HDTenEightyP/NetNews huggingface dataset:
From: ewright@convex.com (Edward V. Wright)
Subject: Re: SSTO vs. 2 stage
Date: Wed, 16 Dec 1992 19:25:16 GMT
Organization: Engineering, CONVEX Computer Corp., Richardson, Tx., USA
X-Disclaimer: This message was written by a user at CONVEX Computer
              Corp. The opinions expressed are those of the user and
              not necessarily those of CONVEX.

In <18585@mindlink.bc.ca> Bruce_Dunn@mindlink.bc.ca (Bruce Dunn) writes:

>        If a DC-1 in SSTO mode can launch 10 tons to LEO and the two stage
>vehicle using the DC-1 as an upper stage can launch 50 tons to LEO, then we
>have the following costs for launching 50 tons:

>DC-1 in SSTO mode:  5 flights needed, incurring 5 DC-1 stage turnaround costs

>DC-1 in 2 stage mode:  1 flight needed, incurring 1 DC-1 stage turnaround and
>1 lower stage turnaround cost.

The 2-stager is a *much* larger vehicle, so your vehicle fabrication 
costs will be much larger.   


>       I will assert that turnaround cost of the lower stage will not exceed
>the turnaround cost of the upper stage (the lower stage is much less stressed
>than the DC-1 upper stage, and uses cheap kerosene and LOX as propellants).

Think again.  The SSTO recovers back at the launch site.  Your first 
stage will splash-down or land somewhere downrange.  It needs to be
retrieved, safed, and returned to the launch site before it can be
used again.  This is not only expensive, it's time consuming.  You're
going to need a lot of extra stages to make up for the down time.

Mating the two stages will take time and manpower also. 

Using a different propellent in the first stage means you're
going to have to invest in another set of propellent storage
and loading facilites.  Fueling will be more complex, requiring
more time and manpower.


>Therefore, as far as turnaround costs go, the two stage vehicle costs 2/5, or
>40% as much as the SSTO.  

That doesn't follow from anything you've said up til now.  Your second
stage is a DC-1, so that's 100% right there.  The first stage, being
much larger, will be a lot more.
 

>        A final advantage to the two stage design comes from the time
>necessary to perform turnaround.   Since the lower stage can be inspected and
>prepared for another flight while the upper stage is making an orbital
>delivery, the frequency of flights will be governed by the turnaround time of
>the upper stage after it gets back.  

Only if the first stage can teleport.

>Say that turnaround time is 1 week.  If you spend your money on two DC-1 
>vehicles and operate them in the SSTO mode, then it will take 5 weeks to 
>put 100 tons in orbit (two flights delivering 10 tons each per week).  

Or 5 days, flying two flights per day.

>If you spend your money on one DC-1 and 1 lower stage, then the same 
>100 tons can be put into orbit in two weeks (two flights, each
>delivering 50 tons).  

Of course, you'll only have enough money to pay for half the first
stage.
From: prb@access.digex.com (Pat)
Newsgroups: sci.space
Subject: Re: DoD launcher use
Date: 16 Dec 1992 22:07:58 GMT
Organization: UDSI
NNTP-Posting-Host: access.digex.com

In article <1992Dec13.183545.9958@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes:
>
>We're talking about Iraq right? No air opposition right? Complete Coalition
>domination of the airspace right? SR71s and U2s that can fly above anything
>Iraq had right? After 28 years of trying, the SU never managed to down a
>SR71 right? Why think Iraq could? What can a satellite do for tactical
>recon that a SR71 can't?
>

To the best of my knowledge,  and i am sure henry knows more on this subject,
NO SR-71  ever flew within Russian borders (or Air Space).  i suspect
they also stayed out of Warsaw Pact areas and china.

After Francis Gary Powers  got shot down/Flamed out over khazakistan
we signed an agreement with the russians never to do this again, and
they gave him back.  The russians never gunned down an SR-71, cuz they
never had a reason to. 

Satellites also have one big advantage no Plane ever will.  Infinite hang time.

With cheap space access,  we could in an emergency,  put 4 sats in Molniya
orbit over an emergency area  or we could put a few birds in
90 minute orbits inclined over an area,  and just watch the video.

