SU487364A1 - Photoelectric sensor - Google Patents

Description

one

The invention relates to instrumentation, in particular to sensors of linear displacements, and can be used in automatic control systems, in devices for non-contact measurement of the surface profile, In measuring equipment.

Photoelectric rotation angle sensors are known that are used to measure linear displacements, which contain a light source, an optical system for forming an image of a light source, an autocollimation optical system with a light separation element in the form of a truncated pyramid with specular edges, and light flux receivers placed in beams reflected from it faces.

However, such sensors cannot provide HIGH sensitivity and accuracy, since a significant part of the luminous flux that creates the autocollimation image of the upper base of the pyramid is scattered and not detected by the light receiver. Usually In known devices, in order to increase the sensitivity, powerful sources of luminous flux are used, as well as increase the size of the photosensitive surface of the receivers of the luminous flux. All this leads not only to an increase in the size and complexity of the manufacture of the sensor, but also to large temperature log fractures.

due to the heating of its structure and radiation receivers.

In addition, the OUTPUT signal of such sensors depends not only on linear displacements of the reflecting surface, but also on its angle of inclination. Since it is almost impossible to withstand a constant angle of inclination of the reflecting surface during its movements, all this leads to an error

linear displacement measurements. Thus, well-known sensors cannot provide HIGH sensitivity and measurement accuracy. The purpose of the invention is to increase the threshold

sensitivity and accuracy of autocollimation linear displacement sensors.

This is achieved by the fact that the proposed sensor is equipped with an annular light collector, and the beam splitting element is designed as a truncated cone with transparent bases and a reflective outer surface, the axis of which coincides with the optical axis of the sensor and passes through the center of the annular light collector, and the upper base is offset from the plane images

a, about the light source at distance / ctgp, where

a is the diameter of the upper base of the cone; .R -

aperture angle of the optical system. Besides

This annular light collector is made of fiber elements, one ends of which are located around the circumference of the light collector, while others are assembled into a bundle to which the luminous flux receiver is connected.

FIG. 1 is a schematic diagram of the proposed photoelectric sensor; in fig. 2 is a section along the line A-A in FIG. one.

The sensor contains a light source 1, an optical system 2 forming a light source, an autocollimation system 3, a beam-splitting element made in the form of a truncated cone 4 with a reflective outer surface and transparent bases. The latter is located in the center of the annular light collector 5, manufactured by ns fiber elements, one ends of which are located around the circumference of the light collector, while others are assembled into a bundle to which the receiver 6 of the light flux is connected.

The sensor works as follows.

The cone-shaped filament of the light source 1 in the form of a circle of light is projected by the optical illumination system 2 into a vertex of a truncated cone 3 with a slight overlap. The image of its upper base by the autocollimation system 4 is projected onto the reflecting surface in the form of a light spot, the diameter of which is approximately equal to the diameter of the upper base of the cone.

If the reflecting surface is located at a distance equal to twice the focal length of the autocollimation system, and its angle of inclination to the optical axis of the sensor is zero, then the autocollimation image of the upper base of the cone exactly coincides with the dimensions of the uppermost base and, therefore, n to the receiver 6 light flux does not come. When the enclosing surface from this position begins to move towards the light source 1, the dimensions of the autocollimation image change, as a result of which the luminous flux hits the annular light collector 5 and the luminous flux receiver 6. The amount of luminous flux entering the photosensitive surface

receiver, proportional to the linear movement of the reflecting surface. Since when moving the reflecting surface, the entire luminous flux of the image of the upper

the cone is fed only to one light receiver, this will significantly increase the threshold sensitivity of the sensor, and determining the ratio between the angular dimensions of the upper base and its

By the image, the angular dimensions of the autocolumnar image of the upper base of the cone should be larger than the angular dimensions of the uppermost base by the maximum inclination angle of the reflecting surface, make it possible to eliminate the influence of the angles of inclination of the reflecting surface on the accuracy of measuring linear displacements.

Subject invention

Claims (2)

1. A photoelectric sensor comprising a light source, a light source optical image forming system, a beam-splitting element, an autocollimation optical system, and a luminous flux receiver, characterized in that, in order to increase the threshold sensitivity and accuracy, it is equipped with an annular light collector, and the beam splitting element is designed as a truncated cone with transparent bases and a reflecting outer surface, the axis of which coincides with the optical axis of the sensor and passes through the center of the annular light collector, and the upper base is shifted in relation to the plane of the image of the light source at a distance of / - ctgp, where a is the diameter of the upper base of the cone; p is the aperture angle of the optical system. 2. A sensor according to claim 1, characterized in that the annular light collector is made of fiber elements, one ends of which are located around the circumference of the light collector, and the others are assembled into a bundle to which the luminous flux receiver is connected. Fig 1 u2