JPS587922B2 - Output angle fine adjustment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light wave interferometer, and particularly to a light wave interferometer that is compact and suitable for an interferometric length measuring device.

Many light wave interferometers suitable for interferometric length measurement devices have been proposed in the past, but most of them have a laser light source section and an interferometer section provided on one substrate.

Due to such an integrated structure, it is impossible to avoid the influence of heat from the laser light source, and it is difficult to make the structure compact, making it difficult to make it portable and lightweight.

Furthermore, since heat from the laser light source section is easily conducted to the interferometer section, errors in length measurement due to thermal expansion cannot be ignored.

In order to avoid this thermal effect, it is possible to separate the interferometer section and the laser light source section, but in this case it is extremely difficult to align the optical axes of both sections.

This optical axis alignment is very important when using a light wave interferometer, but generally the signal from the detector is read with a meter, etc., and the optical axis is aligned at the position where the shake is large. However, this is insufficient for precise length measurement.

The best way to achieve optimal optical axis alignment is to visually observe the interference fringes that actually appear, but with conventional light wave interferometers, alignment is performed in advance in order to observe the interference fringes. It was necessary to remove the detector etc. from the interferometer section.

For this reason, after observing the interference fringes and aligning the optical axes, the detector must be aligned again, making the overall setup extremely difficult.

Furthermore, it is necessary to align the optical axis between the light wave interferometer and the cat's eye on the moving object, but in the conventional configuration, the entire light wave interferometer was moved to align, but this requires very fine adjustments. This makes it difficult to measure the distance, and when the measurement distance becomes long, it becomes difficult to measure the length.

Furthermore, as the measurement distance becomes longer, fluctuations due to changes in air temperature, etc. along the way occur, and due to the effects of relative vibration between the interferometer and the cat's eye on the moving object,
The error increases, making precise length measurement difficult.

An object of the present invention is to make the entire optical interferometer small and lightweight, and to make it portable.

Another object of the present invention is to make optical axis alignment very simple during use and to perform accurate optical axis alignment by directly observing interference fringes without moving any component parts.

Another object of the present invention is to minimize the influence on length measurement due to the heat of the laser light source, the relative vibration of the entire measurement system, the fluctuation of air in the middle, and the like.

Still another object of the present invention is to easily and accurately align the optical axes of a movable reflecting mirror section on a moving object and an interferometer.

Next, the present invention will be explained in detail based on the drawings.

FIG. 1 is a diagram showing the overall appearance of the optical interferometer of the present invention, in which a is a view seen from the front direction and b is a view seen from the rear direction.

Reference numeral 1 denotes a laser light source section, which includes a laser tube and a circuit for the laser tube, and 2 an interferometer section.

Reference numeral 7 indicates a T-shaped leg, and reference numeral 8 indicates a handle, which integrally connect the laser light source section 1 and the interferometer section 2.

Reference numeral 9 denotes a U-shaped connector that electrically connects the interference fringe detection system inside the interferometer section 2 and an electrical console (not shown) via the laser light source section 1 with a cable 191 in a compact manner.

Reference numeral 6 represents a reference side cat's eye for reflecting the reference light of the interferometer, and is detachable from the reference light entrance/exit port 24 .

Reference numeral 12 designates a second laser beam exit port, and the laser light from this exit port 12 can also be used for other purposes.

Reference numeral 22 denotes a second entrance port of the interferometer, and even if the laser light source section 1 is not used, a light beam from another light source may be input through this entrance port 22.

In the configuration shown in FIG. 1, the light beam from the laser light source is bent inside the laser light source section 1 and guided to the interferometer within the interferometer section 2.

Reference numeral 23 denotes an interference fringe observation port through which interference fringes are directly observed when aligning the optical axes.

Reference numeral 25 denotes a length measurement light input/output port, which outputs the light beam from the input/output port 25 to a cat's eye (not shown) on a moving object, and receives reflected light from the cat's eye.

Reference numerals 323a and 323b are measuring light output angle fine adjustment knobs for finely adjusting the output angle of the length measuring light in the vertical and horizontal directions.After fine adjustment with these knobs 323a and 323b, the length measuring light output angle fine adjustment is performed. Fix with lock screw 324.

