OT CDS cell filter
While this specific question is off-topic, the project does include a
stamp...
Can anybody recommend a way to filter a photodiode or CDS cell to respond
only to a specific wavelength of light? I am specifically interested in
the infared (650nm?) wavelengths. Kinda like a band-pass filter, but
with light.
Regards,
Aaron Garber
stamp...
Can anybody recommend a way to filter a photodiode or CDS cell to respond
only to a specific wavelength of light? I am specifically interested in
the infared (650nm?) wavelengths. Kinda like a band-pass filter, but
with light.
Regards,
Aaron Garber
Comments
>While this specific question is off-topic, the project does include a
>stamp...
>
>Can anybody recommend a way to filter a photodiode or CDS cell to respond
>only to a specific wavelength of light? I am specifically interested in
>the infared (650nm?) wavelengths. Kinda like a band-pass filter, but
>with light.
In general, you do this the same way as any other filtering job:
combine a low-pass filter that blocks wavelengths shorter than, say,
640 nm with a high-pass filter that blocks wavelengths longer than,
say, 660 nm. Make sure to evaluate what the shape of the receptor's
spectral response is in the region of interest, too, since if it is
steeply changing in that region it will influence the overall shape
of the passband. "Photodiodes" vary enormously in this respect. If we
know more about what you're trying to do we might be able to
recommend something more specific...
Reg Neale
This is solved by using photography lens filters. You can also get gel film
which is much cheaper and used for darklights and stuff. There is also high
temperature plate glass filters used for floodlights.
Support your local photography shop if it still exists, by asking there.
Failing there, a search on google will probably do the trick.
Regards,
Tony Wells
Original Message
From: "Reginald Neale" <rneale@m...>
To: <basicstamps@yahoogroups.com>
Sent: Wednesday, January 30, 2002 3:52 AM
Subject: Re: [noparse][[/noparse]basicstamps] OT CDS cell filter
> Aaron asked:
>
> >While this specific question is off-topic, the project does include a
> >stamp...
> >
> >Can anybody recommend a way to filter a photodiode or CDS cell to respond
> >only to a specific wavelength of light? I am specifically interested in
> >the infared (650nm?) wavelengths. Kinda like a band-pass filter, but
> >with light.
>
> In general, you do this the same way as any other filtering job:
> combine a low-pass filter that blocks wavelengths shorter than, say,
> 640 nm with a high-pass filter that blocks wavelengths longer than,
> say, 660 nm. Make sure to evaluate what the shape of the receptor's
> spectral response is in the region of interest, too, since if it is
> steeply changing in that region it will influence the overall shape
> of the passband. "Photodiodes" vary enormously in this respect. If we
> know more about what you're trying to do we might be able to
> recommend something more specific...
>
> Reg Neale
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
your best bet.
Clark
agarb@j... wrote:
> While this specific question is off-topic, the project does include a
> stamp...
>
> Can anybody recommend a way to filter a photodiode or CDS cell to respond
> only to a specific wavelength of light? I am specifically interested in
> the infared (650nm?) wavelengths. Kinda like a band-pass filter, but
> with light.
>
> Regards,
> Aaron Garber
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and Body
of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Edmund or a photo supply house. I wouldnt do it with the CDS cell though.
Its sensistivity is a lot like the eye and has little rleative response in
the deep red. stick to a photo diode.
can by phototransistors and other types of sensors made for the
wave length you are looking for.
Original Message
From: "Phillip W Mann" <pwmann@w...>
To: <basicstamps@yahoogroups.com>
Sent: January 30, 2002 5:34 AM
Subject: Re: [noparse][[/noparse]basicstamps] OT CDS cell filter
There are several ways. Easiest is to get some gel color filters
from
Edmund or a photo supply house. I wouldnt do it with the CDS cell
though.
Its sensistivity is a lot like the eye and has little rleative
response in
the deep red. stick to a photo diode.
To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
from the same email address that you subscribed. Text in the
Subject and Body of the message will be ignored.
Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
On Wed, 30 Jan 2002 08:16:02 -0800 "Larry Gaminde" <lgaminde@t...>
writes:
> Are you looking for intensity of IR or just looking for IR you
> can by phototransistors and other types of sensors made for the
> wave length you are looking for.
>
Original Message
> From: "Phillip W Mann" <pwmann@w...>
> To: <basicstamps@yahoogroups.com>
> Sent: January 30, 2002 5:34 AM
> Subject: Re: [noparse][[/noparse]basicstamps] OT CDS cell filter
>
>
>
> There are several ways. Easiest is to get some gel color filters
> from
> Edmund or a photo supply house. I wouldnt do it with the CDS cell
> though.
> Its sensistivity is a lot like the eye and has little rleative
> response in
> the deep red. stick to a photo diode.
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the
> Subject and Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the
> Subject and Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>