Hadamard Transform Imaging

Paul Holcomb

Tasha Nalywajko

Melissa Walden

Problem Definition

• Current 3D spectral imaging systems are relatively slow and possess low resolution

• Hadamard multiplexing greatly enhances signal to noise ratio, thus enhancing resolution

• Use of a digital micro-mirror device makes implementation of the Hadamard transform very fast

Hypothesis

Implementation of the Hadamard transform in a spectral imaging system by using a digital micro-mirror device will decrease the amount of time

necessary to acquire an image and increase the spatial and spectral resolution of the image.

Faster, more accurate spectral imaging will allow for better differentiation of tissue during brain

tumor resectioning and increase survival rates.

3D Spectral Imaging Techniques - Scanning

Wavelength Scanning

http://www.cri-inc.com/instruments/data/pdf/American%20Laboratory%202000.pdf

Line Scanning

http://www.lightforminc.com/Technology/ANIMATION/animation.html

3D Spectral Imaging Techniques - Multiplexing

Fourier Transform

http://scienceworld.wolfram.com/physics/FourierTransformSpectrometer.html

Wuttig and Riesenburg, “Sensitive Hadamard Transform Imaging Spectrometer with a simple MEMS”

Hadamard Transform

Benefits of Hadamard Multiplexing

• Decreased image acquisition time vs. scanning techniques

• Increased signal to noise ratio √n for Hadamard matrix (√n)/2 for S matrix

Wuttig and Riesenburg, “Sensitive Hadamard Transform Imaging Spectrometer”

What do we want?

• Focus a 25 mm square into a 10 mm square

• Bounce the square with specific pixels at specific angles (apply Hadamard matrix)

• Compress the light in one direction line

• Separate the line by wavelength

Goal: Capture the spectrum of the line

Stage 1 – Compress image

Digital Micro-Mirror Device

http://www.ostl.ece.uvic.ca/IMAGES/emiod.png

Stage 2 – Compress into a line

Drawn to scale…

Stage 1

Construction

Lens System with Testing Lens

Testing of Stage 1

Testing with Square Source

Why is this important?

• 71% mortality rate for diagnosed brain tumors

• Correlation between complete resectioning of tumors and improved prognosis

• Complete resectioning requires knowing the location of the tumor, especially tumor margins

• Imaging in a clinical setting should be fast

Future Directions

• Finish construction and testing by mid-January

• Implement 2 leg system (Full Hadamard)

• Miniaturization

Thanks from Group 10!