FIG. 2 is an exploded view of the light wave interferometer shown in FIG. 1.

Here, 11 is the first laser beam exit port, and the laser light source section 1
The laser beam is divided into two directions, one of which is emitted to the outside from the second laser beam exit port 12 in FIG.

The laser beam from this emission aperture 11 enters the interferometer in the interferometer section 2 through a first interferometer entrance aperture 21 provided in the interferometer section 2 .

The first exit port 11 and the first entrance port 21 are opposed to each other and are provided so as to coincide when the laser light source section 1 and the interferometer section 2 are combined.

The grip 8 shown in FIG. 1 includes a grip member 81 and a mounting member 82.
The light source section 1 and the interferometer section 2 are connected by four screws 83.

Similarly, the T-shaped leg 7 connects the light source section 1 and the interferometer section 2 with four screws 71.

The U-shaped connector 9 includes a connector 91a provided in the light source section 1.
The connector 91b connected to the
2a is provided, and the connectors 91b and 92b are connected to each other within the U-shaped connector 9.

When the light source section 1 and the interferometer section 2 are connected as shown in FIG. A cable 191 is compactly electrically connected via the light source section 1 .

FIG. 3 is a diagram showing another usage state of the light wave interferometer of the present invention in which the light source section 1 and the interferometer section 2 are arranged separately.

Generally, when a light wave interferometer is made small and lightweight, the laser light source, which is the largest heat radiator, and other components inevitably come close to each other.

Therefore, the influence of the heat of the laser light source on the length measurement error cannot be ignored.

The present invention also takes into consideration such thermal effects,
This is illustrated in the usage state diagram of FIG. 3.

Here, the light source section 1 and the interferometer section 2, which were fixedly connected by the T-shaped leg 7 and the handle 8 in FIG. Attach T-shaped leg 7 to the opposite sides) with four screws.

In this case, the laser beam emitted from the laser beam second exit port 12 of the light source section 1 is used, and the laser beam is made to enter the interferometer from the interferometer second entrance port 22 of the interferometer section 2.

Also, at this time, the height of the light beam from the length measurement light inlet/output port 25 toward the length measurement side cat's eye (not shown) is made to be the same as the height of the light beam when assembled as shown in Fig. 1. It is configured.

Therefore, even if the usage conditions are changed as shown in FIGS. 1 and 3, the length can be measured without changing the height of the cat's eye on the length measurement side.

90 is a connection cable with connectors 91c and 92c on both ends.
are attached to the connector 91a of the light source section 1 and the interferometer section 2.
The interference fringe detection system and the electrical system console in the interferometer section 2 are electrically connected via the light source section 1 via the cable 191 in a compact manner.

In this way, by separating the laser light source section 1 and the interferometer section 2 and arranging them at a distance, it is possible to prevent the heat from the light source section 1 from being applied to the interferometer section 2 and causing thermal expansion, which would cause errors in measurement. I can do it.

FIG. 4 is a diagram showing the optical path and arrangement of each component of the light wave interferometer of the present invention when the light source section 1 and the interferometer section 2 are combined.

As described above, the laser tube 10 is housed in the laser light source section 1, and the laser light from the laser tube 10 is divided into two parts within the light source section 1, one of which travels straight to the second laser light output port 12, and the other is bent. The laser beam is directed toward the first emission port 11.

Inside the interferometer section 2, a length measurement light collimator 3, a reference light collimator 5, and an interferometer unit 200 are housed.

The laser beam directed toward the first exit port 11 enters the interferometer unit 200 through the interferometer first entrance port 21 .

Details of the interferometer unit 200 will be described later, but in FIG. 4, only the optical path within the interferometer unit 200 is shown by broken lines.

Note that the black circles in the interferometer unit 200 indicate the positions of elements that divide the light beam into two, and are configured to operate even when the light beam enters from the second entrance port 22 of the interferometer.

One of the light beams emitted from the interferometer unit 200 enters the collimator 3 for length measurement, and exits from the length measurement light exit/input port 25 that can change the emission angle of the length measurement light as shown in FIG. Enter moving cat's eye 4.

