JPH0914914A - Laser light projection method and apparatus therefor in device measuring for moving value by laser speckle pattern - Google Patents

Abstract

PURPOSE: To enable recognition of an image without missing and distortion thereof on the side of measurement by aligning an optical axis of irradiation light with the optical axis of the reflected light to eliminate completely shadow and distortion of a picture otherwise generated from a relationship between angles of incidence and reflection in an object to be measured in a means by which light emitted to object to be irradiated also being the object to be measured is reflected to reach the side of identification. CONSTITUTION: Laser light A is oscillated from a laser oscillator 4 and transmitted through a non-spherical lens 10 and a grid plate 9 to be a desiredly set laser light. The position of setting te laser oscillator 4 is set so that a reflector 11 is irradiated with the laser light A. The laser light A made incident on the reflector 11 is polarized and a speckle pattern 3 is projected on a measuring surface of an object 1 to be measured. The speckle pattern is recognized by a CCD camera 5. In this manner, the optical axis of incident light as laser light A is aligned with the optical axis of the reflected between the object 1 to be measured and the reflector 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for measuring the amount of movement of an object to be measured by a speckle pattern using a laser beam, which enables measurement with high accuracy. The present invention relates to a method and an apparatus thereof.

[0002]

BACKGROUND OF THE INVENTION The present invention irradiates an object to be measured with a laser beam, captures a speckle pattern drawn in an image range of an irradiated area as a mark, optically detects this, and performs arithmetic processing. In addition, this is output and displayed as a measured value.

The information recognized by the discriminating side is to be revealed as more accurate information.

[0004]

2. Description of the Related Art In a non-contact method of measuring the amount of movement, a speckle pattern drawn in the image area of the irradiated area is optically recognized as a mark by irradiating the measured object with laser light. In addition, regarding the measuring method and the apparatus for calculating and displaying the measured value by arithmetically processing the recognition pixel, Japanese Patent Application No. 5-277 filed by the same applicant as the present patent application.
No. 437 and Japanese Patent Application No. 5-277438.

[0005]

In the above-mentioned prior art, the oscillator that oscillates the laser beam and the measuring mechanism that receives the reflected light from the object to be measured are installed in a position close to each other. , The optical axis of the laser light oscillated from the oscillator is more than the line orthogonal to the DUT,
Since the optical axis is oblique through a certain angle, a “shadow” is formed in the case where the object to be measured has a surface configuration with large irregularities. When this information is transmitted as reflected light, information having a missing portion may be transmitted from the original current state.

As a drawback other than the above-mentioned shadow generation phenomenon, when the irradiated laser light is irradiated from a direction other than the direction orthogonal to the surface of the object to be measured, in the widened image range, the optical axis is the center. Even within concentric circles farther and closer to the optical axis, an error occurs due to the difference in the projection distance, resulting in an asymmetric image, providing a factor for the occurrence of the distortion phenomenon, and as a result displaying inaccurate measured values. There is an inconvenience.

According to the present invention, when the light irradiated to the object to be irradiated is reflected and the reflected light reaches the identification side, when the relationship between the incident angle and the reflection angle is generated in the measured object. In order to eliminate the generation of shadows and distortion of images, the optical axis of the irradiation light and the optical axis of the reflected light are made to be the same so that the missing image and the image without distortion can be recognized on the measurement side. That is the purpose.

[0008]

The present invention is, as means for achieving the above object, a method for measuring the amount of movement in a non-contact manner as an invention of a method, in which an object to be measured is irradiated with laser light. By optically recognizing the speckle pattern drawn in the image area of the irradiated area as a mark by performing the arithmetic processing of the recognized pixels and displaying and outputting the measured numerical value, the irradiated area is A reflector is provided on the optical axis of the light flux that is more reflected, and the wide-angle laser irradiation light is reflected by the reflector, and the optical axis of the polarized laser irradiation light and the optical axis of the light flux reflected from the irradiation area are aligned. It becomes something like.

