A comparative study of optimization algorithms for wavefront shaping

By manipulating the phase map of a wavefront of light using a spatial light modulator, the scattered light can be sharply focused on a specific target. Several iterative optimization algorithms for obtaining the optimum phase map have been explored. However, there has not been a comparative study on the performance of these algorithms. In this paper, six optimization algorithms for wavefront shaping including continuous sequential, partitioning algorithm, transmission matrix estimation method, particle swarm optimization, genetic algorithm (GA), and simulated annealing (SA) are discussed and compared based on their efficiency when introduced with various measurement noise levels.

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Confocal imaging capacity on a widefield microscope using a spatial light modulator

PLoS ONE ◽

10.1371/journal.pone.0244034 ◽

2021 ◽

Vol 16 (2) ◽

pp. e0244034

Author(s):

Yao L. Wang ◽

Noa W. F. Grooms ◽

Sabrina C. Civale ◽

Samuel H. Chung

Keyword(s):

Cell Body ◽

Spatial Light Modulator ◽

Lower Cost ◽

Scattered Light ◽

Image Data ◽

Confocal Microscope ◽

Confocal Imaging ◽

Optical Sectioning ◽

Light Modulator ◽

Confocal Images

Confocal microscopes can reject out-of-focus and scattered light; however, widefield microscopes are far more common in biological laboratories due to their accessibility and lower cost. We report confocal imaging capacity on a widefield microscope by adding a spatial light modulator (SLM) and utilizing custom illumination and acquisition methods. We discuss our illumination strategy and compare several procedures for postprocessing the acquired image data. We assessed the performance of this system for rejecting out-of-focus light by comparing images taken at 1.4 NA using our widefield microscope, our SLM-enhanced setup, and a commercial confocal microscope. The optical sectioning capability, assessed on thin fluorescent film, was 0.85 ± 0.04 μm for our SLM-enhanced setup and 0.68 ± 0.04 μm for a confocal microscope, while a widefield microscope exhibited no sectioning capability. We demonstrate our setup by imaging the same set of neurons in C. elegans on widefield, SLM, and confocal microscopes. SLM enhancement greatly reduces background from the cell body, allowing visualization of dim fibers nearby. Our SLM-enhanced setup identified 96% of the dim neuronal fibers seen in confocal images while a widefield microscope only identified 50% of the same fibers. Our microscope add-on represents a very simple (2-component) and inexpensive (<$600) approach to enable widefield microscopes to optically section thick samples.

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Time-reversed optical focusing through scattering media by digital full phase and amplitude recovery using a single phase-only SLM

Journal of Innovative Optical Health Sciences ◽

10.1142/s1793545815500078 ◽

2015 ◽

Vol 08 (02) ◽

pp. 1550007 ◽

Cited By ~ 1

Author(s):

Qiang Yang ◽

Xinzhu Sang ◽

Daxiong Xu

Keyword(s):

Single Phase ◽

Scattered Light ◽

Incident Light ◽

Scattering Media ◽

Ballistic Regime ◽

Light Modulator ◽

Speckle Field ◽

Biomedical Optical Imaging ◽

Wavefront Shaping ◽

Optical Focusing

Focusing light though scattering media beyond the ballistic regime is a challenging task in biomedical optical imaging. This challenge can be overcome by wavefront shaping technique, in which a time-reversed (TR) wavefront of scattered light is generated to suppress the scattering. In previous TR optical focusing experiments, a phase-only spatial light modulator (SLM) has been typically used to control the wavefront of incident light. Unfortunately, although the phase information is reconstructed by the phase-only SLM, the amplitude information is lost, resulting in decreased peak-to-background ratio (PBR) of optical focusing in the TR wavefront reconstruction. A new method of TR optical focusing through scattering media is proposed here, which numerically reconstructs the full phase and amplitude of a simulated scattered light field by using a single phase-only SLM. Simulation results and the proposed optical setup show that the time-reversal of a fully developed speckle field can be digitally implemented with both phase and amplitude recovery, affording a way to improve the performance of light focusing through scattering media.

