IR sensor - accuracy/precision

[Manimozhi Baskaran]

I am using an IR sensor to sense the black ice and non black ice
scenarios on the pavements. I find the sensor uses the ambient
temperature to output the object voltage on its output pin. The response
is not quick enough to sense and it detects the source temperature than
the object temperature. Any experience on IR sensors with its object
(ice) temperature Vs ambient temperature and the response time?

Thanks
Mani

 

[Chris]

I am using an IR sensor to sense the black ice and non black ice
scenarios on the pavements. I find the sensor uses the ambient
temperature to output the object voltage on its output pin. The response
is not quick enough to sense and it detects the source temperature than
the object temperature. Any experience on IR sensors with its object
(ice) temperature Vs ambient temperature and the response time?

Thanks
Mani

Hi, Mani. It seems you might have run into a fundamental problem.

I believe research has been done on this for automotive applications
using either thermopiles or silicon sensors which are mounted in a
sealed enclosure with a refractive lens. They claim response time of
better than 0.1 sec. You may have more luck by going this route, and
then using an oven to keep the temperature of the enclosure constant.

If Ed's interpretation of your munged ASCII circuit (last week's post,
to which you did not respond) is correct, you've still got a couple of
spare op amps on your LM324. You might want to use one of those with a
thermistor to control a small resistive heater to maintain constant
temp. Of course, this probably means the 9V battery is out.

If you're actually interested, you also might want to indicate what
you're using for an IR sensor. That's another loose end from your
prior post.

Some of the other regulars on s.e.b. have extensive engineering
experience. If you would describe your problem in some detail, you
might avail yourself of their help. And you might want to download
AACircuit at

www.tech-chat.de

to get good ASCII diagrams you can post on the newsgroups.

Good luck
Chris