HDTenEightyP/NetNews huggingface dataset:
From: zowie@daedalus.stanford.edu (Craig "Powderkeg" DeForest)
Subject: Re: What is a Fresnel lens? -- was Re: That Magic TV screen
Organization: Stanford Center for Space Science and Astrophysics
	<76160028@hpldsla.sid.hp.com> <1992Aug25.172720.7172@athena.cs.uga.edu>
	<1992Aug26.094255.8816@colorado.edu> <1992Aug26.234255.21413@sfu.ca>
Date: 29 Aug 92 03:26:05

In article <1992Aug26.234255.21413@sfu.ca> palmer@sfu.ca (Leigh Palmer) writes:
   >mcovingt@athena.cs.uga.edu writes:
   >Two different devices are called a Fresnel lens:
   >
   >(1) A device that works by diffraction, and is seen mainly in optics
   >textbooks.  This device is very wavelength-specific.

   The first category referred to here is probably a Fresnel zone plate, not a
   Fresnel lens. Such devices are used for making far infrared monochromators 
   and satellite antennae, inter alia. They are more than a textbook curiosity.

Of course, a Fresnel zone plate is also the Green's function for a hologram,
also more than a textbook curiosity :-)
--
     Free the LSJUMB --      | "Damn -- the planetarium's broken!"
 BANNED from Disneyland, the | "The show must go on -- IS THERE AN
  Happiest Place on Earth!   |    ASTROPHYSICIST IN THE HOUSE!?"

Xref: sparky sci.optics:905 aus.photo:24 rec.photo:14684
From: mvolo@ecsvax.uncecs.edu (Michael R. Volow)
Newsgroups: sci.optics,aus.photo,rec.photo
Subject: Re: Help! need info on standard test patterns.
Date: 23 Aug 92 22:35:03 GMT
Organization: UNC Educational Computing Service


Edmund Scientific Co. of Barrington , N.J. has a lens test resolution
chart. It contains multiple USAF photo targets in B&W and in several
colors.
-- 
Michael Volow, Psychiatry, Durham VA Med Center, Durham NC 27712
919 286 0411 Ext 6933               mvolo@uncecs.edu
From: rags@apee.ogi.edu (R. Raghuraman)
Newsgroups: sci.optics
Subject: WALL PLUG EFFICIENCY OF LED's
Date: 1 Sep 92 04:01:18 GMT
Article-I.D.: ogicse.42210
Distribution: world
Organization: Oregon Graduate Institute, Applied Physics & Electrical Engineering, Beaverton

Hi,

would like to know if there are any numbers on the wall-plug efficiency
of LED's (visible)? I thought it was around 1-2% . But if you could tell
me some sources to find the details on this issue.

Thanks..

--rags
(rags@apee.ogi.edu)
--
3120 NW John Olsen Ave.,     |	Dept. of APEE.
#18205,			     |	OREGON GRADUATE INSTITUTE of Sc. & Tech.
Hillsboro, OR 97124	     |	19600, Von Neumann Dr., Beaverton,OR 97006
Ph: Residence:(503)-629-2041 |	Office:(503)-690-1121 (Extn. 7186)
Newsgroups: sci.optics
From: thw@cbnewsh.cb.att.com (thomas.h.wood)
Subject: Re: * Insertion loss *
Organization: AT&T Bell Laboratories, Crawford Hill, Holmdel, NJ USA
Date: Wed, 26 Aug 1992 02:35:00 GMT

In article <1992Aug25.071820.16266@nntp.nta.no> nawaz@tellus.unik.no (Muhammad Nawaz) writes:
>Hallo to everyone !
>
>I want to measure the insertion loss of the multiple
>quantum well (MQW) GaAs/AlGaAs  reflection modulator, used in the
>optical communication system. Does anyone can provide me
>information how to measure this (experimentally or
>theoratically )?
>
>With many thanks.
>MUHAMMAD  NAWAZ  


Newsgroups: sci.optics
From: palmer@sfu.ca (Leigh Palmer)
Subject: Re: What is a Fresnel lens? -- was Re: That Magic TV screen
Organization: Simon Fraser University
Date: Wed, 26 Aug 1992 23:42:55 GMT

In article <1992Aug26.094255.8816@colorado.edu> weverka@csn.org (Robert T.
Weverka) writes:
>In <1992Aug25.172720.7172@athena.cs.uga.edu> mcovingt@athena.cs.uga.edu
writes:
>>Two different devices are called a Fresnel lens:
>>
>>(1) A device that works by diffraction, and is seen mainly in optics
>>textbooks.  This device is very wavelength-specific.
>>
>>(2) A collapsed convex lens, in concentric zones.  This is what "magnifying
>>sheets" are made of, and is also found in projectors and spotlights.
>>It is wavelength-sensitive only to the extent of the chromatic dispersion
>>of the glass.
>>
>In the second catagory, a lense may be made to have each step height
>an integral number of wavelengths at the design wave length.
>
>This theoretically makes the "collapsed convex lens" have the perfect ray
>bending of a thin lens at the design wavelength.  At other wavelengths
>the step height is not an integral number of waves and hence
>the focus is severely degraded.

