JPS6076604A - Method and apparatus for measuring deformation of body having coarse surface by phase modulated speckle interferometer - Google Patents

Abstract

PURPOSE:To perform automatic analysis of the amount of deformation, by obtaining the phase of three sheets or more of speckle images caused by the interference of laser light before the deformation of a body to be measured, and determining the amount of the deformation based on the difference between said phase and the phase obtained by the same way after the deformation. CONSTITUTION:Laser light 2 from a laser light source 1 is divided into light paths 6 and 7 through a mirror 3 and an objective lens 4 by a semitransparent mirror 5. The laser light beams of the light paths 6 and 7 are projected on a body to be measured 8 and a reference surface 9. Scattered light rays 10 and 11 are combined by the semitransparent mirror 5, and an image is formed on a photoelectric converter device 12. The phase of the reference light 11 is changed by N times by 2pi/N (N>=3) by a driving device 4, and the interference intensity is stored in a memory 15. The phase theta1 of a speckle image before deformation is obtained by using the data of a large-capacity memory 17 by an operating device 16. The phase theta2 after the deformation is obtained by the same way. The amount of the deformation is computed by theta2-theta1, and the result is displayed on a display device 18.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a phase variation speckle interferometer to measure the deformation 11 of a rough surface object! +Jllll related to a measuring method and a measuring device thereof.

Measuring the deformation t1 of an object is extremely important not only in a wide range of academic disciplines such as engineering, medicine, and dentistry, but also in manufacturing industries such as electrical and electronic equipment, furnaces, and joints. A total of 8111. Particularly in the manufacturing industry, deformation analysis of structures also determines the basic design concept of the eye-catching product, so there is no need for a simple, real-time measurement method! ;stomach. The mainstream of current deformation measurement methods is to process and analyze multidimensional signals from strain cages. However, when the deformation of an object becomes complex, such multi-point information becomes insufficient, and it becomes essential to obtain one-dimensional information.

Furthermore, in fields such as medicine, objects are soft and it is impossible to attach strain gauges to them. Speckle interferometry is a measurement method that satisfies these requirements, but in the past it was a qualitative measurement method that simply observed a striped pattern representing the uniformity of the amount of deformation.

The present invention has been made in view of the above, and an object of the present invention is to provide a method and an automatic analysis device for automatically analyzing the amount of deformation using a phase modulation speckle interferometry method and a measurement system.

This objective can be achieved by the methods and @communications described below.

At least 3
The phase θ of the speckle image before deformation is determined by creating a third interference speckle image, and the object laser beam from the object to be measured after deformation is caused to interfere with the reference laser beam having a different phase. In both cases, three second interference speckle images are created, the phase θ2 of the deformed speckle images is determined, and the amount of deformation of the fixed object on the fixed side can be determined as 02-01. The first method is to interfere the object laser beam from the surface of the object to be measured before object deformation with the reference laser beam.
The object laser beam from the surface of the deformed object to be measured and the reference laser beam having different phases are made to interfere with each other to create at least three first interference speckle images I. , the square of the difference between the first interference speckle image and the first interference speckle image can be determined, and the amount of deformation of the offshore object can be determined from the value of these differences.

FIG. 1 shows seven examples of block diagrams for implementing the present invention. A laser beam 2 from a laser beam 1 is spread by a mirror 3 and an objective lens 4, and is divided into an optical path 6 and a beam M7 by a semi-transparent mirror 5. The laser light on the optical path 6 illuminates the object to be measured 8 , and the laser light on the optical path 7 illuminates the reference surface 9 . Light scattered from the measured surface 8 and the reference surface 9 10.
11 are superimposed again by a semi-transparent mirror 5, and an image is formed on a light 1 image conversion device 12 (such as a TV camera or COD camera). Here, if the phase shifter (PZT, Faraday Rocheetah, half-wave plate, etc.) 13 and its drive device 14 (high-voltage power supply, rotary drive circuit, etc.) changes the phase of the reference light 110 by φ, then the photoelectric conversion device g#12 The light intensity I at is I=α
It can be written as +βcos(θ, +φ). Here, φ is i/N
(rad) (N≧3) N times and the output signal of the photoelectric conversion device 12 representing this I is recorded in the memory 15, and then passed through the signal processing/arithmetic device 16 to the large capacity memory 17.
0 recorded here, 01 is the phase of the interference speckle image. Using the data in the large-capacity memory 17, the deviation amount fX4 g! , 16 to determine the phase θ of the speckle image. By changing φ by 2π outside [rad] N times, the speckle shape is 12, and by changing φ by 2π outside [:rad'] N times, we get the following image: 1'1z 1'2+...
By creating IIN and performing calculations, the phase θ2 of the deformed speckle image is adjusted. And θ2−
01! 1. This becomes the amount of deformation of the object to be measured.

