JPH03226618A - Auto collimator - Google Patents

Abstract

PURPOSE:To inspect an object of a very small inspecting area by displaying the information output from a second dimensional pickup device along with the index information from an index generating means on a video monitor. CONSTITUTION:A laser light from a semiconductor laser 10 is reflected by a beam splitter 40 and changed to parallel beams with high accuracy by a collimator lens 50. The parallel beams are incident upon the surface to be inspected of an object 56 on a surface plate 55. The light reflected from the to-be-inspected surface of the object 56 is, through the lens 50 and beam splitter 40, formed into a spot image on the receiving surface of a second dimensional pickup device 60. Then, the image signal fed from the device 60 is combined with an index signal from an index generating circuit 63 at an image processing part 61 and, displayed by a video monitor 62. Moreover, the image signal processed in the processing part 61 is fed also to a characteristic detecting circuit 64. The inclination, flatness, surface roughness and the like characteristic of the to-be-inspected surface of the object 56 detected by the circuit 64 are digitally displayed by a digital display part 65.

Description

Detailed Description of the Invention: Industrial Application Field The present invention relates to an autocollimator, and more particularly to an autocollimator that is excellent for use in inspecting the inclination angle, flatness, surface roughness, etc. of a test object. .

:Prior Art] The fifth prisoner is a configuration diagram showing an example of a conventional autocollimator.

In the figure, 12 is a light source such as a tungsten lamp, 70 is a condenser lens, and 40 is a beam splitter 150 such as a half mirror or a half prism (semi-transparent prism).
5 is a collimator lens, and 55 is a surface plate provided perpendicularly to the optical axis of the autocollimator.

The beam splitter 40 forms two focal planes of the collimator lens 50: a focal plane 51 on the transmission side of the beam splitter 40 and a focal plane 52 on the reflection side (in this example, the light source side). . Reference numeral 21 denotes a focus plate having scales such as cross lines and graduations engraved on one side of a transparent glass plate, and is installed so that the scale plane coincides with the focal plane 51. Reference numeral 22 denotes a focus plate having pinholes or cross lines engraved thereon. The focus plate is illuminated by the light source 12 and the condensing lens 70 and is installed so that its scale plane coincides with the focal plane 52. Reference numeral 56 indicates the object to be examined placed on the surface plate 55. Reference numeral 92 indicates the focus plate. This is an eyepiece lens for magnifying and observing the scale surface of the plate 21.

A case will be described in which the autocollimator is used to inspect, for example, a flat parallel plate made of steel and polished on both sides. A surface plate 55 is provided in advance perpendicular to the optical axis t connecting the centers of the collimator lens 50 and the focus plate 21, and a precise parallel plane plate having a reflective surface is placed on the surface plate 55, and the reflection from this reflective surface is The pinhole or crosshair image of the focusing plate 22 that is imaged on the focusing plate 21 by the light emitted from the focusing plate 21 is
Adjust it so that it matches the crosshairs. Next, a plane-parallel plate, which is the object to be inspected 56, is placed on the surface plate 55, and the reflected light j reflected from the upper surface of the plane-parallel plate is reflected by the focus plate 2.
The image formed on the focusing plate 22 is observed through the eyepiece lens 92. At this time, if the pinhole image or the crosshair image of the focusing plate 22 and the crosshair image of the focusing plate 21 match, the front and back surfaces of the parallel plane plate are parallel; The front and back surfaces are tilted due to poor parallelism.
The inclination angle can be determined from the amount of shift and the focal length of the collimator lens 50. Also, if the pinhole image or crosshair image of the focus plate 22 appears clearly without distortion, the flatness and surface roughness are good, and if the pinhole image or crosshair image appears distorted, the flatness is good. If the surface is defective and the contrast is low and there is an unclear T, it can be seen that the surface roughness is large and is a so-called rough surface.

