Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
The methods of measurement for image converter tubes and image intensifier tubes
1 Subject content and applicable scope
This standard specifies the test conditions and methods for photoelectric parameters of image converter tubes and image intensifier tubes (hereinafter referred to as electronic tubes).
This standard is applicable to the photoelectric parameter test of image converter tube (including X-ray image intensifier tube) and image intensifier tube and its components.
2 Test conditions
2.1 Environmental conditions
Unless otherwise specified, the environmental conditions for the test shall meet the normal test atmospheric conditions (temperature of 15–35°C, relative humidity of 45%–75% and air pressure of 86–106 kPa) specified in GB 2421 Basic environmental testing procedures for electric and electronic products—General and guidance.
2.2 Test equipment
2.2.1 Test room
Photocathode is sensitive to radiation, so the test room of electronic tube shall be able to shield external radiation. The selection of test room materials (including paint and any opaque plastic or laminated plate) shall also ensure that they are in the invisible light region of the spectrum and do not affect the accuracy of the test.
The test shall be provided with devices for shielding magnetic and electric fields.
For the test device, the input and output optical axes of the electronic tube shall be positioned.
2.2.2 Filter
The performance of the filter shall not affect the test of photoelectric parameters of the electronic tube.
a. Neutral filter
The spectral transmittance of neutral filters in the specified wavelength range shall be specified in the detailed specification.
b. Monochromatic filter
The minimum peak transmittance, the bandwidth and peak wavelength at 50% (or 10%) peak transmittance, and the maximum transmittance in the specified band outside the passband of the monochromatic filter shall be specified in the detailed specification.
2.2.3 Diffuser
The spectral transmittance and spatial distribution of luminous intensity of diffusers shall be specified in the detailed specification.
2.2.4 Light source
Monochromatic light source is preferred. When a monochromatic light source is not required, a tungsten lamp calibrated by a light source (standard A light source) with a color temperature of 2,856 ± 20K shall be used, except that the test method allows a wide range of color temperature.
The maximum allowable divergence angle of light beam shall be specified in the detailed specification.
3 Photoelectric parameter test
3.1 Photocathode sensitivity
3.1.1 Definition
3.1.1.1 Luminous sensitivity
The quotient of the photocurrent divided by the incident luminous flux.
3.1.1.2 Irradiation sensitivity
The quotient of the photocurrent divided by the radiant power.
3.1.2 Test procedure
Apply a specified voltage between the cathode of the electronic tube and other connected electrodes, evenly irradiate the specified area of the photocathode with the specified luminous flux or radiant power parallel to the input optical axis, and use the specified filter. Measure the cathode current when there is irradiation and no irradiation.
The photocathode sensitivity shall be calculated using Equation (1):
(1)
where,
——the luminous flux or radiant power, lm or W;
I1——the cathode current when there is irradiation (including leakage current and dark current of photocathode), μA or mA;
I2——the cathode current when there is no irradiation (including leakage current and dark current of photocathode), μA or mA;
When the sensitivity is calculated, the luminous flux or radiant power is used to obtain the luminous sensitivity (μA/lm) or radiation sensitivity (mA/W) respectively.
This test is only applicable to electronic tubes that can be connected to each electrode.
Conditions to be specified in the detailed specification:
Working conditions of electronic tubes;
Irradiated area of the photocathode;
Voltage between the photocathode and other electrodes connected together;
Luminous flux and (or) radiant power;
Characteristics of light source (see 2.2.4);
Filter requirements (see 2.2.2).
3.2 Equivalent background illuminance
3.2.1 Definition
The incident illuminance when the output luminance is increased to twice the average background luminance generated only by the dark current of the electronic tube.
3.2.2 Test procedure
Apply voltage to each electrode of the electronic tube according to requirements specified in the detailed specification, do not apply light to the photocathode, and measure the average luminance of the specified area of the fluorescent screen in the direction of the output optical axis with the specified luminance meter after the specified stabilization time, and record the reading.
Use the light parallel to the input optical axis and with the specified illuminance emitted by the specified light source to evenly irradiate the specified area on the photocathode, and record the reading of the luminance meter, then the equivalent background illuminance shall be calculated using Equation (2):
(2)
where,
R1——the reading of the luminance meter when the photocathode is not illuminated;
R2——the reading of the luminance meter when the photocathode is illuminated;
E——the illuminance of photocathode.
Unless otherwise specified in the detailed specification, since the reading R1 or R2 fluctuates, it shall be observed for 30s, and then read R1 and R2.
Conditions to be specified in the detailed specification:
Working conditions of electronic tubes;
Stabilization time (when there is no light);
Illuminated area of the photocathode;
Illuminance of photocathode;
Area of measured luminance of fluorescent screen;
Characteristics of luminance meter (dark current, linearity);
Characteristics of light source (see 2.2.4) and the maximum divergence angle.
