SU958925A1 - Photometric refractometer - Google Patents

Description

(54) PHOTOMETRIC REFRACTOMETER

This invention relates to a technique of refractometry, in particular, to devices for measuring refractive indices of liquids and gases.

A refractometer is known that serves to measure the refractive indices of liquid and gaseous media 1.

However, such a refractometer is not suitable for measuring the refractive indices of strong absorbing liquids and gases.

The closest to the technical essence of the invention is a photometric refractometer containing a light source and a measuring cell with a reflecting surface and a photodetector 2 arranged successively along the radiation path.

A disadvantage of the known device is its block layout, which makes it impossible to significantly reduce its weight and dimensions, and also reduces its reliability.

The aim of the invention is to reduce the weight and size, improving the reliability of the device.

This goal is achieved in that the device containing a light source and a measuring cell with a reflecting surface and a photodetector sequentially arranged along the radiation is made in the form of a monolithic integrated circuit on a semiconductor chip having the shape of a truncated spheroid and serving as a measuring cell, with the reflecting surface being curved the surface of the truncated spheroid, and the light source and the photodetector are made in the form of pn-junctions located on a flat surface truncated a spheroid.

FIG. 1 shows schematically a cross section of a photometric refractometer and the course of rays in it; in fig. 2 - topography of the surface of a semiconductor crystal in the plane of the cross section 1 and a truncated spheroid (type A in Fig. 1); in fig. 3 -

20 shows an experimental curve of the dependence of the current in the photodetector circuit on the refractive index of the measured medium.

The device works as follows.

In the circuit of the light source (emitting

Claims (2)

pn-junction), which includes the ohmic contact 1, p-region 2, p-region 3 (measuring cell) and the second ohmic contact 4, sets the current Ii. At the same time, the generated pn-junction 2-3 light (for example, beam 5) is partially reflected from the reflecting surface 6 (beam 7) and audited to the photodetector circuit (the second pn-junction 3-8), (9 - contact to the roblast 8) photo signal L- To measure the refractive index, the photometric refractometer is placed in the test medium 10. The analytical connection r with the refractive index π of the test medium 10 can be described by the following expression: a г g gPg-A – H - В (п; п ;; 0), where Г, is the internal quantum yield of the pn junction emission 2-3; TJ2 - the internal output of the photoelectric effect of the pn-junction 3--8; R is the reflection coefficient of the reflecting surface 6; n, is the refractive index of the measuring cell 3; A is the coefficient associated with the absorption of light in the volume of the measuring cell; B is an additive due to the dependence of the critical angle in on the refractive indices and design features and dimensions of the measuring cell. In the case when all the rays of light fall on the reflecting surface at small angles, the expression takes the form Lbn, n, Agc .. In accordance with the given expression, the photosignal L decreases with increasing n, which is confirmed by the experimental curve in FIG. 3. The proposed photometric refractometer can be manufactured by well-known semiconductor instrumentation techniques and used for physico-chemical control purposes, as well as for measuring parameters of environmental objects, including in field conditions. The advantages of the proposed device are small dimensions, light weight, ease of manufacture and measurement process and high reliability. A photometric refractometer comprising a light source and a measuring cell with a reflective surface and a photodetector sequentially arranged along the course of radiation, in order to reduce weight and dimensions and increase reliability, it is made in the form of a monolithic integrated circuit on a semiconductor crystal having the shape a truncated spheroid and serves as a measuring cell, with the reflecting surface being the curvilinear surface of the truncated spheroid, and the light source and photo The ground glass is made in the form of pn-junctions located on a flat surface of a truncated spheroid. Sources of information taken into account in the examination of 1.Ioffe B. 6. Refractometric methods of chemistry. L., “Himi, 1974, p. 126-129. 2. In the same place 254-257 (prototype). 1 Phage ..