JPS58169006A - Optical position measuring device - Google Patents

Abstract

PURPOSE:To prevent the measuring error due to defocusing of an image, by detcting the light reflected by an object to be measured through a lens, and measuring the interval between the lens and the object to be measured based on the position of a light source where the amount of the received light becomes the maximum. CONSTITUTION:The image of the light emitted from the small area light source 1 is formed on the surface S of the object to be measured through a beam splitter 5 such as a semitransparent mirror and a lens system means 2. The reflected light from the surface S is inputted to a light detector 4 through the lens system means 2, the beam splitter 5, and an aperture 3 in the reverse direction. The light source 1 is scanned in the forward and reverse directions of (x) by a light source scanning means 15. A reference pulse signal corresponds to the reference position of the light source, which is scanned by a driving signal source 13. When the time between the reference pulse signal and one of peak position pulse signals is measured, the interval between the lens 2 and the surface S can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical position measuring device, and more particularly, it deals with still measuring the position of an object in a non-contact manner using a light beam with high precision.

As a non-contact method for measuring the position or dimensions of an object, methods using an air micrometer or magnification using a magnifying glass have been proposed, but both methods have various problems when measuring objects with complex shapes. However, since the latter method cannot be converted into an electrical signal, it is inefficient to apply to continuous measurements in production processes.

The present invention has been made in order to eliminate the above-mentioned drawbacks inherent in the conventional technology, and therefore, the purpose of the present invention is to electrically process the amount of reflected light to locate an object with high precision. It is an object of the present invention to provide a novel position measuring device that can perform continuous measurement in a non-contact manner.

The above-mentioned objects of the present invention include: a lens system means, a light source means with a small light emitting area that reciprocates periodically in a direction substantially along the optical axis of the lens system means, a light beam branching means, and a light distribution miscellaneous means. A small aperture means designed according to the area,
a photodetector means for detecting light incident through the aperture means, and a photodetector means for detecting the position of the surface to be measured, which is located near the imaging point of the light source means by the nozzle thread means, with respect to a reference point; Notification of the aperture means is determined from the position of the IIjJ era training means when the amount of reflected light from the distribution creation surface becomes maximum in accordance with the movement of the light source means. This is achieved by an optical position measuring device.

The present invention non-contactly measures the position of an object with an accuracy of several micrometers by electrically processing the amount of light reflected, and although it is an optical method, it uses reflection on the surface. To,
The measurement IIK difference due to image defocusing (out of focus) as seen in projection methods is small.

Next, the present invention will be specifically explained with reference to the drawings.

FIGS. 1(a), (b), (-), and (d) are diagrams explaining the present invention in detail.

Now, in the same figure (,), a light beam 1 of a small area enters the surface of the object to be measured rkUs via a beam splitter 5 using a semi-transparent mirror and a lens system means 2. Here table thIS
Assuming that it is a mirror surface with a degree of area of
The light enters through the aperture 6 and is detected at 44-\. here,
The aperture 3 is a pinhole with a fixed diameter determined by the dimensions of the light source 1 and the lens system, and in the state shown in FIG. placed.

Next, the position of ray 1 is moved backward (2) as shown in the same figure (b).
Considering the state where the light is directed in the negative direction), the light travels as shown by the arrow in the figure, the imaging point is in front of the surface S, and the reflected light is converged in front of the aperture 50. For this reason, the light that passes through the aperture 3 (as can be seen from the figure), the peripheral portion is shaved off by the perch 6, so that the amount of light that reaches the photodetector 4 is lowered.

Next, conversely, when the light source 1 moves in the mlj direction as shown in (c) of the same figure, the imaging point of the reflected light exceeds the aperture 5 and becomes a force of 9, so it is the same as in the case (b). (low light intensity), using 1, the position of the ray 1 @z and the output signal rail V of the photodetector 4
As shown in FIG. 2(d), for a change of 2, the peak value is reached at the position ad of the light beam corresponding to the distance d between the lens and tiis, and the level decreases elsewhere. Therefore,
Conversely, by moving the light source 1 in one direction and finding the position - where the output of the photodetector 4 is maximum, the distance d between the lens 2 and fiJs can be found.

Here, semiconductor lasers, photodiodes, etc. are considered suitable as light sources, but there are also other sources, such as H
The most practical example is to take out the output of the aN-laser light through an optical fiber and use the output end of the 7-eyeper as "light-1".

