RU2338167C1 - Method for luminance temperature measurement - Google Patents

Abstract

FIELD: physics, measurement.

SUBSTANCE: method involves registration of object luminance by multielement matrix or linear photo receiver. In calibration mode incandescence current values of reference lamp are numbered in sequence and stored at moments of augmentation of measured signal swing difference for incandescent filament image of reference lamp and photosensitive surface cells of photo receiver screened by opaque mask, at given value. In measurement mode object temperature is defined by stored incandescence current value corresponding to measured signal swing difference for object image and screened photosensitive surface cells of photo receiver.

EFFECT: enhanced accuracy of luminance temperature measurement.

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Description

The invention relates to measuring technique, namely to brightness pyrometry, and can be used in television systems based on CCD cameras for remote measurement of temperature of objects.

There is a method of measuring the brightness temperature of an object by the method of disappearing filament by comparing the brightness of the filament of a reference lamp and an object whose temperature is determined by the magnitude of the filament after equalizing the brightness of the filament and the object, the filament is supplied to the reference lamp only in the pyrometer calibration mode and the brightness of the object is recorded a multi-element matrix or linear photodetector, on the part of the photosensitive cells of which the image of the filament of the reference lamp is projected, the incandescent current of which is in calibration mode change according to a linear law, its values are sequentially numbered and stored at the instants of increment of the output signal of the specified photodetector by a predetermined value, and in the measurement mode, the temperature of the object is determined by the stored value of the glow current corresponding to the magnitude of the output signal of the multi-element matrix or linear photodetector (RF Patent No. 2099674 Cl. G01J 5/52, 1997).

The disadvantage of this method is the lack of accuracy in measuring the brightness temperature of the object due to an error in determining the signal amplitude caused by the instability of the recovery circuits of the DC component of the video signal (black level fixing circuits), the presence of dark currents in the signal, and a number of other factors leading to the instability of a level relative to which the signal swing (reference signal level) is measured.

The indicated error, which depends on the level and brightness distribution over the image field, ambient temperature, and photodetector operating modes, leads to an error in determining the signal amplitude from the object and, thereby, reduces the accuracy of measuring its brightness temperature.

The objective of the proposed technical solution is to increase the accuracy of measuring the brightness temperature of the object by reducing the error in determining the amplitude of the signal from the object by eliminating the influence of instability of the reference signal level on the measurement process.

The technical result of the proposed solution is expressed in improving the accuracy of measuring the brightness temperature of the object. This is achieved due to the fact that the amplitude of the signal from the object is defined as the difference between the measured values of the amplitude of the signal from the image element of the object and the amplitude of the signal from the shaded element of the photosensitive surface of the photodetector. Since the magnitude of the instability of the reference signal level is included in both measured values of the signal span as a term, when determining the specified difference, the resulting error becomes equal to zero.

To achieve a technical result, a method for measuring the brightness temperature of an object by the method of disappearing filament by comparing the brightness of the filament of a pyrometer reference lamp and an object whose temperature is determined by the magnitude of the filament after equalizing the brightness of the filament and the object, the filament is supplied to the reference lamp only in calibration mode the pyrometer and the brightness of the object are recorded by a multi-element matrix or linear photodetector, on the part of the photosensitive cells of which the image of the filament is projected pubic lamp whose filament current calibration mode is changed linearly. In the calibration mode, the values of the incandescent current of the reference lamp are sequentially numbered and stored at incremented values of the difference in the measured signal spans from the image of the filament of the reference lamp and from the cells of the photosensitive surface of the photodetector, shaded by an opaque mask superimposed on it, by a predetermined value. In the measurement mode, the temperature of the object is determined by the stored value of the glow current corresponding to the difference between the measured signal spans from the image of the object and from the shaded cells of the photosensitive surface of the photodetector.

The drawing shows a device for implementing the method, where the following notation:

1 - measurement object;

2 - pyrometer;

3 - optical system of the pyrometer;

4 - CCD matrix of a TV camera;

5 - opaque mask;

6 - TV camera;

7 - reference lamp;

8 - current stabilizer;

9 - node microcontroller;

10 - communication channel;

11 - video capture card of a personal computer;

12 - personal computer.

The method is as follows.

The brightness temperature of the object is measured by comparing the difference in the magnitude of the video signal generated by the photodetector from the object and from the shaded portion of the photosensitive surface of the photodetector, with a calibration dependence connecting the magnitude of the specified difference and the brightness temperature of the object.

The calibration dependence is formed in the calibration mode as follows (see drawing).

The image of the filament body of the reference lamp 7, the current through which is stabilized at a predetermined level by a current stabilizer 8, controlled by the microcontroller assembly 9, is projected onto the photosensitive surface of the CCD matrix 4 of the TV camera 6, part of the photosensitive cells of which are obscured by an opaque mask applied to the surface of the CCD matrix 4 5. The TV camera 6 generates a television signal transmitted over the communication channel 10 to the input of the video capture card 11 of the personal computer 12, in which the difference in the amplitude of the output signal of the photodetector is measured U _{signal i} from the image of the filament body of the reference pyrometer lamp, the brightness temperature of which is known, and from the shaded cells of the photosensitive surface of the CCD matrix 4 U _0i . The measured difference is remembered at the moments of its increment by a given value.

The generated calibration dependence is stored in the computer memory in the form of a table:

(U _{signal 1} -U ₀₁ ) corresponds to the brightness temperature T _{bright 1} ;

(U _{signal 2} -U ₀₂ ) corresponds to the brightness temperature T _{bright 2} ;

......

(U _signal -U _0N ) corresponds to the brightness temperature T _bright.N .

In the brightness temperature measurement mode, the reference lamp 7 is turned off, the image of the measurement object 1 is projected by the optical system 3 onto the photosensitive surface of the CCD matrix 4 of the TV camera 6, some of the photosensitive elements of which are obscured by an opaque mask applied to the surface of the CCD matrix 4. TV camera 6 generates a television signal transmitted through the communication channel 10 to the input of the video capture card 11 of the personal computer 12, in which the difference of the signal _ranges from the image of the object U _{signal i} and from the shaded _{cells is measured} to the photosensitive surface of the CCD matrix 4 U _0i . The brightness temperature of the object is determined by comparing the measured difference with the calibration dependence.

Claims (1)

A method for measuring the brightness temperature of an object by the method of disappearing filament by comparing the brightness of the filament of a reference lamp and an object whose temperature is determined by the magnitude of the filament after equalizing the brightness of the filament and the object, the filament current to the reference lamp is supplied only in the pyrometer calibration mode and the brightness of the object is recorded with a multi-element matrix or linear photodetector, on the part of the photosensitive cells of which the image of the filament of the reference lamp is projected, the incandescent current of which is changed in the calibration mode according to a linear law, characterized in that in the calibration mode the values of the filament current of the reference lamp are sequentially numbered and stored at incremental moments of the difference in the measured signal spans from the image of the filament of the reference lamp and from the cells of the photosensitive surface of the photodetector, shaded by an opaque mask applied to it, to a given value, and in the measurement mode the temperature of the object is determined by the stored value of the glow current corresponding to the value of the difference of the measured signal ranges from expressions shaded by the object and the photosensitive surface of the photodetector cells.