The light beam reflected by the cat's eye 4 returns to the interferometer unit 200 through the same optical path.

The other of the light beams emitted from the interferometer unit 200 enters the reference beam collimator 5 and then enters the reference-side cat's eye 6 .

The light beam reflected by the cat's eye 6 returns to the interferometer unit 200 through the same optical path.

This reference side cat's eye 6 is configured to be freely inserted into and removed from the reference light exit/input port 24 .

23 is an interference fringe observation port provided in the interferometer section 2, through which the interference fringe observation mirror 29 is inserted into the interferometer unit 200 to move the internal optical system or the detector (not shown). The interference fringes incident on the detector can be observed without having to do so, and the optical axes of the interferometer and cat's eye can be aligned extremely easily.

The details of the configuration of this interference fringe observation mirror 29 will be described later.

FIG. 5 is a diagram showing optical elements in the light source section 1, optical elements of the interferometer unit 200 of the interferometer section 2, and optical paths.

In the following explanation, the x, y, and z coordinates shown in the figure are
Polarized light whose electric vector vibrates in the y or Z direction will be referred to as X-polarized light, y-polarized light, or double-polarized light, respectively.

The light source unit 1 includes optical elements such as a quarter wavelength plate 111 and a polarizing prism 132 that increase or decrease the phase difference between the X component and the y component of incident light by 90°.

Laser light 171 from the laser tube 10 shown in FIG. 4 is a combination of right-handed circularly polarized light and left-handed circularly polarized light.

When the laser beam 171 passes through the 1/4 wavelength plate 111,
The light 172 consists of polarized light and y-polarized light.

The X-polarized light component of this light 172 passes through the polarizing prism 132, becomes X-polarized light 174, and is emitted to the outside of the light source section 1 from the laser light second exit port 12 shown in FIG.

Further, the y-polarized light component of the light 172 is reflected by the reflective surface of the polarizing prism 132 in a direction perpendicular to the X-polarized light 174, and becomes the y-polarized light 17.
3, and enters the interferometer unit 200 through the laser beam first exit port 11 and the interferometer first entrance port 21 shown in FIG.

The y-polarized light 173 incident on the interferometer unit 200 is reflected at right angles by the reflective surface of the polarizing prism 232 and becomes y-polarized reflected light 2.
It will be 70.

When used as shown in FIG. 3, the interferometer unit 200 receives the X polarized light 174 from the
The X-polarized light 174 passes through the polarizing prism 232, and the light 270 becomes X-polarized light.

One light 270 enters the π/4 rotator 221, which is an element that rotates the polarization direction of the incident light by π/4 radians.

When the light 270 passes through the rotator 221, it becomes polarized light 271 tilted at 45 degrees with respect to the x and y axes.

That is, the polarized light 271 can be separated into X-polarized light and y-polarized light having the same frequency and the same intensity.

The polarized light 271 then enters a polarizing prism 233, and the y-polarized light component passes through the polarizing prism 233 and becomes y-polarized light 272.

On the other hand, the X-polarized light component is reflected at right angles by the reflective surface of the polarizing prism 233 and becomes X-polarized light 274.

Y-polarized light 27 which is the length measurement light that has passed through the polarizing prism 233
2 passes through the collimator 3 for length measurement shown in FIG.
33.

This re-entering X-polarized light 273 is reflected by the reflective surface of the polarizing prism 233 and travels upward by 90 degrees as X-polarized light 281.

On the other hand, the X-polarized light 274 reflected 90 degrees downward by the reflective surface of the polarizing prism 233 is reflected laterally by the total reflection prism 241, then reflected upward by the total reflection prism 242, and further reflected by the total reflection prism 243. is directed as X-polarized light 275 parallel to y-polarized light 272.

This X-polarized light 275 is the reference light. This X-polarized light 275 passes through the reference light collimator 5 shown in FIG.

The y-polarized light 276 that has entered the prism 243 is sequentially reflected by the prisms 243, 242, and 241 and enters the polarizing prism 233.