The first category referred to here is probably a Fresnel zone plate, not a
Fresnel lens. Such devices are used for making far infrared monochromators 
and satellite antennae, inter alia. They are more than a textbook curiosity.

Leigh Palmer
Organization: University of Illinois at Chicago
Date: Wednesday, 2 Sep 1992 10:34:18 CDT
From: Wesley Bielinski <U53734@uicvm.uic.edu>
Newsgroups: sci.optics
Subject:    WANTED: Cheap CCD Camera Plans

Early this year I saw a posting for making a CCD camera from some type of
chip.  I am working on a 12" Newtonian telescope mirror and I would like to
have a CCD camera to take long "deep sky" exposures with it.
Can someone help me out?   Thank you

Wesley J. Bielinski     U53734@uicvm.uic.edu
SGT, USAR
12th Special Forces Group (Airborne)
From: carleson@apee.ogi.edu (Peter Carleson)
Newsgroups: sci.optics
Subject: Internet Optoelectronic Forum
Date: 28 Aug 92 17:21:14 GMT
Article-I.D.: ogicse.42096
Distribution: world
Organization: Oregon Graduate Institute, Applied Physics & Electrical Engineering, Beaverton

This came across my mbox and I thought others here might be interested:

REGARDING                Forwarded message:  Optoelectronic Forum
                              FIRST NOTICE

It was suggested at the 1992 LEOS Topical meetings in Santa Barbara that
an Optoelectronics Forum, accessible through the Internet, be
established.  The Forum would be a no-fee, near-real-time communications
channel, an electronic bulletin board, for members of the international
optoelectronics community.  There would be few restrictions on message
content; subscribers would be free to post any message they feel would be
of general interest to workers in the field (but no advertising). 
Potential topics include, but are not restricted to, reminders of
upcoming events, technical queries, technical alerts, device or system
notes, people notes, brief abstract-reports on work in progress,
opinions, commentaries on the state of the art and the challenges to
progress, etc.
If you would like to comment on the utility of such an Optoelectronics
Forum, or if you would like to have your name on the list of subscribers,
or if you would like to have your name removed from this preliminary
list, contact, by e-mail of course, Harry Lockwood at GTE Laboratories at
the Internet address given below.  Inclusion of your full address and
your telephone and fax numbers is desireable, but it is also optional.
Finally, you are asked to redistribute this message as widely as possible
among colleagues within, and outside of, your organization.

19 August 1992

Harry F. Lockwood
GTE Laboratories Inc
40 Sylvan Rd.
Waltham MA 02254
Tel (617) 466 2786
Fax (617) 890 9320
E-mail: lockwood@gte.com


Newsgroups: sci.optics
From: rodman@pkr.asd.sgi.com (Paul Rodman)
Subject: High Index glasses
Reply-To: rodman@pkr.asd.sgi.com (Paul Rodman)
Organization: Silicon Graphics Inc.
Date: Fri, 28 Aug 1992 19:17:21 GMT

As some of you may recall, I posted a request for information on the
use of and problems with "high-index" plastics for eyeglasses.

I received 10 pieces of mail and learned that many people have had problems
with these lenses. 

Polycarbonate high-index glasses seem to have more problems with field 
distortion (i.e. warping of the field at the edges) and with chromatic
distortion (prismatic splitting of light sources shining through near the
edges). 

Newer types don't seem to suffer as much from these problems, but can still
suffer from distortion. My problems were not with either distortion or 
chromatic abberation, my problem was the loss of visual acuity (aka "blurry) 
when looking of the glasses off-center. 

A few respondents reported the same problem, but in general it seems rare.
Try this experiment: Turn your head 30 degrees to the right of your 
computer screen, look at the screen without turning your head and see how 
sharp the characters are... Do the same to the left. 

With my old glasses the resolution doesn't change. With the high index, I 
have difficultly reading it. It's pretty pronounced. How many people have the
problem but just assumed it's how vision is supposed to be.? Eye exams don't
check your ability to read the chart from even small angles. 