3.3 Luminance gain or radiation gain
3.3.1 Definition
3.3.1.1 Luminance gain
The quotient obtained by dividing the output average luminance within the specified area of the fluorescent screen by the uniform illuminance of the specified spectral distribution within the specified area on the photocathode.
3.3.1.2 Radiation gain
The quotient obtained by dividing the average radiance of the specified spectral distribution within the specified area of the fluorescent screen by the uniform irradiance of the specified spectral distribution within the measured area projected onto the photocathode.
3.3.2 Test procedure
Uniformly irradiate the specified area of the photocathode with the specified illuminance or irradiance of the specified light source parallel to the input optical axis. Apply voltage to each electrode of the electronic tube according to requirements specified in the detailed specification. After the specified stabilization time, measure the luminance or radiance within the specified area of the fluorescent screen with the specified luminance meter or radiometer. The luminance gain or radiation gain shall be calculated using the following equation:
(3)
where,
L——the luminance or radiance, cd/m2 or W/(sr·m2);
E——the illuminance or irradiance, lx or W/m2.
In calculation, luminance gain is obtained from luminance and illuminance, and radiation gain is obtained from radiance and irradiance.
The luminance gain and radiation gain may also be calculated using the following equation:
(4)
Conditions to be specified in the detailed specification:
Working conditions of electronic tubes;
Characteristics of light source (see 2.2.4) and the maximum divergence angle;
Illuminance or irradiance of photocathode;
Illuminated area of the photocathode;
Corresponding spectral sensitivity and receiving angle of luminance meter or radiometer;
Stabilization time;
Area of measured luminance or radiance on the fluorescent screen.
3.4 Reverse working voltage
3.4.1 Definition
The ability of the electronic tube to withstand reverse power supply voltage.
3.4.2 Test procedure
Uniformly illuminate the whole area of photocathode to reach the specified illuminance, which can be zero. Apply the specified reverse voltage to the specified connection end of the electronic tube for the specified time. After the voltage is removed, at the end of the specified recovery time, the test shall be carried out according to the detailed specification.
This test is only applicable to electronic tubes with combined power supply.
Conditions to be specified in the detailed specification:
Illuminance of photocathode;
Reverse working voltage;
Duration of applying reverse voltage;
Recovery time;
Test requirements after applying reverse working voltage.
3.5 Uniformity of output luminance
3.5.1 Definition
The spatial change of the output luminance of the fluorescent screen under the specified incident light, which is generally expressed by the ratio of the maximum and minimum output luminance.
3.5.2 Test procedure
Uniformly irradiate the whole area of the photocathode with the specified light source and illuminance parallel to the input optical axis. Apply voltage to each electrode of the electronic tube according to the detailed specification, and visually detect the obvious non-uniformity of the luminance of the fluorescent screen. Then, use the luminance meter to measure the output luminance change in the specified area on the fluorescent screen, which can be shown in a chart.
Conditions to be specified in the detailed specification:
Working conditions of electronic tubes;
Tested area of the fluorescent screen;
Light source characteristics (see 2.2.4);
Illuminance of photocathode;
Spectral sensitivity and receiving angle of luminance meter.
3.6 Limit working voltage
3.6.1 Definition
The ability of the electronic tube to withstand limit working voltage.
3.6.2 Test procedure
Irradiate the whole area of the photocathode with the light of the specified illuminance, which can be zero. Apply the working voltage to the electronic tube and adjust it to the specified limit voltage value. Observe the fluorescent screen within the specified time, and bright spot, stripe, flash or defects of other shapes with higher luminance than the average background are not allowed. At the end of the specified observation time, after the limit voltage is removed, the test shall be carried out according to the detailed specification.
Conditions to be specified in the detailed specification:
Illuminance of photocathode;
Working conditions of electronic tubes;
Limit working voltage;
Duration of observation period;
Test requirements after applying limit working voltage.
3.7 Input current
3.7.1 Definition
The current flowing through the input circuit when the electronic tube works.
3.7.2 Test procedure
Apply voltage to each electrode of the electronic tube according to the detailed specification, and evenly irradiate the whole area of the photocathode with the light of the specified illuminance, which can be zero. Measure the average or peak current flowing through the input end.
Conditions to be specified in the detailed specification:
Working conditions of electronic tubes;
Illuminance of photocathode;
Input impedance of power supply (if applicable);
Measure the resistance of the circuit (if applicable).
3.8 Modulation transfer function
3.8.1 Definition
The relationship between modulation transfer factor and spatial frequency. The modulation transfer factor is the ratio of the modulation depth of the output image to the modulation depth of the input image when a sine wave pattern is transferred at a certain spatial frequency.