The light beam incident on the polarizing prism 233 passes through the polarizing prism 233 to become y-polarized light, and travels as X-polarized light in the same direction as the X-polarized light 281 of the length measurement light.

Therefore, the light beam 281 traveling above the polarizing prism 233 is a combination of the X-polarized length measurement light and the Z-polarized reference light.

Therefore, if the component of the light beam 281 in the 45° direction with respect to the X and Z axes is extracted, the length measurement light and the reference light interfere with each other, and an interference fringe signal can be obtained.

This nine bundle 281 is connected to a π/4 rotator 222K in order to easily extract the 45° direction component with respect to the x and z axes.
Therefore, it is converted into a light beam 282 whose polarization direction is rotated by 45 degrees.

This light beam 282 is efficiently focused onto the photo sensor by the condenser lens 201.

A light beam 282 condensed by the condenser lens 201 is divided into light beams 283 and 286 by a semi-transparent mirror 202.

The light beam 283 reflected by the semi-transparent mirror 202 is divided into Y component interference light 284 and X component interference light 285 by the polarizing prism 234.
It is divided into

These two interference lights 284 and 285 are interference fringe signals that differ from each other by 180°, and the photo sensors 251 and 252 respectively
is received and converted into an electrical signal.

On the other hand, the light beam 286 that has passed through the semi-transparent mirror 202 is made incident on the quarter-wave plate 212, and the phase difference between the x and z direction components of the light beam 286 is increased by 90°, resulting in a light beam 287.

This 1/4 wavelength plate 212 provides an interference fringe signal having a phase difference of 90° from the interference fringe signals obtained by the photo sensors 251 and 252 described above.

This light beam 287 is split by the polarizing prism 235 into Z component interference light 288 and X component interference light 289.

These two interference lights 288 and 289 have a phase difference of 1800 from each other, and have a phase difference of 9 from the interference lights 284 and 1285 described above.
The interference fringe signals have a phase difference of 0°, are received by photo sensors 253 and 254, and converted into electrical signals.

Each photo sensor 251 , 252 , 253 , 2
54 are connected to a differential amplifier as a pair of photo sensors 251 and 252 and photo sensors 253 and 254.

Therefore, the influence of the intensity drift of the laser light source can be removed.

In addition, the visibility of interference fringes changes depending on the measurement distance due to the influence of laser beam diffraction, and the DC level of the interference potential changes, but by using a differential amplifier, these effects can be avoided. I can do it.

Here, a total reflection prism 244 shown by a broken line in the optical path in FIG. 5 is attached to the tip of the interference fringe observation mirror 29 shown in FIG. 4, and is inserted when adjustment of optical axis alignment is necessary. Then, the interference light 285 or 289 is reflected to produce reflected light 290.
Take it out of the interferometer and observe the interference fringes.

Note that the interference lights 285 and 289 intersect.

Although the conventional laser beam 171 is composed of circularly polarized lights having opposite directions, the present invention can also use a linearly polarized laser as a light source.

In this case, the quarter wavelength plate 111 is not necessary.

Here, when the configuration is as shown in FIG. 1, the laser beam may be made into Y-polarized light and incident on the polarizing prism 132, and when the configuration is made as shown in FIG. 3, the laser beam is made into X-polarized light. It is sufficient to make the light incident on the polarizing prism 232.

In addition, in order to easily change the polarization direction of the linearly polarized laser beam in response to changes in the configurations of the laser light source section 1 and the interferometer section 2 as described above, the polarization direction is set at the position of the quarter-wave plate 111. A π/2 rotator that rotates 90° may be provided in a manner that can be inserted and removed.

Further, the same effect can be obtained even if the π/4 rotator 221 provided in the interferometer unit 200 is replaced with a 1/4 wavelength plate.

Furthermore, each optical component constituting the interferometer unit 200 is
In order to make the temperature distribution uniform, have a large heat capacity, and reduce the effects of thermal fluctuations, the metal that supports and fixes each optical component has grooves cut along its optical path, and each optical component is inserted into the groove. is embedded.

FIG. 6 is a diagram showing the optical path and configuration of the collimator and cat's eye used in the present invention, and the configuration for length measurement and reference is the same.

