Speckle Noise Reduction in Optical Coherence

Tomography

By:Marisse Foronda

Rishi MataniHardik MehtaArthur Ortega

Cow Retina

Speckle

wave fronts

sample volume

multipleforwardscatter

multipleback

scatter

tissuemodulatedwave fronts

BackgroundMinimally-Invasive to Non-Invasive imaging

systemClinically used High Resolution alternate to ultrasound imagingOne significant problem is speckle formation

Deformable Mirror

Intensity LossVarying Patterns can cause loss of intensity of

image and change in percent reflectivity

First, we must characterize default intensity loss by placing a flat mirror at the sample arm and having no deformations on the deformable mirror

Then, we deform mirror and characterize loss:3 dB loss 50% loss6 dB loss 75% loss9 dB loss 87.5% loss

Image Assembly100%

80%

Amplitude

% light reflected

Pattern 1

Pattern 2

Amplitude

% light reflected

100%

80%

Contrast Ratio

CorrelationIf two images have speckle patterns that are the

same, averaging them gives us no reduction in that speckle

We have to characterize how similar two images are using the formula:

Gantt Chart

Number Task Start End Duration2010

January February March April May

1 Familiarize with Project 1/4/2010 1/22/2010 19

2 Construction of Device 1/26/2010 3/5/2010 39

3 Mirror Testing 3/6/2010 3/12/2010 7

4 Agar Testing 4/1/2010 4/29/2010 29

5 Biological Tissue Testing 5/1/2010 5/29/2010 29

Weekly ProgressWeek 1 Read Papers on our Design

Familiarized ourselves with the lab

Week 2 Took Measurements of Components

Drew out a system diagram

Week 3 Ordered all necessary components

Began assembling the system

Week 4 Fine tune/align the system

Defective Galvo cables diagnosed

Week 5 Waiting for new Galvo cables

Week 6 Finish Assembly of Device

Week 7 Finish Assembly of Device

Week 8 Galvo Wires arrived

Week 9 Fine Tuning/Alignment

Prototype System

Reverse Alignment

deformable mirrorfiber and collimator

2D-galvo scanners

fiber and collimator

3.0 mW

0 µW

2.5 mW

526 W

480 W

deformable mirrorfiber and collimator

2D-galvo scanners

fiber and collimator

3.0 mW

1 µW

2.5 mW

526 W

480 W

deformable mirrorfiber and collimator

2D-galvo scanners

fiber and collimator

3.0 mW

5 µW

2.5 mW

526 W

480 W

deformable mirrorfiber and collimator

2D-galvo scanners

fiber and collimator

3.0 mW

10 µW

2.5 mW

526 W

480 W

deformable mirrorfiber and collimator

2D-galvo scanners

fiber and collimator

3.0 mW

20 µW

2.5 mW

526 W

480 W

deformable mirrorfiber and collimator

2D-galvo scanners

fiber and collimator

3.0 mW

35 µW

2.5 mW

526 W

480 W

deformable mirrorfiber and collimator

2D-galvo scanners

fiber and collimator

3.0 mW

50 µW

2.5 mW

526 W

480 W

deformable mirrorfiber and collimator

2D-galvo scanners

fiber and collimator

3.0 mW

80 µW

2.5 mW

526 W

480 W

deformable mirrorfiber and collimator

2D-galvo scanners

fiber and collimator

3.0 mW

125 µW

2.5 mW

526 W

480 W

C2

M

C1

input

output

G

Forward Alignment

deformable mirrorfiber and collimator

2D-galvo scanners

fiber and collimator

3.0 mW

10 µW

2.2 mW

2.1 mW

486 W

deformable mirrorfiber and collimator

2D-galvo scanners

fiber and collimator

3.0 mW

30 µW

2.2 mW

2.1 mW

486 W

deformable mirrorfiber and collimator

2D-galvo scanners

fiber and collimator

3.0 mW

119 µW

2.2 mW

2.1 mW

486 W

C1

MG

C2

Input

Output

Power ResultsForward Alignment

Path Power % Loss

Input-C1 3.0 mW

C1-M 2.2 mW 26.7%

M-G 2.1 mW 4.5%

G-C2 486 µW 76.9%

C2-Output

119 µW 75.5%

Reverse Alignment

Path Power % Loss

Input-C1 3.0 mW

C1-M 2.5 mW 16.7%

M-G 526 µW 78.9%

G-C2 480 µW 8.7%

C2-Output

125 µW 74%

-AR (anti-reflection) coating on Galvo mirrors (1310 nm) -Fibers (1310 nm)-Power Source (800 nm)

ConclusionQuantitative Benchmark: Reduce contrast ratio

by 25% - 50% with a 6 dB mean intensity loss

Future Applications: Any Imaging system using a coherent light source can easily integrate the deformable mirror component.

Integration of the mirror will be efficient and cost effective.

Questions