Satellites also have a big legal advantage.  THey are called "National
Technical Means"  and protected by treaty.  SR-71's are called spy planes
and when they enter someones air space,  That is an act of war.

Let's say we want to know what's going on in an egyptian nuclear
reservation.  we send an SR-71 over,  they get pissed and close the
suez canal to our boats.  Now what, gary?  do we spend $200 billion
go over and pound the stuffings out of their country?  Imperialism
is dead.  long live the new world order.

Take the new CIS member states.  Ukraine and khazakistan  have beacoup
nukes and lots of old soviet equipment.  we get into a peeing match
and they could toss around a few nukes as point makers.  unlikely, but
we are better off with them sticking by existing treaties.


Newsgroups: sci.space
From: mccreary@sword.eng.hou.compaq.com (Ed McCreary)
Subject: Re: Sea Dragon?
Organization: Compaq Computer Corp.
Date: Thu, 17 Dec 1992 19:06:49 GMT

In article <1992Dec17.140631.1260@cs.ucf.edu> clarke@acme.ucf.edu (Thomas Clarke) writes:
>Did you ever see the Japanese cartoon where the beleagured earthlings
>convert the battleship Yamato (sunk during WWII, but now dry since the 
>seas had dried up as a result of the bombardment of earth by the aliens) 
>into a starship?  The intrepid band takes off, and after many adventures 
>reach the home planet of the aliens and save earth!  It was actually
>pretty clever how the blended the lines of a battleship into a 
>plausible looking starship.

"Starblazers".  A friend a few offices down have all of the first
season on tape sitting on his shelf.  It used to come one right
after "Speed Racer" during my misspent youth.

--
Ed McCreary                                               ,__o
mccreary@sword.eng.hou.compaq.com                       _-\_<,
"If it were not for laughter, there would be no Tao."  (*)/'(*)
Newsgroups: sci.space
From: ewright@convex.com (Edward V. Wright)
Subject: Re: Terminal Velocity of DCX? (was Re: Shuttle ...)
Date: Wed, 16 Dec 1992 19:11:24 GMT
Organization: Engineering, CONVEX Computer Corp., Richardson, Tx., USA
X-Disclaimer: This message was written by a user at CONVEX Computer
              Corp. The opinions expressed are those of the user and
              not necessarily those of CONVEX.

In <1992Dec16.102412.27942@ke4zv.uucp> gary@ke4zv.uucp (Gary Coffman) writes:

>One Shuttle flight is a bit less than half the projected cost of DCX
>development to flight test. It doesn't even begin to cover costs for
>the development of DCY which requires different structures and engines,
>or of DC-1. 

McDonnell Douglas has estimated the total development costs of the DC-1
at $1.5 billion.  I don't recall exactly how much money has been spent
on DC-X, but it's in the range of a couple hundred million.  NASA spends
over a billion dollars on each Space Shuttle flight.  I think you've
indulged in some creative accounting.
From: roberts@cmr.ncsl.nist.gov (John Roberts)
Newsgroups: sci.space
Subject: Re: Chicken guns
Date: 19 Dec 92 23:22:43 GMT
Distribution: sci
Organization: National Institute of Standards and Technology formerly National Bureau of Standards
X-Added: Forwarded by Space Digest
Original-Sender: isu@VACATION.VENARI.CS.CMU.EDU


-From: prb@access.digex.com (Pat)
-Subject: Re: Chicken Guns (was Re: "trivial engineering")
-Date: 18 Dec 92 18:15:34 GMT
-Organization: UDSI

-The F-16 in the early 80's was having a real problem with bird strikes
-fracturing the canopies, so i heard for a while the air force
-was launching Frozen turkeys and chickens at the aircraft
-to test canopies.  i guess the frozen bit was to make the birds
-harder.

I've heard that birds sometimes get caught in an updraft and frozen.

Fortunately, it doesn't seem to happen very often, and aircraft can
presumably avoid such updrafts.

