JPS62190404A - Measuring instrument for body shape - Google Patents

Abstract

PURPOSE:To measure the shape, etc., of a body which has a smooth surface with high accuracy under non-contact state by displaying interference fringes which vary with measurement distance in synchronism with oscillations of laser light oscillated in a pulse shape. CONSTITUTION:Pulsating laser light from a semiconductor laser 12 which is driven with pulses passes through a collimator lens 13, a beam splitter 9, a 1/4-wavelength plate 8, a half-mirror 11, etc., to become illumination light L1 to a moving body 14 to be measured. The reflected light L2 of this illumination light L1 which is reflected by the body 14 and the illumination light L1 form interference fringes corresponding the distance corresponding to the shape of the body 14. The interference fringes are displayed on a display device which performs display operation in synchronism with the laser 12 by TV, etc., through an objective 5, etc. Consequently, variation of the display interference fringes is utilized without using any speckle interference pattern to measure the shape and shape variation with high accuracy even when the moving body has the smooth surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an object shape measuring device that uses interference fringes to measure the shape and shape change of an object traveling at high speed.

[Technical background of the invention and its problems]

Optical measurement methods using laser light are used to non-contactly measure the shape of an object traveling at high speed, especially how the object changes over a short period of time. One of the measurement methods that utilizes this laser light is speckle interferometry. The speckle pattern obtained by this speckle interferometry is a speckled pattern obtained when scattered light interferes with each other when a laser beam is irradiated onto a rough surface. Interference fringes due to the two light beams appear just before the , and these interference fringes become speckle interference fringes on the object plane. These speckle interference fringes indicate the deformation of the rough surface and can therefore be used to inspect the shape of the object traveling at high speed.

However, in speckle interferometry, the speckle pattern is inherently poor, and the contrast depends on the roughness of the surface, and if the surface becomes extremely smooth, the speckle pattern will no longer appear and the shape of the surface will be affected. Inspection becomes impossible.

[Purpose of the invention]

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide an object shape measurement IT capable of non-contact measurement of the shape and shape change of an object to be measured having a smooth surface.

[Summary of the invention]

The device of the present invention includes a semiconductor laser device that is pulsed and driven by a driving source, and a laser beam from the semiconductor laser device that interferes with the irradiation light that irradiates the object to be measured and the irradiation light that is reflected from the object to be measured. an optical system that divides the reference beam into a reference beam that creates fringes; a display means that determines the shape and shape change of the object to be measured from the interference fringes created by this optical system; and a display device that adjusts the oscillation period of the laser beam and The apparatus is equipped with a pulse oscillator that outputs a pulse number 1g for displaying the interference fringes of the object to be measured on the display means 1 in synchronization with the oscillation of the apparatus.

[Embodiments of the invention]

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

The measuring device shown in FIG. 2 is equipped with a microscope (1). A television camera (4) is connected to an eyepiece (2) of this microscope (1) via an optical amplifier (3) that amplifies the intensity of the optical image. Further, an interferometer (6) is arranged opposite to the objective lens section (5) of the microscope (1). This interferometer (6) has an optical system (7) as shown in FIG.

This optical system (force is a beam splitter (9) that extracts one of the P or S polarization components and guides it to the quarter-wave plate (8).
) and a half mirror αυ placed opposite to the quarter wavelength plate (8). The beam splitter (9) is configured so that the laser beam output from the semiconductor laser & The beam is reflected by the beam splitter (9) and transmitted through the 1/4 modification plate (8) to reach the half mirror αυ. A part of the laser light is transmitted through this half mirror (lυ) to the object to be measured. becomes the irradiation light L1 that irradiates u4), and the other part becomes the irradiation light L1 that irradiates the half mirror (
11) and becomes a reference light. The irradiation light is reflected by the object to be measured I and then transmitted through the half mirror αυ, causing interference with the reference source Lt. Therefore, interference fringes are formed according to the shape of the measurement surface of the object to be measured I, and these interference fringes, that is, optical signals, are generated by the microscopic device mentioned above! (1) It is designed so that 1 light is incident.

