JP2748175B2 - Auto collimator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autocollimator, and more particularly, to an autocollimator excellent for use in inspecting an inclination angle, flatness, surface roughness, etc. of a test object. .

[Conventional technology]

FIG. 5 is a configuration diagram showing an example of a conventional autocollimator.

In the figure, 12 is a light source composed of a tungsten lamp or the like, 70 is a condenser lens, 40 is a half mirror, a beam splitter such as a half prism (semi-transparent prism), 50 is a collimator lens, and 55 is perpendicular to the optical axis of the autocollimator. It is a surface plate provided. The focal plane of the collimator lens 50 is changed by the beam splitter 40 to the beam splitter.
In addition to the focal plane 51 on the transmission side of 40, two focal planes 52 are formed on the reflection side (light source side in this example). Reference numeral 21 denotes a focus plate, for example, in which a scale such as a cross line and a scale is engraved on one surface of a transparent glass plate, and the scale surface is set so as to match the focal plane 51. The plate is illuminated by the light source 12 and the condensing lens 70, and the focusing plate is installed so that its scale surface coincides with the focal plane 52. Reference numeral 56 denotes an object placed on the surface plate 55; An eyepiece for magnifying and observing the scale surface of the plate 21.

A case will be described in which a parallel flat plate made of, for example, a steel material and having both surfaces polished is inspected using the autocollimator. A surface plate 55 is provided in advance perpendicular to the optical axis connecting the collimator lens 50 and the center of the focusing plate 21, and an accurate parallel flat plate having a reflection surface is mounted on the surface plate 55, and the light is reflected from the reflection surface. The image of the pinhole or the crosshair of the reticle 22 formed on the reticle 21 by the light is adjusted so as to match the crosshair of the reticle 21. Next, a parallel flat plate, which is the test object 56, is placed on the surface plate 55, and the image of the focusing plate 22 formed on the focusing plate 21 by reflected light reflected from the upper surface of the parallel flat plate is an eyepiece. Observe by 92. At this time, the focusing screen 22
If the image of the pinhole or the crosshairs of (4) and the crosshairs of the reticle 21 match, the front and back surfaces of the parallel flat plate are parallel. The inclination is poor and the inclination angle can be obtained from the amount of deviation and the focal length of the collimator lens 50. In addition, if the pinhole image or the crosshair image of the focusing screen 22 looks sharp and not distorted, the flatness and the surface roughness are good, and if the pinhole image or the crosshair image looks distorted, the flatness is low. Is poor and the contrast is low and unclear, it can be known that the surface is large and is a so-called rough surface.

[Problems to be solved by the invention]

Originally, in the autocollimator, if a point light source having a small luminous area and a high luminance is placed on the focal plane 52 of the collimator lens 50 and this reflected image is formed on the scale plane of the reticle 21, inspection is easy and quick. Can be done.
However, conventionally, there is only a tungsten lamp as a light source that can be used simply. With a tungsten lamp, a sufficient light amount cannot be obtained unless the area of the light emitting section is increased, and the test object 56
If the area is not large, the brightness of the reflected image also becomes dark, and it is difficult to perform a precise inspection. Therefore, conventionally, as shown in FIG. 5, a focusing plate 22 engraved with a pinhole or crosshair is installed on a focal plane 52 on the light source side, and this is illuminated using the light source 12 of a tungsten lamp and a condenser lens 70. However, if the area of the test object 56 is small, the contrast of the scale image is low, the image becomes dark and cannot be inspected, and the optical system is complicated and assembly adjustment is complicated. Was.

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

[Means for solving the problem]

