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A diode laser source for DIAL methane measurements in coal mines
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A diode laser source for DIAL methane measurements in coal mines
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Rights
http://www.ohsu.edu/xd/education/library/services/theses-dissertations/rights-statement.cfm
Title
A
diode
laser
source
for
DIAL
methane
measurements
in
coal
mines
Creator.PersonalName
DeFreez
,
Richard
K
.
Thesis.Degree
Ph.D.
Thesis.Major
Applied Physics
Thesis.DateDegreeAwarded
April
1985
Institution
Oregon Graduate Center
Department
Dept. of Applied Physics
Thesis.Advisor/Mentor
Elliott, Richard A.
Thesis.Committee
Holmes, J. Fred
Kim, DaeMann
Khalil, M.A.K.
Subject.LCSH
Coal mines and mining
Injection lasers
Semiconductor lasers
Call Number
Q183.5.OGC D44 1985
Description.Abstract
The
research
reported
in this
dissertation
was
directed
toward
the
development
of a
coal
mine
methanometer
source
. The
project
encompassed
two
tasks
. The
first
was a
study
conducted
to
determine
if
room-temperature
injection
lasers
could
be
used
as the
source
for a
DIAL
methanometer
for
coal
mine
applications
. As
part
of that
study
,
prior
DIAL
measurements
of
methane
were
reviewed
and the
measurement
technique
was
explored
in a
general
way
. The
absorption
spectroscopy
of
methane
was then
examined
in
detail
and
found
to
contain
an
appropriate
absorption
feature
near
a
wavelength
of
1.65
µm
provided
the
spectral
width
of the
light
source
was
approximately
0.2
cm
[superscript
-1]
. As an
additional
part
of the
study
the
operating
characteristics
of
broad
area
high
optical
output
InGaAs/lnP
injection
lasers
were
examined
. A
detailed
calculation
of the
requirements
for a
diode
laser
DIAL
measurement
of
methane
in a
coal
mine
was then
performed
. By
comparing
the
observed
diode
laser
properties
with the
DIAL
requirements
,
it
was
found
that
broad
area
InGaAs/lnP
injection
lasers
were
suitable
in
most
respects
for
coal
methane
measurements
. The
exception
was the
diode
laser
spectral
bandwidth
.
It
was
found
to be
some
400
times
too
large
. The
second
task
was the
design
and
fabrication
of an
external
grating
cavity
to
reduce
the
bandwidth
of the
injection
lasers
. The
optical
design
of an
off-axis
parabolic
mirror
grating
cavity
was
developed
.
Geometric
optics
was
used
to
determine
the
physical
parameters
for an
external
cavity
which
would
produce
the
desired
spectral
bandwidth
of
0.2
cm
[superscript-1]
. The
fabrication
and
performance
of this
external
resonator
source
is
described
.
Measurement
of the
source
linewidth
showed
it
to be
two
to
three
times
larger
than the
design
value
. An
explanation
of the
resultant
bandwidth
based
on
coupled
mode
theory
is
presented
. In
summary
, an
external
grating
cavity
for a
diode
laser
was
designed
,
assembled
, and
tested
.
It
was
shown
to
approximate
the
optical
properties
required
for a
DIAL
coal
mine
methane
measurement
.
Language
eng
Type
Text
Format.Use
Needs Adobe Acrobat Reader to view.
Format.FileType
pdf
Format.FileSize
5267.663 KB
OCLC number
13111191
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A diode laser source for DIAL methane measurements in coal mines 