Optical EngineeringResolution studies for electronic holography
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The output of an electronic holographic apparatus represents the magnitude and phase of the coherent light reflected from a three-dimensional object. The amplitude and phase can be fed into a spatial light modulator for three-dimensional object reconstruction, and the technique is thus named electronic holography. Resolution studies of recording and display devices for electronic holography are presented. The theoretical analysis for electronic holography is first carried out. Mathematically, the additive noise at the exposure of an electronic hologram is more serious than that at the reconstruction. Simulation is used to verify the theoretical results, and the resolution requirements for an electronic hologram are deduced. In our simulation, the point source is placed 500 mm in front of the recording device and the reference plane wave is tilted at angle π/4 in the -y direction with the normal to the recording plane. To discrimmate a two-point object with 0.17-mm separation, an 8-bit 256x256 charge injection device with a pixel size of 10 x 10 μm2 is necessary. In addition, the additive noise from the ambient light during the exposure or reconstruction of an electronic hologram should be less than 1/100 of the signal amplitude for a 40-dB output SNR.