Radiation intensity spatial distribution of laser diode arrays
and products based on them registering unit

SVETINFO-3D

Application

The SVETINFO-3D module provides registration of the radiation intensity spatial distribution of laser diode bars (LDB) and laser diode arrays (LDA).

For the LDB/LDA pump current pulses forming a SVETINFO-I generator is used, which generates pulses with a duration of up to 300 μs.

Radiation intensity readings registration is carried out by 95 photodiodes (PD) located on a circle with a radius of 520 mm in a plane passing through the geometric center of the radiation source. The diameters of the photodiodes sensitive areas are 3 mm, which is sufficient for averaging the possible fluctuations of the intensitiy field recorded readings caused by interference phenomena.

 

 

Measuring unit SVETINFO-3D

There are 31 photodiodes on the arch of the measuring module in the range of deviation angles -15°<ψ<15° from the normal vector of emitter N. The angular step of placing photodiodes is 1°. In the ranges of deviation angles -80°<ψ<-15° and 15°<ψ<80° there are 64 photodiodes, the angular spacing of which is 2°. Thus, in the region of small deviation angles from the normal vector of the emitter, where changes of its directivity pattern can be significant, intensity readings are recorded at an angular resolution of 1°. In the region of large deviation angles from the vector N, where the changes in the directivity pattern are not so pronounced, the intensity readings are recorded at an angular resolution of 2°.

The intensities field readings registration within the spherical sector of space is performed by rotating the emitter around its normal vector N within 0°<α<180° with a step of 1° and recording readings by all 95 photodiodes of the module. As a result the intensity field readings are determined in a polar coordinate system with a center coinciding with the geometric center of the emitter with a resolution of no worse than 1° in azimuth angle and no worse than 2° in elevation, except for the spherical sector within the elevation angle of 75°<β<90° where a resolution of no worse than 1° is provided, both in azimuth and in elevation.

To reduce the number of required analog communication channels, the 95 photodiodes are divided into 8 groups - 7 groups of 12 photodiodes and 1 group of 11 photodiodes. To obtain data from each group of photodiodes, a single pump current pulse is formed. To complete a full data acquisition cycle, a sequence of 8 pump current pulses is formed from all 95 photodiodes. Averaging the intensity measurement results obtained for L such pulse sequences reduces the noise effect on the measurement results by a factor of √L.

 

Operating mode control panel of measuring unit SVETINFO-3D

Visualization of 3D radiation patterns
according to the results of measurements for two types of emitters.
Translucent spherical segments indicate levels 0,5·I_max, 0,7·I_max , 0,9·I_max.

The unified control commands system makes it possible to use the module as part of automated complexes for measuring the parameters of LDB and LDA, as well as conducting climatic and life tests of such products.
 

Specifications

Radiation source type	LDB or LDA
Parameters of registered radiation pulses – pulse’s leading edge duration, not less than, µs – pulse’s trailing edge duration, not less than, µs	1 1
Azimuth angle resolution, °,not worse than	1±0,1
Elevation angle resolution, °, not worse than	2±0,2
Maximum temperature of the radiation source, °С, at a positive temperature of the refrigerant, not more than	+50 ±0,5
Minimum temperature of the radiation source, °С, at refrigerant temperature +25 °С	-30 ±0,5
Minimum temperature of the radiation source, °С, at refrigerant temperature 0 °С	-50  ±0,5
Power supply - industrial single-phase network Power consumption, not more than, V•А   Cos φ value, not less than	220 V, 50 Hz 800 0,95
Overall dimensions (h×w×d), mm3	700×1300×800
Weight, no more than, kg	30
Operating temperature range, °С	+15 ... +30