Here, the collimator includes a condenser lens 301 and an objective lens 3.
02.

In addition, the cat's eye has a condenser lens 401 and a quarter wavelength plate 4.
02 and a reflecting mirror 403.

When the linearly polarized light 311 of X or Y polarization enters this collimator from the interferometer unit 200, the condenser lens 30
1 and an objective lens 302, the beam diameter is expanded and the beam is emitted toward the cat's eye as a parallel light beam 312.

A parallel light beam 312 from the collimator is converged by a condenser lens 401, passes through a quarter-wave plate 402, and reaches a reflecting mirror 403.

Here, if the light beam 411 incident on the cat's eye is y-polarized light, it becomes clockwise circularly polarized light at the quarter-wave plate, and
03 becomes counterclockwise circularly polarized light, the light beam 414 that passes through the 174-wave plate 402 again has a polarization direction different by 90 degrees from that when it enters the cat's eye, and becomes X-polarized light.

The light beam 414 passes through the condenser lens 401 and emerges as a parallel light beam 415, which passes through the objective lens 302 of the collimator and the condenser lens 301, and becomes linearly polarized light 3 which enters the collimator.
The linearly polarized light 313 whose polarization direction is different from that of 11 by 90° is input into the interferometer unit 200 again.

Further, the output angle from the length measuring light collimator 3 is finely adjusted by moving the objective lens 302 of the collimator.

Here, the 1/4 wavelength plate 402 provided in the cat's eye operates as an interferometer no matter where it is placed between leaving the interferometer unit 200 and the cat's eye reflecting mirror 403.

However, since the beam diameter between the collimator and the cat's eye is large, a quarter-wave plate with a large diameter is required, which is disadvantageous.

Furthermore, since the beam diameter is small at the exit of the interferometer unit 200, the diameter of the quarter-wave plate can be small, which is advantageous in this respect.

However, the output light that passes through the collimator becomes circularly polarized light, so if you try to bend the measurement light or reference light using a reflective prism, the reflectance will differ depending on the polarization direction, so after bending it The light becomes elliptically polarized, causing problems in the structure of the interferometer.

Therefore, in the present invention, a quarter wavelength plate is inserted into the cat's eye to eliminate these disadvantages.

In this way, since the light flux in the cat's eye is a convergent/divergent system, the optical path difference within the quarter-wave plate will differ slightly between the center and the periphery, but if the degree of convergence of the light flux is small, the optical path will be The difference is much smaller than λ/4 and does not pose a problem.

Also, by inserting a 1/4 wavelength plate into the cat's eye like this, both the length measurement light and the reference light can be linearly polarized, and even if you change the direction of the light beam using a reflector, the polarization direction will not change. You can keep it from changing.

Therefore, when measuring the length by changing the length measurement direction arbitrarily, the direction can be easily changed using the reflecting mirror without changing the direction of the interferometric length measuring device itself.

FIG. 7 is a diagram showing an example of a length-measuring light output angle fine adjustment mechanism for aligning the optical axis of the length-measuring light.

A is a diagram showing the mechanism, and b is a diagram explaining the optical operating principle.

In FIG. 7a, 300 is a base body, for example, the housing of the interferometer section 2 shown in FIG.

301 is a condensing lens shown in FIG. 6, which is held in a condensing lens frame 310 fixed to the base 300.

Reference numeral 321 is an objective lens frame that holds the objective lens 302, is screwed into the movable frame 322, and is rotatable in the optical axis direction, so that the parallelism of the emitted light can be adjusted.

The movable frame 322 is connected to the intermediate frame 340 by two parallel leaf springs, a leaf spring 331a and another leaf spring not shown.
It is inked in the direction B so that it can move parallel to the B direction.

This intermediate frame 340 has a cross shape, and portions corresponding to vertical lines and horizontal lines do not intersect but are separated.

There is also a hole in the center that allows light to pass through.

Further, the intermediate frame 340 is suspended from a fixed frame 350 by parallel plate springs consisting of two plate springs 332a and 332b, so that it can move in parallel to the A direction.