Further, as an invention of the apparatus, there is provided a means for measuring a moving amount of an object to be measured using a laser beam, wherein the device uses a speckle pattern utilizing the laser beam,
CCD that reflects from the illuminated area and receives the reflected light
A reflector is provided on the optical axis of the light flux between the cameras so that the optical axis of the laser irradiation light is reflected by the reflector and is polarized, and the optical axis of the light flux reflected from the irradiated area is one. It is composed.

[0010]

The present invention is based on the operation of the system of the basic technical idea, and when the basic operation is touched, there are roughly three elements.

The first is an element for irradiating an object to be measured with laser light.

The second is an element for forming a speckle pattern in the image range of the irradiated area of the laser light on the object to be measured.

Thirdly, an element for capturing a speckle pattern imaged on the object to be measured as a mark, optically detecting the mark, performing arithmetic processing, and outputting and displaying this as a measured value. ,.

By summarizing the above-mentioned elements and summarizing them, a laser beam is applied to the object to be measured, and a speckle pattern is drawn on the rough surface of the object to be measured. Of the speckle pattern in parallel with the movement of the CCD (Charge Couple Device; Charge Couple Device).
d Dev) (hereinafter referred to as CCD) camera, and the electrical signals obtained by the shooting are realized in CCD pixel units by a computer. Time calculation processing is performed and the numerical value of the moving distance is displayed and output.

In order to achieve the method of the present invention, a semiconductor laser oscillator, a high-resolution CCD, an A / D (Analog Digital) converter, an arithmetic processing unit, and a CRT (Cathode R) are used as a verifier of its basic elements.
an ay tube display (monitor), which is a constituent feature of the present invention, and which optically polarizes laser light using a reflector having an optical polarization action, for example, a mirror body or prism. Is.

When an object to be measured having a non-uniform surface is irradiated with a laser beam having a very high coherence from a laser oscillator, the laser lights scattered at various points on the rough surface of the object interfere with each other in an irregular phase relationship. Therefore, a grainy pattern is generated. This granular pattern is called a speckle pattern.

Here, when the object to be measured moves laterally, the speckle pattern also moves laterally.

With this speckle pattern as a marker, C
It continuously captures images with a CD camera, converts an analog signal into a digital signal with an A / D converter, inputs it to a computing device, and outputs the pattern to a CRT.

The operation of the present invention will now be described. In addition to the above-mentioned basic method, the image plane of the object to be measured and a CCD camera for taking a speckle pattern reflected from the object to be measured can be described. Laser light having a reflector interposed on the optical axis of the light flux, a laser oscillator installed at a location separated from the CCD camera, a grating plate sequentially installed from the laser oscillator side, and a lens having an aspherical surface transmitted therethrough. Is oscillated toward the above-mentioned reflector, which is polarized by the reflector to irradiate the object to be measured with laser light.

That is, the optical axes of the laser irradiation light and the reflected light of the speckle pattern are made to be on the same line between the object to be measured and the reflector, which is the main requirement of the present invention. .

As a result, the laser irradiation light has a line orthogonal to the measurement surface of the object to be measured as the optical axis of the laser irradiation light and the optical axis of the speckle pattern reflected light. Even if there is an extremely uneven surface on the measurement surface, it is possible to eliminate the phenomenon of shadow generation, and the contrast in the image area is made uniform, so that an accurate speckle pattern can be reflected to the CCD camera. It is possible.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, as a pre-stage for explaining an embodiment of the present invention with reference to the drawings, each part will be described as an object to be measured and a verification device for achieving the system of the present invention.

1 is an object to be measured. Reference numeral 2 denotes an image range of a CCD (Charge Coupled Device) camera 5. Reference numeral 3 is a speckle pattern drawn by the laser oscillator 4 on the object 1 to be measured with a rough surface when the object 1 is irradiated with laser light. 4 is a laser oscillator. 5 is a CCD camera. 6 is CCD
A for converting analog signal of camera 5 to digital signal
/ D (Analg / Digital) converter. Reference numeral 7 is an arithmetic unit for calculating the vertical and lateral movement amounts using the speckle pattern 3 as a marker. 8 is a CRT (Cathode Ray Tube di) that directly visually observes the speckle pattern 3.
display).