John Roberts
roberts@cmr.ncsl.nist.gov
From: BrianT@cup.portal.com (Brian Stuart Thorn)
Newsgroups: sci.space
Subject: Re: Saturn history
Date: Fri, 11 Dec 92 20:32:16 PST
Organization: The Portal System (TM)
Distribution: world
  <ByyIEK.7H4@zoo.toronto.edu> <Bz0tLs.t0@access.digex.com>
  <Bz20np.n1H@zoo.toronto.edu> <10DEC199219341908@judy.uh.edu>

>This is very true and also what Von Braun wanted to do with the Saturn V. They
>wanted to fly the Saturn first stage, the two stages, etc.... The success of
>the Saturn IB flying the SIVB Saturn stage allowed them to do what they
>called "full up" testing, where the launched the full stack on  the first
>SV flight.
>
>By the way the Saturn I had a perfect record, 28 launches and no failures.
>Also a thing of note is that the Centaur was originally designed and flown
>on the Saturn I as the upper stage.
>
>Dennis, University of Alabama in Huntsville.
>
     Centaur on the Saturn? I think I remember that it was considered
     as a fourth stage for Saturn 5 (with early Voyager planning?) but
     I believe you're confusing the RL-10 and the Centaur. RL-10
     powered the S-IV (predecessor to the J-2 powered S-IVB) but I
     don't think Centaur ever flew anything other than Atlas or Titan.
      
     -Brian
From: haw30@macaw.ccc.amdahl.com (Henry A Worth)
Newsgroups: sci.space
Subject: Re: Terminal Velocity of DCX? (was Re: Shuttle ...)
Date: 18 Dec 92 20:37:01 GMT
Organization: Amdahl Corporation, Sunnyvale CA

In article <1992Dec17.104748.8173@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes:
> In article <1992Dec16.163114.4715@iti.org> aws@iti.org (Allen W. Sherzer) writes:
> >In article <1992Dec16.125638.29623@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes:
> >
> >>Last I heard they're
> >>willing to rent Cosmonaut time at $5 million an hour plus launch costs
> >>for any experimental equipment you want them to use.
> >
> >No offense but I would like some backing for that.
> 
> Oh. Oh. My source is a post by Nick Szabo Sept 19th of last year where
> he quotes a Mir Press article on suited time for sale. Since they offered
> John Denver a ride for $10 million, this must be out to lunch.
> 
> Gary

   I believe the $5M/hr figure was for EVA time. The planning, support,
and resources required for EVA are non-trival, whether performed by the
CIS or the USA. 


--
Henry Worth
No, I don't speak for Amdahl... I'm not even sure I speak for myself.
Newsgroups: sci.space,sci.astro,alt.sci.planetary
From: garym@telesoft.com (Gary Morris @pulsar)
Subject: Re: Galileo's Atmospheric Probe Passes Health Checks
Organization: Alsys Group, San Diego, CA, USA
Date: Wed, 16 Dec 1992 07:00:41 GMT

In <1992Dec15.200023.10436@eng.umd.edu> sysmgr@king.eng.umd.edu (Doug Mohney) writes:
>In article <1992Dec15.170442.1866@elroy.jpl.nasa.gov>, baalke@kelvin.jpl.nasa.gov (Ron Baalke) writes:
>>     Its incandescent shock wave will be as bright as the sun and
>>reach temperatures up to 28,000 degrees Fahrenheit.  

>Will entry be observed by the camera on the orbiter? 

I wonder if Hubble could see the entry?
--GaryM
From: prb@access.digex.com (Pat)
Newsgroups: sci.space
Subject: Re: absolutely, positively overnight
Date: 16 Dec 1992 21:54:34 GMT
Organization: UDSI
NNTP-Posting-Host: access.digex.com

In article <ewright.724353772@convex.convex.com> ewright@convex.com (Edward V. Wright) writes:
>
>"Air Force One" is just a call sign for whatever plane the President
>happens to be riding in.  The Air Force has an entire squadron of planes 
>which, at one time or another, may be Air Force One.  The big 707 (now 
>747) is the most famous, but not every trip requires something that
>large.
>


Well, when he is being flown around in his Sikorsky to andrews and the white
house,   then he is in ?Marine One".  I know the army has a small
helicopter detachment to fly him around and i bet then it's "Army One".

So if the Navy buys the first executive DC, then it will be Navy One that
goes globe-trotting.

