HDTenEightyP/NetNews huggingface dataset:
From: roberts@CMR.NCSL.NIST.GOV (John Roberts)
Newsgroups: sci.space
Subject: Re: Terraforming Mars
Date: 10 Sep 92 04:11:39 GMT
Organization: National Institute of Standards and Technology
	formerly National Bureau of Standards


-From: tomk@netcom.com (Thomas H. Kunich)
-Subject: Re: Is NASA really planning to Terraform Mars?
-Date: 7 Sep 92 23:55:32 GMT
-Organization: Netcom - Online Communication Services  (408 241-9760 guest)

-It is a simple, possibly even elementary, matter to find
-various bacteria, algae, fungi, lichen etc. that can exist
-in the harsh environment of Mars. Or, for that matter, the
-upper reaches of the Venusian atmosphere. These life-forms
-are small, light and quite capable of being transported in
-rather massive quantities to these planets by presently
-possessed technology. 

It's probably harder than you think. The main challenge on Mars is not
necessarily the scarcity of water (though that is a major problem), but 
finding a location where they can get the energy to support life processes
without being killed by the UV in the sunlight or the reducing soil that
destroys organic matter.

-Should there not be appropriate life
-forms, our present knowledge of biotechnology should lead
-us to be able to develop some in fairly short order.

We should think twice before deliberately producing microorganisms that
can survive some of our best sterilization techniques. Remember that in the
realm of microorganisms, "recombinant DNA" isn't something that happens only
with human assistance.

-I suggest that we send a space vessel bearing our life
-substitutes to Mars and Venus. The cost is relatively
-miniscule. Thereon we can sprinkle the makings of man
-himself.

I suggest we make sure we understand the matter thoroughly before we try
anything. This is not a good area for trial and error. (Remember Asimov's
novel "Foundation and Earth".)

John Roberts
roberts@cmr.ncsl.nist.gov
From: keithley@apple.com (Craig Keithley)
Newsgroups: sci.space
Subject: Re: Nasa's Apollo rerun
Date: 14 Sep 92 21:05:05 GMT
Followup-To: sci.space
Distribution: sci
Organization: Apple Computer, Inc.

This talk about revisiting the Apollo style of moon missions reminds me of
some old papers I read about the Apollo program.  Since I don't recall when
(or where) I read them, you'll have to treat this as unsubstantiated.

The gist of the report was that we goofed in our choice of going to the
moon.  During the late 50s and early 60s, we were faced with the choice of
developing things like DynaSoar and MOL (these were Air Force) or going for
the moon shot.  The benefit of the space station route was that we would
have developed the infrastructure for a manned presence in near Earth (and
moon) space.  In retrospect, the problem with the moon shot was that when
all was said and done, we would be left with a few pounds of moon rock, a
fair bit of good science, and little or no infrastructure to support a
manned presence in space.

This isn't to say that I wouldn't support a manned return to the moon using
a non-reusable vehicle, but I'd sure be skeptical about its overall benefit
to the space program.

Perhaps someone could do some back of envelope calculations and determine
how much payload could be delivered to the moon using a translunar vehicle
delivered to LEO via a shuttle mission or two.

Then again, assuming Allen's statements (about using DC-Y as a translunar
vehicle) are correct, I'd strongly consider developing a reusuable DC-Y
rather than a non-reusuable Apollo follow-on.

Allen, whats the max payload DC-Y can put in LEO?  I need dimensions and
weight. 

Craig Keithley
Apple Computer, Inc.
keithley@apple.com
"Progess requires setbacks." - Henry Spencer
Newsgroups: sci.space
From: ruca@pinkie.saber-si.pt (Rui Sousa)
Subject: Food in space
Organization: SABER - Sistemas de Informacao, Lda.
Distribution: sci.space
Date: Mon, 14 Sep 1992 14:24:11 GMT

Anyone can tell me addresses or references on nutricional issues in space?
I.e. what do astronauts eat nowadays while in orbit and what studies are being conducted on this subject.

Thanks (i surely hope this is not a FAQ...)

Rui
-- 
*** Infinity is at hand!                               Rui Sousa
*** If yours is big enough, grab it!                   ruca@saber-si.pt

                All opinions expressed here are strictly my own
Newsgroups: sci.optics
From: toto@fwi.uva.nl (Toto van Inge)
Subject: Question about splitting an image by fibre bundle
Keywords: Imaging, sub-images, fiber-bundles
Organization: FWI, University of Amsterdam
Date: Tue, 15 Sep 1992 16:02:58 GMT

I am looking for papers, articles, or whatever info on the
splitting of an image into sub-images by using a fibre-bundle.
So, having one lens, how do I get sub-images to 2 or more
CCD chips.