The laser oscillator 4 uses high brightness, directivity and visible light in order to draw a stable speckle pattern 3 on the object to be measured 1, is composed of a laser element, a cooling circuit, a drive circuit and a lens, and oscillates. The aspherical lens 10 is transmitted to the optical axis of the laser beam A to be formed so that a light beam having a widening ratio set can be formed, and this is transmitted through the grating plate 9 to draw the speckle pattern 3 of the set pattern. .

The CCD camera 5 is used to capture the speckle pattern 3 drawn on the object to be measured 1 and has a function of converting the speckle pattern 3 into an NTSC signal (analog data). Depending on the size of the speckle pattern 3 determined, a zoom lens may be used to enlarge or reduce the density finely and easily for computer processing.

The A / D converter 6 has a function of converting an analog signal into a digital signal. The NTSC signal is an analog signal. Therefore, it is necessary to convert the speckle pattern 3 into a digital signal in order to store it in the storage element of the computer. Since the speckle pattern 3 is a bright and dark spot pattern, for example, it is converted into binarization in which a bright point is "1" and a dark point is "0".

The arithmetic unit 7 continuously stores the movement state (speckle pattern) of the object to be measured in a storage element, calculates the movement of an arbitrary bright and dark point at CCD pixel intervals (reference length), and as numerical information. Display output.

The CRT8 is used in the verification, experiment and test stages.
The speckle pattern 3 and the moving distance are displayed on the CRT monitor screen and used for the purpose of visualizing the pattern and the moving state. However, on a practical machine, the travel distance is displayed and output as a numerical value on the Seven Segment Display.

The present invention will be described based on the above-described basic arrangement of each part. CC for recognizing the speckle pattern 3 drawn on the DUT 1 described above.
The center line of the field of view of the D camera 5, in other words, Light flux B of the reflected light reflected from the DUT 1 by the speckle pattern 3
The optical axis O of which exhibits an optical polarization effect, for example, a specular body,
The reflector 11 formed of a prism or the like is interposed.

The laser oscillator 4 oscillates and passes through the aspherical lens 10 and the grating plate 9 to become a laser beam A of a desired setting, and the laser beam A is irradiated onto the reflector 11. Set the installation position of.

The laser light A applied to the reflector 11 is polarized and applied, and the speckle pattern 3 is applied to the measurement surface of the DUT 1.
Is projected.

As described above, the speckle pattern 3 projected on the object to be measured 1 is transferred to the CCD camera 5 as described above.
Is what you recognize.

As described above, the optical axis of the incident light, which is the laser light A, and the optical axis of the reflected light are aligned between the DUT 1 and the reflector 11.

In this way, when the optical axes of the incident light and the reflected light are set to be the same, the optical axis is only in the direction orthogonal to the measurement surface of the object 1 to be measured, so that the surface to be measured is temporarily assumed. Even if unevenness is formed, the shadow is not formed.

However, although the reflector 11 is projected in the range of the image recognized by the CCD camera 5, the accurate speckle pattern 3 of the object to be measured 1 is recognized on the outer periphery of the projected range. Therefore, it is possible to identify the portion de-imaged as a shadow as an extension of the recognized image of the accurate speckle pattern 3 beyond the outer circumference of the shadow.

Next, the basic operation for carrying out the embodiment of the present invention will be described with reference to the drawings. When the object to be measured 1 is an aluminum plate, the aluminum plate is irradiated with laser light, A photograph of the speckle pattern actually drawn is shown in FIG.

The object to be measured 1 is irradiated with laser light, the speckle pattern 3 is photographed by the CCD camera 5, the intermediate color due to light and dark is removed by the A / D converter 6, and converted into two signals of light and dark. Input to the arithmetic unit 7.

Here, in order to facilitate the explanation of the method,
For convenience, FIG. 4 shows a state in which the speckle pattern 3 recognized by the arithmetic unit 7 is arranged in bright and dark in CCD pixel units.

