Re: inverting photo detector polarity on a microscope

Posted by Mark Cannell-2 on
URL: http://confocal-microscopy-list.275.s1.nabble.com/inverting-photo-detector-polarity-on-a-microscope-tp7588654p7588664.html

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Why a 2v offset, he said the output is 1->0 V while he wants 0->1. That means at no signal his input is saturated (1v) and goes toward zero...

Mark B. Cannell. Ph.D. FRSNZ FISHR
Department of Physiology, Pharmacology & Neuroscience
School of Medical Sciences
University Walk
Bristol BS8 1TD
 
[hidden email]
 
 

On 6/09/18, 5:43 PM, "Confocal Microscopy List on behalf of Craig Brideau" <[hidden email] on behalf of [hidden email]> wrote:

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    You'd still need to apply a 2V offset then come down from that. By the time
    you splice in the bias offset you might as well have patched in an inverter.
    Craig
   
    On Wed, Sep 5, 2018 at 11:42 PM Mark Cannell <[hidden email]>
    wrote:
   
    > *****
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    > *****
    >
    > You could just record the data as is and invert the image afterwards?
    >
    > Mark B. Cannell. Ph.D. FRSNZ FISHR
    > Department of Physiology, Pharmacology & Neuroscience
    > School of Medical Sciences
    > University Walk
    > Bristol BS8 1TD
    >
    > [hidden email]
    >
    >
    >
    > On 6/09/18, 2:23 AM, "Confocal Microscopy List on behalf of Edward
    > Allgeyer" <[hidden email] on behalf of [hidden email]>
    > wrote:
    >
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    > posting.
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    >
    >     Hi Mike,
    >
    >     I have no commercial interest in either of the things I'm going to
    > mention
    >     but they maybe of interest to you.
    >
    >     First, there is a California based company, Pulse Research Lab, that
    > sells
    >     a selection of high speed off the shelf comparators/sine wave
    > converters
    >     that I've had success with for similar purposes. Their comparators are
    >     fairly forgiving with what you connect as the input and you have a
    > number
    >     of options for the corresponding output. You can browse their selection
    >     here:
    >
    >
    > https://www.pulseresearchlab.com/collections/comparators-sinewave-converters-1
    >
    >     I'll also mention that on their comparators they have preset
    > thresholds but
    >     you can also set an arbitrary threshold by applying a DC voltage to the
    >     complementary input if you want to.
    >
    >     Second, Picoquant also sells a few inverters and adaptors that might
    > work
    >     for you. Specifically the SI100 is a passive inline pulse inverter and
    >     might work for your application. You can browse their adapters,
    > splitters
    >     and cables here:
    >
    >
    > https://www.picoquant.com/products/category/accessories/adapters-splitters-cables-various-accessories-for-photon-counting-setups
    >
    >     Hopefully this helps. Again, no commercial interest in either of these
    >     companies. Just thought I'd mention them as possible options.
    >
    >     Best,
    >     Ed
    >
    >     On Wed, Sep 5, 2018 at 12:58 PM Michael Giacomelli <[hidden email]>
    > wrote:
    >
    >     > *****
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    > posting.
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    >     >
    >     > Hi,
    >     >
    >     > I would like to test out a new detector module in a commerical
    > Olympus
    >     > confocal body.  Unfortunately, the detector uses an inverting
    > amplifier
    >     > (0->-1 V), while the Olympus assumes a non-inverting transimpedance
    >     > amplifier (0->+1 V).  I've spoken with them and there is no way to
    > change
    >     > the A/D configuration on this specific model, and so I cannot use the
    >     > detector as is.
    >     >
    >     > Is there a commerical solution available for adapting something like
    > this?
    >     > I would like to avoid having to design and breadboard an inverting
    > buffer
    >     > amplifier if I can avoid it.
    >     >
    >     > Thanks,
    >     > Mike
    >     >
    >
    >
    >