My doctor tried to find out from the manufacturer what the problem was
or could be and could found out nothing. They kept referring to the problem
as a "distortion" and she kept trying to explain that was not the problem, but
to no avail. Bleh.

I am surprised and baffled at my problem but have decided to avoid high-index
plastics now and in the future until I can find out more about the subject and
the whole manufacturing process.

This experience reenforces my opinon that a lot of people walk around 
with eyesight worse than it could be. Those in the business seem to spend 
99% of their time worrying more about looks rather than eyesight. Double Bleh.

It also reenforces my opinion that many doctors are overpriced middlemen
(or if you prefer "glorified human mechanics")  that get in the way 
of me and my health. Fie on them.

-- 
Paul K. Rodman            "Obsolete power corrupts obsoletely."
rodman@sgi.com                              -Ted Nelson
KA1ZA
From: article@tc.fluke.COM (John F. Berkey)
Newsgroups: sci.optics
Subject: Expert advice needed / Please help
Keywords: optical calibration
Date: 4 Sep 92 20:04:09 GMT
Article-I.D.: tc.1992Sep4.200409.22364
Organization: John Fluke Mfg. Co., Inc., Everett, WA


Expert advice needed, 

A little back ground: 

I'm a C.M.M. (Coordinate Measuring Machine), Dimensional
inspector, with very little knowledge in the optical field. I'm
use to contact and non-contact measurement devices, however I've
been placed in charge of making sure all of our instruments meet
calibration per the National Institute of Standards and
Technology, for our division. I'm very use to calibrating contact
measuring devices, but when it comes to our optical measuring
equipment I'm at a loss.

We have optical measuring equipment ranging from "Pocket
Magnifiers" to "Stereo Microscopes" to even a color camera system
with a cross hair generator, that mounts to the C.M.M. and all of
them except the camera system contains reticle's that run in the
range of 1 mil at what ever power. (ie, .0010 @ X30).

The problem is that I'm required to make sure these optical
instruments are within calibration, at the power given for each
instrument. Oh, and of coarse each instrument is different.

So I guess my questions are:

1. Is there some way of knowing for sure what power I'm looking
at? most of the equipment have zoom lens on them. I can not
assume that just because the zoom lens says that I'm looking at
something at X30, that it really is X30.

2. How to I check the reticle's under magnification? or at the
power given.

I have a lot of questions but for now I think these will suffice,
now that you have some idea of what I'm up against, I'm hoping
someone can at least point me in the right direction.

Thanks.

John.
-- 

John Berkey (article)
Chief Quality Specialist
Service Equipment Group
John Fluke Mfg, Co.   

article@tc.fluke.com

Disclaimer: All views and opinions stated here are my own, and in no way
            represent the views of my employer.                        
Newsgroups: sci.optics
From: thw@cbnewsh.cb.att.com (thomas.h.wood)
Subject: Re: * Insertion loss *
Organization: AT&T Bell Laboratories, Crawford Hill, Holmdel, NJ USA
Date: Wed, 26 Aug 1992 02:47:04 GMT



In article <1992Aug25.071820.16266@nntp.nta.no> nawaz@tellus.unik.no (Muhammad Nawaz) writes:
>Hallo to everyone !
>
>I want to measure the insertion loss of the multiple
>quantum well (MQW) GaAs/AlGaAs  reflection modulator, used in the
>optical communication system. Does anyone can provide me
>information how to measure this (experimentally or
>theoratically )?

Experimentally, here's what you want to do:


                            -------------
                            |   Laser   |
                            -------------
                                 |
                                 |
                                 |  / 50% transmissive beam splitter
                                 X /
                                 |/          --------------
                                 /---------->|Power Meter |
                                /|           -------------- 
                               / |
                              /  |
                                 |
                             ------------
                             |Reflection|
                             |Modulator |
                             ------------
Set up this arrangement and make sure you can see a change in the power
in the power meter when you change the voltage on the modulator.  Then,
with the modulator biased for maximum reflectivity(ie, max power in the 
power meter), record the power reading, P1.  Then move the power meter to
location X, and measure the power there, P0.  The insertion loss should be
10 log(P0/P1) - 6 dB.  The 6 dB makes up for the loss in the beamsplitter.

If there are lenses in the setup, which there probably will be, you must
also account for the losses in the lenses.  You could also try replacing
the modulator with a high reflectivity mirror, and taking the ratio of
the powers observed with the modulator and with the mirror.

