Transcript Poster - MSU Engineering - Michigan State University

Michigan State University Engineering Design Day
East Lansing, MI
April 25, 2014
Diamond Optical Properties Measurement
System
Dan Schulz, Adam Tayloe, Allen Lin, Chunyu Li, Dan Kuang
Michigan State University, East Lansing, MI, 48823, USA
Introduction
Problem Diagnosis and Solution
 The Fraunhofer Center for Coatings and Laser Applications is interested in
improvements to the accuracy and sensitivity of their diamond optical properties
measurement system.
 Some of the highest quality diamond in the world is grown at Fraunhofer. A
senior capstone team was tasked with creating the measurement system in the
spring of 2013, and Fraunhofer was dissatisfied with the result. The goal of this
project is to improve upon the previous system in all areas, including computer
interface, hardware components, and the resulting measurements.
 Fraunhofer makes very high quality synthetic diamonds. They produce
three-dimensional geometries by using chemical vapor deposition (CVD). CVD
is a process where diamond is chemically deposited on a substrate from the
gas phase. A pretreated silicon is coated with diamond by means of microwave
plasma in an ellipsoidal reactor. The advantage to CVD over other processes
such as high temperature high pressure methods is that it allows Fraunhofer to
coat larger substrates, and it produces diamonds of high enough quality for use
in electronic applications.
 The measurement system is physics intensive, and uses the optical property
of birefringence to calculate stresses and impurities in diamond samples.
Stressed diamonds exhibit properties of birefringence, and this is detected by
placing the diamond sample between two linearly polarized filters.
Conclusions
δ = (2π/λ) * (Δn)d
Algorithm that relates pixel
intensity to birefringence:
I/I0≈1/2*sin^2(δ/2)
Once the image reaches the camera
and is uploaded to the computer, the
image is processed in visual studio.
This allows Fraunhofer to see the
location and magnitude of stresses in
the diamond sample.
ACKNOWLEDGEMENTS The electrical and computer engineering department at Michigan
State University for the opportunity, the Fraunhofer center and Shannon Demlow for the
project, and Dr. Virginia Ayres for providing guidance as the groups facilitator.
Computer
-90
Polarizer
Image
Processing
Diamond
Sample
90
Polarizer
Final
Results
Light
Source
By passing linearly
polarized light
through a
diamond, ordinary
and extraordinary
waves are
observed. When
those rays pass
through a
perpendicularly
polarized filter,
only the
extraordinary
waves pass
through. The
team collects this
light through a 5
megapixel camera
to observe and
calculate the
diamond’s
birefringence.
Conclusions
To the left is an image
collected by the 5 MP camera
after light has traveled
through the system. The
areas of higher intensity
represent higher levels of
birefringence, and therefore
higher levels of stress. LEDs
of different wavelengths
(which visually corresponds to
different colors) are capable of
being placed into the system
to compare separate results.
The LED used in the image to
the left had an approximate
wavelength of 650 nm.
Birefringence Algorithm:
5 MP
Camera
 Fraunhofer grows synthetic diamonds used chemical vapor
deposition (CVD). These diamonds are often subject to
stresses and impurities. The goal of this project is to identify
the location and magnitude of these impurities in diamond
samples, with a clean and easy to use interface.
 Diamonds that have stresses and impurities exhibit an
optical property called birefringence. Birefringent materials
spread light into an ordinary wave and an extraordinary wave.
If we can detect the extraordinary wave, we can compute the
birefringence.
The present work shows that nanofibrillar versus
planar surface architectures can be directive for
 To find this extraordinary
wave, the system
involves moving
specific implementations
of long-distance
light from an LED interactions.
through a 90Cell-cell
degree linear
polarizer.
This
interactions
of astrocytes
polarized light then
travels on
through
the diamond,
and
is split
intoto
cultured
nanofibrillar
surfaces
were
shown
an ordinary and extraordinary
wave. extension
These waves
are
then
differ in connective
type,
cell
body type,
passed through a and
polarizer
perpendicular
to the original.
The
the number
of interactions.
Epi-fluorescence
ordinary wave willmicroscopy
be filtered out.
TheAFM
extraordinary
wave will
versus
has the potential
to lead
continue on to thetocamera
forconclusions
our detection.
different
about the lack or
presence of cellular connections, as well as their
 Once an imagetypes.
has been taken, image processing is done in
visual studio to quantify the birefringent properties in the
diamond.
 The primary causes of birefringence that we encounter are
molecular dislocations. These dislocations create a clover
pattern in our data.
REFERENCES
[1] Friel, I., S.l. Clewes, H.k. Dhillon, N. Perkins, D.j. Twitchen, and G.a. Scarsbrook. "Control of Surface and Bulk Crystalline Quality in Single Crystal
Diamond Grown by Chemical Vapour Deposition." Diamond and Related Materials 18.5-8 (2009): 808-15. Print.
[2Lang, A. R. "Causes of Birefringence in Diamond." Nature 213.5073 (1967): 248-51. Print.