SU1481658A1 - Psychometer - Google Patents

Abstract

The invention relates to measurements of environmental characteristics and can be used as part of digital meteorological information collection systems or control of various technological processes, the nature of which depends on the humidity of the air, for example, when generating irrigation rates in automated irrigation systems. The goal is to increase the resolution and accuracy of measurements, as well as to enable the use of the psychrometer in digital control systems. The psychrometer contains dry and wetted thermometers, the capillaries of which are made opaque with a triangular internal channel (VK). The two walls of the VC are at an angle equal to or greater than the angle of total internal reflection. These walls of the VC are placed in the gap of light guides, the ends of which in this gap are made flush with the walls of the VC and are located at each quantization step. The capillaries are filled with a liquid with a refractive index close to that of the optical fibers. 2 Il.

Description

The invention relates to the measurement of environmental characteristics and can be used as part of digital systems for collecting meteorological information or controlling various technological processes, the nature of which depends on the humidity of the air.

The purpose of the invention is to increase the resolution and accuracy of measurements and to ensure its use in digital systems for selecting meteorological information and control of technological processes.

Figure 1 schematically shows a psychrometer; figure 2 is a section aa in figure 1,

The psychrometer contains dry 1 and 2 humidified thermometers with measuring capillaries 3, and a point 4 lights, photo detectors 5 lights, thermometers 1 and 2 are provided with input 6 and output 7 light guides, mounted flush with the inner walls 8 of opaque measuring capillaries 3 filled with transparent working fluid 9 with a refractive index close to the material refractive index of the light guides 6 and 7, the input ends of the input light guides 6 are assembled in the focus of the collecting lens 10 set by waiting for them and the light source 4 under the light-u

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impermeable cap 11, and the output ends of the output light guides 7 are connected to the photodetectors 5, the outputs of which are connected to the system 12 for detecting humidity by the temperature difference between dry 1 and 2 thermometers being humidified.

The psychrometer works as follows.

The beams from the light source 4, installed under the light-tight cap 11, are focused onto the input ends of the input light guides 6, from where through the light guides 6 they reach their output ends. The input and output fibers of each quantization step are located on a common axis constituting the angle // 2 with the normals to these inner walls. In its magnitude, the angle is equal to or greater than the limiting angle of total internal reflection, therefore, the light rays from the source 4 of light, passing through the optical fibers 6 to their ends, undergo glass-air full reflection at the interface. The light from the ends of the light guides 6 is not emitted into the inside of the capillary 3, since the plane of the end of the fiber coincides with the plane of the internal wall of the capillary 3, which is inclined to the central axis of the pair of optical fibers, equal to or greater than the angle of total internal reflection. Light, thus, does not reach the opposite input end of the output light guide 7 and the corresponding photodetector 5. At the transition of the glass-air angle is 41.8 °.

In thermometers, a working fluid is used, the refractive index of which is equal or close in magnitude to the refractive index of the material of the optical fibers. Benzene can be used as such a liquid, the refractive index of which, like in glass, is about 1.5. x quantizing thermometers, which, depending on the temperature, overlap the working fluid in the capillary, the light passes between the ends of a pair of optical fibers 6 and 7 without refraction and reaches the corresponding photodetectors 5 without loss.

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From the outputs of the photodetectors 5, the signals arrive at the device 12 for calculating humidity based on the temperature difference between dry 1 and wetted 2 thermometers, where, after being converted into a binary code, a digital operation is performed to calculate the temperature difference and relative humidity

As the material for the capillaries 3 of thermometers 1 and 2, opaque (darkened) glass is used.

The resolution in the psychrometer reaches a value equal to half the diameter of the fiberglass (fiber) l due to the fact that the source of 4 s.vnta is closed by a protective cap 11 and removed from the thermometers 1 and 2 by a distance that prevents their heating, the accuracy of temperature measurements is improved and air humidity, and since the working fluid 9 of thermometers is one-component, the measurement accuracy will be the same over the entire measuring range.

Claims (1)

Invention Formula A psychrometer containing dry and wetted thermometers, the measuring capillaries of which are filled with a clear liquid, a light source and photodetectors, a recording system, characterized in that, in order to increase the resolution and measurement accuracy, dry and wetted thermometers are equipped with input and output light guides, flush mounted with angles cf. one to another, the inner walls of the opaque measuring capillaries, and the input and output fibers of each quantization step are located on a common axis that makes an angle d / 2 to the internal walls equal to or greater than the maximum angle of total reflection, and the input ends the input light guides are installed in the focus of the collecting lens, installed between these ends and the light source. at 1