SU1281668A1 - Apparatus for observing optical image in downhole photoelastic transmitters - Google Patents

Abstract

The invention relates to a weed case and makes it possible to increase the accuracy of rock stress measurements by forming a uniform flux of radiation on the sensor surface. For this, the illuminator 3 is installed in the housing 1 by a polarization filter, including a series-installed compensator 8 and a quarter-wave 5 and a polarized 6 tf, 1 ,. / L4XV wXXX XXX.4yJ (U / OAI of the plate. The viewing tube 4 is coaxial with it and the illuminator 3. The housing 1 is made with intake part in the form of a tube (T) 2 in front of the filter. The illuminator 3 is complete in the form of an annular reflector 9 with a source light (IC) 10, installed in front of the reflecting surface of the reflector evenly around the circumference. The ratio of the outer diameter of the illuminator 3 d and the outer diameter T 2 D satisfy the condition d D. At the wellhead place T 2. The rays of light from the IC 10 pass through the plates 6 and 5 and further along T 2 fall onto the sensor. On reflection from the mirror layer of the sensor, the rays of light come back. To determine the order of the strips of the optical pattern, the compensator 8 is inserted into the last 2 through slot 7 in T2. If there are internal voltages in the sensor, due to the increase in voltages in the surrounding rock , an optical picture appears in it. 2 Cp f-crystals, 3 d., i (L 00 o: 00 / g

Description

1128

The invention relates to mining, more specifically to devices for measuring rock stress.

The aim of the invention is to improve the measurement accuracy of rock stresses due to the formation of a uniform flux of radiation on the sensor surface.

Figure 1 shows the device, a general view; in Fig.2, section A-A in Fig .; FIG. 3 shows the principal optical scheme for observing a photoelastic sensor located in a well.

A device for observing an optical picture in downhole photoelastic sensors consists of body I (Fig. 1) with intake part in the form of tube 2, illuminator 3, and telescope 4. Tube 2 is located in the front part of body 1. Behind it is a polarization filter, consisting of a quarter-wave plate 5, a semi-solid plate 6 and a compensator 8 placed in the pro 7, the illuminator 3 consists of an annular reflector 9 and sources of light 10, which are set perpendicularly to the reflecting surface of the reflector evenly around the circumference. The telescope 4 is placed coaxially to the illuminator and coaxially with the polarization filter. It consists of a lens 1 I, an eyepiece 12 and a body 13. The power of the light sources is provided from an independent source (not shown).

During operation, the device is placed in front of the wellhead 14 (Fig. 3), in which a photoelastic sensor 15 is installed, with a mirror layer 16. For convenience of fixing the instrument, the housing tube 2 is placed directly at the wellhead 14. Light rays from light sources 10 pass through the floor The tube 6, the quarter-wave plate 5 and further along the tube 2 and the well 14 get into the sensor 15. Reflecting from the mirror layer 16 of the sensor is, the rays of light come back, pass again through the even-. wavelet plate 5, poloid 6 and further get into the lens And the telescope 4, Passing through the telescope and out of its eyepiece 12, rays of light get into the eye of the observer 17 (or into the camera), to determine the order of the bands of the optical image in the process of observing the latter through slot 7 in tube 2 in

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The optical circuit of the instrument is inserted into a compensator 8. The design of the latter may be different and is determined by the specific conditions of use of the instrument, in particular, the order of the stripes observed in the picture sensor and the required accuracy of readout.

If there are no internal stresses in the photoelastic sensor 15, then in the proposed scheme it is observed in the form of a bright floor. If there are internal stresses in the sensor, due, for example, to an increase in stresses in the surrounding rock, an optical pattern appears in the form of a complex pattern of color bands — isochrome. The device is designed to observe this picture.

To ensure the clarity of the observed picture, it is necessary to ensure the flow of the entire luminous flux from the sources 10 of the light into the sensor 15. To do this, it is necessary that the outer diameter d of the illuminator 3 be not

Claims (1)

greater than the diameter D of the well 14, I Formula of the invention 1, A device for observing an optical picture in downhole photoelastic sensors, including an illuminator and a housing with a telescope located in it and a polarization filter including a successively installed compensator, a quarter-wave plate and a polaroid a plate, characterized in that, in order to improve measurement accuracy by forming a uniform radiation flux, the illuminator is installed in the housing behind the polarization filter, and the viewing tube is placed coaxially with the illuminator and coaxially with the polarization filter, while the housing is filled with the intake part in the form tubes in front of a polarization filter, 2, The device according to claim 1, 1, so that the illuminator is designed as an annular reflector with light sources installed in front of the reflecting surface, evenly around the circumference, 3, The device according to claim 1, characterized in that the ratio of the outer diameter of the illuminator d to the outer diameter of the intake part of the housing D satisfy the condition d .D w /five Phi2. g w 17 fig.Z