[Laser induced fluorescence spectrum characteristics of common edible oil and fried cooking oil].

In order to detect the trench oil the authors built a trench oil rapid detection system based on laser induced fluorescence detection technology. This system used 355 nm laser as excitation light source. The authors collected the fluorescence spectrum of a variety of edible oil and fried cooking oil (a kind of trench oil) and then set up a fluorescence spectrum database by taking advantage of the trench oil detection system It was found that the fluorescence characteristics of fried cooking oil and common edible oil were obviously different. Then it could easily realize the oil recognition and trench oil rapid detection by using principal component analysis and BP neural network, and the overall recognition rate could reach as high as 97.5%. Experiments showed that laser induced fluorescence spectrum technology was fast, non-contact, and highly sensitive. Combined with BP neural network, it would become a new technique to detect the trench oil.

[The echelle grating monochromator's design of pure rotational Raman Lidar].

The pure rotization oal Raman Lidar temperature measurement system usually retrieve atmospheric temperature according to the echo signal of high and low-level quantum numbers of N2 moleules. An effective method to detect the rotational Raman spectrum is taking a grating monochromator. In the present paper the detection principle and the structure of the echelle grating monochromator are described, the high order and lower order quantum number of the probe spectrum is resolved. The focal length of the collimating-focusing optical system is calculated by analyzing echelle grating's spectroscopic principle and dispersion ability. Subsequently spectral effect is simulated with Zemax software. The simulation result indicates that under the condition of the probe laser wavelength of 532 nm and using echelle grating monochromator, Rarnan spectrums of 529.05, 530.40, 533.77, 535.13 mn can be separated well, at the same time, the SNR of the system is enhanced by summing the spectral signals of symmetric quantum number. The echelle grating monochromator is small in size, and can easily meet the requirements of the miniaturization of Raman Lidar temperature measurement system.