Next, when the reflective surface S has a surface roughness of several microns in the m direction and is not a mirror surface, the situation is slightly different from the above case. In other words, in thlS, the υ emitted from light source 1 is not reflected by a mirror surface, but is scattered in each direction, so at the position of aperture 3, the light ray is scattered by 8 planes instead of 1, and the multiplication table is A secondary light source is formed. Here, in the state of 1W (a), the secondary light beam on 5ITi becomes a small spot because light #A1 is still condensed; In state (C), S
Since the direction is shifted from the image point of ray 1, the secondary ray becomes a large spot. Therefore, although the light intensity and sensitivity of the light beam passing through the aperture 6 are different from those of the 11Il period, the relationship is similar to that shown in Figure -1 (d).

Next, in FIG. 2 showing one embodiment of the present invention, the light beam 1 is scanned in the front and rear direction of z by the light source scanning means 15. As a result, the waveform of the relationship between the output of the photodetector 4 and time is shown in the figure (
b) is obtained, which is processed by the amplifier 11 and after death,
As the output of the peak pulse output circuit 12 that generates a pulse at the peak point by the peak detection circuit, the output shown in the same figure (
As shown in d), two peak position pulses are output per cycle of the through-ray. On the other hand, the scanning of the light beam is driven by the output signal of the construction signal 16. Therefore, it is possible to obtain the reference pulse signal corresponding to the basic position of the light line scanned by m-taiiro-go-16 as shown in the same figure (g). ! In order to
By measuring d, the distance between lens 2 and 5lIi can be determined.

In the case of this method, it is necessary to appropriately select the dimensions of the light beam, the dimensions of the aperture, the focal length of the lens, etc., and it can be used for a wide range of measurements, from high-accuracy measurements of 1 μm collection to wide-range measurements of about 100 µm. A range of non-contact measurements is possible.

Since the light spot on the reflective surface is small, it has the advantage of being able to perform local measurements even on complex cedar-shaped objects, so it is particularly useful for applications such as scanning the object and finding its outline. It is.

Next, in FIG. 3 showing another embodiment of the present invention, a light emitter 21
The emitted light is sent to the lens system through the optical fiber 22. As a result, if the output end of the optical fiber 22 is made to vibrate in the direction 2 in the figure by utilizing the flexibility of the optical fiber, this becomes equivalent to the optical wave 1 of the embodiment described in 1IiI. On the other hand, if the illustrated optical fiber 23 is also used on the photodetector side and is coupled to the photodetector 24, the optical fiber 25
The eye body functions equivalent to the aperture 3 in the 17th embodiment. Using the Hikari 7-I IPA increases the degree of freedom in terms of device configuration.

That is, when using a large gas laser such as Hm-Ng or Ar as a light emitter, the structure shown in Figure 5 allows the optical system for measurement and the light emitter to be separated.
It has the advantage of being able to measure freely by attaching only the optical system to the object to be measured.

As an example of how to move the end of an optical fiber, which is "pre-drilling" in this embodiment, as shown in FIG. The purpose can be easily achieved by bending the optical fiber and vibrating the prism in two directions at the same time.

In the above explanation, for simplicity, the lens thread is a single lens; however, in a practical device, a set of lenses or a prism or lens (not shown) may be used to align the optical path. , are omitted because they are not related to the gist of the present invention.

However, the scanning means for photoconception still uses an electrostrictive vibrator.
Various types of vibrators using magnetic force or a combination of a cam and a motor are conceivable, but any type of type may be used as long as it meets the gist of the present invention.

According to the present invention, as explained above, it is possible to measure the position r1t or dimension of an object non-contactly and continuously with an accuracy of 1%.

Although the present invention has been described above with respect to its preferred embodiments, these are merely examples, and it goes without saying that the present invention is not limited to the nine embodiments described herein.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a basic embodiment of the present invention; Fig. 2 is a schematic diagram showing one embodiment of the invention; Fig. 6 is a schematic diagram showing another embodiment of the invention; FIG. 4 is a diagram showing an example of a method of moving the optical nose using an optical fiber. 1-... Genryo, 2... Lens-based hand beast, 6- Fist/Aperture, 4.24... Photodetector, 511... Ray splitter, 11... Addition radiator, 12...・Beak pulse output circuit, 16...HAllll (gi number -, 14... time meter 11J -t= &, 15---original-scanning + stage, 2
1・011+4 shakers, 22.23・−1 optical fiber, 25＠・Φburi agent Kumagaya
Thick part Xd 7 (d) Figure 1 Figure 2 Li

Claims (1)

[Claims] Designed to correspond to the light emitting area of the lens system means, the light source means with a small light area that reciprocates periodically in a direction roughly along the optical axis of the lens system means, the light beam branching means, and the #M light distribution means. an aperture means having a small aperture, and a photodetector means for detecting light incident through the aperture means;
The lens system means determines the position of the target field surface located near the junction point of the light source means with respect to the reference point. Optical position measurement 811° characterized in that the amount of reflected light is determined from the position of the light source means described in #IIJ when the amount of reflected light becomes maximum with the movement of the light source means.