The effect of chromatic background on luminance contrast-sensitivity function (CSF) is studied. We selected three
background-grey, orange and yellow-green from CIE 17 color center. The mean luminance of these colors is
approximately equal. We use CRT monitor display the rectangular stripe. Every rectangular stripe has six spatial
frequencies (0.4, 1, 2, 3.5,7 and 14cpd) .The method of limits is used in the experiment, 5 observers, who have normal
vision and test of vision is all over 1.0, participated in the experiment. The results of experiment show that the luminance
contrast sensitivity on chromatic background is lower than the luminance contrast sensitivity under grey background.
Fitting results show that Movshon model is better than Barten model, especially for the chromatic background. Both of
the models have deviation in the high spatial frequency part.
Laser induced damage in the visible window glass, such as K9 glass, irradiated with Nd:YAG laser operating at 1.064μm wavelength and approximately 10ns pulse duration was investigated in the present experiments. The pulse energy, duration, and beam spot size were taken as changeable factors to study the laser damage results. The experimental arrangement consists of a Q-switched Nd:YAG laser with pulse duration of about 10ns operating at 1.064μm, a lens of 40cm focal length which focus the laser beam onto the sample, a diaphragm to adjust the incident laser energy, a power stabilized He-Ne laser at 0.6328μm providing a diagnostic beam onto the Nd:YAG spot size, a detector which can measure the 0.6328μm reflected from the spot during the pulses beating. Images analysis was conducted at different laser induced damage level. At last, the dynamic damage threshold measuring method was discussed.
The samples of semiconductor’s surface temperature increased abruptly, when illuminated by laser pulse. The sample’s surface melted and remained liquid phase for a few hundreds ns. That caused reflectivity enhancement of the sample surface. In this article, numerical calculation was carried out on HgCdTe and PbS. And a 1mm-thick HgCdTe was used as the sample in the experiments. In the experiments, the sample was illuminated by laser pulse of 60ns duration from a Q-switched Nd:YAG laser. A beam from He-Ne laser was used as the monitor beam to illustrated the reflectivity changes of the sample. The results of the experiments were the conclusive evidences of our numerical calculation of the dynamic behavior in the sample.
The time-dependent optical reflectivity of HgCdTe detector at 0.63μm has been measured during irradiating by a 1.06-μm Q-switched Nd:YAG laser of 50-ns duration. The reflectivity was observed to increase abruptly to a value and to remain at that value for a period of time, which ranged from several nanoseconds to several hundreds of nanoseconds, depending on the irradiating pulse intensity. The duration of the “flat-top” portion of the reflectivity waveform represents the total time that the surface is melting. Subsequently, the reflectivity dropped abruptly to a value less than the initial one. The difference shows that the damage takes place in the incidence point. By measuring the time-resolved reflectivity and simulating physical structures of PbS and HgCdTe detector, whose dynamic mathematical model was created. By solving the equations of energy transport and thermal diffusion, the temperature rises of PbS and HgCdTe detector irradiated by pulse laser beam were studied, the relationship of power and temperature rises were discussed and the numerical solutions of dynamic temperature field were obtained. The experimental result of the reflectivity of HgCdTe detector was compared with calculated result. The results show finite element analysis is effective in solving the temperature field.
The miniature blackbody radiation source is a kind of very small IR radiation source. It is mainly used to simulate moving IR targets. It is one of the key component parts of IR missile test stations. Because of its very small dimension, it is very difficult to develop. This article reports our technical project of the miniature blackbody radiation source. The final testing result same also presented in the end.