consumer telescopes @ 1550 nm

Hi - I'm working on a project to measure atmospheric turbulence using
transmissions from a
1550 nm laser and a receiver built around an off-the-shelf telescope
(like the Meade LX and RCX series). I'm trying to find out, roughly,
what the transmission losses are at this wavelength, and the Meade
technical guys don't seem to answer their telephones.

Does anyone out there have a ball park idea what the losses are for
these telescopes at this
wavelength ?

Thanks
Alan

p.s. I'm trying to build a simpler version of the instrument described
in

http://www.dur.ac.uk/g.d.love/downlo...slodar2005.pdf

al wrote:
Hi - I'm working on a project to measure atmospheric turbulence using
transmissions from a
1550 nm laser and a receiver built around an off-the-shelf telescope
(like the Meade LX and RCX series). I'm trying to find out, roughly,
what the transmission losses are at this wavelength, and the Meade
technical guys don't seem to answer their telephones.

They shouldn't be too bad out to 2000nm and then the glass becomes
opaque.

Subaru aluminised mirror wavelength profile is online at
http://snfactory.in2p3.fr/notes/doc/...mirror_alu.txt

Soda lime glass is at
http://www.valleydesign.com/Soda%20Lime.jpg

Does anyone out there have a ball park idea what the losses are for
these telescopes at this
wavelength ?

I'm guessing 10-20%. Unless there is a longwave IR block coating on the
front element - and only Meade can answer that question. Although some
of the amateur spectrscopists might have measured it if you are lucky.

Regards,
Martin Brown

al wrote:
Hi - I'm working on a project to measure atmospheric turbulence using
transmissions from a
1550 nm laser and a receiver built around an off-the-shelf telescope
(like the Meade LX and RCX series). I'm trying to find out, roughly,
what the transmission losses are at this wavelength, and the Meade
technical guys don't seem to answer their telephones.

Does anyone out there have a ball park idea what the losses are for
these telescopes at this
wavelength ?

Thanks
Alan

p.s. I'm trying to build a simpler version of the instrument described
in

http://www.dur.ac.uk/g.d.love/downlo...slodar2005.pdf

You could always use a Newtonian reflector (which only uses mirrors)
and have the mirrors recoated to reflect your wavelength as efficiently
as possible.

Greg

On 2006-09-08, al wrote:
Hi - I'm working on a project to measure atmospheric turbulence using
transmissions from a
1550 nm laser and a receiver built around an off-the-shelf telescope
(like the Meade LX and RCX series). I'm trying to find out, roughly,
what the transmission losses are at this wavelength, and the Meade
technical guys don't seem to answer their telephones.

Does anyone out there have a ball park idea what the losses are for
these telescopes at this
wavelength ?

The telescopes you mentioned have Al coatings on the mirrors and
glass corrector plates. The mirror may or may not have
additional dielectric coatings to increase reflectivity and the
corector plate will have antireflective coatings to increase
transmissivity in visual wavelengths, which have an effect
unknown to me on the infrared wavelength you want to use.
Aluminum apparently has good reflectivity, about 96%, at 1550
nm. You may want to consider newtonian telescopes instead of
the types you mentioned if a completely enclosed system is not
required. They are available off the shelf and there would be
less cost. Attachments would be to the side instead of at the
rear.

Bud

I have a friend who was working on a similar project at 1064 and he had
a big problem with transmission, I believe the green plate glass
corrector was the primary culprit. Also, spherochromatism becomes a
problem so far from the design wavelength.