Thanking you in advance.           Toto.

-- 
Anthony van Inge Phone: +31 20 525 7533/fax:7490 
EMAIL:           toto@fwi.uva.nl
SNAIL:           Dept. of Math. and Computing Science, University of Amsterdam,
                 Kruislaan 403, 1098 SJ  Amsterdam, The Netherlands
From: jdevries@apple.com (Jeff DeVries)
Newsgroups: sci.optics
Subject: Possible reference on Computer-Generated Holograms...
Date: 9 Sep 92 00:34:00 GMT
Organization: Apple Computer Inc, Cupertino, CA

I noticed a few queries in this group concerning computer-generated holograms.
I was reading the August/September issue of Circuit Cellar Ink when I saw
(on page 91) an advertisement for a book titled "The Circuit Cellar Project
File, Volume 1" and one of the projects was Computer Generated Holograms.

Since I haven't actually seen the book, I don't know how useful it would be.
Based on other Circuit Cellar projects, the article is probably more of a
practical nature, rather than a theoretical one.

For those who may be interested, the ordering information is:

  "The Circuit Cellar Project File, Volume 1"
  Circuit Cellar
  4 Park Street
  Vernon, CT  06066
  (203) 875-2199 (phone)
  (203) 872-2204 (fax)
  Price: $17.95 w/shipping

[I have no affiliation with Circuit Cellar whatsoever!]

Jeff DeVries
jdevries@apple.com
Newsgroups: sci.optics
From: swami@sauron.eece.unm.edu (Swami srinivasan)
Subject: Re: Diode Laser Holograms...
Date: Fri, 11 Sep 92 22:19:06 GMT
Organization: University of New Mexico, Albuquerque


	As Don pointed out, 50 cm is probably difficult to achieve 
with the inexpensive types  of diode lasers.

	A typical high-power broad area laser has a spectral width 
of over 1 nm, i.e, a few hundred GHz @ 650nm. If my calculation is 
correct, this leads to a coherence length of less than a millimeter. 
Even a single-longitudinal (and spatial mode) narow-stripe laser will
not be useful, as the spectrum won't be narrow enough..

To classify a laser as useful for Holography, with a minimum coherence 
length of 10 cm, say, we need a linewidth of < 3 GHz, and it better
be in the visible.

	DFB and DBR lasers may have the spectral purity to be used for
holography, but cost upwards of $5K or so. Besides, most of these
are in the 1.3 - 1.6 micron range, not useful for visible-light 
holography.

	So unless someone makes DFB/DBR lasers en masse  in the 
visible (red lasers between 610 and 680 nm, most likely), I don't see
diode lasers being used for Holography directly.

	However, diode-pumped doubled Nd:YAG lasers are useful in this
respect. There was an exhibit at CLEO'92 with such a green laser with
a compact external cavity, with a linewidth of a few 10s of kHz. This
had an output in the green of over 50 mW, and would have been ideal for
holography if only the price was lower. It cost $30 K ! The system was
very compact, measuring about 8"x6"x4" or so, besides a smaller power
supply for the diode laser. 

	Diode lasers help miniaturize such solid-state laser systems, and
something like the one described above might cost much less a couple
of years from now...

		 However, we are far from being able to use diode
lasers directly for holography. There are things these wonderful devices
can't do at present. Who knows what the future has in store!


							swami srinivasan

========================================================================
swaminathan srinivasan
center for high tech materials
eece, university of new mexico,
albuquerque, nm 87131			swami@chtm.eece.unm.edu 
=======================================================================
Newsgroups: sci.optics
From: mcwhirtj@unvax.union.edu (Jim Mcwhirter)
Subject: Re: Slide projectors can too produce collimated light!
Organization: Union College, Schenectady, NY
Date: Thu, 10 Sep 1992 17:59:08 GMT

An interesting point is that, although you can increase the transverse
coherence length of a broad-band thermal source by illuminating
a pin-hole, the longitudinal coherence length, and hence the ability
to collimate, will still be limited by the fact that the source is
poly-chromatic.  Further, if you were to monochromate the source 
using a filter or grating, combined with the pin-hole trick,
the resulting light, although possesing large transverse and 
longitudnal coherence lengths, would NOT be "laser" light.  The
photon statistics would still be that of a thermal source, not
of a coherent source.  

