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Photonics
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Photonics is a big subject and we intend to cover large segments
of it our reference areas. To start, we herein present a few often-sought
references. As always, we are looking for your suggestions
of what to add next.
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... or what?
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We seem to have no agreement on what to call
our industry. "Photonics" seems reasonable because of the
analogy to electronics. Unfortunately, it is not that simple due to a
variety of competing historical and commercial interests evident in the usage of
the following common terms.
Photonics - See the Photonics
Dictionary from Laurin Publishing for their definition. This is of
the all-inclusive sort covering essentially anything that is associated with any
electromagnetic radiation that on the scale of a small room is useful to consider as
particles. Will microwave imaging be subsumed when the antenna arrays
become practical? SPIE seems to think
so. We think this a little broad - better the word apply to only those
devices in which photons do all of the work. On the other hand, we resist
the attempt by the telecom industry to hijack the term for use only to describe
the components in their optical networks.
Optronics - The
publication Lasers
and Optronics is gone, so we can't ask them. Perhaps it is nearly
a synonym for "electro-optics" with a little more emphasis on the
mechanical. Companies with "Optronics" in their names don't
convey a unified concept - their products range from optical
power meters to video
cameras to lens
grinders to gun lights.
Electro-optics - The Photonics Dictionary
restricts this use of term to devices in which an electric field controls the
generation or propagation of photons. This makes lasers electro-optic
devices. LEOS
applies the term almost as broadly as "photonics" in its
charter. It would seem to be most valuable if narrowed to apply only to
devices in which the interaction between the fields and the photons is direct - a
mechanical shutter, even when motorized, is not an electro-optic shutter.
Optoelectronics - "Optoelectronics" used to
designate devices that convert photons to electrons or vice versa by quantum
processes. The Photonics Dictionary extends the meaning a little
but OIDA treats it
synonymously with "Photonics". For technical purposes, at least,
the original narrow meaning might be most valuable.
So... they all mean everything to someone. Feel free to
send us e-mail if you find other
definitions.
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Dye Filter Curves
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Although modern thin-film filter technology permits
fabrication of nearly arbitrary transmission curves, the old gelatin and glass
dye filters continue to satisfy many needs. It used to be that every
optical engineer had a copy of the Schott and Corning filter glass books and
Kodak's Wratten gelatin filter guide. Now Corning has passed its line to
Kopp, Kodak doesn't even list the Wratten filters or the guide on its website
and the set of filter books now includes one from Hoya. Most of the curves
in these guides have found their way into websites although they are not all at
one location.
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Looking for - Online
tables to match more of the filter curves listed above.
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| Window Curves |
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Lawrence
Berkeley Laboratory |
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This table
of over 20 infrared window materials gives transmission bands, index of
refraction and practical information on use but has no curves or
transmission tables. |
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Almaz
Optics |
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Transmission curves and other
data on about 30 optical window materials of all types are accessible from
this list.
No transmission tables are provided. |
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Präzisions
Glas & Optik |
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Listing
of transmission curves for BK7, Zerodur, Pyrex, VICOR and a variety of
low-alkali and borosilicate float glasses. |
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Schott |
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Schott provides a downloadable
catalog
containing all of its optical glass data. (Win 3.x/9x) |
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Source Emission
Curves
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Blackbody - Oddly,
most of these entries come from departments of astronomy. None have tables
but since blackbody emission is accurately described by a formula, they would be
redundant anyway. Incidentally, the politically correct name is now Ideal
Radiation Source.
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University
of British Columbia |
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An easy-to-use Java
applet that plots blackbody curves from 200-30,000K from Rob Scharein
in the UBC astronomy department. Includes buttons for star types. A
visible spectrum bar provides a nice reference. No numerical output
is provided. A 1024 x 1280 display is needed to show it all. |
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University
of Tennessee |
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This Java
applet from Mike Guidry plots up to 10 simultaneous blackbody curves
from 3,000 to 30,000K with linear or log scales. Other applets allow
you to view guess
the temperature of a mystery curve data or to view Wein
or Stefan-Boltzman data. |
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University
of Colorado |
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Andrew Hamilton presents a
color
temperature chart and a plot of these overlaid on the CIE chromaticity
chart. |
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LED - The
variety of LED emission wavelengths is expanding constantly so that now over an
order of magnitude in wavelengths is covered. Combination chips and
stimulated phosphor devices now provide white light as well. Due to the
sheer number of parts available, there are no longer many spectral emission or
radiation pattern curves online. Essentially everyone has now converted to
PDF files. Unfortunately, these render the data nearly impossible to
extract for computational use even using the real Acrobat software.
Lamp
- Most lamp spec sheets are also in PDF form now and much of it is just
scans of paper so the data is completely inaccessible electronically. Here
are a few items worth looking up anyway.
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General
Electric |
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This page has links for software
for computing illumination levels with directional lamps,
voltage-brightness-life curves and the cost of lighting in various
settings. Also available are spectral
power distribution curves of various lamp
types. These are part of an extensive set of lighting reference
materials on this site. |
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Meggaflash |
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You know how you are always
told that flashbulbs are only good to 10 feet or so. Well, that is
because your flashbulb is not big enough. This
picture was taken with one bulb. Look around on the site until
you find the bulb that puts out 60,000 lumens for 1.75 seconds. |
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Cress
Photo |
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Here are reprints of old Philips
flashbulb data sheets, mostly interesting for the light output vs.
time curves. |
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Phosphor
- Now that CRTs are getting displaced by flat displays, the majority of
which do not need phosphors, and the time-smearing function of phosphors on
radar screens, for example, has been replaced by digital memory, phosphor data
is getting harder to find. There are still new phosphors for white LEDs
and plasma displays and x-ray imaging but not much of this information gets
gathered together anymore.
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Clinton
Electronics |
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A company that still makes
specialty CRTs still needs specialty phosphors. Here is a table
with another new set of designators. No
curves. |
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Detector
Sensitivity Curves
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Imaging Arrays - While
there are dozens of materials that are used for light detection, here only those
available in imaging arrays are listed. Photocathodes are included because
they have a long history in intensified image tubes and now coupled to CCDs.
Many energy converters are also available for coating on CCDs to image in the
ultraviolet and at all energies in the x-ray spectrum.
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Texas
Instruments |
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Page 15 of the TC-241 data
sheet shows a spectral response curve typical of the virtual phase sensor
type: high blue response but with periodic variation in sensitivity vs.
wavelength from interference effects. |
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SITe |
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The 512x512 data
sheet shows clearly the effects of trading UV for IR sensitivity in
thinned, back-illuminated CCDs. It also shows how insensitive
front-illuminated multiphase CCDs with straight-line electrodes are. |
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Photek |
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Photocathodes haven't changed
much in the last 30 years. The curves of the various alkali types on
fused silica
and fiber optic
windows will be familiar. |
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PULNiX |
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This datasheet
compares several CCD sensors, mostly interline, and gives curves for
typical color sensors, both RGB and CMY. The variety of curve
shapes, even in this narrow technology range, demonstrates how dangerous
it is to make any generalizations about CCD spectral response. |
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