SU422946A1 - PHOTOELECTRIC DEVICE FOR MEASURING LINEAR DISPLACEMENTS - Google Patents

Description

one

The invention relates to photovoltaic systems and is intended to accurately measure linear displacements, for example, in instrumental microscopes, projectors, as well as in readout devices of machine tools.

A photoelectric device for measuring linear displacements is known, which contains an illuminator with a cond sensor, a raster scale, an optical system, photodetectors for obtaining reference electrical signals, and an electronic circuit for processing these signals.

The optical system is designed to combine the image of the slits with the continuation of the slits themselves within the same area of the slides and contains two separation prisms, one reflective prism, lenses and three channels with an objective in each channel.

Two lenses have a special motion to obtain the necessary phase shift.

A disadvantage of such devices is design complexity and alignment.

The proposed device differs from the known ones in that it is provided with a dividing device located in the plane of the image of the bitmap of the raster scale and dividing this image into two parts mutually shifted by 1/4 schaga. The separation device is made in the form of two plane-parallel plates, fastened with an ontnical contact node angle, providing svvng parts on 1/4 schaga. This embodiment simplifies the design and adjustment of the device.

FIG. 1 shows a diagram of the proposed photovoltaic device; in fig. 2 - the design of the separation device; in fig. 3, 4 - pictures of combining images of shtrikhs with the plane of scale lines.

The photovoltaic device contains an illuminator 1, a condenser 2, a raster scale 3,

the optical system consisting of two lenses 4, a deflection of a young-1 prism 5, a separation prism 6, a separation arrangement 7, lenses 8 and 9, rhombic prisms 10, 11, a photon-receiver 12 for receiving reference electrical signals, a photocell 3 generating an electrical signal for automatic stabilization of the total light current, and an electronic circuit for processing these signals (not shown). FIG. 1 parts 7 and

10 rotated 90 °.

The device works as follows. Illuminated by a light source (illuminator 1) a part of schtrikhs (approximately half of their length) of raster Pkalka 3 (in Fig. 3 this

the part is indicated by the number I) through a prism 11,

6 and 5 are designed by lenses 4 to continue the strokes of the same portion of the raster scale (in Fig. 4, they are indicated by the numbers II and III). The separation prism 6 serves to isolate a part of the batt, its luminous current supplied to the photocell 13, which, by issuing an electrical signal through feedback, stabilizes the magnitude of the total luminous flux originating from it, from the illuminator. The separation device 7 is intended to divide the image of the field given by the lenses 4 into two equal parts, shifted one relative to the other by 1/4 of a step.

Thus, the electrical signals taken from the photodetectors 12 are shifted in phase by 90 °, which provides a reversible readout of the values of smash, s.

The separation device (Fig. 2) consists of two plane-parallel plates interconnected by optical contact so that they form a certain angle between the normals to their planes m. Tolsh, other and the angle of mutual inclination of the plates are chosen so that one half of the floor is shifted from the other half of the floor by 1/4 step (Fig. 4). The offset of the light beams, given by one inclined plate with a small amount of slope, is determined by the known formula

- I -1 1 -

P

where ai is the mixing of the beams; di is the plate thickness; ii is the angle of inclination of the plate; n-indicator of refraction of glass nlastina.

Accordingly, the second plate will give a shift

, and -1

ttf ajjj.

P

The total mutual displacement of the beams with the same thickness of both plates made of the same type of glass

 (i, + / 2) -,

is a value that is independent of the small slopes of the entire arrangement. Accurately made such a device automatically creates the necessary shift in

phase and makes adjustment of the lens 4 unnecessary. In addition, it ensures the continuity of this shift regardless of the position disorder of the lens. Since the small slopes and shifts of the device

If there is no phase failure, the system is non-configurable in this respect.

When moving the raster scale, the images of the illuminated part of the shtrikhs, designed by the lenses to continue the shtrikhs of the same part of the raster scale, move towards the strokes themselves and periodically open the photodetectors to receive the reference electrical signals through the amplifier and the electronic signal processing circuit to the reading device .

Subject invention

Claims (2)

1. A photoelectric device for measuring linear displacements, containing an illuminator with a condenser, a raster scale, an optical system consisting of prisms, lenses and lenses, photodetectors for receiving reference electrical signals and an electronic processing circuit for these signals, distinguish the neck from the purpose of the design and device alignment adjustment, it is equipped with a separating device located in the image plane of the raster scale lines and dividing this image into two parts mutually shifted by 1/4 schaga. 2. The photoelectric device according to claim 1, characterized in that the separating the device is made in the form of two plane-parallel plates fastened with an optical contact at an angle, which provides for the shift of parts by 1/4 of a step. sixteen d 9 ij Fig i fui i i i. T i Fig.Z