[Problem to be solved by the invention]

Originally, in the autocollimator, a point light source with a small light emitting area and high brightness is placed on the focal plane 52 of the collimator lens 50, and the reflected image is formed on the scale plane of the focal plate 21. This makes inspection easier and faster. can be done. However, the only light source that can be easily used in the past is a tungsten lamp, and with a tungsten lamp, a sufficient amount of light cannot be obtained unless the area of the light emitting part is large, and the brightness of the reflected image will be low unless the area of the test object 56 is large. It was dark and it was difficult to conduct a detailed inspection. Therefore, conventionally, as shown in FIG. 5, a focus plate 22 with a pinhole or a crosshair engraved thereon is installed on the focal plane 52 on the light source side, and this is illuminated using the light source 12 of a tungsten lamp and the condensing lens 70. Perhaps because the area of the object to be inspected 56 is small, the contrast of the scale image is low and it becomes too dark to inspect, and the optical system is complicated, making assembly and adjustment difficult. Ta.

The present invention solves these problems and provides an autocollimator that has a simple optical system, is easy to assemble and adjust, is easy to inspect, and can be easily inspected even if the area of the object to be inspected is small. With the goal.

[Means to solve the problem]

The above object is to provide a beam splitter between a collimator lens and its focal plane, and to connect a semiconductor laser to one of the two focal planes of the collimator lens formed by the beam splitter or a plane conjugate to this focal plane. A light source is provided, a two-dimensional imaging device is provided on another focal plane or a plane conjugate to this focal plane, and an index generating means is provided separately, and information output from the two-dimensional imaging device is transmitted from the index generating means. Autoco 1 characterized in that it is configured to be displayed on a monitor television together with index information.
This is achieved by data.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

1 to 4 are diagrams showing embodiments of the autocollimator of the present invention. The same or equivalent parts as in FIG. 5 are indicated using the same reference numerals, and detailed explanation thereof will be omitted.

FIG. 1 is a block diagram showing an embodiment of the present invention.

In the figure, IO is a semiconductor laser that emits laser light with a single wavelength of 780 nm, for example, and 60 is a two-dimensional image sensor (hereinafter referred to as an image sensor) such as a CCD sensor or a vidicon tube having a two-dimensional light-receiving surface. The light emitting part of the laser 10 is located on the optical axis of the focal plane 52, and the image sensor 60
The light-receiving surface of is located at the focal plane 51, and the center thereof is placed so as to coincide with the optical axis. 61 is an image processing section that processes the image signal sent from the image sensor 60; 62 is a video monitor consisting of a CRT or liquid crystal display that displays an image in response to the signal from the image processing section 61; and 63 is a video monitor. 6
64 is an image processing unit; 64 is an image processing unit; 64 is an image processing unit; The test object 56 is detected by the signal from 61.
A characteristic detection circuit 65 detects and calculates the characteristics such as the inclination, flatness, surface roughness, etc. of the surface to be tested, and 65 is a digital display unit that digitally displays the above-mentioned characteristics based on the signal sent from the characteristic detection circuit 64. The center of the scale is adjusted during assembly so that it coincides with the optical axis (center) on the light receiving surface of the image sensor 60.

The light emitting part of the semiconductor laser IO has a diameter of IX3. Although it is as small as um, it has a large optical output of 5 to 50 mW and is extremely bright, and is coherent at a single wavelength.
The collimator lens generates an aberration-free parallel light beam, and a diffraction image corresponding to the shape of the object to be examined can be formed on the light receiving surface of the image sensor 60. However, it is difficult to observe directly with the naked eye using near-infrared light of 780 nm, which is currently the common wavelength for semiconductor lasers. shorter wavelength (for example, 6
It is possible to observe with the naked eye using semiconductor laser light (70 nm), but when observing a large-area object with a high reflectance, the light image formed on the focal plane 51 becomes extremely bright, and the retina It is dangerous as there is a risk of burning out.

