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Ambient Light Filter for Infrared (IR) Sensor

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zaidpirwani

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Hi,

I am working on a project that requires IR sensors to detect a line and respond accordingly, I have made the sensor etc, but now want to improve upon it, the one major problem is AMBIENT LIGHT, as the project has to work outside in daylight....

Although the sensor is below the robot and most of the AMBIENT LIGHT is blocked, but I was still wondering if there was any cheap way to block that AMBIENT light and only let the IR pass....

I have searched for it and have found something called COLD MIRROR which does the same thing, I then searched for it and found many OPTICAL COMPANIES selling them, but at very expensive prices.

Here, I have a theory of my own, On all TV sets, I have seen that there is a DARK BROWN PLASTIC, which covers the IR receiver of the TV, I think that it acts as the AMBIENT LIGHT FILTER, does anyone know anything about this.... am I right... I am wrong most of the time, when I think... :p

Help is required, not URGENT, but it is required....

I have searched for LINE FOLLOWERS and many other stuff the past weeks, but this has not been covered anywhere.....

Thanks for any help I may get here in advance, though I will be checking in QUITE OFTEN on this post....

Regards,

Zaid Pirwani
 
I know, in the days of digital cameras this may not be easy, but: **broken link removed**
Buy a roll of slide film, take it to a photo shop, and have it developed (unmounted). Sell the excess to you friends. ;)

Ken
 
Last edited:
I know, in the days of digital cameras this may not be easy, but: **broken link removed**
Buy a roll of slide film, take it to a photo shop, and have it developed (unmounted). Sell the excess to you friends. ;)

Ken

Great idea man.... have looked on it... will be applying this and report back here in a few days....


Thanks Ken.....
 
modulating the iIR radiation is agreat idea it's done normaly at 38 kHz...
 
Sunlight produces plenty of IR.

For any IR detector to work in the presence of sunlight, you have to chop the IR sender at a kHz rate, use a high-gain ac-coupled amplifier at the IR detector, followed by a synchronous ac demodulator to detect the chopping frequency, which is what the TSOP type of IR receiver does. A DC coupled system is doomed...
 
Does the film also block UV light?
I really need a filter to block ambient light but not UV

Welcome to ETO.

I believe you have hijacked a much older thread and have created some confusion in doing that. Do you want to block visible light and allow both UV and IR? Or, do you just want to block visible and allow UV? Or, did you mean IR and type "UV?"

The answers are different for each.

John
 
For any IR detector to work in the presence of sunlight, you have to chop the IR sender at a kHz rate, use a high-gain ac-coupled amplifier at the IR detector, followed by a synchronous ac demodulator to detect the chopping frequency, which is what the TSOP type of IR receiver does. A DC coupled system is doomed...
But when the high continuous IR from the sun saturates the IR detector diode then the system is also doomed...
 
@KMoffett
Don't welding lenses block UV?

John
Right John. That's what happens if I answer posts early in the morning, with too low a coffee to blood ratio.
Ken
 
I knew you knew that. Same problem here with waking up.

Anyway, I hope the second OP will clarify his question. Without that, his question could cover a large part of the light spectrum from <200nm to >25000 nm.

My advice would be to either open a new thread or have a moderator move it. Otherwise, confusion will reign.

John
 
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