Newsgroups: sci.optics
From: Ben Burch <Burch_Ben@wes.mot.com>
Subject: Imaging 880 nm?
Organization: Motorola, Inc.
Date: Fri, 11 Dec 1992 16:21:38 GMT
X-Xxmessage-Id: <A74FC2B5DD01B081@ben_burch.pb.wes.mot.com>
X-Useragent: Nuntius v1.1.1d9
X-Xxdate: Sat, 12 Dec 92 10:24:21 GMT

Hello!  I'm helping with an IR remote control type device that uses an IR
LED
with a centerline wavelength of 880 nm.  We are trying to figure out if
we can
image the footprint in some way.  We looked at an industrial IR imager
earlier,
but that cuts out at 3300 nm.  Will Kodak IR film record this frequency? 
I
can get that at the camera store.  Any good pointers would be appreciated.

Thanks!

-Ben Burch
Newsgroups: sci.optics
From: eshkoli@itexjct.jct.ac.il (Noam Eshkoli)
Subject: Digital Interferometerm (?)
Organization: ITEX, Jerusalem, Israel
Date: Wed, 16 Dec 1992 19:15:46 GMT
Keywords: interferometer  Is anybody know about 'Digital Interferometer' for measuring liquid's  index reflection?


     Noam Eshkoli.
Newsgroups: sci.optics
From: mlevin@husc8.harvard.edu (Michael Levin)
Newsgroups: sci.optics
Subject: a qustion about holograms
Date: 13 Dec 92 19:30:47 GMT
Distribution: usa
Organization: Harvard University Science Center


    I have read that if you cut a hologram into pieces, each piece can
be used to recover the whole, albeit fuzzier, image. What properties
of the hologram process is responsible for this non-locality effect? I
am not a physics major, so be gentle... I know that the hologram is
produced by somehow combining interference from two separate laser
beams. What is it about this that produces the non-locality
phenomenon? Please reply to mlevin@husc8.harvard.edu.

Mike Levin
Newsgroups: sci.optics
From: palmer@sfu.ca (Leigh Palmer)
Subject: Re: Fluorescent bike headlight?
Organization: Simon Fraser University
Date: Fri, 11 Dec 1992 21:57:22 GMT

In article <1992Dec11.171259.19245@EE.Stanford.EDU> siegman@EE.Stanford.EDU
(Anthony E. Siegman) writes:

>I'd bet that a 55 watt headlamp designed for 12 V
>operation won't even glow visibly if you put just 6 V on it.

I haven't done the experiment, but I'd bet the other way. A 12V tungsten
filament lamp hooked to a 6V supply draws considerably more than half its rated
current at 12V. Because the filament temperature varies strongly with output,
the resistance does also. If a 12V tungsten filament glows at 2500 K, say, then
even one quarter the power would heat it to 1770 K if it were cooled
principally by radiation. That's quite visible, of course.

Leigh
From: rxv6@po.CWRU.Edu (Rajesh Venkateshaiyer)
Newsgroups: sci.optics
Subject: Optical design package
Date: 16 Dec 1992 17:38:17 GMT
Organization: Case Western Reserve University, Cleveland, Ohio (USA)
NNTP-Posting-Host: slc12.ins.cwru.edu


I may looking for an optical design package for a Mac. The
basic stuff we would need is ray tracing, diffraction analysis etc.
I would appreciate any info regarding the availability of such a 
package and the company details if any.

Thanks

Rajesh
--
From: rxv6@po.CWRU.Edu (Rajesh Venkateshaiyer)
Newsgroups: sci.optics
Subject: Optical design package
Date: 16 Dec 1992 17:42:07 GMT
Organization: Case Western Reserve University, Cleveland, Ohio (USA)
NNTP-Posting-Host: slc12.ins.cwru.edu



I am looking for an optical design package for a Mac. The basic
features we would need are ray tracing, diffraction analysis etc.
Any info regarding the availibility of such a package and the 
details of the vendor would be appreciated.

Thanks

Rajesh
-- 
Newsgroups: sci.optics
From: mcovingt@aisun3.ai.uga.edu (Michael Covington)
Subject: Address of R. Kingslake
Organization: AI Programs, University of Georgia, Athens
Distribution: usa
Date: Fri, 11 Dec 1992 21:51:09 GMT

Does anybody know if the eminent lens designer Rudolf Kingslake
(retired from Kodak, now almost 90 years old) is still active and,
if so, how I can contact him?

