Research Of Hyperspectral Imaging Acquisition Technology Based On CMOS Sensor

Thanks to the lightweight, small and low-power, light hyperspectral camera has been an important requirement for social development, and light hyperspectral camera can also bring society a huge commercial value. CMOS detector with high-integrity can greatly simplify the external circuit design for hyperspectral imaging system, so that the system can obtain advantages of light weight, small size and low power consumption, and also can be applied to the new small UAV platform.Based on the principle and performance characteristics of CMOS image sensors, the back-illuminated CMOS sensor has higher sensitivity for a spectral imaging system, with the almost 100% of the high pixel fill factor. Meanwhile, filters, prisms, grating, three kinds of spectroscopic methods and their application environment are introduced. CMOS spectral imaging system has some evaluation parameters, which is spectral resolution, spatial resolution, signal to noise ratio and dynamic range, etc. Based on the particularity of the CMOS sensor, the performance of CMOS hyperspectral imaging system cannot be generalized, and it should be comprehensively assessed of each parameter combined with the specific applicable environment.The research of electronic part with the system has based on the E2V’s commercial CMOS imaging detector EV76C661.With the Specim’s V10 M VNIR spectrometer, a prototype of the system has been set up and also accomplished the push-broom imaging experiment. Spectral wavelength of the prototype range 400 nm to 1000 nm with the spectral sampling interval of 3.6nm.After timing optimization, the system achieve multi-modal imaging functions of spectral pixel merge, spatial binning and spectral pixel merge after spatial binning, which can not only reduce the transmission load but also enhance the SNR. For non-uniform response, two-point correction method has been used in the output image, and the non-uniformity coefficient of the correction result has been controlled in 3%.Because of the special threshold response mode of detector, we can’t get the dark current noise from the traditional method, so, we propose a new method to infer dark current noise with the threshold time. Eventually after using this method we got the evaluation result of noise and SNR, which, SNR of image at about 0.3 albedo can reach 141(i.e. 43 d B) and the system’s highest SNR can reach 316.8(i.e. 50dB) with the dynamic range of 55.6dB.At the end of this article, by a comparison the CMOS sensor with sensitivity advantage for low light condition is analyzed. Because of the development of the CMOS process and small UAV technology, hyperspectral imaging technology based on CMOS sensor has broad space of development and application.