In the present invention, an image sensor 60 is used, and the image signal output is displayed on a separately provided video monitor 62 such as a CRT or liquid crystal display through a signal processing section 61, so that the advantages of using a semiconductor laser can be realized. However, the above-mentioned dangers are avoided.

Next, the structure and operation of the present invention will be explained.

The laser light emitted from the semiconductor laser 10 is reflected by the beam splitter 40 and converted into a highly accurate parallel beam by the collimator lens 50, which is incident on the test surface of the test object 56 on the surface plate 55. The reflected light reflected from the test surface of the test object 56 passes through the collimator lens 50 and the beam sinter 40 again, and forms a dot-like image on the light receiving surface of the image sensor 60 (hereinafter referred to as an optical image). . The image signal sent from the image sensor 60 is combined with the index signal sent from the index generation circuit 63 in the image processing section 61 and displayed on the video monitor 621 as shown in FIG.

In this embodiment, the image signal (image scanning signal) processed by the image processing unit 6j is also sent to the characteristic detection circuit 64, and the inclination, flatness, etc.
The measurement results of characteristics such as surface roughness are digitally displayed on a digital display section 65.

The method of detecting the shape of the light image from the image scanning signal and determining the center position of the light image, the area of the light image, the illuminance distribution of the light image and its integral value from this data is possible using well-known techniques. Therefore, detailed explanation will be omitted.

FIG. 3 is a block diagram showing an example of a circuit for outputting an image signal according to the present invention. In the figure, 612 is a pinched object measurement button that is pressed when digital display is desired; 64]
, 642, 643 detect the shape of the optical image based on the image signal obtained by scanning the image plane sent from the image processing unit 6I, and determine the inclination, flatness, and surface of the object 56 from the data. Characteristic detection circuit 6 that detects and calculates characteristics such as roughness
4 detection circuits.

641 is a conversion memory 641a that detects the shape of the optical image, calculates its center position, calculates the deviation of this center position from the optical axis, and stores a coefficient determined by the focal length of the collinator lens 50. 642 is an object inclination detection circuit that converts the amount of inclination to the amount of inclination using a coefficient from . A sandwiched object flatness detection circuit compares the standard area from the standard area memory 642a and converts it into a numerical value representing the flatness of the surface to be inspected of the specimen 56, and 643 detects the illuminance of the optical image and calculates this illuminance. The integrated value is compared with the standard value determined from the reflectance and reflection area of the test surface of various test objects from the standard value memory 643a which has been input and stored in advance. hand,
This is a test object surface roughness detection circuit that converts a value corresponding to the surface roughness of the test surface of the test object 56 (corresponding to, for example, Rmax according to the JIS standard). Reference numerals 651, 652, and 653 are a test surface inclination display section, a test surface flatness display section, and a test surface surface roughness display section of the digital display section 65.

Note that the digital display section 6S can be provided in common without having to provide a separate number, or it can be displayed on a part of the video monitor 62 as shown at 65a in FIG.

62a in FIG. 4 is the parallelism (inclination) of the surface to be tested of the test object 56.
, shows an optical image with good flatness and roughness, and is a minute circular optical image located at the center of the scale.

As the parallelism of the test surface worsens, the light image shifts from the center of the scale; as the flatness worsens, the light image becomes larger and distorted from a circular shape; and as the smoothness worsens, the light image becomes unclear. Its brightness decreases. 62b shows an example of an optical image when the surface to be inspected is defective.

For measurement, place the test object 56 on the surface plate 55,
After confirming that the optical image is displayed on the video monitor 62, when the object measurement button 612 is pressed, the image sensor 60
The image signal sent from the image processing section 61 and the characteristic detection circuit 64 are then digitally displayed on a digital display section 65 or a part of the video monitor 62.

As described above, since the autocollimator of the present invention uses a semiconductor laser IO, the brightness of the light source is high, and the light image is clearly displayed on the video monitor 62, making it possible to easily obtain necessary information in an analog manner at once. The digital display section 65 allows for accurate and easy-to-understand information.
Or it will be displayed on a part of the video monitor 62.

