Point Spread Function Engineering for the Advanced Optics...

transcript

ThoeryComputational Imaging

Point Spread Function Engineeringfor the Advanced Optics Lab

Tony Barsic

University of Colorado at BoulderDepartment of Electrical, Computer, and Energy Engineering

Dr. Piestun’s Research Groupanthony.barsic@colorado.edu

March 3rd, 2014

A. Barsic PSF Engineering 1

PSFMTF

Point Spread Function

I The response of an imaging system to a point source

I It’s the imaging version of the impulse response of a linearsystem.

I Assumptions:I linearI shift-invariant

PSFMTF

Modulation and Optical Transfer Function

PSFMTF

Modulation

DefocusComputational ImagingCubic PhaseDH-PSF

DefocusIs this the best we can do? Is the information lost forever?Can we recover more information?

Yes, with PSF Engineering. (a.k.a. ”wavefront coding.”)A. Barsic PSF Engineering 5

Computational Imaging

Cubic Phase

Double Helix PSF

4fset-upSLMPrelab Help

4f Imaging SystemThis is what you will actually be working with in lab (conceptually).

What can we do with this system? What do we see in the ”SLM”plane?

I Optical signal processing.I modulate phase? amplitude?I if we put, say, DH-PSF there, what has changed? Are we

getting more information? Why/how?A. Barsic PSF Engineering 11

Lab Setup

This is the same idea, but folded up.

Why would we fold it? Why don’t we (researchers in Rafael’sgroup) actually fold it for experiments?

Spatial Light ModulatorThese are expensive.

I array of pixels (”spatial”)I vary phase delay (”light modulator”)

I Does this work with both polarizations?I What happens to the other pol.?I How to fix it? (3 ideas)

How to simulate PSF

Think about the 4f system.

I Put a pt source on axis in object plane

I How does shifting the pt source in the plane affect phase inthe pupil?

I axial shift?

DH-PSF

You will generate a DH-PSF

I superposition of modes from the Gauss-Laguerre modal plane

I GL plane is just a way to describe patterns (similar to zernike)

I The prelab gives details

I write a matlab function that generates a GL mode

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