coloremeter

Archiver

Hi,
I am trying to read a filter strip for color. The paper strip is 2
cm long and 5 mm wide it has different bands of colors (paper
Chromatography). I want to use either a CdS photocell or a
phototransistor. The possibilities are:

1.) Send white light through the paper strip and record measurements.
2.) Reflect white light and record using a phototransistor.

Any ideas?
Thanks for your help!!

Curtis Desselles

Archiver

In a message dated 2/28/02 6:38:57 PM Central Standard Time,
cenlasoft@y... writes:


> 1.) Send white light through the paper strip and record measurements.
> 2.) Reflect white light and record using a phototransistor.
>
> Any ideas?
>

Rotate a set of gel filters (red, green, blue or cyan, magenta, yellow)
between your source and your phototransistor before taking the reading.

-- Jon


[noparse][[/noparse]Non-text portions of this message have been removed]

Archiver

At 12:38 AM 3/1/2002 +0000, you wrote:
>Hi,
>I am trying to read a filter strip for color. The paper strip is 2
>cm long and 5 mm wide it has different bands of colors (paper
>Chromatography). I want to use either a CdS photocell or a
>phototransistor. The possibilities are:
>
>1.) Send white light through the paper strip and record measurements.
>2.) Reflect white light and record using a phototransistor.
>
>Any ideas?
>Thanks for your help!!
>
>Curtis Desselles
>
>Hi Curtis -
How many colors are involved, or are there infinite variations ?

Bruce

Archiver

Taos makes sensors that should work for you below is their description
the sensors are about $2.50 each but you must buy 10 of each.
http://www.taosinc.com/products.htm#tslx257

TSLx257 (Color)
The TSLB257, TSLG257, and TSLR257 are high-sensitivity low-noise
light-to-voltage optical converters that incorporate onboard
blue, green, and red optical filters, respectively. These devices
combine a photodiode and a transimpedance amplifier on a single
monolithic CMOS integrated circuit with a color filter over the
photodiode. Output voltage is directly proportional to light intensity
(irradiance) on the photodiode. Each device has a transimpedance gain
of 320 Megohm with improved offset voltage stability and low power
consumption, and is supplied in a 3-lead clear plastic sidelooker
package with an integral lens. These devices are ideal for applications
such as colorimetry, printing process control, display color
correction, and selectively ambient light detection or rejection.

Craig