ABSTRACT
For obtaining spectrum information and space distribution information of metameric targets at the same time, an AOTF-based imaging spectrometer was developed, which consists of a front imaging lens assembly, an AOTF filter imaging module, an AOTF driver, a plane array CCD, an image acquisition card and a PC. Under the control of the PC, a spectral image cube can be obtained by a fast wavelength scanning process, thereby the spectrum information of any point on the image is available. The developed imaging spectrometer, with a spectral range from 550-1,000 nm and a spectral resolution of 2.6 nm (@ 632 nm), and a less than 80 s switch time between any two wavelengths, has the characteristics of no mechanical moving part, low power dissipation and strong vibration resistance. The identification test of true and false roses and the information recovery experiment of altered physical evidence were carried out, The true and false roses were identified and the altered physical evidence was recovered, The experimental results showed that the imaging spectrometer has an excellent ability of identifying metameric targets, indicating a good application prospect.
ABSTRACT
Aiming at the existing problems such as weak environmental adaptability, low analytic efficiency and poor measuring repeatability in the traditional spectral oil analyzers, the present paper designed a portable mid-infrared rapid analyzer for oil concentration in water. To reduce the volume of the instrument, the non-symmetrical folding M-type Czerny-Turner optical structure was adopted in the core optical path. With a periodically rotating chopper, controlled by digital PID algorithm, applied for infrared light modulation, the modulating accuracy reached ±0.5%. Different from traditional grating-scanning spectrophotometers, this instrument used a fixed grating for light dispersion and avoided rotating error in the course of the measuring procedures. A new-type MEMS infrared linear sensor array was applied for modulated spectral signals detection, which improved the measuring efficiency remarkably. Optical simulation and experimental results indicate that the spectral range is 2 800 - 3 200 cm(-1), the spectral resolution is 6 cm(-1) (@3 130 cm(-1)), and the signal to noise ratio is up to 5 200 : 1. The acquisition time is 13 milliseconds per spectrogram, and the standard deviation of absorbance is less than 3 x 10(-3). These performances meet the standards of oil concentration measurements perfectly. Compared with traditional infrared spectral analyzers for oil concentration, the instrument demonstrated in this paper has many advantages such as smaller size, more efficiency, higher precision, and stronger vibration & moisture isolation. In addition, the proposed instrument is especially suitable for the environmental monitoring departments to implement real-time measurements in the field for oil concentration in water, hence it has broad prospects of application in the field of water quality monitoring.
ABSTRACT
A novel interferometer system based on the combinations of cube-corner reflectors and fixed plane mirrors was designed, the moving mirror drive system was designed and analysed, and its governor PID algorithm was used to ensure that the movement of the moving mirror is collimated, uniform and smooth. The parameters of the optical system of the interferometer and the optical devices were described. Finally, after validation of the experiment, it was indicated that the wave number accuracy, resolution, signal to noise ratio and other key indicators can meet the needs of practical application.
