3D dynamic holographic display by modulating complex amplitude experimentally

Abstract

Complex amplitude modulation method is presented theoretically and performed experimentally for three-dimensional (3D) dynamic holographic display with reduced speckle using a single phase-only spatial light modulator. The determination of essential factors is discussed based on the basic principle and theory. The numerical simulations and optical experiments are performed, where the static and animated objects without refinement on the surfaces and without random initial phases are reconstructed successfully. The results indicate that this method can reduce the speckle in reconstructed images effectively; furthermore, it will not cause the internal structure in the reconstructed pixels. Since the complex amplitude modulation is based on the principle of phase-only hologram, it does not need the stringent alignment of pixels. This method can be used for high resolution imaging or measurement in various optical areas.

Speckle-reduced holographic display by modulating complex amplitude in single-lens system

“…The double-phase hologram method, e.g., is employed to realize complex-amplitude modulation, in which the desired complex amplitude is decomposed into two phase-only distributions, then a phase-only CGH is synthesized by mixing the two-phase distributions spatially. 19 Recently, Shibukawa proposed a similar method that uses a random diffuser in the 4-f optical system to encode and reconstruct arbitrary complex amplitude from a phase-only CGH. [13][14][15] In addition, Yero proposed a method of complex-amplitude modulation based on the combination of two spatially sampled phase elements using a low-pass filter at the Fourier plane of a 4-f optical system.…”

Dynamic holographic three-dimensional projection based on liquid crystal spatial light modulator and cylindrical fog screen

“…The reconstructed image will be disturbed by speckle noise introduced by the coherence of laser beam. Some approaches have been proposed to reduce speckle noise, like time-averaging effect [17,18], pixel separate method [19,20], short-coherent light [21], complex modulation [22,23].…”

Accurate complex modulation by the iterative spatial cross-modulation method

“…Several methods have been proposed in regard to complex modulation. A well-known method for generating complex fields is by displaying an off-axis computergenerated hologram (CGH) on a phase-only SLM, in which the amplitude information is encoded as part of the phase information through interference with an off-axis reference plane wave [12,13] . Using this method, however, consumes energy of the incident plane wave, not only for the desired diffraction order, but also for unwanted diffraction orders, which limit the achievable diffraction efficiency.…”

“…The RMSE is used to measure the difference of the amplitude and phase between the target complex amplitude distributions and the reconstructed complex amplitude field. To further evaluate the performance of our proposed method, we compare it with the conventional SCMM, the off-axis method [13] , and DPH method [19] , respectively. The specifications of the phase-only SLM modeled in the simulations are as follows: the number of pixels is 1920 × 1080, the pixel pitch is 8 μm, the modulation range is [0, 2π], and the number of gray levels is 256.…”

“…5(a) and 5(e) is better than the reconstruction of the conventional SCMM without iteration that is shown in Figs. 5(b) and 5(f), the off-axis method in [18] , Off-axis Method [13] , and DPH Method [19] Proposed method Table 1 presents us the RMSEs of the reconstructions. It shows that the RMSE of the amplitude of the proposed method is smaller than 0.0017 after 50 iterations, and the RMSE of the phase is smaller than 0.0088 after 50 iterations.…”