This fixed frame 350 is fixed to the base 300, and has a hole in the center through which light passes.

323a is a length measurement light output angle fine adjustment knob in the A direction;
0, and is pressed against the opposite part of the screw of the fine adjustment knob 323a by parallel leaf springs 332a and 232b.

Moreover, 323b is a length measurement light output angle fine adjustment knob in the B direction, which is screwed into the base body 300, and is pressed against the part of the fine adjustment knob 323b opposite to the screw by two parallel plate springs (not shown) with 331a.

The fine adjustment knobs 323a and 323b can be turned from the outside of the panel 326.

324 is a lock screw after fine adjustment, and 325 is a washer.

As described above, the fixed frame 350, intermediate frame 340, movable frame 32
2. Leaf springs 331a, 331b (not shown), 332a
, 332b are engaged to move the objective lens frame 321 between A and B.
It is held on the base body 300 so as to be movable in the direction.

Next, the operation of this length measurement light emission angle fine adjustment mechanism will be explained.

First, when the fine adjustment knob 323a is turned, the movable frame 322 moves in the A direction, and since the movable frame 322 and the intermediate frame 340 are connected by another set of parallel leaf springs 331a, the intermediate frame 340 is fixed. Parallel leaf springs 332a, 3 to the frame 350
32b in parallel.

Next, when the fine adjustment knob 323b is turned, the intermediate frame 340 and the fixed frame 350 are replaced by a pair of parallel plate springs 332a, 332b.
Since the intermediate frame 340 does not move, the movable frame 3
22 moves parallel to the intermediate frame 340 in the B direction against the parallel leaf spring 331a.

Therefore, the movable frame 322 as a whole can freely move within a plane parallel to the A and B directions.

After fine adjustment, lock the washer 325 with the lock screw 324.
The movable frame 322 is attached to the panel 32 by tightening the movable frame 322 through the
Fixed to 6.

Here, in the present invention, in order to make the strength of the springs in the A direction and the B direction the same, each of the parallel plate springs 331a, 331b, 33
2a and 332b have the same width, length, and thickness. In particular, in order to make the spring lengths the same, the intermediate frame 340 has the same width, length, and thickness. The mounting positions are staggered.

According to the mechanism configured in this way, the center position of the objective lens 302 can be freely adjusted within a plane perpendicular to the axis.

The amount of adjustment cannot be changed very drastically, but for example ±0.
It can be moved about 5 mm.

FIG. 7b is an explanatory diagram of the operating principle of fine adjustment of the length measurement light emission angle.

Here, 301 is a condenser lens, 302 is an objective lens, and 3
11 is a light beam incident on the collimator, and 312 is a parallel light beam after adjusting the emission angle.

When the objective lens 302 is arranged on the same axis as the condenser lens 301, that is, at the position of the objective lens 302' indicated by the broken line, the outgoing light 312' is emitted in parallel with the incoming light 311.

Next, in a plane perpendicular to the axis of the objective lens 302, δ
When the output light 312 is shifted by an angle of Δθ - δ/f radians, the emitted light 312 is bent in the shifted direction.

Here, f is the focal length of the objective lens 302.

In a light wave interferometer, the length measurement light must match the movement direction of the length measurement cat's eye, that is, the movement direction of the measurement stage.
Interference fringes no longer appear and length measurement cannot be performed.

According to the present invention, in the configuration shown in FIG. 1, the direction of the emitted light can be easily finely adjusted by moving knobs in both directions arranged at right angles to each other, instead of the conventional method of moving the entire unit.

Furthermore, in the configuration shown in FIG. 3, conventionally the light source section 1 and the interferometer section 2 had to be moved together, but according to the present invention, the output light can be easily adjusted by moving the knobs in both directions. You can fine-tune the direction.

In addition, in the above description, fine adjustment of the emission direction was performed by moving the objective lens 302, but the condenser lens 301
A similar effect can be obtained by moving the .

8 is a diagram showing details of the reference side cat's eye 6 shown in FIG. 1, in which a is a perspective view showing its appearance, b is a sectional view showing its internal structure, and C is another embodiment according to the present invention. It is a figure showing an aspect.

