A turbulent simulating device in inner field, which is used to research the process of laser propagation in atmospheric
turbulent, could avoid to be disturbed by many casual factors from the atmosphere disturb. For the sake of eliminating
uncertainty of the atmosphere disturb, a physical simulation turbulent system using phase plates based on Kolmogorov
spectrum is designed to carry out a beam spot scintillation experiment of laser propagation. The physical simulation
turbulent system employs two phase plates with micro-fabricated surfaces with the characteristic of Kolmogorov
spectrum. The formula of simulated atmospheric coherent length of the optical system is given for the motive of
adjusting different turbulent conveniently. With the movement in a cone-shape path optical system, the different
coherence length to simulate atmospheric turbulent can continuously be adjusted in a wide range. In the experiment of
beam spot scintillation, a He-Ne laser of 632.8 nm wavelength with 3.5 mm beam diameter is adopted as the propagation
source, which is expanded to 10mm diameter with the expanded lens. The beam passes through all the optical element of
the whole turbulent simulation system in sequence. Finally the beam spot reaches the CCD for picking spot images and
the detector of laser energy meter for collecting the power of spot scintillation. When the distance between the phase and
field lens is adjusted to a longer simulated coherent length, it is observed that whole spot is fractured due to serious phase
aberration. We measured the power of spot in one rotation period of the phase plate. The normalized power amplitude
distribution histogram and the normalized logarithm power amplitude distribution histogram of the intensity scintillation
data in the experiment are given in the paper.
KEYWORDS: Stars, Calibration, Single photon, Signal to noise ratio, Black bodies, Single photon detectors, Charge-coupled devices, Light sources, Photodetectors, Scene simulation
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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