Laser spectrum detection is an important technology which is used in laser reconnaissance and laser warning receiver.
The identification of the laser spectrum can provide the information for optic-electronic countermeasure. On the basis of
analysis of and research on the current laser spectrum detection technology, a passive laser spectrum detection system
based on the theory of coherent spectrum detection and Fourier Transform spectrum detection technology was designed.
The fiber optical antenna and modified wedge interferometer are system's important component parts, and the
parameters of them are expatiated detailedly. The spectrum information was obtained after the Opto-Electronic transform
by liner charge couple device (CCD) and Fourier transform by fast digital signal processor (DSP). The design method
and the structure principle of key parts were analyzed detailedly in this paper, it also consisted the correlative
performance analyze and setting up of experiment system. The result shows that the measure of wavelength of eight
different semiconductor lasers, The test results indicate that the response time of the designed system is less than 10ms
and the wavelength resolution is less than 10nm.
Methane explosion accident is always the main threat to mine production. The two main physical factors of methane
explosion are the concentrations of methane and oxygen comes to the explosive limits and the existence of fire source. It is
very important to measure the concentration of methane in real-time and accurately for protecting the production safely.
Among many methods of methane gas concentration measurement, harmonic detection is one of more effective methods
for measuring the weak signal and raising the sensitivity of detection. The study based on the spectrum absorption
properties of methane, adopted the Distributed Feedback LD, high performance gas absorption cell. The lock-in amplifier
SR830 is adopted to measure the first and second harmonic signals for different methane concentration in this paper. And
analyzed the data with LabVIEW. The analysis data validated the good linearity among the methane concentration and
I2f/If (second harmonic/first harmonic) in the range from 0% to 5%, confirmed the superiority of second harmonic theory.