Further, it is also possible to discriminate between good products and defective products using digital signals and to issue an alarm, thereby significantly improving inspection efficiency.

Furthermore, when using a semiconductor laser IO, the laser light emitted from it is linearly polarized, so the intensity of the light can be reduced and adjusted simply by inserting a single polarizing filter into the optical path and rotating it. This is extremely convenient for adjustment.

Note that in the above configuration, the two-dimensional image sensor 60 is placed on the focal plane 52 on the reflection side of the beam splitter 40, and the semiconductor laser l
It goes without saying that O may be provided at the focal plane 51 on the transmission side. Of course, it is also possible to protect the semiconductor laser 10° two-dimensional imaging device 60 by disposing a heat ray absorption filter on the optical path.

FIG. 2 is a block diagram showing another embodiment of the present invention. Book 5
1! In the embodiment, the optical image formed on the focal plane 51 is projected onto the image sensor 60 by the imaging lens 90. The imaging lens 90 is a zoom lens, and the magnification can be changed as necessary (2-inch imaging function). 91 is its zoom section. As the magnification is changed, the index interval of the index generation circuit 63, the converted value in the characteristic detection circuit 64, and the standard value are also changed. In this embodiment, a beam splitter 41 whose reflecting surface is a dichroic mirror is further provided in the optical path in close proximity to the beam splitter 40, and a beam splitter 41 is provided in the optical path to emit, for example, red or green light at a position approximately corresponding to the focal plane of the collimator lens 50. A marker light source 14 made of a light emitting diode or the like that emits visible light is provided, and a marker light source 14 is provided that emits a parallel light beam (marker light) that can be seen with the naked eye toward a surface plate 55 to exhibit a marker function of displaying an inspection range. It is now possible to do two things. Since the dichroic mirror of the beam splitter 41 reflects red or green light and transmits light on the longer wavelength side, there is almost no attenuation of the laser light. Further, the marker light reflected from the object 56 and returned is all reflected by the beam splitter 40 and therefore does not enter the image sensor 60. In this way, the present embodiment has the test object 56.
The mounting position of the test object 56 can be easily determined, which is particularly effective when the test object 56 is located at a long distance. It also has the excellent feature that the magnification can be freely changed depending on the required measurement accuracy and visual field range.

The marker function and zoom imaging function may each be implemented independently. For example, if a semiconductor laser that emits visible light with a wavelength of 670 nm is used, this light source itself can have a marker function.

〔Effect of the invention〕

According to the present invention, due to the configuration and image signal processing as described above, the configuration of the optical system is extremely simple, and the brightness of the light source is high, making it possible to inspect even a small inspection area.
In addition, it has become possible to provide an autocollimator that is easy to assemble and adjust, and has the excellent effect of accurately obtaining various inspection information every time.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a block diagram showing another embodiment of the present invention, and FIG. 3 is a block diagram showing an example of a circuit that performs image signal processing of the present invention. , FIG. 4 is a diagram showing a video monitor image obtained by the autocollimator of the present invention, and FIG. 5 is a configuration diagram showing a conventional autocollimator. 10... Semiconductor laser 14... Marker light source 4
0.41...Beam splitter 50...Collimator lens 51.52...Focal plane 55...Surface plate 56...
Test object

Claims (1)

[Claims] A beam splitter is provided between a collimator lens and its focal plane, a light source made of a semiconductor laser is provided on one of the two focal planes of the collimator lens formed by the beam splitter, or a plane conjugate to this focal plane, and A two-dimensional image sensor is provided on the focal plane of the image sensor or a plane conjugate to the focal plane, and an index generating means is provided separately, and the information output from the two-dimensional image sensor is combined with the index information from the index generating means to generate a video. An autocollimator characterized in that it is configured to be displayed on a monitor.