Hope this helps.  Insertion losses are one of the most frequently mis-measured
quantaties.

Tom Wood
Newsgroups: sci.optics
Subject: HUD simulation
From: misdcc@otago.ac.nz (Chris Hinch)
Date: 24 Aug 92 12:51:37 +1300
Organization: Dunedin City Council, Dunedin, NZ

I would like some input on the following problem :-)

I am developing a replica cockpit for an F16A Block 15 simulator,
and am about to dive into the intricacies of HUDs.

I am unsure as to how the actual HUD in a F16 works, but have been thinking
along the following lines for simulation -

The HUD image is created on a small CRT, which is then passed through
a collimating lens (?), which is then bounced off a mirror up
onto a sheet of 'glass' which has a 'selective reflectivity index' ?
(can you tell I don't know what I am talking about yet? :-))

Any image drawn on the monitor is then presented to the pilot
in the normal way.

Is this the right approach? Is there a better way?  Can anyone
point me in the right direction?

(I only have a moderate physics background, with no real knowledge
of optics, so please be gentle with me...)

Thanks in advance

Chris
-- 
Chris Hinch                <misdcc@otago.ac.nz>
PC Administrator
Dunedin City Council                      DUNEDIN. It's all right here!
Dunedin, New Zealand                                        ~~~~~
Newsgroups: sci.optics,aus.photo,rec.photo
From: phantom@casbah.acns.nwu.edu (James Choi)
Subject: Help!  need info on standard test patterns.
Organization: Northwestern University, Evanston Illinois.
Date: Sun, 23 Aug 1992 20:43:03 GMT


I urgently need to find the names and vendors of the following type of test
devices or patterns (if they exist).  Any suggestions, lead to literature,
recommendation will be greatly appreciated.

1. Lens resolution measurement.
2. Photographic Image density measurement (on slide or movie film)
3. Image blur measurement
4. Image constrast measurement.

I have a question for the experts.  Does it make sense to have color test
pattern since the resolution is color dependent?

Thank you in advance

James Choi
From: tomk@netcom.com (Thomas H. Kunich)
Newsgroups: sci.nanotech
Subject: Re: Evolution and nanotech
Date: 31 Aug 92 05:58:33 GMT
Organization: Netcom - Online Communication Services (408 241-9760 guest)

(Paul Rodman makes plenty of good comments about nanotech)

Paul, I'm not arguing what the possible future of nanotech 
could be.

You make many good points and I agree with almost all of them.

What I'm saying is that all sciences work in a competitive
atmosphere. Nanotech is only a _possibility_ of becoming
a successful industrially significant science. Remember liquid
computers? Where are they? (Actually some of their methods are
used quite commonly in industrial control these days but not
as the computer envisioned by it's inventors.)

Nanotech must compete economically and effectively with many other
sciences that are presently at a much higher state of development.
Chemistry and biotechnology are both much further along the
development curves and both can presently put stronger claims
to being able to produce those things that present nanotechnology is
just beginning to think about.

Building new drugs is becoming so commonplace with biotechnology that
it is reaching the point where it is no longer science, but industrial
practice.

Materials sciences has made tremendous strides towards doing anything
that nanotechnology might attempt, such as growing perfect crystals,
making multi-material films, molecular manipulation and many 
other far more fantastic proposals.

What my whole point has been is that for nanotechnology to succeed
it will have to compete. While it certainly is true that we 
can't now see what nanotechnology will someday become, it is
also true that if it is out-competed today it will never develop
into anything.

Rather than giving this whole conference the Buck Rogers treatment
with fantasy ideas like reproducing a specific human being by
some 'simple' means, there ought to be real discussions about
real projects and real possibilities. Or else all of the talk
about nanite war machines will simply be Buck Rogers death rays
or Star Trek's 'force fields' -- just so much to laugh about.

[Actually any use of the term "nanite" is Star trek -derived and
 tends to make me wince...
 --JoSH]
From: shearson!snark!pmetzger@uunet.uu.net (Perry E. Metzger)
Newsgroups: sci.nanotech
Subject: Funding
Date: 27 Aug 92 02:44:14 GMT
Organization: Lehman Brothers

willdye@helios.unl.edu (Will Dye) writes:
>I agree that we need to keep making the case for better funding of 
>nanotech.  I recall Cong. Newt Gingrich scolding the L-5 society 
>(or some related group), telling them that the reason dairy farmers 
>get more federal funding than NASA is that the dairy farmers are 
>better organized.  

I question whether funding either dairy farmers or scientific research
is an appropriate use of the coercive powers of government.


