RU2758149C1 - Container for optical-electronic devices - Google Patents

Abstract

FIELD: optical instrumentation.

SUBSTANCE: invention relates to optical instrumentation, in particular to devices for protecting the optical path of optoelectronic devices and systems from the influence of thermal disturbances. The declared container for optoelectronic devices, containing filled with a gaseous medium with a thermal conductivity of at least 0.05 W/(m °K), the dew point of which is not higher than - 50°С, a sealed housing with at least one window, with a fitting, a temperature sensor, communication unit and control unit. The novelty is that in the device the body and the fitting are made of metal and are separated by an electrical insulating sleeve, the control unit is made in the form of a tracking system containing a medium immitance meter with a power source, a computing device with memory and a timer. In this case, one input of the immitance meter of the medium is electrically connected to the body, the second - to the fitting, the outputs of the immitance meter and the temperature sensor are connected to the computing device, and the gaseous medium is selected from the condition (c₁ρ₁+c₂ρ₂+…+c_nρ_n)≤934.2 J/(m³ °K), where ci is the specific heat capacity of the gas medium component, J/(kg °K); ρ_i is the density of the component of the gaseous medium, kg/m³; n is the number of components of the gaseous medium.

EFFECT: improving the efficiency and accuracy of measurements.

1 cl, 2 dwg, 2 tbl

Description

The invention relates to optical instrumentation, in particular to devices for protecting the optical path of optoelectronic devices and systems from the influence of thermal disturbances.

Known devices for the protection of optical paths of optoelectronic devices and systems from temperature and turbulent inhomogeneities of the refractive index of the gaseous medium, allowing to reduce or completely eliminate the effect of thermal effects.

For example, a device for protecting the optical path of an optoelectronic system (see RF Patent No. 137630, IPC G12B 07/00, prior 17.09.2013), including a gaseous medium filled at a reduced pressure with a thermal conductivity of at least 0.05 W / (m ° K ) and a dew point not higher than -50 ° C a sealed metal case with a fixed internal surface area within elastic deformations, with windows and a fitting in the case. Such an optical path protection device does not allow monitoring the state of the optical medium.

A large number of optical measuring instruments for obtaining high measurement accuracy are placed in sealed, equipped with optical windows, filled with dry gas or evacuated containers. Among the optical measuring devices, there are those that require their installation inside the container on platforms that allow them to be leveled. Many of them have heat-generating devices in their drives. Thermal disturbances arising in such cases lead to a change in the settings of optical devices and the appearance of convective and turbulent heat fluxes in the optical medium, which worsen the measurement results. Under such conditions, when both external and internal thermal disturbances act simultaneously in the measurement process, the task of monitoring the parameters of the state of the gaseous medium inside a closed volume and adjusting the settings of optical devices based on the results of this control comes to the fore.

The closest to the claimed invention in terms of most of the essential features is a container for optoelectronic devices (see RF Patent No. 2689898, IPC G12B 07/00, prior 15.08.2018.), Including a base, a casing, on the inner walls of which thermoelements are installed , and a control unit with a thermal sensor, while the base and the casing form a sealed container filled with an inert gas; a communication unit and two fittings are built into the container body.

The main disadvantage of this device is the long preparation time for optoelectronic devices for measurements, as well as low measurement accuracy due to the lack of information about the state of the gaseous medium.

During our research, we showed that the most informative characteristic of the gaseous medium, which is simultaneously related to the temperature of the optical medium and determines its refractive index, is the dielectric constant, on which the capacitance and dielectric loss tangent of the gaseous medium of the device depend. We also determined the conditions for choosing a gas or a gas mixture with the lowest entropy during temperature fluctuations.

The dependence of the power dissipated in a gas medium on the temperature P (° T) was found experimentally and determined as

Р (° Т) = k2πfΔC (° T) Δtgδ (° T), W, where

k - coefficient of proportionality;

f is the frequency of the power source at a source voltage of 1 V, Hz. The dependence of the value of the internal energy of the gaseous medium of the device on the temperature Q (° T) is defined as

Q (° T) = (i / 2) (m / μ) R ° T, J, where

i is the number of degrees of freedom of gas atoms;

m is the mass of the gaseous medium in the device, g;

μ is the molecular weight of the gas, g / mol;

R - universal gas constant, J / (mol ° K).

