Color Sensor for Light

[amirahmadian]

Hi everybody.
I need a color light sensor for my project, I mean a circuit or IC that is able to detect the color of the light (And I want to send its output to a microcontroller). I've seen some of the related projects on the internet which use three LEDs (Red,Green,Blue) to radiate light and then measure the reflected light intensity. But actually I think this method is useful for sensing the color of surfaces or objects. But in this case, I need to detect the color of a light source (the received light, but not an object).
Do you have any ideas?

 

[ahsan_i_h]

Hi amirahmadian,
1. You can use TCS230 color sensor IC. or
2. You can use red green and blue filters to cover three photo diodes.

 

[amirahmadian]

thank you ahsan_i_h !
TCS230 is a good IC but unfortunately I'm not able to use it for some reasons (it's not available in my country, price,etc).

You can use red green and blue filters to cover three photo diodes

What are these filters? Can I build them at home? Are they available on the market?

 

[godfreyl]

What are these filters? Can I build them at home?

Yes, you just need small pieces of transparent colored plastic, glass or cellophane.

 

[amirahmadian]

Yes, you just need small pieces of transparent colored plastic, glass or cellophane.

Does transparent colored plastic really filter the light? e.g a red transparent plastic (or glass) blocks blue light and green light? I've tested it ,I put a red transparent plastic on a source of green light, but it doesn't seem to filter the light effeciently, I can see the green light radiating through that red plastic and glowing on near objects. How can I bulid a filter for color using that?

 

[FvM]

Does transparent colored plastic really filter the light? e.g a red transparent plastic (or glass) blocks blue light and green light? I've tested it ,I put a red transparent plastic on a source of green light, but it doesn't seem to filter the light effeciently, I can see the green light radiating through that red plastic and glowing on near objects. How can I bulid a filter for color using that?

"Filter efficiently" is a somehow vague term. Dedicated color sensors like the Taosinc/AMS ICs are using interference filters that can be made with any bandwidth, depending on the production effort (number of layers, processing accuracy). The sensor datsheets reveal that the filters are still far from being perfect. Coloured plastic or glass filters are using dyes and have only limited filter effect. You would need spectrometric measurements to know the exact filter curves.

 

[amirahmadian]

Well, so what is your suggestion if I want to make a sensor (for color of light) without using that dedicated sensors?

 

[FvM]

The dedicated sensors probably turn out as the most economic solution unless you have suitable optical filters in your drawer.

 

[kkdelabaca]

You can check the sensors from Hamamatsu: https://www.hamamatsu.com/jp/en/product/category/3100/4009/index.html

BR,

 

[FvM]

Compared to Taos/AMS, the Hamatsu sensors have really good filters that don't need additional IR blocking. I fear, the price might reflect the better performance.

 

[laiza]

AMS TAOS are good.

 

[reidintransit]

adding more layers of the color filter will improve the filtering. If your source is truly emitting only green light then a filter that blocks green light completely will not show any light through it. but if the source is white(mix of all colors) or an imperfect source then you can get theother colors through the filter.

 

[ngochaigv888]

you can use prism to build a filter.