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Proceedings Paper

Application of ZOOM-FFT for scanning-type spectrometer based on digital signal processor
Author(s): Peng Xu; Yue-xiang Peng; Li-qiang Wang; Hua Kang
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Paper Abstract

The Fourier transform spectrometer is based on a scanning-type Michelson interferometer with two optical-beams including reference laser and measurement light. The optical spectrum of measurement light can be obtained by colleting the analog signal of measurement light with the sampling time-scale based on interference fringes pulse of reference laser. The optical interferogram signal of the reference laser is converted to pulse signal, and it is subdivided into 16 times. So the sampling rate is constant only depending on frequency of reference laser and irrelative to the scanning-motor velocity. This means the sampling rate of measurement channel signal is on a uniform time-scale. In order to get optical spectrum, the analog signal of measurement channel should be collected and Fourier-transformed. Digital Signal Processor (DSP) TMS320-F2812 is used. Its internal 12-bit Analog-to-Digital Converter (ADC) for measurement channel is triggered by the 16-times pulse signal of reference laser. The DSP is used to process optical interferogram signal with ADC sampling rate up to about 1.5MHz. The optical spectrum of measurement channel signal is processed with 1024 points-Fast Fourier Transform (FFT) method. Then, the ZOOM-FFT is adopted. By digital frequency-shift conversion and low-pass filter, these digital signals are processed with 1024 points-FFT once again to improve the frequency measurement resolution. Finally, the optical spectrum of measurement channel will be displayed on LCD with high frequency-resolution.

Paper Details

Date Published: 11 October 2010
PDF: 6 pages
Proc. SPIE 7656, 5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, 76563B (11 October 2010); doi: 10.1117/12.865576
Show Author Affiliations
Peng Xu, Beijing Univ. of Technology (China)
Yue-xiang Peng, Beijing Univ. of Technology (China)
Li-qiang Wang, Tianjin Univ. of Technology and Education (China)
Hua Kang, Beijing Univ. of Technology (China)


Published in SPIE Proceedings Vol. 7656:
5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment
Yudong Zhang; Jose M. Sasian; Libin Xiang; Sandy To, Editor(s)

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