Having determined the temperature dependence of the dielectric constant of the optical medium and the value of the active resistance of the gaseous medium of the device, we were able to determine the power dissipated in the gaseous medium and the completion time in the device of transient processes as a result of thermal disturbances.

The technical effect of the claimed invention is to improve the efficiency and accuracy of measurements.

We obtained such a technical effect when, in a container for optoelectronic devices, containing a sealed casing filled with a gaseous medium with a thermal conductivity of at least 0.05 W / (m ° K), the dew point of which is not higher than -50 ° C, at least one window, with a fitting, a temperature sensor, a communication unit and a control unit, the new thing is that in the device the body and the fitting are made of metal and separated by an electrical insulating sleeve, the control unit is made in the form of a tracking system containing an immittance meter * (* Immitance is impedance or admittance [Ya.N. Luginsky, M.S. Fezi-Zhilinskaya, Yu.S. memory and timer, while one input of the medium immittance meter is electrically connected to the case, the second - to the fitting, the outputs of the immittance meter and the temperature sensor are connected to the computing device, and knowing the environment is selected from the condition

(c ₁ ρ ₁ + c ₂ ρ ₂ +… + c _n ρ _n ) ≤934.2 J / (m ³ ° K), where

c _i - specific heat capacity of the gas medium component, J / (kg ° K);

ρ _i is the density of the component of the gaseous medium, kg / m ³ ;

n is the number of components of the gaseous medium.

Making a gasket in the gap between the side surface of the windows and the surface of the body made of a low-melting material allows you to combine technological operations in the manufacture of the container and significantly simplify the design of the device, significantly reducing the labor intensity and, accordingly, its cost (see clause 2 of the Formula).

FIG. 1 shows a general diagram of the device, where a sealed housing 1, a window 2, a gasket 3, a fitting 4, a temperature sensor 5, a communication unit 6, an electrical insulating sleeve 7, a medium immittance meter 8 with a power source, a computing device 9 with a memory and a timer;

← → ↔ direction of signal transmission.

FIG. 2 graphically presents the dependences obtained by us, where curve 10 is the dependence of the dielectric constant on the temperature of the АС (° Т), pf; curve 11 - dependence of the dielectric loss tangent on temperature Δtgδ (° T); curve 12 - the dependence of the power dissipated in the gas environment depending on the temperature P (° T), W; straight line 13 - the dependence of the value of the internal energy of the gaseous medium of the device on the temperature Q (° T), J;

Δt is the time interval set by the timer during which the specified values are measured and averaged, sec;

the dotted line indicates the middle of the interval Δt;

P _i is the average power value in the measurement interval, W;

Q ₁ - the initial value of the internal energy of the gaseous medium of the device, J;

Q ₂ - the final value of internal energy, J.

The declared container works as follows.

The metal body of the container is made with a metal fitting installed through an electrical insulating sleeve. The container body is evacuated and filled with gas.

Thanks to the installation of a metal fitting through an electrical insulating sleeve, between the body and the fitting we obtain a capacitive pair, the capacitance value of which is determined by the dielectric material and the smaller area of the capacitor plates. The characteristics of a capacitive pair are determined by an immittance meter - a device for measuring electrical capacitance and dielectric loss tangent, the inputs of which are connected to the fitting and the container body.

The execution of the control unit in the form of a tracking system allows you to continuously receive information about the state of the gaseous medium, to compare the obtained data with basic values and to predict its behavior, taking into account the parameters of disturbances and characteristics of the device.