A first driving device 4 for driving the television camera (4) is connected to the television camera (4). A monitor uQ is connected to the first drive device α. Further, the semiconductor laser device (13 has a second drive device (13) for pulse-driving the semiconductor laser device (13).
11 are connected. Then, the first drive device 0
An oscillator (181) is provided between 9 and the second drive device αD.
is provided, and the pulse 1 from the output from this oscillator time is
In synchronization with the rise of the g ST.

In other words, the first two-pivot device (15) to which the pulse signal S'v is triggered and this pulse signal 8T is input outputs a pulsed mJ'+M number SL, and by this drive signal SL. Laser light is output from the semiconductor laser device 1.1, and an image from the television camera (4) is captured on the monitor (IF5) in synchronization with the oscillation of the laser light. Pulse signal ST
The period P0 can be adjusted with 1 oscillator and 0 barrels. Further, the pulse width T of the pulse signal ST is set (ζ) to be longer than the time required for one frame of the monitor aO. On the other hand, the pulse width T of the drive signal SL is
As will be described later, the time width is set so that the interference fringes are not blurred.

According to the measuring device configured in this way, the laser light output from the semiconductor laser device (1) is divided into the irradiation light and the reference light L2 by the -7 mirror (11). Interference fringes are created by the light according to the shape of the object to be measured Q41 irradiated by the irradiation light,
Since this interference fringe is displayed on the monitor αe, it is possible to know the shape of the object to be measured 04).

Furthermore, since the semiconductor laser device σ2 is pulse-driven by the second driving device (Iη) based on the pulse signal BT, if the interference fringes for each pulse are compared, the change in the shape of the object to be measured (14) during that time can be seen. You can also ask for

By the way, if the object to be measured I is tape-shaped as shown in FIG. 4 and is traveling at high speed in the direction of arrow (V), If there is a deformation of H, and if the wavelength of the laser beam is λ, then
The number m of interference fringes that appear in response to deformation is expressed by the linear equation.

m −2H/λ ...■ Also, the average interval Δd of interference fringes is expressed by the linear equation 〇.

Δd = d / 2m = d *λ/4H-,, ■ If the permissible movement amount of the object to be measured I to avoid blurring the interference fringes is Δd/10 or less, then the pulse width T of the semiconductor laser device (I21 is It is expressed by the linear equation (■).

Tt<Δd/1O-v)d・λ/40・H・■・・・■
For example, V = 1 (m/s), d = 1 (II
'+), H = 100 (μm When λ = 08 (μm), the formula -Tt < 0.2μ is obtained. In this embodiment, the pulse width of the synchronization signal ST from one oscillator is determined by the above V, d, By changing it in accordance with H and λ, blurring of interference fringes can be prevented.

〔Effect of the invention〕

According to the object shape measuring device of the present invention, the shape of an object to be measured that has a smooth surface and moves at high speed can be measured in terms of oblateness. In particular, since the interference fringes are displayed on the display means 1 in synchronization with the oscillation of the pulsed laser beam, continuous changes in the interference fringes can be observed accurately.

[Brief explanation of drawings]

Is the drawing an implementation of this invention? Fig. 1 is a block diagram of the interferometer, Fig. 2 is a schematic diagram of the entire device, and Fig. 3 (1)...
Microscope, (3)... Optical amplifier. (4)...TV camera, (9)...beam splitter. (11) Half mirror 1α2 Semiconductor laser device. )・C14)...Object to be measured, (Le
. . . Monitor (display means), C171 . . . Second drive source, Bet . . . Oscillator. Agent Patent Attorney Nori Ken Yudo Takehana Kikuo Figure 1 +7 +FI 16th
2 Figure 111-T1---/'7 Figure 4 Figure 5

Claims (2)

[Claims] (1) A semiconductor laser device that is pulse-driven by a driving source, an interference pattern formed by the irradiation light that irradiates the object to be measured with pulsed laser light from the semiconductor laser device, and the irradiation light that is reflected from the object to be measured. an optical system that divides the reference beam into a reference beam that produces Object shape measurement characterized by comprising a pulse oscillator that outputs to the drive source and the display means a pulse signal that causes the display means to display interference fringes of the object to be measured in synchronization with laser beam oscillation. Device. (2) The object shape measuring device according to claim 1, wherein the pulse width of the laser beam is set to a width that does not blur interference fringes.