JP2003083723A - Three-dimensional shape measuring optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three-dimensional shape measuring optical system capable of detecting the elevation position of a measuring object with high accuracy. SOLUTION: The three-dimensional shape measurement optical system uses a confocus detection method. An object optical system (12) focuses illumination light (L1) toward the measuring object (15) and focuses reflection light (L2) from the measuring object (15) toward a line sensor (14). A polarization beam splitter (11) splits the illumination light (L1) and the reflection light (L2) into paths, and a line sensor (14) detects the quantity of the reflection light (L2). The illumination light (L1) goes in the object optical system (12) with inclination so as to pass only one side region of an iris separated into two with the light axis center (AX2) of the object optical system (12) and the light among the reflection light (L2) having passes the one side region is shielded with a shield mask (16).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional shape measuring optical system, and more particularly to a confocal detection type three-dimensional shape measuring optical system.

[0002]

2. Description of the Related Art A confocal detection method is known as one of methods used for measuring a three-dimensional shape. The confocal detection method includes a pinhole method, a slit method, etc. Here, the basic configuration will be described below by taking an example of the pinhole method. The illumination light emitted from the light source forms a light source image at the position of the illumination pinhole and passes through the illumination pinhole. Then, after being reflected by the polarization beam splitter, it is projected onto the surface to be measured of the object to be measured by the objective optical system. The reflected light from the surface to be measured enters the detection pinhole through the objective optical system and the polarization beam splitter.
Then, the reflected light that has passed through the detection pinhole is incident on the sensor and the amount of light is detected.

The illumination pinhole and the detection pinhole are arranged at optically equivalent positions (that is, confocal positions) with respect to the objective optical system. Therefore, when the surface to be measured is in a position conjugate with the pinhole for illumination, the conjugate relationship between the pinhole for detection and the surface to be measured is established, and the amount of illumination light passing through the pinhole for detection is maximum. Becomes Then, when the surface to be measured deviates from the conjugate position of the illumination pinhole, the amount of reflected light passing through the detection pinhole is significantly reduced. Therefore, the height position of the measurement target (that is, the object size in the direction parallel to the optical axis) can be detected from the imaging relationship when the amount of light detected by the sensor becomes maximum.

[0004]

However, if the surface to be measured includes a diffusing surface (for example, a diffusing surface in which mirror surfaces are mixed),
Even if the surface to be measured is out of the conjugate position of the illumination pinhole, part of the diffuse reflected light follows the same optical path as the illumination light and passes through the detection pinhole, and is detected by the sensor. Sometimes. This causes measurement noise to deteriorate the detection accuracy of the height position of the measuring object.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a three-dimensional shape measuring optical system capable of detecting the height position of an object to be measured with high accuracy. .

[0006]

In order to achieve the above object, a three-dimensional shape measuring optical system according to a first aspect of the present invention directs a light source that emits illumination light and the illumination light from the light source toward an object to be measured. An objective optical system that forms an image with the reflected light from the object to be measured, and a beam splitter that performs optical path separation between the illumination light that enters the objective optical system and the reflected light that exits from the objective optical system; A confocal detection type three-dimensional shape measuring optical system including a sensor that detects the amount of reflected light emitted from an objective optical system, the pupil being divided into two parts about the optical axis of the objective optical system. Illumination light obliquely enters the objective optical system so as to pass through only one side region,
It is characterized in that the reflected light from the object to be measured that passes through the one side region is shielded.

In the three-dimensional shape measuring optical system of the second invention, in the structure of the first invention, the light amount detection position of the sensor is the confocal position of the light source, the confocal position of the light source image, or the confocal position. Is a conjugate position of.

A three-dimensional shape measuring optical system according to a third aspect of the present invention is the relay optical system according to the configuration of the second aspect, between the sensor and the confocal position of the light source or light source image with respect to the objective optical system. Are arranged.

In the three-dimensional shape measuring optical system of the fourth invention, in the configuration of the first invention, an illumination optical system for increasing the light quantity utilization efficiency is arranged between the light source and the objective optical system. It is characterized by

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A three-dimensional shape measuring optical system embodying the present invention will be described below with reference to the drawings. In Figure 1,
Slit illumination optical system that forms part of the three-dimensional shape measurement optical system
An example of the configuration of (9) is shown. FIG. 2 shows a slit confocal detection type three-dimensional shape measuring optical system including the slit illumination optical system (9) of FIG.

