s c a t t e r i n g s
Hubble Reveals Deepest View of the Universe
T
he Hubble Space Telescope has
p r o d u c e d the deepest, m o s t
detailed optical view of the universe
(see i m a g e ) . Since the image's
unveiling in January, scientists have
been busy analyzing the faintest,
most remote galaxies ever seen.
"This gives us new insight into how
galaxies evolve, and how old the
universe is," says Jerry Nelson, professor of a s t r o n o m y a n d a s t r o physics at the University of California, Santa Cruz and project scientist
at the Keck Observatory.
Researchers are trying to determine just how far away the galaxies
are, and how their shapes and colors
relate to distance. The first p u b lished analysis of galaxy images in
the Hubble Deep Field indicates that
many of the most remote galaxies
can't be classified using the system
devised
by Edwin
Hubble
( 1 8 8 9 - 1 9 5 3 ) . The H u b b l e Deep
Field was assembled from 342 separate exposures taken for 10 consecutive days in December. The essentially dark patch of sky (uncluttered
by nearby objects) is near the handle
of the Big Dipper, and is about the
size of a dime 75 ft. away. At least
1500 galaxies in various stages of
evolution appear in the picture. The
results show a higher proportion of
irregular galaxies in the Deep Field
image than in closer galaxies. "The
differences are d r a m a t i c , " says
Roberto Abraham, a scientist with
the Institute of Astronomy at the
University of Cambridge.
A b r a h a m c o l l a b o r a t e d with
researchers from the Anglo-Australian Observatory and the Dominion Astrophysical Observatory in
C a n a d a . The researchers used a
c o m p u t e r to classify a b o u t 300
galaxies within a selected brightness
range according to their size and
shape. They also simulated how
closer galaxies would appear in the
deep field for accurate comparison.
Analysis of the galaxies in the
Deep Field image continues on the
g r o u n d . Researchers at Keck are
measuring spectra of the galaxies.
Determining the "red shift" indicates the relative velocity of the
galaxy away from E a r t h , which
T h e Hubble D e e p Field image s h o w s the m o s t distant galaxies ever s e e n . Every smudge on
the image is a galaxy, typically the size of our o w n .
Fiber
S
Fiber Bragg gratings, s u c h a s t h e s e sold by 3 M , are an enabling
technology for commercial W D M s y s t e m s .
10
O p t i c s
&
P h o t o n i c s
N e w s / M a y
1 9 9 6
Bragg
Gratings
Advance
in
the
Marketplace
purred by applications in telecommunications, the
Canadian Communications Research Centre (CRC)
estimates that fiber Bragg gratings will create a $100
million market in a few years. The emerging market is
illustrated by 10 companies that have licensed the technology. "Bragg gratings are pretty much the technology,
that's why people are excited about it," says Salim Juma,
director of business development for QPS Technology
Inc., which recently licensed the fiber Bragg grating
patent portfolio from CRC.
"It looks as though Bragg gratings are one of the
pieces required to implement WDM [wavelength division multiplexing] in practice," says CRC scientist Ken
Hill. "It will probably allow implementation of WDM
in the subscriber loop." Hill discovered photosensitivity
in optical fiber, the principle on which Bragg gratings
are based. While Bragg gratings are poised for commer-
MEMBERS MAKING NEWS
yields the distance a n d age o f the
galaxy. "We're finding out that
they're v e r y far away," says Nelson.
The time it takes light to traverse
the distance between Earth and the
galaxy yields the galaxy's age. "You
basically have a time machine," says
N e l s o n . " W h a t we see is t h e w a y
they used to be." Scientists estimate
that some of the galaxies date back
to the b e g i n n i n g o f t h e u n i v e r s e ,
estimated at 15 billion years old.
Since Hubble is above the Earth's
atmosphere, which distorts groundbased images, it has superior imaging capability. But H u b b l e doesn't
collect enough light to run an effective s p e c t r o g r a p h , so a v e r y large
telescope like Keck is used to measure spectra. Typically, a low-resolution imaging spectrograph attachm e n t for the t e l e s c o p e is u s e d to
collect spectra. "It's a good example
of serendipity between Hubble and
ground telescopes," Nelson says.