Furthermore, using the system shown in FIG. 1, the amount of deformation can also be automatically analyzed by the following method. Scattered light 10 from the surface 8 of the object to be measured before the object is deformed and light 11 scattered by the reference surface 9 are caused to interfere in the photoelectric conversion device P112, and a streak image (2) is obtained. This is photoelectric ψ
The converted signal is converted into an electric signal by a conversion device ^°12, and after being recorded in a memory 15, it is recorded in a thick one-layer memory 17 via a converter wt16. Next, while the object 8 is being deformed, the phase shifter 13 and its drive circuit 14 are used to change the position d of the reference laser beam 11 to:ln/N[rad'J (N > 3) 4'N times. : Also, N first interference speckle images 11.
, P2...IIN is created, converted into an electric signal representing the light intensity 11' by the photoelectric conversion device g112K, recorded in the memory l5, and transmitted through the arithmetic unit 16 to the electric signal representing the light intensity 11'. It is recorded in the capacity memory 17. Based on the data recorded in the "thick" memory 17, we will first say /+-(+,-t,)2(+=1.2..
......, N) to form N speckle interference fringes. At this time, the speckle interference pattern f1 has a phase difference of 02-0 before and after the object deformation, and (2πI/N
) l/(Σflcos(2πlΔ0)], it is determined that 1=1. Since this instrumentation result still contains noise, the performer/processor 16 performs spatial filtering,
A median filter, a spatial differential operation, etc. are performed, and the amount of deformation, i, stress, bending moment, etc. are output to the display device 18.

EXAMPLE An aluminum disc with a diameter of 20πm1 and a depth θ/2 was used as the object 8 to be deformed, and its surface was spray-painted white. The outer circumference of this object is fixed, and a P with a diameter of 31 um is placed in the center.
ZT was bonded and deformed by applying high voltage. As the laser source 1, a He-Ne laser of SθmW was used, and as the phase shifter 13, an acrylic flat plate with a white surface coated on PZT was used.
A high voltage circuit was used as the dispatch device @14 to change the phase of the reference laser beam J1. The photoelectric conversion device 12 - (is T
A V camera is used, and the memory 15 is T for /frame.
A mini-computer was used as the digital frame memory for recording V images and the processing unit 16, and a magnetic disk was used as the large-capacity memory 17.

The output signal from the TV left camera 2 was converted to VD.

A Glotter was used as the output display device 18.

Figure 2 shows the output results as equal displacement lines,
The line spacing corresponds to an out-of-plane displacement of 0.3 μm.

Figure 3 is a representation of the same output as Figure 2 as a Totetsu diagram, and the deformation of the object can be clearly seen.

As described in detail above, the present invention provides a method and device that can automatically and non-contact online split 11 the shaped needles of an object, so that it can be used for manufacturing products, especially aviation tires, ICs, etc. It can contribute to faster and more accurate internal product management and process control, such as detecting damage due to thermal deformation and abnormalities in composite particles.

[Brief explanation of the drawing]