The object is to provide a beam splitter between a collimator lens and its focal plane, and to provide a light source comprising a semiconductor laser on one of two focal planes of the collimator lens formed by the beam splitter or a plane conjugate with the focal plane. And a two-dimensional image sensor is provided on another focal plane or a plane conjugate to this focal plane, and a separate index generating means is provided, and information output from the two-dimensional image sensor is output from the index generating means. The present invention is also achieved by an autocollimator characterized in that it is configured to be displayed on a monitor television in addition to the above.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1 to 4 show an embodiment of the autocollimator of the present invention. The same or corresponding parts as those in FIG. 5 are indicated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, 10 is a semiconductor laser that emits a laser beam of, for example, a single wavelength of 780 nm, and 60 has a two-dimensional light receiving surface, for example.
In a two-dimensional image sensor (hereinafter referred to as an image sensor) such as a CCD sensor or a vidicon tube, the light emitting portion of the semiconductor laser 10 is on the optical axis of the focal plane 52, and the light receiving surface of the image sensor 60 is on the focal plane 51. It is installed so that the center coincides with the optical axis. 61
Denotes an image processing unit that processes an image signal transmitted from the image sensor 60; 62, a video monitor including a CRT or a liquid crystal display that receives a signal from the image processing unit 61 and displays an image; and 63, a video monitor 62 An index generating circuit which is an index generating means for transmitting a signal for displaying a polar coordinate having the origin at the center of the display unit or a scale indicating a distance from the crosshair and the center to the image processing unit 61; A characteristic detection circuit that detects and calculates characteristics such as the inclination, flatness, and surface roughness of the surface of the test object 56 based on a signal from 61, and 65 digitally converts the characteristics based on a signal sent from the characteristic detection circuit 64. It is a digital display unit for displaying. The center of the scale is the image sensor
Adjusted during assembly to match the optical axis (center) on the 60 light receiving surfaces.

Although the light emitting part of the semiconductor laser 10 is as small as 1 x 3 µm in diameter, the light output is as large as 5 to 50 mW and extremely high brightness, and since it is coherent at a single wavelength, a collimator lens generates a parallel light beam with no aberration. As a result, a diffraction image corresponding to the shape of the test object can be formed on the light receiving surface of the image sensor 60. However, it is difficult to directly observe with the naked eye with near-infrared light of 780 nm, which is a general wavelength of a semiconductor laser at present. Observation with the naked eye is possible using semiconductor laser light of shorter wavelength (for example, 670 nm),
When observing an object having a high reflectivity and a large area, the light image formed on the focal plane 51 has extremely high brightness, and the retina may be burned, which is dangerous.

In the present invention, the image sensor 60 is used, and its image signal output is displayed on the video monitor 62 provided separately for the CRT and the liquid crystal display via the signal processing unit 61, so that the advantage of using the semiconductor laser is utilized. The above danger is avoided.

 Next, the configuration and operation of the present invention will be described.

The laser light emitted from the semiconductor laser 10 is reflected by the beam splitter 40, and is collimated by a collimator lens.
50 makes the parallel light beam with high accuracy and the test object on the platen 55
The light is incident on 56 test surfaces. The reflected light reflected from the test surface of the test object 56 passes through the collimator lens 50 and the beam splitter 40 again, and then forms a point image on the light receiving surface of the image sensor 60 (hereinafter, this is referred to as an optical image). The image signal transmitted from the image pickup device 60 is combined with the index signal transmitted from the index generation circuit 63 in the image processing section 61 and the fourth signal is output to the video monitor 62.
It is displayed as shown in the figure.

Further, in this embodiment, the image signal (scanning signal of the image) processed by the image processing unit 61 is also sent to the characteristic detection circuit 64, for example, the inclination, flatness, and surface roughness of the surface of the object 56 to be inspected. The measurement results of characteristics such as height are digitally displayed on the digital display section 65.

Since the method of detecting the shape of the light image from the scanning signal of the image and obtaining 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 the data is already possible by a known technique. Detailed description is omitted.

FIG. 3 is a block diagram showing an example of a circuit for performing image signal processing according to the present invention. In the figure, reference numeral 612 denotes a test object measurement button to be pressed when a digital display is desired;
2, 643 detects the shape of the light image based on the image signal obtained by scanning the image surface sent from the image processing unit 61,
Each detection circuit of the characteristic detection circuit 64 that detects and calculates characteristics such as the inclination, flatness, and surface roughness of the test object 56 from the data. 641 calculates the center position after detecting the shape of the optical image, calculates the deviation of the center position from the optical axis, and stores the coefficient determined by the focal length of the collimator lens 50 from the conversion memory 641a which is input in advance. A test object tilt detection circuit 642 calculates the area from the shape of the light image, converts the area into a tilt amount by the coefficient of the standard, and inputs and stores a standard area corresponding to the type of the test object 56 in advance. A test object flatness detection circuit that converts the standard area from the area memory 642a into a value representing the flatness of the test surface of the test object 56, and 643 detects the illuminance of the light image and detects this illuminance. A standard value memory that integrates the entire light image, and preliminarily inputs and stores a standard value determined from the integrated value and the reflectance and reflection area of the test surface of various test objects.
This is a circuit for detecting the surface roughness of a test object, which is converted into a numerical 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) as compared with the standard value from 643a. 651,65
Reference numerals 2 and 653 denote a display surface tilt display unit, a test surface flatness display unit, and a test surface roughness display unit of the digital display unit 65. In addition,
The digital display section 65 can be provided in common without being provided separately, or can be displayed on a part of the video monitor 62 as shown at 65a in FIG.

