Abstract
Computational ghost imaging (CGI) achieves single-pixel imaging by using a Spatial Light Modulator (SLM) to generate structured illuminations for spatially resolved information encoding. The imaging speed of CGI is limited by the modulation frequency of available SLMs, and sets back its practical applications. This paper proposes to bypass this limitation by trading off SLM’s redundant spatial resolution for multiplication of the modulation frequency. Specifically, a pair of galvanic mirrors sweeping across the high resolution SLM multiply the modulation frequency within the spatial resolution gap between SLM and the final reconstruction. A proof-of-principle setup with two middle end galvanic mirrors achieves ghost imaging as fast as 42 Hz at 80 × 80-pixel resolution, 5 times faster than state-of-the-arts, and holds potential for one magnitude further multiplication by hardware upgrading. Our approach brings a significant improvement in the imaging speed of ghost imaging and pushes ghost imaging towards practical applications.
Highlights
Computational ghost imaging (CGI) achieves single-pixel imaging by using a Spatial Light Modulator (SLM) to generate structured illuminations for spatially resolved information encoding
All of the work on computational ghost imaging use a SLM working at tens or hundreds hertz to generate illumination patterns, and the low coding efficiency highly limits the imaging speed and quality and sets back putting ghost imaging into practical use
These two mirrors are kept parallel to each other during rotating, so the beam leaving galvanic mirror #2 (GM2) keeps parallel to the beam entering galvanic mirror #1 (GM1) and hits the digital mirror device (DMD) at the same incident angle, which enables the DMD reflecting back the beam exactly in the opposite direction
Summary
Yuwang Wang[1], Yang Liu[1], Jinli Suo[1], Guohai Situ[2], Chang Qiao1 & Qionghai Dai[1] received: 01 November 2016 accepted: 22 February 2017 Published: 30 March 2017. We notice that the spatial resolution of computational ghost imaging (typically less than 100 × 100 pixels) is much lower than that of SLM (usually higher than 800 × 600 pixels) Unitizing this gap, we propose a sweeping based approach to multiply the illumination modulation speed, by trading off relatively redundant spatial resolution of SLM for a much faster modulation. Please note that our pattern modulation speed is highly limited by the galvanic mirror’s working frequency Fg, for some high-end galvanic mirrors with the working frequency achieving 1 kHz e.g. CTI 6200 H, the speed of the same pixel resolution will be as high as 485 kHz. The pixel resolution is mainly determined by the size of the scanning beam, given the specifications of DMD. The diameter of the beam is 4mm, and the largest pixel resolution we can achieve is about 200 × 200
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