This reference side cat's eye 6 is normally screwed into the reference light entrance/exit port 24 of the interferometer section 2, but it can be removed as needed, as shown in FIG. 8a.

FIG. 8b shows this cat's eye 6 on the base 3 of the interferometer section 2.
00 is a diagram showing a state in which it is screwed into a reference destination entrance/exit port 24 provided in 00.

This cat's eye 6 consists of a condensing lens 601, a quarter-wave plate 602, and a reflecting mirror base glass 604 with a reflecting mirror film surface 603 provided on the quarter-wave plate 602 side, and each of these optical elements is a reference cat's eye. It is attached to the eye frame 610.

This reference cat's eye frame 610 includes a screw portion for screwing into the base body 300 and a tapered surface 211 of the reference light exit/input port 24.
It has a tapered surface 611 that matches.

Reference numeral 612 is a lid that prevents dirt, dust, etc. from entering after each optical element is attached to this cat's eye frame 610.

Further, a reflective mirror base glass 604 having a reflective mirror film surface 603
is held and fixed by a plurality of adjustment screws 620.

By rotating this adjustment screw 620 from the outside of the cat's eye frame 610, the reflector base glass 604 is moved to adjust the centering of the reflector film surface 603. After adjustment, the adjustment screw is fixed with lock paint varnish, etc. do.

Further, the tapered surface 611 of the cat's eye frame 610 is connected to the base body 30.
This makes it possible to align the center of the reflecting mirror with the optical axis with good reproducibility.

FIG. 8C is a diagram showing another usage mode of the reference side cat's eye 6. In this case, the reference side cat's eye 6 is connected to the interferometer section 2.
More detached.

This separated reference-side cat's eye 6 is attached to a fixed point on the system to be measured 100, and the movable cat's eye for length measurement 4 is attached to the measurement stage 101 on the system to be measured 100.

With this configuration, even if the optical path from the beam splitter of the interferometer to the cat's eye becomes long, the reference side cat's eye 6 and the moving cat's eye for length measurement 4 are brought as close as possible and are kept in the same position. Since it is installed in the measured system iooh, it is possible to avoid as much as possible the effects of fluctuations due to changes in air temperature between the beam splitter and both cat's eyes, and the effects of relative vibrations between both cat's eyes, making it possible to perform precise measurements. can be long.

FIG. 9 is a diagram showing in detail the configuration of the interference fringe observation mirror 29 shown in FIG. 4.

The interference fringe viewing mirror 29 collects interference fringe incident light 29 at the tip of the lens barrel 291.
A total reflection prism 244 receiving 0 is provided, and the prism 24
An entrance window 292 is provided in a portion of the lens barrel 291 facing 4.

Further, a lens frame 293 having a screen 245 and a magnifying lens 246 is provided at the other end of the lens barrel 291.

The interference fringe observation mirror 29 having such a configuration is inserted through the interference fringe observation port 23 shown in FIG. 4, and the interferometer unit 20 shown in FIG.
Total reflection prism 244 for interference light 285 or 289 within 0
The image is projected onto the receiving screen 245 using a magnifying lens 246.
Zoom in and observe.

Here, by simply rotating this interference fringe observation mirror 29 by 90° around the optical axis in the direction of arrow 294, interference light 285 or 2
89 can be taken out and observed at will.

Furthermore, by removing the lens frame 293 from the lens barrel 291, the incident light 290 can be projected onto another screen separate from the interference fringe observation mirror 29 for observation.

In the present invention, by providing such an interference fringe observation mirror 29, the interference fringes incident on the photo sensor can be easily observed without moving the photo sensor, and the optical axis of the interferometer and cat's eye can be accurately aligned. be able to.

For this reason, accurate length measurement values can be obtained, good interference fringes can be obtained, and interference fringe signals with a high S/N ratio can be obtained.

As described above, according to the present invention, it is possible to achieve portability with a small configuration,
It is possible to reduce the weight, and even though it is made small, the influence of heat from the laser light source section can be reduced and precise length measurement can be performed.

