Optical Scattering
Kelly Neubauer
Xiaoqi Yu
Dr. Steven Mellema
Background
•Medical Imaging
•Benefits over X-Ray
•Optical Coherence Tomography
Modified Mach-Zehnder Interferometer
Agilent34401A.vi
GPIB (General Purpose Interface Bus)
Agilent 34401A.vi
Agilent 34401A.vi
Agilent 34401A.vi
Agilent 34401A.vi
Stepper Motor and Micrometers
Differential Micrometer
Micrometer
Stepper-Final Version.vi
Stepper-Final Version.vi
Stepper-Final Version.vi
Stepper-Final Version.vi
Stepper-Final Version.vi
Stepper-Final Version.vi
Stepper-Final Version.vi
Stepper-Final Version.vi
Stepper-Final Version.vi
Stepper-Final Version.vi
Calibration of Stepper with Micrometer
Current Position
(x
i)
Target Position
Steps Travelled
(s)
Final Position
(x
f)
0.00
±.003 mm
20.0 mm
127,389
19.90
±.003 mm
Difference between Micrometers
Step Size
Micrometer
156.21
±.03 nm/step
Differential Micrometer
15.621
±.003 nm/step
Michelson Interferometer
Steppervoltage_noevents4.vi
Steppervoltage_noevents4.vi
Steppervoltage_noevents4.vi
Steppervoltage_noevents4.vi
Steppervoltage_noevents4.vi
Steppervoltage_noevents4.vi
Steppervoltage_noevents4.vi
Steppervoltage_noevents4.vi
Steppervoltage_lockin2.vi
Steppervoltage_lockin2.vi
Steppervoltage_lockin2.vi
Steppervoltage_lockin2.vi
Steppervoltage_lockin2.vi
Steppervoltage_lockin2.vi
Steppervoltage_lockin2.vi
Steppervoltage_lockin2.vi
Coherence Length
•“Coherence is a measure of the ability of a light source to
produce high contrast interference fringes when the light
is interfered with itself in an interferometer.”
-World of Lasers
Mach-Zehnder Interferometer
Modified Mach-Zehnder Interferometer
He-Ne Laser
He-Ne Laser
Path Difference: 17.292 inches
He-Ne Laser
Path Difference: 100 inches
Coherence Ratio of He-Ne Laser
Distance
(inches)
Min 1
Min 2
Min
Average
Max
Contrast
Ratio (R)
8.6604
42.595
32.384
37.490
131.431
.556
20
30.749
54.203
42.476
145.213
.547
22.64
17.378
27.675
22.527
119.810
.535
25.4
20.355
55.250
37.803
125.124
.536
27
30.441
28.490
29.4655
106.192
.568
29
43.584
25.772
34.678
101.192
.490
50
25.509
42.495
34.002
120.023
.558
Diode Laser
Path Difference: .30 mm
Diode Laser
Path Difference: 20.8 inches
Diode Laser
Path Difference: 88.8 inches
Coherence Ratio of Diode Laser
Distance
(inches)
Min 1
Min 2
Min
Average
Max
Contrast
Ratio (R)
0
43.414
30.394
36.904
150.395
.606
.0157
21.137
19.141
20.139
173.266
.792
7.6
31.259
23.131
28.71
134.326
.648
8
19.059
23.546
21.3025
154.397
.758
9
32.863
47.234
40.0485
150.953
.581
10.2
16.127
25.433
20.78
139.591
.741
44.4
16.431
20.830
18.6305
147.786
.776
Piezoelectric Actuator
Voltage
Displacement
(
±10%)
100 V
15
μm
1 V
150 nm
.1 V
15 nm
Thorlabs
Piezo2.vi
Piezo2.vi
Piezo2.vi
Piezo2.vi
Piezo2.vi
Example of Voltage vs. Intensity
Data
Voltage Between Peaks
Future Work
•Continuing work with the Piezo
•Addition of the Acoustic Optical Modulator
•Find the coherence length of the near infrared diode laser
Acknowledgments
•FYRE program