1 Subject content and applicable scope
2 Test conditions
3 Photoelectric parameter test
Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
The methods of measurement for image converter tubes and image intensifier tubes
1 Subject content and applicable scope
This standard specifies the test conditions and methods for photoelectric parameters of image converter tubes and image intensifier tubes (hereinafter referred to as electronic tubes).
This standard is applicable to the photoelectric parameter test of image converter tube (including X-ray image intensifier tube) and image intensifier tube and its components.
2 Test conditions
2.1 Environmental conditions
Unless otherwise specified, the environmental conditions for the test shall meet the normal test atmospheric conditions (temperature of 15–35°C, relative humidity of 45%–75% and air pressure of 86–106 kPa) specified in GB 2421 Basic environmental testing procedures for electric and electronic products—General and guidance.
2.2 Test equipment
2.2.1 Test room
Photocathode is sensitive to radiation, so the test room of electronic tube shall be able to shield external radiation. The selection of test room materials (including paint and any opaque plastic or laminated plate) shall also ensure that they are in the invisible light region of the spectrum and do not affect the accuracy of the test.
The test shall be provided with devices for shielding magnetic and electric fields.
For the test device, the input and output optical axes of the electronic tube shall be positioned.
2.2.2 Filter
The performance of the filter shall not affect the test of photoelectric parameters of the electronic tube.
a. Neutral filter
The spectral transmittance of neutral filters in the specified wavelength range shall be specified in the detailed specification.
b. Monochromatic filter
The minimum peak transmittance, the bandwidth and peak wavelength at 50% (or 10%) peak transmittance, and the maximum transmittance in the specified band outside the passband of the monochromatic filter shall be specified in the detailed specification.
2.2.3 Diffuser
The spectral transmittance and spatial distribution of luminous intensity of diffusers shall be specified in the detailed specification.
2.2.4 Light source
Monochromatic light source is preferred. When a monochromatic light source is not required, a tungsten lamp calibrated by a light source (standard A light source) with a color temperature of 2,856 ± 20K shall be used, except that the test method allows a wide range of color temperature.
The maximum allowable divergence angle of light beam shall be specified in the detailed specification.
3 Photoelectric parameter test
3.1 Photocathode sensitivity
3.1.1 Definition
3.1.1.1 Luminous sensitivity
The quotient of the photocurrent divided by the incident luminous flux.
3.1.1.2 Irradiation sensitivity
The quotient of the photocurrent divided by the radiant power.
3.1.2 Test procedure
Apply a specified voltage between the cathode of the electronic tube and other connected electrodes, evenly irradiate the specified area of the photocathode with the specified luminous flux or radiant power parallel to the input optical axis, and use the specified filter. Measure the cathode current when there is irradiation and no irradiation.
The photocathode sensitivity shall be calculated using Equation (1):
(1)
where,
——the luminous flux or radiant power, lm or W;
I1——the cathode current when there is irradiation (including leakage current and dark current of photocathode), μA or mA;
I2——the cathode current when there is no irradiation (including leakage current and dark current of photocathode), μA or mA;
When the sensitivity is calculated, the luminous flux or radiant power is used to obtain the luminous sensitivity (μA/lm) or radiation sensitivity (mA/W) respectively.
This test is only applicable to electronic tubes that can be connected to each electrode.
Conditions to be specified in the detailed specification:
Working conditions of electronic tubes;
Irradiated area of the photocathode;
Voltage between the photocathode and other electrodes connected together;
Luminous flux and (or) radiant power;
Characteristics of light source (see 2.2.4);
Filter requirements (see 2.2.2).
3.2 Equivalent background illuminance
3.2.1 Definition
The incident illuminance when the output luminance is increased to twice the average background luminance generated only by the dark current of the electronic tube.
3.2.2 Test procedure
Apply voltage to each electrode of the electronic tube according to requirements specified in the detailed specification, do not apply light to the photocathode, and measure the average luminance of the specified area of the fluorescent screen in the direction of the output optical axis with the specified luminance meter after the specified stabilization time, and record the reading.
Use the light parallel to the input optical axis and with the specified illuminance emitted by the specified light source to evenly irradiate the specified area on the photocathode, and record the reading of the luminance meter, then the equivalent background illuminance shall be calculated using Equation (2):
(2)
where,
R1——the reading of the luminance meter when the photocathode is not illuminated;
R2——the reading of the luminance meter when the photocathode is illuminated;
E——the illuminance of photocathode.
Unless otherwise specified in the detailed specification, since the reading R1 or R2 fluctuates, it shall be observed for 30s, and then read R1 and R2.
Conditions to be specified in the detailed specification:
Working conditions of electronic tubes;
Stabilization time (when there is no light);
Illuminated area of the photocathode;
Illuminance of photocathode;
Area of measured luminance of fluorescent screen;
Characteristics of luminance meter (dark current, linearity);
Characteristics of light source (see 2.2.4) and the maximum divergence angle.
