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Zhang L.,Nanjing University of Science and Technology | Zhang L.,Science and Technology on LLL Night Vision Laboratory | Shi F.,Science and Technology on LLL Night Vision Laboratory | Zou Y.,Nanjing Military Representation Bureau | And 4 more authors.
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2015

In this paper, a double-threshold filter strategy was proposed and experimentally tested to improve the accuracy of photon counting imaging with an electron multiplying charge-coupled device, by taking into account the addition bias noise and Pseudo-photon noise during photon counting mode. Photon counting event detection was achieved by using amplitude threshold and frequency threshold filter to eliminate the bias noise and Pseudo-photon noise. Based on Bayesian estimation on multi-imaging, an optimal detection rule was found with minimum error cost. Experiment indicates that double-threshold filter strategy improves the photon detection accuracy than usual integrate method, and is suitable for imaging in ultra-low-light conditions such as biological dim light detection. ©, 2015, Chinese Society of Astronautics. All right reserved.


Liu C.,Nanjing University of Science and Technology | Yin W.,Nanjing University of Science and Technology | Yin W.,Science and Technology on LLL Night Vision Laboratory | Miao Z.,Science and Technology on LLL Night Vision Laboratory | And 4 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

We present the use and characterization of a Single Photon Detector (SPD) for active micro-pulse laser imaging. Laser active imaging technology obtains the two dimensional (2D) intensity information of objects by using the active continuous or pulsed laser illumination and an image sensor array. The Maximum range of laser active imaging is limited by the performance of image sensor, whose noise can seriously lower the obtainable SNR and degrade the quality of the reconstructed image. This paper presents a photon counting scheme based micro-pulse laser active imaging method that utilizes the SPD as the receiver and the micro-pulsed laser as the source. In this case, SPD was used to detect the laser echo. By using repeated multi-cycle detection strategies, every detected photon event is treated as an independent measurement of laser echo and thus the intensity information of objects is acquired with the response possibility estimation of laser echo. We chose a Geiger-Mode Avalanche Photodiodes (GM-APD) based approach, extending the methods of micro-pulse laser active imaging. In our implement, the number of TTL pulses output from the GM-APD within the duration of the pixel dwell time was recorder by a LabView pre-programmed instrument and then the laser echo response possibility of GM-APD was established by Full Waveform Analysis algorithm. This approach combined remote imaging with single photon sensitivity and laser active imaging. © 2013 SPIE.


He R.,Science and Technology on LLL Night Vision Laboratory | He R.,Nanjing University of Science and Technology | Chen Q.,Nanjing University of Science and Technology | Chen Y.,Science and Technology on LLL Night Vision Laboratory | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

Traditional assessment methods don't fit for photon-counting image (PCI) system because the output of PCI system is the number of photon instead of the gray value. Normalized mutual information is presented to assess Photon-counting image system performance and calculated based on improved 2D entropy for PCI system to provide the fidelity of PCI system. Probabilities of target classification error are introduced by Bayesian posterior probability classification method under the different fidelity conditions and the result confirms fidelity values. This method applied in the PCI experiments can reflect image fidelity and system performance well in different experiment conditions and supplies the evidences for assessing the quality for photon-counting image. © 2012 SPIE.


Wang C.,Science and Technology on LLL Night Vision Laboratory | Wang C.,Nanjing University of Science and Technology | Miao Z.,Science and Technology on LLL Night Vision Laboratory | Feng W.,Nanjing University of Science and Technology | And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

Compression is a kernel procedure in hyperspectral image processing due to its massive data which will bring great difficulty in date storage and transmission. In this paper, a novel hyperspectral compression algorithm based on hybrid encoding which combines with the methods of the band optimized grouping and the wavelet transform is proposed. Given the characteristic of correlation coefficients between adjacent spectral bands, an optimized band grouping and reference frame selection method is first utilized to group bands adaptively. Then according to the band number of each group, the redundancy in the spatial and spectral domain is removed through the spatial domain entropy coding and the minimum residual based linear prediction method. Thus, embedded code streams are obtained by encoding the residual images using the improved embedded zerotree wavelet based SPIHT encode method. In the experments, hyperspectral images collected by the Airborne Visible/ Infrared Imaging Spectrometer (AVIRIS) were used to validate the performance of the proposed algorithm. The results show that the proposed approach achieves a good performance in reconstructed image quality and computation complexity.The average peak signal to noise ratio (PSNR) is increased by 0.21∼0.81dB compared with other off-the-shelf algorithms under the same compression ratio. © 2013 SPIE.


He W.-J.,Nanjing University of Science and Technology | Chen Y.,Science and Technology on LLL Night Vision Laboratory | Chen Q.,Nanjing University of Science and Technology | Gu G.-H.,Nanjing University of Science and Technology | Cheng W.,Science and Technology on LLL Night Vision Laboratory
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

We present the use and characterization of a Single Photon Avalanche Detector (SPAD) for shot-noise-limited imaging at ultra-low light-level. Many demanding photonic applications, such as fluorescence laser scanning microscopy, require the acquisition of very weak optical signals, generally composed by few photons mostly in the visible and near infrared wavelength. Conventional photo detector that utilizes analog current integration is generally not able to detect such low intensity signal due to the excessive noise at low signal levels. In this paper, we demonstrate shot-noise-limited imaging by scanning and using N-photon photo-detection implemented with a Single Photon Avalanche Detector. We choose a LabView based approach, extending the methods of N-photon photo-detection. In our implement, the number of TTL pulses received from the Single Photon Avalanche Detector within the duration of the pixel dwell time is recorder by a LabView pre-programmed instrument and then wrote into a pre-allocated image array, using the pixel clock and line sync signals to determine the position within the image. Experiments show that our N-photon photo-detection exhibits extreme sensitivity even down to single photon level. This characteristic of the ultra-sensitivity makes this scheme very suitable for low signal levels in fluorescence laser scanning microscopy. Related with the dynamic range, the maximum count rate of our N-photon photo-detection scheme reaches 106 counts per second (cps) while maintaining high detection efficiency. It has also been demonstrated that the thermoelectrically cooled Single Photon Avalanche Detector neutralizes dark counting noise of detector and thus obtain a nearly shot-noise-limited imaging performance. © 2012 SPIE.

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