Computational Ghost Imaging

Ghost imaging is a transverse imaging modality that has been receiving considerable and increasing attention of late, owing to its novel physical characteristics. Aside from minor implementation variations, virtually all ghost-imaging demonstrations thus far exploit the cross correlation between the photocurrents obtained from illumination of two spatially separated photodetectors by a pair of highly correlated optical beams. One beam interrogates a target (or sample) and then illuminates a single-pixel (bucket) detector that provides no spatial resolution. The other beam does not interact with the target, but it impinges on a scanning pinhole detector or a high resolution camera, hence affording a multiple pixel output. The term "ghost imaging" was coined soon after the initial experiments were reported, to emphasize that neither of the photocurrents alone yields a target image:the light hitting the bucket detector has interacted with the target, but that detector has no spatial resolution, whereas the light hitting the multipixel detector has not interrogated the target. However, cross correlating the two photocurrents does produce a target image. There is differences on the qualitative description of the ghost imaging Is ghost image formation a quantum effect, or is it classical? Ghost imaging is achieved in the experiment that is by parametric down-conversion light, and standard imaging techniques provide great potential, and then classical light ghost imaging is actualized. Classical light ghost imaging realized and especially pseudo thermal light ghost imaging achieved, ghost imaging application greatly expanded[1-17]. However, when it comes to the real sensing and imaging applications, the objects of the contrast is not very high, or a bunch of parallel rays in a small obstacle, the signal to noise ratio of the conventional ghost imaging will be very low, and it needs long measurement time. Therefore, the ghost imaging enormous potential will not be able to use, so we used spatial light modulator in experiments. Random phase pattern is given to the spatial light modulator, a bunch of parallel object light hit the probe of the spatial light modulator, the beam of reflected light is modulated, but the reference beam does not require modulation.The thesis includes the following three parts:1、the theoretical derivation of ghost imaging2、a brief introduction of spatial light modulator3、the ghost imaging experiment with spatial light modulator and computer.