Re: Can Lasers Be Used To Detect Color of Objects?

I guess the simple, quick answer is "Yes" - lasers can be used for detecting colors. The various colors correspond to various wavelengths of light:

Lasers come from the acronym, Light Amplification through Stimulated Emission of Radiation. Most lasers generate light with a very narrow range of wavelengths - even narrower than the range of light emitting diodes (LED's):

This web page discusses various types of lasers, and the wavelengths of light that each laser can output:

Laser Classification

In that web page, you can find that dye lasers can be tunable, so they can cover a wider range of wavelengths of light, as illustrated below with an image from that web page:

So, yes, lasers can be used to emit only certain colors of light - and the intensity of the light reflected back will depend on the color of the object - a black object will reflect back no colors, a red object will reflect some wavelengths of light in the range of about 650 to 750 nm (nanometers, or billionths of a meter). The tunable dye laser could be tuned to various wavelengths of light, and the intensity of the light reflected from the object could be compared to the intensity of the light emitted from the laser, so that the color of the object could be determined in pretty fair detail.

I'm not certain that this approach would be more efficient or give any greater insight than simply shining white light on the object, and then putting the reflected light through a prism or grating to get the spectrum of reflected light. There might be some advantages. In any case, perhaps this explanation will stimulate some additional ideas of creative ways to use lasers (hmmm - idea stimulation through stimulated emission of radiation? Issers?..oh, well)

[Moderator note: Many substances exhibit flouresence, the emission of light at frequencies other than the frequency they are exposed to. This means that even with a narrow band source of light like a laser, you could get back a complex emission spectrum from your object.]