A calibration method of faint star magnitude of the star scene simulation device is proposed
in this paper. In the research of simulation star magnitude, luminometers and CCD devices
are the general calibration devices which are used to measure the illumination intensity and
calibrate its magnitude. But if the simulation magnitude is only sixth magnitude, its
illumination intensity is only 1.0x10-8 Lux. This illumination intensity level is the lowest
illumination intensity that the commercial luminometer can detect. Hence the simulation
star magnitude lower than six magnitude cannot be calibrated by luminoters. Likewise CCD
devices also need an additive cooler in this case. When the single photon characteristic is
presented due to the low luminosity of simulating light sources, the simulation star
magnitude can be calibrated by detecting its photon flux of radiation with the method of
single photon count. In this paper the detection principle of single photon based on a
compact designed PMT detecting of the radiation level of simulation star magnitude is
advanced. Especially a spectrum match method is proved theoretically to be an effective
means for selecting PMT photosensitive type. In the case of the detection object of the
simulation star in visible wavelength, a analysis indicates that the material of tri-alkali
cathode materials its best choice after being compared the Signal-to-Noise of photon
detector of several PMT photosensitive materials based on the different spectrum match
ratio of different object light sources and different cathode materials. An experiment is
employed to show the relationship of control voltage of PMT and its dark counte, the
relationship of the environment temperature of PMT and its dark counter, which proves its only decades of CPS at room temperature. The so low dark counter avoids a bulky cooler
and is convenient for installing it on the star scene simulation equipment. Finally in the experiment of calibrating the simulation star magnitudes the ability of its calibration is confirmed to reaches up to 12m, meanwhile its calibration error is within ±0.2m.
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