-- 
:-  Michael A. Covington     internet mcovingt@uga.cc.uga.edu :   Verbum caro
:-  Artificial Intelligence Programs       phone 706 542-0358 :    factum est
:-  The University of Georgia                fax 706 542-0349 :  et habitavit
:-  Athens, Georgia 30602-7415 U.S.A.     amateur radio N4TMI :   in nobis...
Newsgroups: sci.optics
From: mcovingt@aisun3.ai.uga.edu (Michael Covington)
Subject: Re: Imaging 880 nm?
Organization: AI Programs, University of Georgia, Athens
Date: Sat, 12 Dec 1992 04:56:52 GMT

Infrared film goes to about 900 nm, so it should work.

But I'm told the easiest way to see infrared is to use an ordinary
camcorder; they apparently see IR rather well.  Haven't tried it.

-- 
:-  Michael A. Covington     internet mcovingt@uga.cc.uga.edu :   Verbum caro
:-  Artificial Intelligence Programs       phone 706 542-0358 :    factum est
:-  The University of Georgia                fax 706 542-0349 :  et habitavit
:-  Athens, Georgia 30602-7415 U.S.A.     amateur radio N4TMI :   in nobis...
Xref: sparky sci.optics:1311 comp.graphics:12986
From: halazar@media.mit.edu (Michael Halle)
Newsgroups: sci.optics,comp.graphics
Subject: Re: Output for computer generated holography
Date: 17 Dec 92 04:58:40 GMT
Article-I.D.: media-la.HALAZAR.92Dec16235840
	<71231@cup.portal.com>
Organization: M.I.T. Media Laboratory


> This made me wonder if using a monitor for realtime reflection holograms
> might be feasible. 

Probably not. Anyway, "reflection holograms" have nothing to do with this.


> The only difference between that and a _bone fide_
> hologram would be the frequency; it's as if one were generating a hologram
> (at pixel resolution - say 0.28mm wavelength) for a much lower frequency.

How about "monochromaticity"?  CRTs aren't monochromatic.  

> If there were a technique to up-convert the resultant "microwave" output
> to optical frequencies, perhaps a visible hologram would result. 

Oops, that's the step from Amiga screen to acousto-optic modulator....


Anyone trying to do this stuff is most likely in for major league
disappointment.  Even with an ideal 4K x 4K film recorder, the highest
diffraction angle you can get is 2 degrees in red light.  That means that
your image of muffy is within 2 degrees of your glaring illumination
source.  Dim, too.  

Sort of like the kids looking for Halley's comet after watching Star Wars.
Hey, it's there, but it ain't the Princess.


						Michael Halle
						Spatial Imaging Group
						MIT Media Lab
						mhalle@media.mit.edu
From: hnr@ecs.soton.ac.uk (Harvey Rutt)
Newsgroups: sci.optics
Subject: Re: Laser Range Finding
Date: 17 Dec 92 17:47:40 GMT

The ultrasonic kind are widely used by estate agents (=realtors in US
speak??!!) here in the UK.
Harvey Rutt Southampton UK

Newsgroups: sci.optics
From: a722756@roper.mc.ti.com (W. Donald Rolph)
Subject: Re: holography?
Originator: a722756@roper.mc.ti.com
Organization: Texas Instruments / Attleboro Mass / USA
Date: Fri, 18 Dec 1992 23:02:22 GMT


Nicely done explanation!
-- 

Regards.
 
Don Rolph  a722756@pan.mc.ti.com WD3 MS10-13 (508)-699-1263
Xref: sparky sci.optics:1310 comp.graphics:12984
From: halazar@media.mit.edu (Michael Halle)
Newsgroups: sci.optics,comp.graphics
Subject: Re: Output for computer generated holography
Date: 17 Dec 92 04:35:53 GMT
Article-I.D.: media-la.HALAZAR.92Dec16233553
	<ByMC7M.2AA@news.cso.uiuc.edu>
	<1992Dec3.194326.20668@bert.eecs.uic.edu>
Organization: M.I.T. Media Laboratory


> sizes up to 30"x30".  PHSColograms are made by an entirely digital process,
> unlike computer generated holograms, which are optically encoded.  The

What sort of recording technology could you possibly use that is "entirely
digital"?  The world is pretty analog.  How do you get to film if you don't
ever go optical or mechanical?  

