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I work with all kind of telecommunication lasers many years
@1550 no any diode laser with power more than 30-40 mW
it is technically impossible to get more with reasonable life time
You need laser based on erbium doped fiber.
Number of firms produce such kind of lasers, but take in account
cost will be 20k$ or more
I'm find that SONABEAM's free space communicator use 4x160mW 1550nm VCSEL diodes and cost about 10k$.
That's mean one diode with 160mW power can't cost more than 1500$.
It's too much for me, I need some diode about 500$.
You talk about 1550nm laser
as far as I know most of InGaAs diode lasers
intended for fiber telecommunication use.
I never seen 1550nm laser for free space communication, sorry.
1550nm is transparency window for fiber, but not for air
so it seems very strange to use it.
In all case, try to describe your project,
and may be I'll can help you really.
I work some years for JDSU laser division, one of
biggest diode laser vendors in the word, so I familiar with
diode lasers more or less.
I build low budget project with full price about 1000$ per one device like this : hxxp://www.fsona.com/product.php?sec=155m
And 500$ for laser diode is too much for me, I'm very very bad with money.
I'm find some laser diodes on 780, 875 and 1020nm for about 50-150$ with power about 50-150mW. This is so much money too, but I except that one day will be back.
I try to find some laser diodes on 1550nm for small difference in prices (about 200$ for one 100mW diode will be excellent price on this wavelength for me).
Any laser more than 20-30 mW dangerous for eye !
And more than 60-70 mW even for skin .
So in all case you must work very carefully, no any reflective objects on working table etc. It is serious ! I know number of peoples that lost their eye thanks to accidental reflection.
As far as I know - to buy 2-3 lasers will not a problem,
nobody not buy at once 1000 witout sample testing !
If you need not more than 150-200 mW of power @0.8 range
real price will be 30-150 $ mostly depend of packaging.
Unpackaged sandwich (only laser between 2 copper heatsinks) = 30-50$
but you'll need active cooling, I meen termoelectrical cooling with appropriate thermal capacity ( Melcor for example, approx. 20-30 buks) and some electronics for driving of course. As a rule uncollimated laser
light is unusable, beam profile for diode laser is cone with 3-5 degree
@ top, and try to calculate what your reciever will get after 200-300m !
A few nanowatts (if not pico-!). So for real working open space communication line you'll need 2 telescopes (collimators) for laser and for reciever with max. achievable aperture... and lenses with 15-20 sm
diameter will be, I think, most expensive part of project.
Also you will need narrowband optical filter for your reciever
to avoid sunlight that have enough power @0.8 mkm, it's price 10-15$
but it hard to get, becouse most of filters is customize devices so
as a rule it is not "on shelf" product.
I not meen that such project is unreal, I try to show you possible buttlenecks! :roll:
I think that laser ray can be reflect from wall (no need mirror or glass) and will be dangerous. What minimal safety power or do you know coefficient of reflection in this case?
You are in right for narrowband optical filter, where you find this price(10-15$)?
The best way (and simplest) for laser safety is to fix laser on the
table and build "trap" for laser beam from bricks, ceramic plates
or tube (best !)
or something like, that cann't fire and have diffusive reflection.
By the way I think that reflection from walls is not actually dangerous
thanks to high beam expansion and diffusive reflection
of standart wall coating, but let's not check this clame :roll:
For the first experiments you can use optical filter from any
old VCR with IR remote control it is not best solution, but better
than nothing. Collimator could be build with plastic lenses
that much cheaper, but for 0.8mkm will be well enough.
For example relatively big plastic magnifier glass for reading
will cost about nothing.