Can light be filtered using red fabric?

oem7110

If I put a red fabric under the Sun, what can this fabric be filtered in term of light frequency spectrum?
Thanks in advance of any suggestions

Drakkith

Are you asking the spectrum of light that passes through the cloth, reflects off of it, or what?

oem7110

I would like to know the spectrum of light passing through the cloth,
since the Sunlight pass through the red cloth, will the red color of light or infrared be greater increase within the spectrum?
Thanks everyone very much for any suggestions

Vanadium 50

No, a filter can only remove light, never increase it.

johnbbahm

The way I understand your question, The amount of red in the sunlight would be reduced
by passing through a red cloth. A portion of the red spectrum would be reflected, and therefore not transmitted. In Practice, cloth would make a poor filter, as it has all sorts of
irregular surfaces. A true red filter would reflect most of the red leaving the remaining spectrum.

davenn

huh ??
you better reread optics 101 ;)

all my optical filters of various colours that I use in photography PASS the colour of the filter and STOP other colours

Another example... why do you think they use RED filters in front of IR receiver sensors ?
...so that the red end of the spectrum is passed and the rest of the spectrum is filtered out
thereby avoiding false triggering and reduced sensitivity of the IR sensor

Dave

oem7110

I would like to know the reason why IR receiver use IR within spectrum instead of other spectrum, does it have any specific property for IR?
Thanks everyone very much for any suggestions

davenn

sorry I dont really understand your question
care to rephrase ?


Dave

Chronos

If you look through a red filter, everything looks red. Like Dave said, the filter color is the light frequency that is unblocked.

oem7110

I am interested and would like to know more about why use RED filters in front of IR receiver sensors, and the reason to select IR instead of other spectrum on this receiver sensors device.

Does anyone have any suggestions?
Thanks everyone very much for any suggestions

davenn

I gave the answer in post #6

Dave

oem7110

... and the reason to select IR instead of other spectrum on this receiver sensors device.

Thanks everyone very much for any suggestions

davenn

1) cuz its invisible to the naked eye so you dont see the remote control transmitters flashing light all the time.
2) Lighting up an area at nite time for camera survlence (sp?) doesnt flood the area with unwanted light
3) IR is so much easier to filter than light within the visible spectrum

Dave

Drakkith

Infrared light is used for various purposes, including remote controls, night vision, and to observe different things in space that are either blocked in the visible range or don't emit in the visible range. Do you know what the EM spectrum is?

oem7110

If I apply a red filter, are Infrared, Microwave and Radio passed? and are Gramma ray, X-ray, Ultraviolet, Visible filtered out?

Does anyone have any suggestions?

Thanks everyone very much for any suggestions

davenn

I have already clarified visible light is filtered out other than the red end of the spectrum.
Radio wavelengths ... microwave or otherwise and not filtered nor are Xrays or gamma rays
Radio wavelengths ... microwave or otherwise you need a metallic screen --- basically a Faraday shield
You can filter radio/microwave frequencies using a metallic screen where the holes in the screen are
considerably less than a 1/4 wavelength in diameter...... look at the screen on the front of your microwave
oven... the holes are large enough that we can see what's cooking but the 2.4 GHz radio energy cannot pass


the RED filter of the topic IS AN OPTICAL FILTER !!



Dave

Drakkith

This isn't easy to answer, it totally depends on the material. And is your signature set to ask for suggestions every post? It really doesn't make any sense.