1 and 2, 1 is a laser diode, 2 is a collimator lens, 3 is a rectangular aperture plate, 4 is a wedge prism pair, 5 is a half-wave plate, and 6 is a variable ND (N
eutral Density) filter, 7 anamorphic prism pair, 8 cylindrical lens, 9 slit illumination optical system, 10 slit mask, 11 polarizing beam splitter, 12 objective optical system, 13 XY stage, 14 line A sensor, 15 is an object to be measured, and 16 is a light-shielding mask. L1 is a laser beam (illumination light), L2 is reflected light, AX1 is an optical axis of the slit illumination optical system (9), and AX2 is an optical axis of the objective optical system (12). In addition, X, Y, and Z in each figure indicate directions orthogonal to each other in the optical path expanded state, and FIG.
Corresponds to the YZ section, and FIG. 1B corresponds to the XZ section.

The laser diode (1) is a point light source that emits a laser beam (L1) as illumination light. And
Laser beam emitted from laser diode (1)
(L1) is a Gaussian beam emitted in the shape of an elliptical cone. The laser beam (L1) emitted from the laser diode (1) is collimator lens (2), rectangular aperture plate (3), wedge prism pair (4), 1/2 wavelength plate (5), variable ND filter (6). ), Anamorphic prism pair (7) and cylindrical lens (8) slit illumination optical system (9)
As a result, an image is formed in a slit shape at the opening position of the slit mask (10) (that is, the position of the slit (10h)) as described below.

The laser beam (L1) emitted from the laser diode (1) is first converted from emitted light into collimated light (that is, parallel light) by a collimator lens (2) which is a rotationally symmetric collimator optical system. Then, the laser beam (L1) is limited to a necessary luminous flux range by passing through the rectangular aperture (3h) of the rectangular aperture plate (3). Figure 3 shows the beam shape of the laser beam (L1) and the rectangular aperture (3
The relationship between the cross-sectional light intensity distribution (i: light intensity, r: beam diameter position) in the use range of the elliptic cone-shaped Gaussian beam corresponding to h) and the slit direction (dL, dS) is shown. Laser diode (1)
Are arranged so that the major axis direction of the ellipse of the laser beam (L1) coincides with the slit longitudinal direction (dL) of the slit (10h) as shown in FIG. As a result, it is possible to improve the light quantity utilization efficiency while keeping the light quantity distribution in the slit longitudinal direction (dL) substantially uniform.

The laser beam (L
1) enters the wedge prism pair (4). The wedge prism pair (4) is an optical axis direction deflection means for finely adjusting the image forming position of the laser beam (L1) to a desired position. By rotating the lens barrel of the wedge prism pair (4) around the optical axis (AX1), the slit-shaped light source image can be finely shifted in parallel. Therefore, by finely adjusting the position of the laser beam (L1), the position of the slit mask (10) and the slit image forming position can be aligned during the optical adjustment.

The laser beam (L1) emitted from the wedge prism pair (4) passes through a half-wave plate (5), a variable ND filter (6), an anamorphic prism pair (7), and a cylindrical lens (8). A slit-shaped light source image is formed at the slit (10h) position by sequentially passing through. The half-wave plate (5) is a polarization direction conversion element for rotating the polarization direction of the laser beam (L1) by 90 ° as shown in FIGS. 1 (A) and 1 (B). The anamorphic prism pair (7) consisting of the first and second prisms (7a, 7b) is an expander that expands the laser beam (L1) only in the elliptical major axis direction (that is, slit longitudinal direction (dL)}. It is an optical system. Laser diode (1)
Is the direction parallel to the junction surface (that is, the minor axis direction of the elliptical cone beam), similar to a typical laser diode.
It emits a laser beam (L1) polarized into a beam and is arranged so that the major axis direction of the ellipse of the laser beam (L1) coincides with the slit longitudinal direction (dL) (FIG. 3). Therefore, the laser beam (L1) is a half-wave plate.
It is incident on the anamorphic prism pair (7) after being converted from S polarized light to P polarized light by (5).