In the operating state of the device, the signal from the thermal sensor located on the device body is continuously fed to the input of the differentiating unit of the computing device. When a heat pulse arrives, indicating rapid heating or cooling of the device body, a timer and an immittance meter are turned on. The timer sets the measurement period and the end time, and the immittance meter determines the parameters C _n and tgδ _{n of the} capacitive sensor formed by the surface of the device body and the surface of the nozzle. The measured values are fed to the input of the comparison unit of the computing device. At the same time, temperature values are received from the temperature sensor to the input of the computing device. _{The values of С n} and tgδ _n entering the input of the comparison unit of the tracking system are _{compared with the values С в} and tanδ _в , selected from the memory of the computing device, corresponding to the current temperature value T ° K. The values of the differences ΔС and Δtgδ, determined in the comparison unit, are fed to the input of the multiplication unit of the computing device with a time interval set by a timer. When the value of the internal energy of the gaseous medium is reached, corresponding to its temperature, and determined by the value of its mass, the timer generates a command ready for measurements. This command can be displayed on the indicator light.

The differentiating unit, the comparison unit, the multiplication unit in the computing device can be implemented in software.

An example of a specific execution.

The authors developed working design documentation, according to which two prototypes of the container were manufactured.

The body of the device is made of titanium and plated with black nickel.

A stanchion made of copper was used as a fitting, an electrical insulating sleeve was made of caprolon. An LCR-817 capacitance and dielectric loss tangent meter was connected to the fitting and the body, the body temperature was measured with a TL-19 mercury thermometer GOST 2045-71.

In the design of the device, a wire 0.4 mm in diameter made of low-melting indium (In) material was laid in the gap between the side surface of the windows and the surface of the body. During the removal of adsorbed moisture, the device was heated to the melting point of indium, which at the same time filled the gap, forming an airtight seal during cooling, while the device was evacuated. This combination of technological operations made it possible to significantly simplify the design of the device and the technological process of its manufacture, significantly reducing the labor intensity and its cost.

After checking for tightness, we experimentally obtained the thermal characteristics of the device in an evacuated and gas-filled state; the dependence on the temperature at which the dielectric constant of the gaseous medium of the device changes is determined.

Before starting work, the parameters of the dependence of the device on the temperature in the evacuated state C _in and tgδ _in , the composition and mass of the components of the gas mixture were determined, and recorded in the memory of the computing device.

Values of capacitance and dissipation factor as a function of temperature after filling the device with gas are given in Table 1 and Table 2.

After processing the experimental data, we obtained the characteristics of the device reduced to a temperature of 20 ° C. (Approaches to solving the problem of extrapolating experimental data are known).

C _n = 4.84e ^{[0.0075 (t-20) +0.0002 (t-20) ^ 2]} , pf;

C _in = 4.59e ^{[0.0057 (t-20) +0.0002 (t-20) ^ 2]]} , pf;

tgδ _n = 0.042е ^{0.0402 (t-20)} ;

tgδ _in = 0.032e ^{0.0383 (t-20)} .

The declared design of the container is supposed to be used when carrying out work on the modernization of the azimuth transmission systems, for example, for the used azimuth transmission device, according to US Pat. No. 2408840.

Claims (6)

1. A container for optoelectronic devices, containing a gaseous medium filled with a thermal conductivity of at least 0.05 W / m ° K, the dew point of which is not higher than -50 ° C, a sealed casing with at least one window, with a fitting, a temperature sensor, communication unit and control unit, characterized in that the body and the fitting are made of metal and separated by an electrical insulating sleeve, the control unit is made in the form of a tracking system containing a medium immitance meter with a power source, a computing device with memory and a timer, with one input of the medium immitance meter electrically connected to the body, the second - to the fitting, the outputs of the immitance meter and the temperature sensor are connected to the computing device, and the gaseous medium is selected from the condition (c ₁ ρ ₁ + c ₂ ρ ₂ +… + c _n ρ _n ) ≤934.2 J / (m ³ ° K), where c _i is the specific heat capacity of the gas medium component, J / (kg ° K); ρ _i is the density of the component of the gaseous medium, kg / m ³ ; n is the number of components of the gaseous medium. 2. The device according to claim. 1, characterized in that the window is made with a gasket made of a material, the melting point of which is lower than the melting point of the electrical insulating sleeve.

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