A.Williams: Objectives and Literature Review

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20.345: Bioinstrumentation Project Lab

Objectives and Literature Review

Project Overview

  • Spatial Light Modulation
    • SLM Characteristics,Properties & Holography
      • Calibration, pixels, crystals, diffraction to gray scale imaging
      • Learn about algorithms for holography + set up weekly meetings with someone who can explain concepts I get stuck on
      • Write script for simple lens
      • Test script for simple lens and then perform mini experiment using a modified version of Young's double split experiment.
  • Optical Filtering: Spiral Phase Plate Contrast & Edge Detection
    • Write phase mask needed to create a spiral phase for isotropic edge detection
    • Write script needed to create a spiral phase mask for relief detection
    • Bright field imaging of red blood cells using spiral plate phase mask ( created by writing a hologram image onto the SLM)
    • Measure lose of resolution due imaging with a spiral phase plate mask
  • Bessel Beam and Optical Micromanipulation
  • Write hologram script to create a Bessel beam from a Gaussian beam
  • Measure the optical properties of the Bessel Beam with CCD
    • Beam waist width
    • Intensity Profile
  • Attempt increase resolution for fluorescent microscopes
    • Use Bessel beam passing through holographic "axicon"
    • Compare PSF generated for 'normal' fluorescent microscope set up and 'bessel beam with axicon' fluorescent microscope set up

I divided the project up into mini-projects because I think have intermediary milestones will help me stay on track. A big part of this final project will be making sure that I'm learning at a pace that will allow me to implement several of the mini-projects listed about in a timely manner (i.e. in 9weeks). The best way to ensure that I'm learning at an appropriate pace is to build optical set-ups that cause me to demonstrate my understanding of a particular aspect of SLM technology. I let Bessel Beam and Optical Micromanipulation as a final project even though it is not a difficult As of now my final goal ( or test of knowledge will be designing an optical trap with a crossed bessel beam and guassian beam and then measuring the optical properties of the bessel beam I create. I saved this part of the project for last because even though it is not hard I think it is a good and if I succeed in all of the successor mini-projects I should be in good shape to build the - give myself 3weeks. 1.5 weeks for each miniproject although some of the projects should take less than that and that will give me 1.5 build and test the optical trap with two bessel beams. My goal is to be that time be familiar enough with matlab and bessel beams and holography algorithms, calibrations that should take less than 3 days.

Spatial Light Modulators: What are they?

Programmable spatial light modulators (PSLM’s) are two-dimensional electrically addressable devices that function as reusable transparencies on which spatially varying amplitude or phase patterns can be written electronically, often with an output signal from a computer1. In practice, there is cross coupling between the amplitude and phase modulation of such devices so that the modulation is really complex, although it is possible to operate them in a phase-mostly or amplitude-mostly mode. The PSLM, we have in lab(courtesy of Justin) can only modulate phase. This presents some advantages such as:

  • Better diffraction efficiency
  • Explanation: The diffraction efficiency of phase holograms is better than that of amplitude holograms. Why?

  • Ability to eliminate the zeroth order beam (i.e. the undiffracted beam which allows for the possibility for all of the optical power to be used for constructing your object of interest.

However it also prevents certain challenges. One of these challenges concerns determining how to make a phase only SLM also create changes in amplitude.
I have decided to work with SLM's for my final project because they are extremely useful devices that can be used in a variety of ways. For example, SLM are currently used in signal processing, wavefront sensing, wavefront correction, wavefront manipulation and many other applications in imaging and nonimaging optical systems APPLICATIONS OF PROGRAMMABLE SPATIAL LIGHT MODULATORS by Michael K. Giles


""When I was younger, I always did it for half an hour a day. Why, sometimes I've believed as many as six impossible things before breakfast." Alice in Wonderland."

While I don't think my project is impossible, I do think that it will be a challenging project to complete. For the project to be successful, I'm going to have to learn a large breath of things in a contracted amount of time. However, I think the project is still feasible. I think having mini-projects inside my big project will assist in making the project a success. Most of the equipment I will need is already in lab and the project is not to difficult to make it impossible. The basic premise of my project is using what is available in the current optic and optical engineering disciplines(concerning SLM technology) to improve/ modify microscope or image processing methods already used in 20.345.


The project is not novel but I will be adding new functionality to equipment that is already in lab.

What I Hope to Have Learned

  • Mathematical optics
    • Fourier Optics
    • Hologram Algorithms
    • Resolution and Calibration of SLM
  • Optical Systems
    • Interface optical theory, programming and electronics
    • From theory to microscope: building a microscopes to test performance of the holograms I write for the SLM
    • More about diffraction,Fourier transforms, lens systems

    Literature Reviewed

    A.Jesacher,A.Schwaighofer.Wavefront correction of spatial light modulators using optical vortex image. 2007
    J.Neff,R.Athale. Two-Dimensional Spatial Light Modulators:A Tutorial.
    [http://mit.edu/joke021/Public/Two%20Dimensional%20Spatial%20light%20Modulators.pdf Spatial Light Modulators and Modern Optical Systems]
    A.Vyas1,M.Roopashree1.Spatial Light Modulator for wavefront correction
    P.Barbier,G.Moddel. Spatial Light Modulators : Processing in Real Time
    K.Christian, S.Xavier,O.Wolfgang. Optimally tuned spatial light modulators for digital holography
    J.Davis,J Guertin,D. Cottrell.Diffraction-free beams generated with programmable spatial light modulators
    J. L. de Bougrenet de la Tocnaye,L. Dupont.Complex amplitude modulation by use of liquid-crystal spatial light modulators

    NOTE: All aforementioned papers can be found in my public folder domain(joke021).