By changing the polarization direction in the half-wave plate (5), a laser is applied to the prism surface of the anamorphic prism pair (7) {especially each first surface of the first and second prisms (7a, 7b)}. It is possible to maximize the transmittance when the beam (L1) is incident. Therefore, the loss of the light amount in the anamorphic prism pair (7) is reduced, and the efficiency of the light amount utilization can be improved. Further, by making the incident angle close to the Brewster angle, the antireflection film on the prism incident surface can be eliminated. Further, since the polarization direction matches the slit direction, the laser beam (L1) can efficiently pass through the slit. Although not shown in FIG. 1,
A polarizing plate may be arranged immediately after the half-wave plate (5) to align the polarization direction of the laser beam (L1) more accurately.

The anamorphic prism pair (7) can expand the laser beam (L1) only in the slit longitudinal direction (dL). While obtaining the desired slit length, the beam width in the slit lateral direction (dS) does not change, so the desired NA (Numerical Aperture) can be obtained without extending the focal length of the cylindrical lens (8) that is the slit imaging optical system. Therefore, the total length of the slit illumination optical system (9) can be made short and compact. As shown in FIG. 5 (A), it is also possible to expand the luminous flux in one direction by using a lens group including a negative cylindrical lens (G1) and a positive cylindrical lens (G2) as an expander optical system. However, when the anamorphic prism pair (7) is used, it is more likely that the lens group (G1, G2) is used than in the case of FIG.
As shown in, the decrease in the luminous flux density at both ends in the expansion direction is reduced. That is, it is not easy to construct an optical system with a small aberration when using the lens group. Therefore, the use of the anamorphic prism pair (7) is also effective for keeping the light amount in the slit longitudinal direction (dL), which is the expanding direction, substantially uniform.

As shown in FIG. 4, the variable ND filter (6) includes an ND vapor deposition section (6a) having an ND vapor deposition film formed on a glass substrate and an ND vapor deposition film having no ND vapor deposition film formed on the glass substrate. It has a structure having a non-deposition portion (6b). The laser beam (L1) passes through either the ND vapor deposition section (6a) or the ND non-vapor deposition section (6b) so that the laser beam (L1) passes through the ND vapor deposition section (6a) or the optical path of the laser beam (L1). It is possible to switch and insert the ND non-deposition portion (6b).

When measuring the height position (Z direction) of the object to be measured (15), the scanning is performed twice, the forward path and the return path. In the forward scanning {scanning in the Z direction from the low position to the high position of the measuring object (15)}, the laser beam (L1) passes through the ND non-deposition portion (6b) and the returning scanning {measuring object ( 15) Z from high position to low position
In the direction scanning}, the laser beam (L1) is ND
It passes through the vapor deposition section (6a). Variable ND filter like this
(6) can be used to switch the lighting of the laser beam (L1) to increase or decrease the dynamic range of measurement by the line sensor (14), and thus the measurable reflectance range of the measurement object (15). Can be extended.

The laser beam (L) expanded in the slit longitudinal direction (dL) by the anamorphic prism pair (7)
1) is a cylindrical lens that is a slit imaging optical system
By (8), an image is formed only in the short-axis direction {that is, the slit lateral direction (dS), FIG. 1 (B)} of the elliptical light beam cross section, and the long-axis direction {that is, the slit longitudinal direction (dL), FIG. The collimated state is maintained in (A)}. The imaging position of the laser beam (L1) is the slit (10h) position of the slit mask (10).
The slit mask (10) is formed by forming an image in a slit shape like this.
Light loss can be reduced by using so-called critical illumination that allows light to pass through. Instead of forming a light source image at the slit (10h) position by the slit illumination optical system (9), a slit light source that emits divergent light similar to the light source image may be arranged at the slit (10h) position.

As shown in FIG. 2, the slit illumination optical system (9) is arranged at an angle to the optical axis (AX2) of the objective optical system (12). That is, the slit illumination optical system
The optical axis (AX1) of (9) is inclined with respect to the optical axis (AX2) of the objective optical system (12). For this reason, the slit mask (1
The laser beam (L1) that passed through the slit (10h) of (0) is
It will enter the objective optical system (12) as obliquely incident illumination light. However, the laser beam (L1) enters the polarization beam splitter (11) before entering the objective optical system (12). The polarization beam splitter (11) is the illumination light (L1) that enters the objective optical system (12) and the reflected light (L2) that exits from the objective optical system (12).
A polarization splitting element for performing optical path splitting with. Since the laser beam (L1) as the illumination light is polarized in the Y direction, it enters the polarization beam splitter (11) as S-polarized light. Therefore, the laser beam (L1) is deflected along the optical path toward the objective optical system (12).