3.3 Luminance gain or radiation gain
3.3.1 Definition
3.3.1.1 Luminance gain
The quotient obtained by dividing the output average luminance within the specified area of the fluorescent screen by the uniform illuminance of the specified spectral distribution within the specified area on the photocathode.
3.3.1.2 Radiation gain
The quotient obtained by dividing the average radiance of the specified spectral distribution within the specified area of the fluorescent screen by the uniform irradiance of the specified spectral distribution within the measured area projected onto the photocathode.
3.3.2 Test procedure
Uniformly irradiate the specified area of the photocathode with the specified illuminance or irradiance of the specified light source parallel to the input optical axis. Apply voltage to each electrode of the electronic tube according to requirements specified in the detailed specification. After the specified stabilization time, measure the luminance or radiance within the specified area of the fluorescent screen with the specified luminance meter or radiometer. The luminance gain or radiation gain shall be calculated using the following equation:
(3)
where,
L——the luminance or radiance, cd/m2 or W/(sr·m2);
E——the illuminance or irradiance, lx or W/m2.
In calculation, luminance gain is obtained from luminance and illuminance, and radiation gain is obtained from radiance and irradiance.
The luminance gain and radiation gain may also be calculated using the following equation:
(4)
Conditions to be specified in the detailed specification:
Working conditions of electronic tubes;
Characteristics of light source (see 2.2.4) and the maximum divergence angle;
Illuminance or irradiance of photocathode;
Illuminated area of the photocathode;
Corresponding spectral sensitivity and receiving angle of luminance meter or radiometer;
Stabilization time;
Area of measured luminance or radiance on the fluorescent screen.
3.4 Reverse working voltage
3.4.1 Definition
The ability of the electronic tube to withstand reverse power supply voltage.
3.4.2 Test procedure
Uniformly illuminate the whole area of photocathode to reach the specified illuminance, which can be zero. Apply the specified reverse voltage to the specified connection end of the electronic tube for the specified time. After the voltage is removed, at the end of the specified recovery time, the test shall be carried out according to the detailed specification.
This test is only applicable to electronic tubes with combined power supply.
Conditions to be specified in the detailed specification:
Illuminance of photocathode;
Reverse working voltage;
Duration of applying reverse voltage;
Recovery time;
Test requirements after applying reverse working voltage.
3.5 Uniformity of output luminance
3.5.1 Definition
The spatial change of the output luminance of the fluorescent screen under the specified incident light, which is generally expressed by the ratio of the maximum and minimum output luminance.
3.5.2 Test procedure
Uniformly irradiate the whole area of the photocathode with the specified light source and illuminance parallel to the input optical axis. Apply voltage to each electrode of the electronic tube according to the detailed specification, and visually detect the obvious non-uniformity of the luminance of the fluorescent screen. Then, use the luminance meter to measure the output luminance change in the specified area on the fluorescent screen, which can be shown in a chart.
Conditions to be specified in the detailed specification:
Working conditions of electronic tubes;
Tested area of the fluorescent screen;
Light source characteristics (see 2.2.4);
Illuminance of photocathode;
Spectral sensitivity and receiving angle of luminance meter.
3.6 Limit working voltage
3.6.1 Definition
The ability of the electronic tube to withstand limit working voltage.
3.6.2 Test procedure
Irradiate the whole area of the photocathode with the light of the specified illuminance, which can be zero. Apply the working voltage to the electronic tube and adjust it to the specified limit voltage value. Observe the fluorescent screen within the specified time, and bright spot, stripe, flash or defects of other shapes with higher luminance than the average background are not allowed. At the end of the specified observation time, after the limit voltage is removed, the test shall be carried out according to the detailed specification.
Conditions to be specified in the detailed specification:
Illuminance of photocathode;
Working conditions of electronic tubes;
Limit working voltage;
Duration of observation period;
Test requirements after applying limit working voltage.
3.7 Input current
3.7.1 Definition
The current flowing through the input circuit when the electronic tube works.
3.7.2 Test procedure
Apply voltage to each electrode of the electronic tube according to the detailed specification, and evenly irradiate the whole area of the photocathode with the light of the specified illuminance, which can be zero. Measure the average or peak current flowing through the input end.
Conditions to be specified in the detailed specification:
Working conditions of electronic tubes;
Illuminance of photocathode;
Input impedance of power supply (if applicable);
Measure the resistance of the circuit (if applicable).
3.8 Modulation transfer function
3.8.1 Definition
The relationship between modulation transfer factor and spatial frequency. The modulation transfer factor is the ratio of the modulation depth of the output image to the modulation depth of the input image when a sine wave pattern is transferred at a certain spatial frequency.
Contents of GB/T 14184-1993
1 Subject content and applicable scope
2 Test conditions
3 Photoelectric parameter test
