Research of base 4 FFT algorithm in infrared interference imaging spectrometer based on GPU

Abstract

Imaging spectroscopy technology combines imaging technology with spectroscopy technology. The most common imaging spectrometers are dispersive imaging spectrometers and interferometric imaging spectrometers. The incident slit of dispersive imaging spectrometers is located on the front focal plane of the collimation system, and the incident light passes through the collimator. After the straight optical system is collimated, the light energy is imaged on different positions of the detector in the order of wavelength by the imaging system after dispersion by the prism or grating, and the target spectrum is directly obtained. The principle is simple and the technology is relatively mature, but the light flux will be affected by the incident slit. The interferometric imaging spectrometer forms an interferogram by introducing different optical path differences into the incident beam, and then uses the Fourier transform relationship between the interferogram and the spectrogram to obtain the spectral information of the object, with high luminous flux, multi-channel and high spectral resolution.The CUDA architecture was developed by NVIDIA and is mainly used in the field of parallel computing. Its core idea is to use the GPU as a co-processor of the CPU, which is responsible for the calculation of a large amount of data and greatly shortens the data calculation time. It has been widely used in finance. Simulation, biological computing, physical simulation, simulation computing and artificial intelligence and other fields.The spectral data processing of the infrared interference spectrometer system mainly includes steps of data rearrangement,de-DC,apodization and Fourier transform.Due to the large amount of calculation of Fourier transform and long calculation time,it seriously affects the real-time application capability of the system.Therefore,this paper proposes a method using base 4 FFT algorithm for implementing fast Fourier transform on GPU platform using CUDAin infrared interference spectrometer system.GPU and the base 4 FFT algorithm are used at the same time to greatly improve the degree of parallelism and shorten the calculation time. A spectral raw image of 640*480*256 band,using the traditional base 2 fast Fourier transform on the CPU takes about 20 minutes to invert into a pseudo-color image.With the algorithm of this paper,the time is shortened to less than 2 minutes.