This property can only be measured by performing experiments that
meaure second order correlations of the photon field (youngs double
slit and the Michelson interferometer being the first order
correlation measurements for transverse and longitudial coherence,
respectively).  The Hanbury Brown and Twiss experiment is a 2nd order
correlation type experiment.

Jim McWhirter
Physics Dept.
Union College
Schenectady, NY
mcwhirtj@unvax.union.edu


Newsgroups: sci.optics,misc.forsale
From: abc@banjo.concert.net (Alan B Clegg)
Subject: For-Sale -- 2 watt Ion Laser
Summary: laser forsale high-output best-offer $300
Organization: Concert Network -- Internet Operations Group
Date: Thu, 10 Sep 1992 20:37:27 GMT

For-Sale -- Coherent Radiation Model 54 Ion Laser.

		Rated at 2 watts output.

		Don't have power supply or coolant pump.

		Tube in (seemingly) good condition
			 -- no way to test (see above)

		No internal damage apparent.

	Asking $300/obo with $100 minimum.

-abc
-- 
abc@concert.net				Alan Clegg - Network Programmer
KD4JML                               	MCNC -- Center for Communications
   CREDIMUS IN EXISTIMATIONEM INCOMPTAM ET TABULAS MANDATORUM CURRENTES
         I'm contaminated by BSDi source code, how about you?
Newsgroups: sci.optics
From: palmer@sfu.ca (Leigh Palmer)
Subject: Re: QUESTION ?
Organization: Simon Fraser University
Date: Wed, 16 Sep 1992 00:40:59 GMT

In article <Sep.15.19.46.46.1992.4823@andromeda.rutgers.edu>
murtza@andromeda.rutgers.edu (SANDMAN) writes:

>I was just wondering last night that if anti-noise technology can be used 
>to decrease noise can't anti-light be produced as light is also thought 
>to have wave characteristics ?

Well, yes, I suppose, in principle. But if you have to put up light producers
to generate antiphase wavefronts at the positions of the light wavefronts you
will occult the sky there anyway. Wouldn't a piece of cardbord (which stops the
light) be a simpler remedy? If you're thinking of this for astronomical
purposes, how would your system discriminate between noise and signal?

Leigh Palmer
Newsgroups: sci.optics
From: mcdonald@aries.scs.uiuc.edu (J. D. McDonald)
Subject: Re: slide projectors cannot produce collimated light
Organization: UIUC SCS
Date: Mon, 7 Sep 1992 14:46:57 GMT
Keywords: projectors, collimated light

In article <1992Sep6.220529.15423@husc3.harvard.edu> habersch@husc9.harvard.edu (Oren Haber-Schaim) writes:


>     In article <1992Sep4.205510.22755@athena.mit.edu> wtsang@athena.mit.edu
>     (Pui Ho Wilson Tsang) writes: 
>     >The title says it all.  Thanks.


>The responding title says it all too.  You're welcome.

Phooey.

Put a pinhole where the film goes and focus. Voila, collimated light.

Doug McDonald
Newsgroups: sci.optics
From:  fisun@ifftr.msk.su (Oleg Fisun)
Subject: Help: Programs for Computer Generated Holograms
Date: Mon, 31 Aug 1992 19:54:43 GMT
Reply-To: fisun@ifftr.msk.su
Organization: Institute of Physics & Technology


Dear Colleagues,

Would someone please tell me where I can get the programs
for designing of computer generated holograms (CGH) and,
in particular, those that use the binary cell-oriented,
pixel-oriented and fringe-oriented encodings.
I use IBM-compatible mashine (IBM 386) working under DOS.

Thanks in advance,

Oleg Fisun
Institute of Physics & Technology,
Prechistenka str. 13/7,
119034 Moscow, Russia.
Internet: fisun@ifftr.msk.su

Newsgroups: sci.optics
From: palmer@sfu.ca (Leigh Palmer)
Subject: Re: Diode Laser Holograms ?
Organization: Simon Fraser University
Date: Sat, 12 Sep 1992 00:16:33 GMT

In article <1992Sep11.182819.1658@gnv.ifas.ufl.edu> jrm@gnv.ifas.ufl.edu (Jim
Mason) writes:

>        One question about the relevance of coherence length. I seem
>        to recall that crude holograms had been made well prior to
>        the invention of the laser - normally using one of the lines
>        from a mercury arc. While the quality wasn't good, they still
>        got a hologram. So, MUST holograms be made with coherent 
>        light or will well-collimated monochromatic light do ? I admit
>        my memory on this may be defective. Perhaps they ran the
>        light thru a long optical path replete with lots of pinholes
>        to try and isolate just a speck of 'good' light ?

