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Bob May
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 Posted: Mon Oct 13, 2008 5:03 am Post subject: Re: Gas sensor |
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Retransmission of power kind of depends upon the material doing the job.
Most of the processes do it rather rapidly but there are some that will take
a short period of time. A simple check of lighting the material and
checking the response time in a lab enviroment will show you how long it
takes.
I>ll note that with the detecting of the signal, once you have the signal,
you amplify it to where you can play with it, convert it to DC and then
compare that voltage to what is allowed. All simple electronic processes.
--
Bob May
rmay at nethere.com
http: slash /nav.to slash bobmay
http: slash /bobmay dot astronomy.net
<lionelgreenstreet@gmail.com> wrote in message
news:59d88218-e2c0-4f84-a208-3c3e7f34e255@c36g2000prc.googlegroups.com...
Thanks for your answer....
[quote]
What happens in reality (for broadband IR absorption) is that you use two
receivers one with a filter that corresponds to the wavelength region
where
the absorption band is and another that is removed from the absorption
region that acts as your reference signal.
As the light source for both the reference and measurand is the same the
reference signal is used to compensate for any changes in the source
intensity, dirty optics, etc.
If using a laser diode based system then the measurement techniques are a
little bit different.
[/quote]
If i use a laser diode the reference signal isn>t so important,right?
I think that laser diode makes a more
predictable signal....or not?
In general how much time is present between radiation absorption by
gas and radiation re-emission?
Thanks |
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DM
Guest
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| Posted: Mon Oct 13, 2008 1:27 pm Post subject: Re: Gas sensor |
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lionelgreenstreet@gmail.com wrote:
[quote]Thanks for your answer....
What happens in reality (for broadband IR absorption) is that you use two
receivers one with a filter that corresponds to the wavelength region where
the absorption band is and another that is removed from the absorption
region that acts as your reference signal.
As the light source for both the reference and measurand is the same the
reference signal is used to compensate for any changes in the source
intensity, dirty optics, etc.
If using a laser diode based system then the measurement techniques are a
little bit different.
If i use a laser diode the reference signal isn>t so important,right?
I think that laser diode makes a more
predictable signal....or not?
[/quote]
How much money do you have to do this?
If you REALLY want a laser based system to measure methane then I can do it
for you.
A laser based system can present a representation of the complete absorption
line. The laser can be scanned right across the absorption feature so
essentially one end of the scan provides the reference signal level. It
delivers a lot more signal information than a two point reference/signal
absorption measurement.
[quote]In general how much time is present between radiation absorption by
gas and radiation re-emission?
Thanks
[/quote]
You are only measuring the absorption. Re-emission does not come into it.
cheers
David |
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Gerlof Verhees
Guest
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| Posted: Mon Oct 20, 2008 5:54 pm Post subject: Re: Gas sensor |
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DM wrote on 13/10/2008 :
[quote]lionelgreenstreet@gmail.com wrote:
Thanks for your answer....
What happens in reality (for broadband IR absorption) is that you use two
receivers one with a filter that corresponds to the wavelength region
where
the absorption band is and another that is removed from the absorption
region that acts as your reference signal.
As the light source for both the reference and measurand is the same the
reference signal is used to compensate for any changes in the source
intensity, dirty optics, etc.
If using a laser diode based system then the measurement techniques are a
little bit different.
If i use a laser diode the reference signal isn>t so important,right?
I think that laser diode makes a more
predictable signal....or not?
How much money do you have to do this?
If you REALLY want a laser based system to measure methane then I can do it
for you.
A laser based system can present a representation of the complete absorption
line. The laser can be scanned right across the absorption feature so
essentially one end of the scan provides the reference signal level. It
delivers a lot more signal information than a two point reference/signal
absorption measurement.
In general how much time is present between radiation absorption by
gas and radiation re-emission?
Thanks
You are only measuring the absorption. Re-emission does not come into it.
cheers
David
[/quote]
I agree |
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