Perry Metzger		pmetzger@shearson.com

		  Just say "NO!" to death and taxes.
			 Extropian and Proud.

[A laudable ethical stance, but it is just as true that we need to make 
 a better case for businessmen to invest in nanotech development.  In
 fact we need to make a much better case, since it will be their own
 money they will be spending, and they will not be nearly as profligate.
 --JoSH]
From: tomk@netcom.com (Thomas H. Kunich)
Newsgroups: sci.nanotech
Subject: Re: Snowballing tomk
Date: 28 Aug 92 01:46:41 GMT
Organization: Netcom - Online Communication Services (408 241-9760 guest)

In article <Aug.26.22.36.12.1992.1545@planchet.rutgers.edu> tsf@CS.CMU.EDU (Timothy Freeman) writes:
>In article <Aug.23.19.51.35.1992.4618@planchet.rutgers.edu> tomk@netcom.com (Thomas H. Kunich) writes:
>
>   Who's going to pay for this completely new science? And why?
>
>Maybe someone trying to build a faster computer after other
>alternatives have been exhausted, and they'll do it to make money?
>Maybe enough work will be done with STM's and molecular biology that
>the science won't be completely new.

Do I understand you to be saying that you think that a mechanical
computer can be constructed that is _faster_ than an electronic
computer? There are several orders of magnitude difference in the
inertia of an electron and that of several atoms.

I'm not _against_ the idea of nanotech, mind you. It's just
that I have yet to see any duscussion of it that doesn't
ignore the development of all of the other sciences available
today. Nanotech is this fine challenge that lots of people are
getting wonderful ideas about. Unfortunately, none of them seem to
involve making serious money with it. And there is the key to
whether or not this will become one of the industries of the future.

[A mechanical nanocomputer can be constructed that is faster
 (not to mention smaller) than *current* electronic computers.
 (Clock speeds ca. 1 GHz appear feasible) However I for one believe
 that electronic nanocomputers will be faster--but we don't know how
 design them. Yet.
 --JoSH]
From: mckendre@sal-sun50.usc.edu (Thomas Mc Kendree)
Newsgroups: sci.nanotech
Subject: Re: Un-Nanotech-able?
Date: 31 Aug 92 19:25:38 GMT

In article <Aug.26.22.31.34.1992.1300@planchet.rutgers.edu> hagerman@ece.cmu.
edu (John Hagerman) writes:
>Some goods we currently manufacture take advantage of the nuclear
>features of matter.  [e.g. radiation]
 John then asks, in essence, how might these features be used with
 nanotechnology?
 JoSH mentions isotopic separation, for example for waste processing.
 The problem with mixing nuclear technology and nanotechnology is that
 nuclear effects could not be induced in particular atoms.  Thus, there
 is a scale mismatch between the precision to which you can handle things
 like bonding with nanotechnology, and the precision to which you can place
 nuclear effects.  Indeed, for many nuclear technologies (e.g. critical 
 mass) have characteristic sizes which tend to be much larger than nano-
 mechanisms.

 As Dr. Drexler points out in UNBOUNDING THE FUTURE, however, nanotechnology
 can provide vast wealth, which could then be applied to dealing with
 nuclear technologies as you wished.

 Tom McKendree                                      mckendre@chaph.usc.edu
From: gwilliam@mrc-crc.ac.uk (Gary Williams x3294)
Newsgroups: sci.nanotech
Subject: Re: Snowballing tomk
Date: 28 Aug 92 01:39:07 GMT
Organization: MRC Human Genome Resource Centre


I'm not involved in the nanotech field, except as an interested observer
who can't wait to see nanorobot DNA readers/editors produced :-)

Does anyone know of any group working on Feynman's idea of making
millimeter-sized workbenchs and robot arms, which are used to make
micron-sized workbenches and robot arms, which are used to make
nano-sized workbenches and robot arms (eg. assemblers) ?

The emphasis of current nanotech-related work appears to be very heavily
on AFMs with various hypothetical tips for holding onto things in
addition to their primary role as sensors.  This appears to be ignoring
Feynman's (very neat) idea.  Why? Are micron-scale known materials weak
and messy to work with?


-- 
GARY WILLIAMS,  Computing Services Section,  Janet:       G.Williams@UK.AC.CRC
MRC-CRC & Human Genome Mapping Centre,       Internet:    G.Williams@CRC.AC.UK
Watford Rd, HARROW, Middx, HA1 3UJ, UK
Tel 081-869 3294   Fax 081-423 1275