Re: inverting photo detector polarity on a microscope

Posted by Craig Brideau on
URL: http://confocal-microscopy-list.275.s1.nabble.com/inverting-photo-detector-polarity-on-a-microscope-tp7588654p7588665.html

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
Post images on http://www.imgur.com and include the link in your posting.
*****

Yes, typo on my part, should be 1V bias. Looks like he found an inverting
amp out of the boards I suggested which can be set to a gain of -1, which
will avoid the need for any biasing anyway, except perhaps a small offset
to nullify any dark signal. A nice feature of many of these boards is they
usually come pre-loaded with components, but the offset/bias and gain
resistors are replaceable, or even actually potentiometers to allow for
easy adjustment for the users' conditions.

Craig

On Thu, Sep 6, 2018 at 2:53 PM Mark Cannell <[hidden email]>
wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> Post images on http://www.imgur.com and include the link in your posting.
> *****
>
> 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:
>
>     *****
>     To join, leave or search the confocal microscopy listserv, go to:
>     http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>     Post images on http://www.imgur.com and include the link in your
> posting.
>     *****
>
>     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:
>
>     > *****
>     > To join, leave or search the confocal microscopy listserv, go to:
>     > http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>     > Post images on http://www.imgur.com and include the link in your
> posting.
>     > *****
>     >
>     > 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:
>     >
>     >     *****
>     >     To join, leave or search the confocal microscopy listserv, go to:
>     >     http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>     >     Post images on http://www.imgur.com and include the link in your
>     > posting.
>     >     *****
>     >
>     >     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:
>     >
>     >     > *****
>     >     > To join, leave or search the confocal microscopy listserv, go
> to:
>     >     > http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>     >     > Post images on http://www.imgur.com and include the link in
> your
>     > posting.
>     >     > *****
>     >     >
>     >     > 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
>     >     >
>     >
>     >
>     >
>
>
>