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Confocal imaging capacity on a widefield microscope using a spatial light modulator

10.1101/2020.12.03.409581 ◽

2020 ◽

Author(s):

Yao L. Wang ◽

Noa W. F. Grooms ◽

Sabrina C. Civale ◽

Samuel H. Chung

Keyword(s):

Spatial Light Modulator ◽

Lower Cost ◽

Scattered Light ◽

Image Data ◽

Confocal Microscope ◽

Confocal Imaging ◽

Optical Sectioning ◽

Light Modulator ◽

C Elegans ◽

Confocal Images

AbstractConfocal microscopes can reject out-of-focus and scattered light; however, widefield microscopes are far more common in biological laboratories due to their accessibility and lower cost. We report confocal imaging capacity on a widefield microscope by adding a spatial light modulator (SLM) and utilizing custom illumination and acquisition methods. We discuss our illumination strategy and compare several procedures for postprocessing the acquired image data. We assessed the performance of this system for rejecting out-of-focus light by comparing images taken using our widefield microscope, our SLM-enhanced setup, and a commercial confocal microscope. The optical sectioning capability, assessed on thin fluorescent film, was 0.85 ± 0.04 μm for our SLM-enhanced setup and 0.68 ± 0.04 μm for a confocal microscope, while a widefield microscope exhibited no sectioning capability. We demonstrate our setup by imaging the same set of neurons in C. elegans on widefield, SLM, and confocal microscopes. SLM enhancement greatly reduces background from the cell body, allowing visualization of dim fibers nearby. Our SLM-enhanced setup identified 93% of the dim neuronal fibers seen in confocal images while a widefield microscope only identified 48% of the same fibers. Our microscope add-on represents a very simple (2-component) and inexpensive (<$600) approach to enable widefield microscopes to optically section thick samples.

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A thorough study on genetic algorithms in feedback-based wavefront shaping

Journal of Innovative Optical Health Sciences ◽

10.1142/s1793545819420045 ◽

2019 ◽

Vol 12 (04) ◽

pp. 1942004 ◽

Cited By ~ 4

Author(s):

Daixuan Wu ◽

Jiawei Luo ◽

Zhaohui Li ◽

Yuecheng Shen

Keyword(s):

Genetic Algorithms ◽

Natural Selection ◽

Optimization Algorithms ◽

Superior Performance ◽

Noisy Environment ◽

Scattering Media ◽

Phase Map ◽

Numerical Tools ◽

Wavefront Shaping ◽

Phase Optimization

Feedback-based wavefront shaping focuses light through scattering media by employing phase optimization algorithms. Genetic algorithms (GAs), inspired by the process of natural selection, are well suited for phase optimization in wavefront shaping problems. In 2012, Conkey et al. first introduced a GA into feedback-based wavefront shaping to find the optimum phase map. Since then, due to its superior performance in noisy environment, the GA has been widely adopted by lots of implementations. However, there have been limited studies discussing and optimizing the detailed procedures of the GA. To fill this blank, in this study, we performed a thorough study on the performance of the GA for focusing light through scattering media. Using numerical tools, we evaluated certain procedures that can be potentially improved and provided guidance on how to choose certain parameters appropriately. This study is beneficial in improving the performance of wavefront shaping systems with GAs.

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Wavefront shaping assisted design of spectral splitters and solar concentrators

Scientific Reports ◽

10.1038/s41598-021-82110-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Berk N. Gün ◽

Emre Yüce

Keyword(s):

Experimental Method ◽

Spatial Light Modulator ◽

Large Scale ◽

Low Cost ◽

Optical Element ◽

Light Modulator ◽

Solar Concentrators ◽

Spectral Splitting ◽

Wavefront Shaping ◽

First Time

AbstractSpectral splitters, as well as solar concentrators, are commonly designed and optimized using numerical methods. Here, we present an experimental method to spectrally split and concentrate broadband light (420–875 nm) via wavefront shaping. We manage to spatially control white light using a phase-only spatial light modulator. As a result, we are able to split and concentrate three frequency bands, namely red (560–875 nm), green (425–620 nm), and blue (420–535 nm), to two target spots with a total enhancement factor of 715%. Despite the significant overlap between the color channels, we obtain spectral splitting ratios as 52%, 57%, and 66% for red, green, and blue channels, respectively. We show that a higher number of adjustable superpixels ensures higher spectral splitting and concentration. We provide the methods to convert an optimized phase pattern into a diffractive optical element that can be fabricated at large scale and low cost. The experimental method that we introduce, for the first time, enables the optimization and design of SpliCons, which is $$\sim 300$$ ∼ 300 times faster compared to the computational methods.

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