Kelvin Liddane is now OptoSigma
butions to engineering theory and
Corp.'s OEM Business Manager, in
practice," and those who have
in charge of developing OptoSigma's d e m o n s t r a t e d " u n u s u a l a c c o m OEM business unit. The company
plishcment in the pioneering of new
manufactures high precision optics
and developing fields of technoloand optomechanical
hardware forgy." Ishimaru, who is Boeing Martin
laser applications in research, OEM,
Professor of Electrical Engineering
a n d manufacturing. Before joining
at the University of W a s h i n g t o n ,
O p t o S i g m a , L i d d a n e was O E M
Seattle, was elected for his contribuProduct Manager for Instruments
tions to the theory and application
of wave propagation and scattering
in random media.
R o b e r t A. S m y t h e has been
elected c o - v i c e president o f Zygo
Corp. Smythe, who graduated from
Michigan State University, was formerly director of sales & marketing
for the company, and served for a
number of years as chief liasion with
its customers and markets, defining
and d e v e l o p i n g solutions to high
technology metrology and production yield improvement problems
for industry. Smythe is also a m e m ber of the American Society for Precision Engineers.
Adrian, who is a professor at the
University of Illinois-Urbana, was
elected for his development of measurement techniques to characterize
single and m u l t i p h a s e t u r b u l e n t
flows and for the interpretation of
turbulence measurements.
Talal Findakly has been appointed vice president of Isowave, division of Deltronic Crystal Industries
Inc. Findakly, who has held various
technical and m a n a g e m e n t positions at Hoechst Celancse, United
Technologies, and TRW, is responsibe for engineering, manufacturing, and planning for Isowave isolator and other fiber optic products.
Akira Ishimaru and Ronald J.
A d r i a n are a m o n g 7S e n g i n e e r s
elected to m e m b e r s h i p in the
National Academy of Engineering.
Academy membership honors those
who have made "important contri-
cial success, a few issues need to be sorted out before the
market opens up.
W D M filters in optical fiber networks are the hottest
application of fiber Bragg gratings, according to Juma.
Before gratings can be widely used in filters, however,
standard channel spacing must be determined. Gratings
tend to shift with temperature, so they need to be stable
o v e r a greater range of t e m p e r a t u r e s to b e used in
W D M modules.
Other network applications of Bragg gratings are
dispersion compensation in optical fibers and gain flattening in Er-doped fiber amplifiers (EDFAs). Undetermined amplifier spacing in fiber networks makes it difficult to put out a standard dispersion compensation
product. Bragg gratings are not the only way to flatten
gain, b u t t h e y seem to be the e m e r g i n g choice, says
Juma.
Another promising market for Bragg gratings is sensors. Bragg gratings are already used in some sophisticated sensor applications, and they m a y provide a mass
market for Bragg gratings that drives costs down, Hill
contends.
—Jennifer
Rice
Because Bragg gratings are readily r e p r o d u c i b l e ,
they're n o longer a laboratory curiosity. "With a phase
mask, we can w r i t e h u n d r e d s of t h e m , " notes Juma.
Making phase masks requires an elaborate facility (not
unlike a microelectronics c l e a n r o o m ) , so b u y i n g the
masks can be more cost effective for grating manufacturers. QPS supplies phase masks for Bragg grating
manufacturers, and recently entered a cooperative
agreement with SpecTran Specialty Optics Co. Under
this agreement, Spectran will produce specialty fiber for
Bragg gratings and in return act as North American distributor of QPS Technology's products.
~
QPS is the fourth Canadian company to license the
technology from CRC. CRC shares the patent portfolio
with United Technologies (UT), which is responsible for
marketing and licensing the technology outside of
Canada. Six American companies, starting with AT&T
in late 1994, have licensed the technology. United Technologies developed a holographic technique for producing the gratings in 1989, w h i c h spurred the practical
application of the technology. In 1993, Hill devised a
m e t h o d of making gratings using phase-masks.
Optics
&
P h o t o n i c s
N e w s / M a y
1 9 9 6
11