CS276759B6 - A device for contactless continuous measurement of the transverse dimension of an object by expanding the la serial beam - Google Patents

Abstract

The essence of the solution is that to enlarge the measuring field, a three-lens optical system (4) consisting of three separate connecting lenses (41), (42), (43) of the same refractive index made of the same glass with a high refractive index is used as a collimator, of which the first lens (41) is a meniscus with the hollow side facing the scanning unit (3), the second lens (42) is a biconvex lens with unequal curvature of the surfaces facing the first lens (41) with a surface with a smaller curvature, and the third lens (43) is a symmetrical biconvex lens, and as a collector, a cemented doublet (7) consisting of a symmetrical *_ coupler (71) and an asymmetrical diffuser (72) located closer to the detector (3).

Description

The invention solves the problem of a device for non-contact continuous measurement of a transverse dimension by sweeping a laser beam, consisting of a laser beam source, a flat holographic diffraction scatterer, a lens system and a light detector with an electronic evaluation unit.

So far, in a device for non-contact continuous measurement of the transverse dimension using a holographic diffraction scatter for sweeping, two simple connecting lenses with an almost minimal aperture defect are used as a lens system: planconvex lenses. The first function of the collimator, it is rotated by a flat interface to the scattering unit and ensures a certain degree of linear dependence of the distance of the laser beam from the axis in a parallel scattering behind the lens on the angle in the angular scattering in front of it. Parallel sweeping must also be understood in terms of a certain tolerance. The second lens works as a collector, faces the flat interface to the detector and ensures that the scattered laser beam is focused on the surface of the detector.

The first lens was also designed as a four-member composite lens system. According to calculations, this system guarantees parallel sweeping and linear dependence within very wide limits.

A device in which only two simple contact lenses are used as the lens system has a number of disadvantages. These include, in particular, the fact that optical aberrations cause systematic measurement errors and make it very difficult to compensate for the travel of the laser trace on the detector. Thus, for example, the residual aperture aberration of the collimating lens results in a very small measuring field for the required measurement accuracy, which is less than 1x1 mm for an accuracy of + 1 μm when measuring fibers or wires with a diameter of 0.1. mm.

The device, in which the first lens is replaced by a compound lens system, guarantees a wide measuring field of up to 10 mm or more, but at the cost of four precisely manufactured and assembled lenses. At the same time, however, the compensation of the travel of the laser heating on the detector is not solved, even though it occurs to a lesser extent than with a simple first lens.

The device according to the invention eliminates these disadvantages, where the lens system is formed by a collimating objective consisting of three separate contact lenses of the same refraction formed from the same high refractive index glass and assembled so that the first is a meniscus facing the hollow surface to the spreading unit. , followed by a biconvex lens with unequal surface curvature facing the meniscus with a surface with less curvature and the last member being a symmetrical biconvex lens, in which a sealed doublet consisting of a symmetrical coupler and an asymmetric scattering located closer to the detector serves as a collector.

The advantages of the device according to the invention lie in the magnification of the measuring field several times for a given accuracy of measurement in relation to single lenses and in the simplification in relation to a four-lens collimation system. In addition, much easier processing of the measuring signal is ensured.

An exemplary embodiment according to the invention is shown in the accompanying drawing in a schematic diagram.

A flat holographic diffraction scatter £ is placed behind the laser beam source £ after its necessary directional and structural adjustments, followed by a collimating optical system £ consisting of sc three lenses ££, £ 2, £ 3, in the front focus of which is the point of impact. laser beam 2 ^{to the} spreader 2 ^and whose rear focus 5 forms the center of the measuring field 5. 3a, a collector-sealed doublet 7 consisting of lenses 71, 72 is provided by the measuring field 2 so that its front focus is identical with the center of the measuring field 2 and a light detector 2 connected by a connection 2 ^{3 by an} electronic evaluation unit 10 is ^{placed in the rear focus.}

Example of an embodiment of a collimating optical system 4 and a collector-sealed doublet

7. is summarized in the attached table of design parameters.

Table 1

^R 1 = -122.00 - 3.00 1.79382 R_ = - 67.00 - 2 ”1 - 0.50 air R_ = 418.00 3 d _? - 3.00 1.78382 R. = -230.00 4 ^and 2 - 0.50 air ^R 5 = 297.00 ^on 3 =: 3.00 1.79832 ^r g = -297.00 E, π 125.22 air ^R 7 = 20.00 d- - 9.50 1.54048 0 R '> = - 20.00 d. 3.00 1.79882 υ ^R s = 350.00

The function of the device is such that the laser beam 2 is swept by the angular flat holographic spreader 2 during its rotation. This angular sweeping is converted by the collimating optical system 2 into a sweeping parallel with high accuracy of the linear dependence of the distance on the angle and with a high parallelism. The measured object 2 ^SG located in the measuring field 2 shades the laser beam 2 »for a certain time ^and - apart from the shading it impinges on the collector doublet 2» which concentrates the cut beam with high accuracy on the light detector 2 · The signal behind the light detector 2 ³¹³ leads via to the elotric evaluation unit 10, which evaluates the dimension of the object 2 · with the shading time

The device according to the invention can advantageously be used for continuous and non-contact accurate measurement of the transverse dimension of an object by sweeping a laser beam with a flat holographic diffraction scatter in a larger measuring field.

Claims (1)

Device for non-contact continuous measurement of the transverse dimension of an object by sweeping a laser beam with a flat holographic diffraction diffuser, consisting of a laser beam source, a sweeping unit, a lens system and a light detector with an electronic evaluation unit, characterized in that the lens system is a collimating objective. consisting of three separate coupling lenses (41, 42, 43) of the same attractiveness formed of the same high refractive index glass, of which the first lens (41) is a meniscus facing the hollow side towards the spreading unit (3), the second lens (42) being a double convex lens with unequal surface curvature facing the first lens (41) with a smaller curvature surface and the third lens (43) is a symmetrical double convex lens, and a collector-sealed doublet (7) consisting of a symmetrical coupling (71) and an asymmetrical scatter (72) located closer to the detector (8).