At any rate, I would suspect that someone attempting to make computer
generated holograms on their CRT would probably be out of the market
for a > $7500 custom parallax barrier display, perfect images and
commercial plugs aside.

						Michael Halle
						Spatial Imaging Group
						MIT Media Lab
						mhalle@media.mit.edu



"inventors of the Stealth Positive KILogram, the medicine you
unknowingly take with diet pills that puts the weight back on"
Newsgroups: sci.optics
From: yjj@rhea.ctr.columbia.edu (Yuan Jiang)
Subject: Re: Imaging 880 nm?
Organization: Columbia University Center for Telecommunications Research
Date: Sat, 12 Dec 1992 23:43:46 GMT
X-Posted-From: rhea.ctr.columbia.edu
NNTP-Posting-Host: sol.ctr.columbia.edu

In article <1992Dec12.224020.29626@ugle.unit.no> nareid@due.unit.no (Helge Nareid) writes:
>In article <1992Dec11.162138.26060@lmpsbbs.comm.mot.com> Ben Burch <Burch_Ben@wes.mot.com> writes:
>>Hello!  I'm helping with an IR remote control type device that uses an IR
>>LED
>>with a centerline wavelength of 880 nm.  We are trying to figure out if
>>we can
>>image the footprint in some way.  We looked at an industrial IR imager
>>earlier,
>>but that cuts out at 3300 nm.  Will Kodak IR film record this frequency? 

I don't understand why an imager which has long wavelength cutoff at
3300nm>880nm does not work for you.

Try the cheapest one, a regular camcorder with cutoff at ~1000nm.

Newsgroups: sci.optics
From: Kwok Chi Wing <chiwingkwok@cuhk.hk>
Subject: Re: More HeNe/Argon lasers for sell
X-Xxmessage-Id: <A7513D0FBA020798@maca02.csc.cuhk.hk>
X-Xxdate: Sun, 13 Dec 92 18:18:39 GMT
Organization: The Chinese University of Hong Kong
X-Useragent: Nuntius v1.1.1d9
Date: Sun, 13 Dec 1992 13:14:31 GMT

>Path:
hp9000.csc.cuhk.hk!saimiri.primate.wisc.edu!zaphod.mps.ohio-state.edu!wupo
>st!kuhub.cc.ukans.edu!wellison
>From: wellison@kuhub.cc.ukans.edu
>Newsgroups: sci.optics
>Subject: More HeNe/Argon lasers for sell
>Message-ID: <1992Dec8.090324.45488@kuhub.cc.ukans.edu>
>Date: 8 Dec 92 09:03:23 CST
>Organization: University of Kansas Academic Computing Services
>Lines: 16


What is the shipping for Hong Kong ?
From: bercov@bevsun.bev.lbl.gov (John Bercovitz)
Newsgroups: sci.optics
Subject: Re: Address of R. Kingslake
Date: 12 Dec 1992 03:18:48 GMT
Organization: Lawrence Berkeley Laboratory, California
Distribution: usa
NNTP-Posting-Host: 131.243.192.10

In article <1992Dec11.215109.13508@athena.cs.uga.edu> mcovingt@aisun3.ai.uga.edu (Michael Covington) writes:
>Does anybody know if the eminent lens designer Rudolf Kingslake
>(retired from Kodak, now almost 90 years old) is still active and,
>if so, how I can contact him?

The back cover of his latest book says he is currently Emeritus Professor
of the University of Rochester.  Might try there.

John Bercovitz

Newsgroups: sci.optics
From: mcovingt@aisun3.ai.uga.edu (Michael Covington)
Subject: Re: Need source for Olympus and Nikon microscopes
Organization: AI Programs, University of Georgia, Athens
Distribution: usa
Date: Fri, 11 Dec 1992 21:48:58 GMT

Contact a hospital lab near you.  They will know about the nearby
microscope repair places (many of which deal in used microscopes) and
will also let you know if they are selling off any older ones.

-- 
:-  Michael A. Covington     internet mcovingt@uga.cc.uga.edu :   Verbum caro
:-  Artificial Intelligence Programs       phone 706 542-0358 :    factum est
:-  The University of Georgia                fax 706 542-0349 :  et habitavit
:-  Athens, Georgia 30602-7415 U.S.A.     amateur radio N4TMI :   in nobis...
Newsgroups: sci.optics