The objective optical system (12) is a both-side telecentric optical system, which forms the illumination light (L1) in a slit shape toward the measuring object (15) and reflects the reflected light from the measuring object (15). (L2) is imaged in a slit shape toward the line sensor (14). In the objective optical system (12), a quarter wave plate (1
2q) is arranged as a polarization direction conversion element. The illumination light (L1) that is obliquely incident on the objective optical system (12) is the optical axis (AX2).
The reflected light (L2) from the measured surface (15s) of the measurement object (15) that passes through the quarter-wave plate (12q) in one of the two divided areas with the optical axis (AX2) It passes through the quarter-wave plate (12q) in the other region divided into two with the center as the center.

As the optical path reciprocates through the quarter-wave plate (12q) as described above, the polarization direction of the reflected light (L2) is changed to the illumination light (L2).
It is rotated by 90 ° with respect to the polarization direction of 1). As a result, the reflected light (L2) emitted from the objective optical system (12) enters the polarization beam splitter (11) as P-polarized light. Therefore, the reflected light (L2) can be transmitted through the polarization beam splitter (11), and the reflected light (L2) that has passed through the polarization beam splitter (11) is incident on the light receiving surface (14s) of the line sensor (14). . Instead of using the 1/4 wavelength plate (12q) to change the polarization direction for the illumination light (L1) and the reflected light (L2), use the 1/2 wavelength plate for the illumination light (L1) or the reflected light.
The configuration may be such that the polarization direction is converted with respect to (L2).

The line sensor (14) is a one-dimensional array type CC
D (Charge Coupled Device), which has a light receiving surface (14s) composed of a plurality of light receiving elements at the confocal position of the slit (10h), and has an object to be measured (15s) on the light receiving surface (14s). ) Is fixedly arranged so that the image of is projected.
That is, the slit (10h) and the light-receiving surface (14s) are both in a positional relationship that is conjugate with the measurement object (15) {that is, the objective optical system (1
2) is located at the optically equivalent confocal position}. Therefore, the measured surface (1
5s) is in focus, the reflected light (L) is reflected on the light receiving surface (14s) of the line sensor (14) at the conjugate position.
2) forms an image, and the amount of reflected light (L2) is detected for each pixel.

The objective optical system (12) is moved to the image side conjugate position by the movement of the focus lens group (12f) arranged therein.
Only {that is, the conjugate position on the measurement object (15) side} is moved to perform scanning in the height direction (Z direction) of the measurement object (15). Since the scanning in the Z direction is performed with a simple structure by moving the focus lens group (12f), it is possible to downsize the scanning mechanism and speed up the scanning. Further, the XY stage (13) moves in the X and Y directions together with the mounted measurement object (15), so that the relative position of the measurement object (15) and the illumination light (L1) in the X and Y directions. Is changed to measure the entire measurement region for the measurement object (15).

In the measurement of the three-dimensional shape of the measuring object (15), the size in the X direction is obtained by moving and scanning the measuring object (15) by the XY stage (13), and the size in the Y direction is determined by the objective optical system. It is obtained from the size of the image projected on the light receiving surface (14s) by the system (12). However, if the projected image is
4s) in the Y-direction range, XY stage (13)
Is controlled in the Y direction. On the other hand, Z direction
The size (that is, the height position) in the direction parallel to the optical axis (AX2) is the same as the light received by the line sensor (14) while moving the focus lens group (12f) along the optical axis (AX2). The output fluctuation from the element is read, and the measurement object (15) is
(that is, the measured surface (15s) and the light receiving surface (14s)
It is obtained by detecting the position of the focus lens group (12f) when the output peaks due to the formation of the conjugate relation with (s). Therefore, while moving the measuring object (15) on the XY stage (13), the focus lens group (12f)
When is moved, the cross-sectional shape of the measuring object (15) is sequentially detected, and by calculating it, the 3
The dimensional shape is measured.