In FIG. 4, reference numeral 62a denotes the parallelism (inclination) of the test surface of the test object 56,
It shows an optical image when the flatness and roughness are good, 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, and as the planarity worsens, the light image becomes larger and distorted from a circle, and as the smoothness worsens, the light image becomes more indistinct. The brightness decreases. 62b shows an example of a light image when the surface to be detected is defective.

In measurement, the test object 56 is placed on the surface plate 55, and after confirming that an optical image is displayed on the video monitor 62, the test object measurement button 612 is pressed. After passing through the image processing section 61 and the characteristic detection circuit 64, the image signal is digitally displayed on the digital display section 65 or a part of the video monitor 62.

As described above, in the autocollimator of the present invention, since the semiconductor laser 10 is used, the brightness of the light source is high, the light image is clearly displayed on the video monitor 62, and the necessary information can be easily and simultaneously obtained in an analog manner. As a result, the digital display is displayed on a part of the digital display unit 65 or the video monitor 62 in a digital form that can be easily grasped.

Further, it is also possible to discriminate a non-defective product from a defective product by a digital signal and to issue an alarm, so that the inspection efficiency can be remarkably improved.

In addition, the use of the semiconductor laser 10 can reduce and adjust the intensity of light simply by inserting one polarizing filter in the optical path and rotating since the laser light emitted from the laser is linearly polarized. It is very convenient for adjustment because it can be done.

Needless to say, the above configuration may be changed so that the two-dimensional image pickup device 60 is provided on the focal plane 52 on the reflection side of the beam splitter 40 and the semiconductor laser 10 is provided on the focal plane 51 on the transmission side. In addition, it is of course possible to dispose a heat ray absorption filter on the optical path to protect the semiconductor laser 10 and the two-dimensional imaging device 60.

FIG. 2 is a block diagram showing another embodiment of the present invention. In the present embodiment, the light image formed on the focal plane 51 is transferred to the image sensor 60 by the image forming lens 90. The imaging lens 90 is a zoom lens, and the magnification can be changed as needed (zoom imaging function). Reference numeral 91 denotes the zoom unit. 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 accordance with the change of the magnification. Further, in this embodiment, a beam splitter 41 having a reflecting surface formed of a dichroic mirror is provided in the optical path in close contact with the beam splitter 40, and visible light such as red light or green light is provided at a position substantially corresponding to the focal plane of the collimator lens 50. A marker light source 14 composed of a light emitting diode or the like that emits light is provided, and a parallel light beam (marker light) that can be seen with the naked eye is transmitted toward the surface plate 55 so as to exhibit a marker function of displaying a testable range. I can do it. Since the dichroic mirror of the beam splitter 41 reflects red or green light and transmits light on the long wavelength side, the laser light is hardly attenuated. In addition, the marker light reflected and returned from the test object 56 is entirely reflected by the beam splitter 40 and does not enter the imaging device 60. In this way,
This embodiment is particularly effective when the placement position of the test object 56 can be easily understood, and particularly when the test object 56 is at a long distance. Further, it has an excellent feature that the magnification can be freely changed according to the required measurement accuracy and the visual field range.

The marker function and the zoom imaging function may be performed independently. When a semiconductor laser 10 that emits visible light having a wavelength of 670 nm is used, the light source itself can have a marker function.

〔The invention's effect〕

According to the present invention, the configuration of the optical system is extremely simplified by the above-described configuration and image signal processing, and the luminance of the light source is high, so that a test object having a small test area can be inspected. It is possible to provide an autocollimator having an excellent effect that adjustment is easy and various kinds of inspection information can be accurately obtained at one time.

BRIEF DESCRIPTION OF THE 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 performs image signal processing of the present invention. FIG. 4 is a block diagram showing an example of a circuit, 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 40, 41 Beam splitter 50 Collimator lens 51, 52 Focal plane 55 Platen 56 Test object 60 Two-dimensional image sensor ( Image sensor 61 Image processing unit 62 Video monitor 63 Index generation circuit 64 Characteristic detection circuit 65 Digital display unit 90 Imaging lens

Claims (1)

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