A pattern recognized by the arithmetic unit 7 when the object to be measured 1 is irradiated with the laser beam A is shown in FIG.

From this state, the object to be measured 1 is CCD as shown in FIG.
FIG. 6 shows a state in which the object 1 is moved to the left by one pixel, and FIG. 6 shows a state in which the DUT 1 is moved downward by one pixel in the CCD.

FIG. 7 shows a state in which the DUT 1 is further moved downward by one pixel.

As a result, FIGS. 4 to 7 show that the DUT 1 has moved one pixel to the left and two pixels downward.

The distance per CCD pixel is 10 μm.
When m is set, in FIG. 4 to FIG. 7, the DUT 1 has moved 10 μm to the left and 20 μm downward, and the amount of movement can be measured without contact.

In the case of a long object, immediately before the speckle pattern 3 as a marker is out of the field of view of the CCD camera 5, the pattern generated on a new surface is recognized again as a marker, and the amount of movement is measured by repeating the recognition. To do.

[0045]

INDUSTRIAL APPLICABILITY According to the present invention, since the optical system is directly irradiated with the laser light, the optical system can be simplified, and it is effective against external vibration and shock. The laser light is monochromatic light. Therefore, the speckle pattern itself has the characteristic that blur does not occur. By adding a telephoto lens to the CCD camera, it is possible to easily measure the vertical and horizontal movement amounts of distant objects, and to apply this method. By doing so, there is a basic effect that can be applied to acceleration, average velocity, seismic intensity meter, etc.

The present invention is based on the above-mentioned basic operation and effect, and makes the irradiation laser light incident on the object to be measured from the direction orthogonal to the measurement surface of the object to be measured. Since the optical axis of the reflected light taken by the CCD camera is naturally aligned with the optical axis of the incident light, it is possible to recognize the accurate speckle pattern projected on the object to be measured. By this, it is effective to be able to display accurate measured values.

[0047]

[Brief description of the drawings]

FIG. 1 Configuration diagram of an embodiment according to the present invention FIG. 2 Plan view of FIG. 1 FIG. 3 Actual speckle pattern drawn on an aluminum plate FIG. 4 Speckle pattern diagram for each CCD pixel unit recognized by an arithmetic unit for convenience 5 The figure in which the object to be measured has moved to the left by one CCD pixel. Figure 6 The figure in which the object to be measured has moved downward by one CCD pixel. Figure 7 The figure in which the object to be measured has moved downward by one CCD pixel.

[0048]

[Explanation of symbols]

 1 Object to be Measured 2 Image Range 3 Speckle Pattern 4 Laser Oscillator 5 CCD Camera 6 A / D Converter 7 Arithmetic Device 8 CRT 9 Lattice Plate 10 Aspherical Lens 11 Reflector A Laser Light B Luminous Flux of Reflected Light O Optical Axis

Claims (2)

[Claims] 1. A non-contact means for measuring a movement amount, wherein a speckle pattern drawn in an image range of an irradiated area is optically recognized as a mark by irradiating a measured object with a laser beam. In the measuring method in which the recognition pixel is arithmetically processed and the measured numerical value is displayed and output, a reflector is provided on the optical axis of the light flux reflected from the irradiation area, and the widened laser irradiation light is applied to the reflector. Laser light in a device for measuring the amount of movement by a laser speckle pattern, characterized in that the optical axis of the laser irradiation light that is reflected and polarized on the optical axis is aligned with the optical axis of the light beam that is reflected from the irradiated area. Irradiation method. 2. A device for measuring the amount of movement of an object to be measured using laser light, comprising: an apparatus using a speckle pattern using laser light, wherein the reflected light is reflected from an irradiation area and A reflector is provided on the optical axis line of the light flux between the CCD cameras for receiving light, and the optical axis of the laser irradiation light is reflected by the reflector to be polarized, and the optical axis of the light flux reflected from the irradiated area is one. An apparatus for irradiating a laser beam in an apparatus for measuring a movement amount by a laser speckle pattern, which is configured as described above.