Gabor made his holograms before the invention of the laser with, as you
surmise, mercury light. His subjects were thin, virtually two-dimensional.
They were not crude; they were the best that had ever been made, and Gabor
received a Nobel Prize in recognition of their magnificence. That was only
after Lieth had made much better ones, of course! :<)

Leigh
From: mw4j+@andrew.cmu.edu (Mark Weinstock)
Newsgroups: sci.optics
Subject: Re: slide projectors cannot produce collimated light
Date: 7 Sep 92 09:22:36 GMT
Article-I.D.: andrew.QeeszQe00WBNQ2NXw_
	<mcdonald.284@aries.scs.uiuc.edu>
Organization: Carnegie Mellon, Pittsburgh, PA

On 07-Sep-92 in Re: slide projectors cannot..
user J. D. McDonald@aries.scs writes:
>In article <1992Sep6.220529.15423@husc3.harvard.edu>
habersch@husc9.harvard.edu
> (Oren Haber-Schaim) writes:
> 
> 
>>     In article <1992Sep4.205510.22755@athena.mit.edu> wtsang@athena.mit.edu
>>     (Pui Ho Wilson Tsang) writes: 
>>     >The title says it all.  Thanks.
> 
> 
>>The responding title says it all too.  You're welcome.
> 
>Phooey.
> 
>Put a pinhole where the film goes and focus. Voila, collimated light.
> 
>Doug McDonald
> 

Yeah, but you can't focus a slide porojector's lens at infinity, which
you would need to do to get collimated light. That's the whole point of
a projector - to project an image onto a new focal plane.

Although there is sure to be a way to modify the projector lens
transport to allow it to move to the proper position, without
modification it won't work.

-Mark W.
From: jrm@gnv.ifas.ufl.edu
Newsgroups: sci.optics
Subject: Diode Laser Holograms ? 
Date: 9 Sep 92 18:59:40 -0500

OK now, I have heard conflicting reports from dubious sources, so can
anyone here answer me one question --- ARE DIODE LASERS SUITABLE FOR
MAKING HOLOGRAMS ? If not, why not ? If so, are any special specs or
techniques required ? As the price of high-powered diode lasers comes
down rapidly, it would sure be nice to be able to use them for this
purpose. Already we get a 10:1 power/price advantage over gas lasers
in the 2-30 mw zone. 

One other question ... does anyone know a source for *affordable*
fresnel lenses with negative FLs ? I'm looking for the kind done
in hard plastic, not those PVC window-stickups. Edmund only seems
to sell posivive FL lenses in the hard plastic.

-- Jim Mason
Xref: sparky sci.optics:974 sci.physics.fusion:2155 sci.physics:14693 sci.research:1098 sci.space:12961
From: jcs@phy.duke.edu (John C. Swartz)
Newsgroups: sci.optics
Subject: Need phone number of  Jaeger optics
Date: 4 Sep 92 21:30:44 GMT
Article-I.D.: news.5130
Distribution: usa

Folks,
Jaeger was mentioned a couple of ago as being in business again.
 If anyone has Jaeger's phone number, I would much appreciate a repost
or reply. Thanks in advance.

--
* John C. Swartz			Duke University
* jcs@phy.duke.edu  <= primary email	Dept. of Electrical Engineering
* jcs@egr.duke.edu  <= secondary email	Physics Bldg. Rm 160  (Lab, Rm. 161)  
* Tel: 919-660-2518 (office)		Duke University
*      660-2519 (lab) 660-2525(FAX)	Durham, NC USA      27708-0309
From: swami@chtm.eece.unm.edu (Swami srinivasan)
Newsgroups: sci.optics
Subject: Re: Slide projectors can too produce collimated light!
Date: 8 Sep 92 21:45:44 GMT
Organization: University of New Mexico, Albuquerque


 Guess I missed out on the original post, but why are we talking about
getting collimated light from a projector?

Why not use a positive Fresnel lens at an appropriate location to 
collimate the beam? This way there wouldn't be as big a loss of power
as with the use of a pin-hole. Any catches?

BTW, are negative Fresnel lenses available from any supplier? It could
be a little more expensive, due to the lack of demand, but.....


							swami 

======================================================================
swaminathan srinivasan
center for high tech materials
eece, university of new mexico		swami@chtm.eece.unm.edu
albuquerque, nm87131.
======================================================================
From: barron@lsl.co.uk
Newsgroups: sci.optics
Subject: Cheap Laser Diodes (Britain)
Date: 15 Sep 92 15:30:28 GMT
Organization: Laser-Scan Ltd., Cambridge

Hello,
	Does anyone know of a source of cheap laser diodes in Britain?
I've had a look through various electronics catalogues with little
success. Are they viewed as components not to be tinkered with by
the average hobbyist?