When a general confocal optical system detects, for example, the height position of a measuring object such that a mirror surface and a diffusing surface are mixed on the surface, the focus of the objective optical system is not on the measured surface. However, the diffused reflected light from the diffusing surface may enter the sensor through an optical path similar to the irradiation optical path for the measurement object, and affect the measurement accuracy. This will be described with reference to FIG. Fig. 6 (A) shows the case of full aperture illumination.
(B) is the case of oblique incidence illumination. In each case, the measured surface (15s) is off the image side conjugate position (P2), but the pinhole of the pinhole plate (19) placed at the object side conjugate position (P1).
Part (R1) of the diffuse reflected light (R1, R2) passes through (19h). Even if the pinhole plate (19) is arranged as a spatial filter in this way, the diffuse reflected light (R1) will pass through the pinhole (19h), so when scanning the measurement target (15) in the height direction. When detecting the height position where the sensor output has a peak, the diffuse reflection light (R1) affects the measurement accuracy as noise, and causes a difference in the height measurement data between the mirror surface and the diffusion surface.

As a method of blocking the diffuse reflection light (R1), an illumination optical system in which the optical axis is inclined with respect to the normal direction of the stage surface on which the object to be measured is set, and light of the illumination optical system are used. The optical system is composed of a condensing optical system whose optical axis is aligned with the regular reflection direction of the axis.
A method is known in which 1) is not incident on the sensor. However, that configuration requires a mechanism for moving the entire optical system or the stage in the vertical direction when scanning in the height direction. Therefore, the device configuration becomes large, which is not effective for speeding up the scanning.

In the three-dimensional shape measuring optical system shown in FIG. 2, as shown in FIGS. 7 (A) and 7 (B), the illumination light (L1) at each image height is directed to the objective optical system (12) which is telecentric on both sides. Oblique incidence (S
T: diaphragm), the optical axis of the objective optical system (12) as shown in FIG.
The pupil of the objective optical system (12) divided into two with the (AX2) as the center
The measured surface (15s) is illuminated by passing only one side area (A1) of (EP). Then, the reflected light (L2) from the measured surface (15s) is
The objective optical system (12) is emitted through the other side area (A2). The diffuse reflection light (R1) in question will follow the same optical path as the illumination light (L1) and pass through the one side area (A1),
Polarizing beam splitter (11) as shown in FIG. 2 and FIG.
The light is blocked by the light-shielding mask (16) arranged between the line sensor (14) and the line sensor (14). Thus, the measurement target (1
Diffuse reflected light (R1) that has passed through one side area (A1) of the reflected light (L2) from 5) is a light shielding mask (16) as a spatial filter.
Since the light is shielded by, the measurement noise due to the diffuse reflected light (R1) is reduced and the height position detection accuracy is improved even when the measured surface (15s) is out of the image side conjugate position (P2).
This configuration is effective not only in the slit confocal detection method but also in the pinhole confocal detection method.

FIGS. 9A to 9C show the case of full aperture illumination in FIG.
(D) to (F) are changes in the defocus optical path with respect to the light receiving surface (14s) of the line sensor (14) in the case of oblique incidence illumination.
(A, D), change in light intensity distribution (B, E; i: light intensity)
And change in detected light amount (C, F; q: light amount). As can be seen by comparing FIGS. 9 (A) to 9 (C) with FIGS. 9 (D) to 9 (F), by using the obliquely incident illumination light (L1), the incidence on the defocus at the light receiving surface (14s) can be improved. The contrast of the change in light quantity is improved, and the height position detection accuracy is also improved. Also, it is better to let the illumination light (L1) pass through a position as far as possible from the optical axis (AX2) of the objective optical system (12).
The light-shielding effect on the diffuse reflection light (R1) is improved, and the contrast of the change in the detected light amount is also improved.

In the three-dimensional shape measuring optical system shown in FIG. 2, the light receiving surface (14s) of the line sensor (14) is located at the confocal position of the light source image formed at the slit (10h) position. The detection position is not limited to the confocal position of the light source image with respect to the objective optical system (12), and may be the confocal position of the light source with respect to the objective optical system (12) (for example, when the slit light source is used). The confocal position of the optical system (12) may be the conjugate position of the relay optical system. Figure 10 (A), (B)
FIG. 3 shows a three-dimensional shape measuring optical system having a relay optical system (18) on the line sensor (14) side. The feature of this three-dimensional shape measuring optical system is that the slit mask (17) is arranged at the confocal position of the slit mask (10), and the relay optical system (18) is provided between the slit mask (17) and the line sensor (14). ) Is placed. Other than that, the configuration is similar to that of the three-dimensional shape measuring optical system shown in FIG. In this case, the slit (17h) is located at the confocal position of the slit (10h) related to the objective optical system (12), and the line sensor (14) at the conjugate position of the slit (17h) related to the relay optical system (18). The light receiving surface (14s) is located. If you use a relay optical system, you have more flexibility in the position of the sensor, and the objective optical system for measuring the part to be measured
An observation optical system (not shown) for observing through (12) can also be provided.

