Re: Is pink light a different wavelength than red light?

Greetings:

The specification of the mixture of colors in white light has been standardized since 1931 by the Standard CIE Chromaticity Diagram. This diagram is used as the legal definition for color mixtures in contracts, litigation, manufacturing etc. A replica of the CIE diagram can be found in an excellent book on Visualization the Web from York University in the Color Specification Section of the Chapter on Color/Color Vision located at the following URL:

http://www.yorku.ca/eye/thejoy.htm

You will find a complete discussion on colors and color mixing in the York book. The fine detail of the colors on the Web CIE chart are not very accurate but the color wavelengths are close. High quality CIE Charts can be found in most good art stores.

Specific colors such as the yellow on a Kodak film box are specified by the x and y coordinates (mixtures of specific light wavelenghts) on the CIE diagram. Our eyes perceive this mixture as Kodak yellow. Pastel colors such as pink are mixtures of complementary colors. Complimentary colors are located on opposite sides of the white region of the CIE diagram. For example the compliment of 570 nanometer wavelength yellow light is 450 nanometer wavelength blue light. You can generate any perceived color of light, including white light, between 570 nanometers (pure yellow) and 450 nanometers (pure blue) along a straight line between the two points connecting the two colors. By changing the relative intensity of the yellow light and the blue light you can generate a perceived color that can range from pure yellow to pastel yellow, to white, to pastel blue or to pure blue.

Color TV picture tubes generate many different perceived colors by mixing 3 different intensities of red, green and blue light from phosphors with colors that are located at the points of the triangle on the CIE diagram. All of the colors that the TV tube can generate are located inside of the triangular boundaries within the CIE diagram as shown in the York book.

Laser light is the only perfectly pure colored light with one single exact wavelength and one single exact frequency (vibrations per second). Laser light wavelengths are on the boundaries of the CIE chart. Laser light colors are often called saturated colors. Quantum mechanics teaches us that each frequency of laser light is a different color; however, our eyes cannot distinguish the minute difference between the 750 thousand, billion exact color frequencies of reds, oranges, yellows, greens, blues, lavenders and violets that lasers can generate. However, we can exactly measure color frequencies using standard lasers with known wavelengths just as a piano tuner can measure and tune piano the frequency of piano strings by beating the sound from the strings with sound from standard tuning forks. In fact the techniques are very similar and in the laboratory we can generate sound by zero beating laser light beams together in a photodetector.

Best regards, Your Mad Scientist
Adrian Popa