Phase Retrieval and Reconstruction of Coherent Synthesis by Genetic Algorithm

In the context of diffractive optics, phase retrieval is a heavily investigated process of recreating an entire complex electric field from partial amplitude-only information through iterative algorithms. However, existing methods can fall into local minima during reconstructions or struggle to recover unusual and novel electric field distributions. We present a numerical method based on a global-optimization genetic algorithm that reconstructs non-trivial electric field distributions from single diffracted intensity distributions. Diffraction and propagation of the optical fields over arbitrary distances is modeled through implementation of the angular spectrum technique. Additionally, a coherently-locked laser array system is used as an experimental case-study demonstrating $0.09 \pi$ phase reconstruction accuracy of initial laser parameters from single intensity images.

Improved playback uniformity of random-phase free holograms by pixel separation method

Random-phase free computer-generated holograms offer excellent quality of virtually noise-free playback of low-frequency images, but have limited efficiency in the case of highly contrast binary images with dominant high spatial frequencies. Introduction of weak random phase allows the partial suppression of this problem, but causes strong noise in the outcome. Here we present the influence of pixel separation technique on the uniformity of far field reconstructions from such random-phase free holograms. We show the improved image quality with no additional speckle noise. Full Text: PDF ReferencesJ.W. Goodman, Roberts and Company (2005). DirectLink R.W. Gerchberg, W.O. Saxton, "A practical algorithm for the determination of phase from image and diffraction plane pictures", Optik 35, 237 (1972). DirectLink M. Makowski, "Minimized speckle noise in lens-less holographic projection by pixel separation", Opt. Express 21, 29205 (2013). CrossRef I. Ducin, T. Shimobaba, M. Makowski, K. Kakarenko, A. Kowalczyk, Jaroslaw Suszek, M. Bieda, A. Kolodziejczyk, M. Sypek, "Holographic projection of images with step-less zoom and noise suppression by pixel separation", Opt. Comm. 340, 131 (2015). CrossRef T. Shimobaba, T. Ito, "Random phase-free computer-generated hologram", Opt. Express 23, 9549 (2015). CrossRef T. Shimobaba, T. Kakue, Y. Endo, R. Hirayama, D. Hiyama, S. Hasegawa, Y. Nagahama, M. Sano, M. Oikawa, T. Sugie, T. Ito, "Random phase-free kinoform for large objects", Opt. Express 23, 17269 (2015). CrossRef M. Sypek, "Light propagation in the Fresnel region. New numerical approach", Opt. Comm. 116, 43 (1995). CrossRef K. Matsushima, T. Shimobaba, "Band-Limited Angular Spectrum Method for Numerical Simulation of Free-Space Propagation in Far and Near Fields", Opt. Express 17, 19662 (2009). CrossRef

Numerical optimization of writing computer-generated holograms in threshold media

Recent developments in binary photo-magnetic materials showed efficient and ultra-fast rewriting of holograms where the intensity threshold allows for a dense, sub-diffraction limit packing of hologram points. This paper describes the numerical optimization of the process of writing and reconstructing of 2-D images in a binary-phase computer-generated holograms stored in the said threshold-like medium. Global optimization of the free parameters of the writing process is shown, including the intensity threshold level, propagation distance, hologram spot size and the shape of the boundary regions of the written spots. We present the optimal set of parameters for the best possible writing quality. Full Text: PDF ReferencesA. Stupakiewicz, K. Szerenos, D. Afanasiev et al., "Ultrafast nonthermal photo-magnetic recording in a transparent medium", Nature 542, 71 (2017). CrossRef J. Starobrat, A. Frej, J. Bolek, R. Trybus, A. Stupakiewicz, and M. Makowski, "Photo-magnetic recording of randomized holographic diffraction patterns in a transparent medium", Opt. Lett. 45, 5177 (2020). CrossRef V. Ostroverkhov, et al., "Micro-Holographic Storage and Threshold Holographic Recording Materials", Jap. J. App. Phys. 48.3S1, 03A035 (2009). CrossRef K. Matsushima, T. Shimobaba, "Band-Limited Angular Spectrum Method for Numerical Simulation of Free-Space Propagation in Far and Near Fields", Opt. Express 17, 19662 (2009). CrossRef F. Wyrowski, O. Bryngdahl, "Iterative Fourier-transform algorithm applied to computer holography", JOSA A 5.7, 1058 (1988). CrossRef I. Ducin, T. Shimobaba, M. Makowski, K. Kakarenko, A. Kowalczyk, Jaroslaw Suszek, M. Bieda, A. Kolodziejczyk, M. Sypek, "Holographic projection of images with step-less zoom and noise suppression by pixel separation", Opt. Comm. 340, 131 (2015). CrossRef M. Makowski, "Minimized speckle noise in lens-less holographic projection by pixel separation", Opt. Express 21, 29205 (2013). CrossRef