[0032]

As described above, according to the present invention, since the reflected light from the measurement object that affects the detection accuracy is shielded, the height position of the measurement object is reduced. Can be detected with high accuracy.

[Brief description of drawings]

FIG. 1 is an optical configuration diagram schematically showing a configuration example of a slit illumination optical system according to the present invention.

FIG. 2 is a schematic configuration diagram schematically showing a three-dimensional shape measuring optical system including the slit illumination optical system of FIG.

FIG. 3 is a diagram for explaining the relationship between the beam shape of a laser beam, its cross-sectional light amount distribution, and the slit direction.

FIG. 4 is a diagram for explaining the operation of the variable ND filter for expanding the dynamic range of the measurement system.

FIG. 5 is an optical path diagram for explaining beam shaping of a laser beam by an expander optical system.

FIG. 6 is a diagram for explaining an optical path of diffusely reflected light that affects measurement accuracy.

FIG. 7 is a diagram for explaining the relationship between a reflected light passage region and a reflected light shield region on the pupil plane.

8 is a perspective view showing an arrangement of light-shielding masks in the three-dimensional shape measuring optical system of FIG.

FIG. 9 is a diagram for explaining changes in the defocus optical path with respect to the light receiving surface of the line sensor, changes in the light intensity distribution thereof, and changes in the detected light amount.

FIG. 10: 3 with a relay optical system on the line sensor side
The optical block diagram which shows typically a three-dimensional shape measuring optical system.

[Explanation of symbols]

1… Laser diode (light source) 9… Slit illumination optical system 10… Slit mask 10h ... slit 11… Polarizing beam splitter 12… Objective optical system 12f… Focus lens group 12q… 1/4 wave plate 14… Line sensor 14s… Light receiving surface 15… Object to be measured 15s… Surface to be measured 16… Shading mask 17… Slit mask 17h ... slit 18… Relay optics L1… Illumination light (laser beam) L2 ... Reflected light AX1… Optical axis of slit illumination optical system AX2 ... Optical axis of objective optical system EP ... Hitomi

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshio Kono             2-3-3 Azuchi-cho, Chuo-ku, Osaka             Kokusai Building Minolta Co., Ltd. F term (reference) 2F065 AA53 BB05 DD04 FF01 FF04                       FF10 GG06 GG12 HH03 HH08                       JJ02 JJ09 JJ25 LL08 LL21                       LL28 LL33 LL47 MM03 PP12                       PP22 UU07

Claims (4)

[Claims] 1. A light source that emits illumination light, an objective optical system that images illumination light from the light source toward a measurement target, and images reflected light from the measurement target, and the objective optical system. 3 of the confocal detection method, which includes a beam splitter for separating the optical path of the illumination light incident on the lens and the reflected light emitted from the objective optical system, and a sensor for detecting the amount of the reflected light emitted from the objective optical system. A three-dimensional shape measuring optical system, wherein illumination light obliquely enters the objective optical system such that the illumination light is obliquely incident on the objective optical system so as to pass through only one side area of a pupil which is divided into two parts about the optical axis of the objective optical system. A three-dimensional shape measuring optical system, characterized in that, of the reflected light from, the light passing through the one side region is shielded. 2. The three-dimensional shape measuring optical system according to claim 1, wherein the light amount detection position of the sensor is a confocal position of the light source, a confocal position of a light source image, or a conjugate position of the confocal position. system. 3. A relay optical system is arranged between a confocal position of the light source or a light source image with respect to the objective optical system and the sensor.
Dimensional measurement optical system. 4. The three-dimensional shape measuring optical system according to claim 1, further comprising an illumination optical system disposed between the light source and the objective optical system for increasing a light quantity utilization efficiency.