Further, by optionally inserting an interference fringe observation mirror into the interferometer unit, it is possible to closely observe the interference fringes incident on the detector without moving the internal optical system or the detector.

Therefore, accurate optical axis alignment between the interferometer and the cat's eye can be easily performed, and an interference fringe signal with a high S/N ratio can be obtained.

Further, since the emission angle of the length measurement light can be adjusted by the length measurement light output angle fine adjustment mechanism provided in the interferometer section, adjustment can be easily performed whether the light source section and the interferometer section are integrated or separated.

Therefore, there is no need to move the entire optical interferometer, and even if the measuring distance becomes long, there will be no problem in measuring the length.

Furthermore, even when the measurement distance becomes long, the reference side cat's eye can be removed from the interferometer section and attached to a fixed point on the measured system, so there is no need to worry about air fluctuations or interference with the measuring side moving cat's eye. Precise length measurement with little error can be performed without being affected by relative vibration.

Furthermore, since a 1/4 wavelength plate is inserted into the cat's eye, both the length measurement light and the reference light can be linearly polarized, and the polarization direction will not change even if the direction of each beam is changed using a reflector. When measuring length by changing the length measurement direction arbitrarily, the length can be measured by changing the direction using the reflecting mirror without changing the direction of the interferometric length measuring device itself.

[Brief explanation of drawings]

Fig. 1 is an external view of the optical interferometer of the present invention, Fig. 1a is a perspective view from the front direction, Fig. 1b is a perspective view from the back direction,
Fig. 2 is an exploded view of the light wave interferometer of the present invention, Fig. 3 is a diagram of another state of use of the light wave interferometer of the present invention in which the light source section and the interferometer section are arranged separately, and Fig. 4 is the light wave interferometer of the present invention. Fig. 5 is a diagram showing the arrangement of each optical element and the optical path of an embodiment of the light source section and interferometer unit; Fig. 6 is an optical path of an embodiment of the collimator cat's eye. FIG. 7 is a diagram showing an embodiment of the length measurement light output angle fine adjustment mechanism, FIG. 7a is a diagram of its mechanism, FIG. Figure 8 is a diagram showing one embodiment of the reference side cat's eye, and Figure 8a is a perspective view showing its appearance.
FIG. 8B is a cross-sectional view showing the internal structure, FIG. 8C is a view showing another embodiment of the present invention, and FIG. 9 is a detailed view of one embodiment of the interference fringe observation mirror. DESCRIPTION OF SYMBOLS 1... Laser light source part, 2... Interferometer part, 3... Length measurement light collimator, 4... Length measurement side moving cat's eye, 5... Reference light collimator, 6... Reference side cat's eye, 25... Length measurement light inlet/outlet, 29...Interference fringe observation mirror.

Claims (1)

[Claims] 1 In the mechanism for finely adjusting the output angle of the output light, the base 3
00, a plate-shaped fixed frame 350 in which a through hole is formed, a block-shaped intermediate frame 340 in which a through hole is similarly formed, and a connection between the through hole of the intermediate frame 340 and the fixed frame 350. The through holes are arranged to face each other, and the intermediate frame 340 is arranged in one dimension, that is, A, with respect to the fixed frame 350.
at least two parallel plate springs 332a and 332b for movability in the A direction, which connect the intermediate frame 340 and the fixed frame 350 so as to be movable in the directions; a plate-shaped movable frame 322 in which a through hole is formed; The through hole of the movable frame 322 and the through hole of the intermediate frame 340 are arranged to face each other, and the movable frame 322 is movable relative to the intermediate frame 340 in a direction perpendicular to the direction A, that is, in the direction B. As such, at least two parallel plate springs for movement in the B direction connecting the movable frame 322 and the intermediate frame 340 are disposed in the through hole of the movable frame 322 directly or through a lens frame. The objective lens 302 and the base 30 for moving the movable frame 322 in the A direction with respect to the base 300 for fine adjustment.
0 and the movable frame 322, and the base for finely adjusting the position by moving the movable frame 322 in the B direction relative to the base 300. An output angle fine adjustment device comprising a B direction position fine adjustment means 323b disposed between a table 300 and the movable frame 322.