[Laser] New RX

[Garnier Yves]

Hi Tim
The two Zeiss tank mirrors are now mounted on a special frame to built two associated receivers for stereo recordings or for correlate the two channels by multiplying one to the other in a ring mixer. 
This rectangular big frame has now to be install to a motorised equatorial mounting and it stays lot of work to do !
The mirrors quality gives less than 1/10 mm² picture from bright stars but the focusing point good position is very critical.
The less offset out of parabola axe gives a very strong astigmatism.
As these mirrors are rectangular and offset type, the good focal point finding had been very difficult !!!
Because the rectangular size, the focusing picture contains four very thin aigrettes.
73 QRO 
Yves F1AVY
http://f1avyopto.wifeo.com


--- En date de : Dim 5.4.09, Tim Toast <toasty256 at yahoo.com> a écrit :

> De: Tim Toast <toasty256 at yahoo.com>
> Objet: Re: [Laser] New RX
> À: "laser mailinglist" <laser at mailman.qth.net>
> Date: Dimanche 5 Avril 2009, 4h31
> hi Yves
> That looks like a good design. I like how you can switch
> between the two modes easily. It's about that time of
> year again when the moon is high in the sky between new moon
> and first quarter phase. It is also near perigee at those
> times. Have you tried out those yet?
> 
> http://www.aladal.net/toast/moon.html
> 
> 
> ```````````````````````
> 
> Hello all.
> You will find at:
> http://sd-1.archive-host.com/membres/images/22679775843705539/UltimateRX6.jpg
> ... my new charge amplifier photodetector for low rate
> optical pulses in astronomy or pulsed laser cloud bounce.
> This receiver uses the Miller capacitance of the 2N4117 FET
> as feedback integrator.
> This device can extract very short and weak pulses from a
> low frequency background (scintillation) if their rate is
> lower about one hundred by second.
> With the second FET fitted in cascode, the response becomes
> linear with a bandwidth better the K3PGP classical schematic
> and can reach over the kilohertz with a very good
> sensitivity.
> The specified FETs types are mandatory and some resistors
> values can be adjusted to centre the static output voltage
> point at PSU/2.
> Of course the cooling (without moisture!) of the first FET
> 2N4117 and the S5973 photodiode improuves again the
> sensitivity.
> 73 Yves F1AVY
> http://f1avyopto.wifeo.com
> 
> 
> 
>       
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