		Thanks,
			Barry
Newsgroups: sci.optics
From: coates@newton.physics.uq.oz.au (Tony Coates)
Subject: Re: Diode Laser Holograms ? 
Organization: Physics Dept. The University of Queensland
Date: Thu, 10 Sep 1992 04:04:00 GMT

I think that you will find that diode lasers tend to have a
coherence length of around 30cm or 50cm or the like, which
means that all the path lengths for the holograms would have
to be kept rather short.  Whether this is impossibly short
depends on the specifics of the hologram setup, of course.

						Tony.
_______________________________________________________________________________

Anthony.B.Coates (Tony)
Department of Physics
The University of Queensland  QLD  4072
Australia

Phone: (+617)365 3424           (Physics Departmental Office)
Fax:   (+617)365 1242           (   "         "         "   )
Email: coates@physics.uq.oz.au

"My messages mirror my feelings, but do not reflect University policy."
_______________________________________________________________________________
Newsgroups: sci.optics
From: joelfire@leland.Stanford.EDU ( Firehammer)
Subject: Re: Diode Laser Holograms ? 
Organization: DSG, Stanford University, CA 94305, USA
Date: Thu, 10 Sep 92 23:30:58 GMT

In article <BuCGMp.L0o@bunyip.cc.uq.oz.au> coates@newton.physics.uq.oz.au (Tony Coates) writes:
>I think that you will find that diode lasers tend to have a
>coherence length of around 30cm or 50cm or the like, which
>means that all the path lengths for the holograms would have
>to be kept rather short.  Whether this is impossibly short
>depends on the specifics of the hologram setup, of course.
>
A rule of thumb that I've always used in making holograms is to
keep your path length difference between your obj. and ref. beams
well within the coherence length.  What this usually meant was that
your resolvable object depth was limited by the coherence length.
The total path lengths were always much longer than the coherence length.

-joel
From: dinsdale@chtm.eece.unm.edu (Don McDaniel)
Newsgroups: sci.optics
Subject: Re: Diode Laser Holograms ?
Date: 11 Sep 92 16:11:30 GMT
Organization: University of New Mexico, Albuquerque

In article <1992Sep10.190056.1651@gnv.ifas.ufl.edu> jrm@gnv.ifas.ufl.edu writes:
>In article <BuCGMp.L0o@bunyip.cc.uq.oz.au>, coates@newton.physics.uq.oz.au (Tony Coates) writes:
>> I think that you will find that diode lasers tend to have a
>> coherence length of around 30cm or 50cm or the like, which
>> means that all the path lengths for the holograms would have
>> to be kept rather short.  Whether this is impossibly short
>> depends on the specifics of the hologram setup, of course.
>> 
>> 						Tony.
>
>	Thanks for this info. A 50cm coherent length need not be
>	fatal - just have to keep the whole setup small (which
>	may translate into cheap & convenient). My interest is
>	mostly recreational at the moment anyway. For such a
>	purpose though, the cost of a nice bright gas laser is
>	a great deterent. I did a few holos while in college and
>	learned right away that a dim source = long exposure times 
>	= vibration problems. The diode lasers offered hope of
>	getting a bright source w/o the financial pain - oh well,
>	as they say, you can't always get what you want.
>
>-- Jim Mason 
>
I think you'll find a further problem (beyond coherence length) in
trying to use a diode laser.  Unless you get your hands on a vertical
cavity laser (they're not very powerful yet), the severe astigmatism
of the output will make collimation of the beam difficult.

The best way to get a reasonable beam is by using an anamorphic prism
pair to correct the astigmatism.  Good ones are quite expensive which
will add substantially to the system cost.  The cheap and easy way
is to use a pinhole to spatially filter the beam.  Unfortunately, this
approach will rob you of much of the output.

Finally, I think the estimate of 30-50 cm coherence length is a bit
generous for many devices, particularly the higher power ones which
tend to have somewhat broader linewidth's (than quarter-wave-shifted
DFB lasers).  As mentioned, it's only the difference in optical path
lengths that must be within the coherence length, not the total
path lengths. Still, I think this will couse some problem.




--
_________________________________________________________________
Don McDaniel                           dinsdale@chtm.eece.unm.edu
Center for High Technology Materials
University of New Mexico