PIN photometer 3

[Dominic-Luc Webb]

Had problems with mouse. I hope the link copies this
time. Below is the photometer I am discussing...

http://www.megspace.com/science/stp/pmt/sfh2030f.html


Dominic

 

[John Larkin]

On Sat, 28 Feb 2004 17:57:15 +0100, Dominic-Luc Webb <dlwebb@canit.se>
wrote:

Had problems with mouse. I hope the link copies this
time. Below is the photometer I am discussing...

http://www.megspace.com/science/stp/pmt/sfh2030f.html


Dominic

This can't work:

http://www.megspace.com/science/stp/pmt/detector_preamp.jpg


John

 

[Jamie]

after checking INtels specs on that OPAMp i don't think it
can work because it does not appear to have any internal self
biasing, if the diode was generating energy then i would say
yes it would create a rail-rail output but still not useable.
its my opinion that you need feedback resisters.

Btw.
nice pre'amp to use on Hi-z projects..



Dominic-Luc Webb wrote:

Had problems with mouse. I hope the link copies this
time. Below is the photometer I am discussing...

http://www.megspace.com/science/stp/pmt/sfh2030f.html


Dominic

 

[Dominic-Luc Webb]

Thanks for all responses. I know with a single 0.82 pF cap
as feedback using a single opamp, these work, but I was
hoping to get more gain. Maybe you know some very simple
example circuits to amplify using a second opamp that
would not risk losing linearity?

Also, it seems that input bias current increases with
temperature (from specsheet of LMC662). I wonder if
anyone ever puts these inside a cooling unit to keep
the temp down, and thus, the input bias?

Dominic



On Sun, 29 Feb 2004, Jamie wrote:

after checking INtels specs on that OPAMp i don't think it
can work because it does not appear to have any internal self
biasing, if the diode was generating energy then i would say
yes it would create a rail-rail output but still not useable.
its my opinion that you need feedback resisters.

Btw.
nice pre'amp to use on Hi-z projects..



Dominic-Luc Webb wrote:

Had problems with mouse. I hope the link copies this
time. Below is the photometer I am discussing...

http://www.megspace.com/science/stp/pmt/sfh2030f.html


Dominic

 

[Winfield Hill]

Dominic-Luc Webb wrote...

Had problems with mouse. I hope the link copies this
time. Below is the photometer I am discussing...
http://www.megspace.com/science/stp/pmt/sfh2030f.html

Dominic, the circuit fails to function because it is
*nonsense* and not because of the properties or size
of any of its components. Please study the subject
a bit more, and read up on resistors. Very handy.

Thanks,
- Win

whill_at_picovolt-dot-com

 

[Steve J. Noll]

On Sat, 28 Feb 2004 17:57:15 +0100, Dominic-Luc Webb <dlwebb@canit.se>
wrote:

Had problems with mouse. I hope the link copies this
time. Below is the photometer I am discussing...

http://www.megspace.com/science/stp/pmt/sfh2030f.html


Dominic

Might I recommend "Photodiode Amplifiers: OP AMP Solutions" by Jerald
Graeme. ISBN 007024247X. See info on T-networks for high gain
feedback with smaller resistor values.

Also "Building Electro-Optical Systems: Making It All Work" by Philip
Hobbs (ISBN 0471246816) is a great resource.

Steve J. Noll | Ventura California |
| The Used High-Tech Equipment Dealer Directory
| http://www.big-list.com
| The Peltier Device Information Site:
| http://www.peltier-info.com

 

[Dominic-Luc Webb]

Might I recommend "Photodiode Amplifiers: OP AMP Solutions" by Jerald
Graeme. ISBN 007024247X. See info on T-networks for high gain
feedback with smaller resistor values.

Also "Building Electro-Optical Systems: Making It All Work" by Philip
Hobbs (ISBN 0471246816) is a great resource.

Steve J. Noll | Ventura California |

Thanks for these leads! I just now searched and found both books
from local technical library and also from local mail order business.
In case these books do not cover this (most do not), do you know if
dark current can be reduced significantly in a PIN? Can they survive
and operate with nitrogen cooling? I am thinking to place the PIN
inside an aluminum housing and to have cooling lines for nitrogen
running through the aluminum block. Any ideas?

Again, application is measurement of red/infrared from faint stars from a
telescope.

Dominic

 

[Steve J. Noll]

On Thu, 4 Mar 2004 12:30:39 +0100, Dominic-Luc Webb <dlwebb@canit.se>
wrote:

Might I recommend "Photodiode Amplifiers: OP AMP Solutions" by Jerald
Graeme. ISBN 007024247X. See info on T-networks for high gain
feedback with smaller resistor values.

Also "Building Electro-Optical Systems: Making It All Work" by Philip
Hobbs (ISBN 0471246816) is a great resource.

Steve J. Noll | Ventura California |



Thanks for these leads! I just now searched and found both books
from local technical library and also from local mail order business.
In case these books do not cover this (most do not), do you know if
dark current can be reduced significantly in a PIN?

Choose the smallest active area that will still capture all of your
signal. Sort several detectors for lowest dark current.
But, I think if noise is your concern that other noise sources, like
the transimpedance amp feedback network, might be a bigger concern.
Others on this forum may be more qualified to comment on this.

Can they survive
and operate with nitrogen cooling? I am thinking to place the PIN
inside an aluminum housing and to have cooling lines for nitrogen
running through the aluminum block. Any ideas?

I'm almost certain that they will operate fine that cold. Mechanical
damage from too fast thermal shock is probably the only concern.
But this adds the significant problem of forming frost on the detector
housing window, so a lot of dry nitrogen gas flushing would be needed.

I have seen output offsets from high gain transimpedance amps
(>=1G) significantly reduced by flushing the amp housing with dry
nitrogen. Reduced the leakage paths - which were most significant
across the op amp package surface - more than across the feedback
components. It can make a dramatic difference. Painting everything
with red corona dope helps too once the surfaces have been cleaned
and the leakage tested.

Again, application is measurement of red/infrared from faint stars from a
telescope.

Dominic

Steve J. Noll | Ventura California |
| The Used High-Tech Equipment Dealer Directory
| http://www.big-list.com
| The Peltier Device Information Site:
| http://www.peltier-info.com