of a conventional device.

FIG. 3 is an explanatory diagram of an abbreviation of a projected image position.

FIG. 4 is a direct image light path diagram of a conventional device.

FIG. 5 is an optical path diagram of a reflected image in the vicinity of a work end surface of the conventional apparatus.

FIG. 6 is an optical path diagram of a reflection image of a work having a high aspect ratio of a conventional apparatus.

FIG. 7 is a configuration diagram of the present embodiment (device of the present invention).

FIG. 8 is a configuration diagram of an optical axis blocking member of the present embodiment.

FIG. 9 is an optical path diagram of a reflected image according to the present embodiment.

FIG. 10 is a direct image optical path diagram of a conventional device and the present embodiment (device of the present invention).

FIG. 11 is a light path diagram of a reflected image in the vicinity of a work end surface in the present embodiment.

FIG. 12 is a configuration diagram of the present embodiment (an embodiment according to the fifth aspect of the present invention).

FIG. 13 is a simplified optical axis blocking member diagram of the present embodiment.

Claims (5)

(57) [Claims] An optical axis blocking member that blocks an optical path near an optical axis of a projection optical system is provided near an objective lens for projection with the optical axis as a center, and is substantially parallel to the optical axis and substantially coincides with the optical axis. An optical measuring device using an optical stylus, which projects projection light onto a minute area on a measured wall surface. 2. An optical axis blocking member for blocking an optical path near an optical axis of an observation optical system is provided near an observation objective lens around the optical axis, and is substantially parallel to the optical axis and substantially coincides with the optical axis. An optical measuring device using an optical stylus, which observes a minute area on a measurement wall. 3. An optical measuring device which is provided with a projection optical system and an observation optical system at opposite positions and on the same optical axis via a wall surface to be measured, and measures a distance between the plurality of wall surfaces to be measured. 2. The optical stylus according to claim 1, wherein an optical axis blocking member that blocks an optical path near an optical axis of the projection optical system is provided near a projection objective lens centered on the optical axis. Optical measuring device. 4. An optical measuring device for providing a projection optical system and an observation optical system at opposite positions on the same optical axis via a wall surface to be measured and measuring a distance between the plurality of wall surfaces to be measured. 3. The light according to claim 2, wherein an optical axis blocking member that blocks an optical path near an optical axis of the observation optical system is provided near an observation objective lens around the optical axis. Optical measuring device with stylus. 5. A projection optical system and an observation optical system are provided at opposite positions and on the same optical axis via an object to be measured, and a distance between a plurality of wall surfaces at a position coinciding with the optical axis of the object to be measured is determined. In an optical measuring device for measuring, an optical axis blocking member for blocking an optical path near an optical axis of the projection optical system is provided near an objective lens for projection with the optical axis as a center. The optical measuring device using an optical stylus according to claim 3 or 4, wherein an optical axis blocking member that blocks an optical path near the axis is provided near the observation objective lens centered on the optical axis.