Distortion correction for wide angle holographic projector

This letter presents distortion correction method enabling distortion minimized, large size image in wide angle holographic projector. The technique applies numerical predistortion of an input image used for hologram generation. It is based on estimation of distortion coefficients by comparing optically reconstructed point test chart with the original one. Obtained experimental results prove that the technique allows reconstruction of high-quality image. Full Text: PDF ReferencesM. Makowski, Experimental Aspects of Holographic Projection with a Liquid-Crystal-on-Silicon Spatial Light Modulator, in Holographic Materials and Optical Systems, M. Kumar, ed. (IntechOpen, 2019). CrossRef H. Pang, A. Cao, W. Liu, L. Shi, and Q. Deng, "Effective method for further magnifying the image in holographic projection under divergent light illumination", Appl. Opt. 58, 8713 (2019). CrossRef Y. Qi, C. Chang, and J. Xia, "Speckleless holographic display by complex modulation based on double-phase method", Opt. Express 24, 30368 (2016). CrossRef E. Buckley, "Holographic Laser Projection", J. Display Technol. 99, 1 (2010). DirectLink M. Chlipała, T. Kozacki, H. Yeom, J. Martinez-Carranza, R. Kukołowicz, J. Kim, J. Yang, J. Choi, J. Pi, and C. Hwang, "Wide angle holographic video projection display", Opt. Lett. 46, 4956 (2021). CrossRef Z. He, X. Sui, L. Cao and G. Jin, "Image-Distortion Correction Algorithm for Computer-Generated Holographic Display," 2018 IEEE 27th International Symposium on Industrial Electronics (ISIE), 1331 (2018). CrossRef A. Kaczorowski, G.S. Gordon, A. Palani, S. Czerniawski and T.D. Wilkinson, "Optimization-Based Adaptive Optical Correction for Holographic Projectors", J. Display Technol. 11(7), 596 (2015). CrossRef Z. He, X. Sui, G. Jin, L. Cao, "Distortion-Correction Method Based on Angular Spectrum Algorithm for Holographic Display", IEEE Trans. Industr. Inform. 15, 6162 (2019). CrossRef O. Mendoza-Yero, G. Mínguez-Vega, and J. Lancis, "Encoding complex fields by using a phase-only optical element", Opt. Lett. 39, 1740 (2014). CrossRef T. Kozacki, K. Falaggis, "Angular spectrum method with compact space–bandwidth: generalization and full-field accuracy", Appl. Opt. 55, 5014 (2016). CrossRef

Fast 3D Content Update for Wide-Angle Holographic Near-Eye Display

Near-eye holographic displays are the holy grail of wear-on 3D display devices because they are intended to project realistic wide-angle virtual scenes with parameters matching human vision. One of the key features of a realistic perspective is the ability to move freely around the virtual scene. This can be achieved by addressing the display with wide-angle computer-generated holograms (CGHs) that enable continuous viewpoint change. However, to the best of our knowledge there is no technique able to generate these types of content. Thus, in this work we propose an accurate and non-paraxial hologram update method for wide-angle CGHs that supports continuous viewpoint change around the scene. This method is based on the assumption that with a small change in perspective, two consecutive holograms share overlapping data. This enables reusing the corresponding part of the information from the previous view, eliminating the need to generate an entirely new hologram. Holographic information for the next viewpoint is calculated in two steps: first, a tool approximating the Angular Spectrum Propagation is proposed to generate the hologram data from previous viewpoint; and second, the efficient Phase Added Stereogram algorithm is utilized for generating the missing hologram content. This methodology offers fast and accurate calculations at the same time. Numerical and optical experiments are carried out to support the results of the proposed method.

Investigation of Angular Spectrum of Scattered Inert Gas Ions from the InGaP (001) Surface

It has been shown that this method is quite suitable for surface studies and diagnostics of many component materials. The values of the azimuthal angle of distribution of Ne, Ar and Xe ions scattered from InGaP (001) <110> are obtained. The relationship between the spatial variables of the scattered beam (mainly azimuthal angular spectra) and the type of ions has been established. The correlation between focusing properties of surface semichannel with a type of bombardment ion at the different angle of incidence has been shown.

Contact Angle Measurement of Melting SnAgCu Solder Paste Mix with Carbon Allotropes Using In-Line Digital Holography Technique

In this research we investigated the contact angle of commercial SnAgCu solder paste mixing with some carbon allotropes such as graphite, graphene quantum dots, and fullerene of varying concentrations with melting temperature, wettability, interfacial microstructure. The wettability was assessed in terms of the contact angle. The in-line digital holography was used for determining the contact angle and morphological of samples at each temperature which the samples have been heating from room temperature until the melting temperature. In the experiment, only one beam was used as the object and reference beams which recorded by a CMOS camera. The recorded image was reconstructed by the angular spectrum digital holography numerical programing. Using the reconstructed images of our results, the shape and contact angle of solder pastes can be investigated.

Switchable Purcell enhancement of photoluminescence by GST film

In the present paper perovskite radiation enhancement on crystalline GST film compared to amorphous one has been studied. The photonic local density of states has been calculated by angular spectrum representation of the dyadic Green’s function. The Purcell factor has been calculated for perovskite luminescent on both amorphous and crystalline GST film. Almost 80% enhancement has been observed at wavelength 950 nm for system with perovskite thickness 25 nm, GST thickness 110 nm.

FOV constrained guidance law for nonstationary nonmaneuvering target interception with any impact angle

This paper presents the nonstationary nonmaneuvering target interception with all possible desired impact angles in a two-dimensional (2D) aerial engagement scenario, where the target can move in any direction. The paper also considers the field-of-view (FOV) constraint for designing the guidance law so that the target is always visible while following the missile trajectory in the entire engagement time, which makes it feasible for real world applications. The guidance law is based on the pure proportional navigation (PPN) to achieve any impact angle of the entire angular spectrum. The proposed guidance law is then simulated for intercepting a nonstationary nonmaneuvering target using a kinematic model of a missile to demonstrate the efficacy of the presented scheme. A comparison with the related work existing in the literature has also been added to establish the superiority of the present work.