Fig. 1 is a block diagram for explaining the present invention, and Figs. 1 and 3 are a contour map and a bird's eye diagram of displacement amounts obtained in an embodiment of the present invention. Code in the diagram: 1...Laser surface", 2161
7.10.11... Laser light, 4...
...Objective lens, 5...Semi-transparent mirror, 8...
・Object, 9...Reference plane, 12...
Light weight conversion device, 13... Phase shift device, 14...
...Multi-phase device drive bean production, 15...Memory,
16...Arithmetic/processing device, 17...Large capacity memory, 18...Display device. Figure 2 Figure 3 Showa year month/day 1, case description 1984 Patent Application No. 184932 3
, Relationship with the person making the amendment Applicant name (679) RIKEN 4, Agent 5, Date of amendment order Voluntary 6, Subject of amendment Claims column 7 of the specification, Contents of amendment Attachment 91N, Claims (1) Object laser beam from the surface of the object to be measured before deformation is caused to interfere with a reference laser beam having a different phase to form at least three first interference speckle images. The phase θ1 of the created speckle image before deformation is set, and the object laser beam from the object to be measured after deformation is made to interfere with a reference laser beam having a different phase to form at least three second interference speckle images. A method for measuring deformation of an object, characterized in that the phase θ2 of a speckle image after being created and deformed is determined, and the amount of deformation of the object to be measured is determined as 02−θ1. (2) Set the phase of the reference laser beam to 2π [rad]
(N≧3) N times, and N corresponding first interference speckle images 1. , L , ... IM and after deforming the phase θ1 of the speckle image before deformation,
The phase of the reference light is changed N times by 2π [rad], and N corresponding second interference speckle images 1' are created.
, I'2 , ... l'2, and the phase θ2 of the deformed speckle image is jE I '3 cos(2πj
2. The method for measuring deformation of an object according to claim 1, wherein J=1 and the amount of deformation of the object to be measured is determined as θ2 to θ1. (3) Create a first interference speckle image 11 by interfering the object laser beam from the surface of the object to be measured before object deformation and the reference laser beam, and create the object laser beam from the surface of the object to be measured after deformation by interfering with the reference laser beam. At least three second interference speckle images are created by interfering the light with a reference laser beam having a different phase, and the square of the difference between the second interference speckle image and the first interference speckle image is calculated. A method for measuring deformation of an object, characterized in that the amount of deformation of the object to be measured is determined from the square of these differences. [4] After object deformation, change the phase of the reference laser beam to 360
”/N (N≧1) N times, and N corresponding second interference speckle images 1'1°1'2...
・Create I'o and combine the second interference speckle image and the first
The square of the difference between the interference speckle image and the interference speckle image f1-(de, , +,
>2. f2=(do, -+,)"..., fN=(1'w +, f, and the amount of deformation of the object to be measured is determined by the method for measuring deformation of an object according to claim 4. (5) A first optical path from the laser light source to the surface of the object to be measured and from the surface of the object to the imaging tube, a second optical path from the laser light source to the imaging tube via the phase shift means, and An apparatus for creating an interference speckle image of an object, comprising a driving device for driving the phase shifting means. (6) The apparatus according to claim 7, wherein the phase shifting means is a vibration reflecting surface. ( 7) The device according to claim 7, wherein the phase shifting means is an electrically controlled Faraday rotor. (8) The device according to claim 7, wherein the phase shifting means is a rotating half-wave plate.
? Apparatus according to claim 7.

Claims (8)

[Claims] (1) Speckle images before deformation by making at least three first interference speckle images by interfering with the object laser beam from the surface of the measured object before deformation and a reference laser beam with a different phase. At least three second interference speckle images are created by interfering the object laser beam from the deformed object to be measured with a reference laser beam having a different phase, with a phase θ1 of the deformed speckle image. A method for measuring deformation of an object, characterized in that the phase θ2 of the object is determined, and the amount of deformation of the object to be measured is determined as 02-01. (2) The phase of the reference laser beam is changed N times by 2 ('rad) (N-3), and the corresponding N first interference speckles (& 11 r 12 +...・
・・Create IN, determine the phase θ of the speckle image before deformation, (2πI/N ) ), and after deforming the object,
The phase of the reference light is changed N times by 2 yr/N [rad), and the corresponding N-th interference speckle images ■'1゜■'2...ILN are obtained. The phase θ2 of the speckle image after creation and deformation is determined from (2πI/N months), and the amount of deformation of the object to be measured is determined as 02-0. Deformation measurement method. (3) The object laser beam from the surface of the object to be measured before object deformation and the reference laser beam are caused to interfere with each other to form a first interference speckle image 11. The object laser beam and the reference laser beam having different phases are made to interfere to create at least three U-th interference speckle images, and the difference between the U-th interference speckle image and the first interference speckle image is calculated. A method for measuring deformation of an object, characterized in that the amount of deformation of the object to be measured is determined from the square of the difference. (4) After object deformation, change the phase of the reference laser beam to 3 A
Oc/NCN≧g) N times, and N corresponding first interference speckle images I'. 1/ , ......1', is created, and the square of the difference between the second interference speckle image and the first interference speckle image /, = (1'1- t,)2+ 72-(1'2-1.
)2. The method for measuring deformation of an object according to claim 11, wherein the amount of deformation of the object to be measured is determined as /N-(T', -1). (5) a first optical path from the laser light source to the surface of the object to be measured and from the surface of the object to the imaging tube; a first optical path from the laser light source to the imaging tube via the phase shifting means; An apparatus for creating an interference speckle image of an object, which is equipped with a driving device that drives a phase shifting means. (6) The @trade according to claim 7, wherein the phase shifting means is a fixed reflection surface. (7) The foil manufacturing according to claim 7, wherein the phase shifting means is a Faraday low-cheater controlled by lh. (8) Claim 1) in which the phase shifting means is a rotating plate;