Differential Absorption Lidar for detecting atmospheric NO<sub>2</sub> (NO<sub>2</sub>-DIAL) is used extensively for its high precision and
spatial resolution, and the measurement can be done real-time with a wide range. The uniaxial crystal reflectivity must
be considered in optical path adjustment. From the point of view of energy, based on optical electromagnetic theory and
Jones matrix, the relationship between intermediary reflectance and polarization state of incident light is discussed, and
the normal relational expression of them is gained. An experiment example is given, and the measured value of the
example is in conformity with the computer simulation curve. The result shows that the regulation of crystal reflectivity
has useful significance for adjusting the optical path of NO<sub>2</sub>-DIAL.
To achieve high quantum efficiency and good stability has been a main direction to develop GaAs photocathode
recently. Through early research, we proved that variable doping structure is executable and practical, and has great
potential. In order to optimize variable doping GaAs photocathode preparation techniques and study the variable doping
theory deeply, a real-time quantum efficiency measurement system for GaAs Photocathode has been designed. The
system uses FPGA (Field-programmable gate array) device, and high speed A/D converter to design a high signal noise
ratio and high speed data acquisition card. ARM (Advanced RISC Machines) core processor s3c2410 and real-time
embedded system are used to obtain and show measurement results. The measurement precision of photocurrent could
reach 1nA, and measurement range of spectral response curve is within 400~1000nm. GaAs photocathode preparation
process can be real-time monitored by using this system. This system could easily be added other functions to show the
physic variation of photocathode during the preparation process more roundly in the future.
A new high spectrum difference technique was discussed in this paper, which use exploitation of quantum effects to
detect and warn low observable objects (include missile, stealth etc.). It is a new technique in photoelectric
reconnaissance area, and has many advantages such as wide radiation regions and greatly strengthens signal intensity. In
this paper radiation spectrum intensity, atmosphere attenuation and effect distance are studied. We found that high
intensity of stimulated emission spectrum can be obtained in atmosphere transmit window. So the sensitiveness and
distance of detect can be enormously improved.