Understanding Lasers and Wavelength

* Click on image *


The psychological perception of color is commonly thought of as a function of the power spectrum of light frequencies impinging on the photoreceptors of the retina. In the simplest case of pure spectral light (also known as monochromatic), the spectrum of the light has power only in one narrow frequency band peak. For these simple stimuli, there exists a continuum of perceived colors which changes as the frequency of the narrow band peak is changed. This is the well known rainbow spectrum, which ranges from red at one end to blue and violet. When looking at the image above (click on image) 500-600 range is most visible and 550 is optimal visibility.
Lasers


Laser light is very different from normal light. Laser light has the following properties:

* The light released is monochromatic. It contains one specific wavelength of light (one specific color). The wavelength of light is determined by the amount of energy released when the electron drops to a lower orbit.
* The light released is coherent. It is “organized” -- each photon moves in step with the others. This means that all of the photons have wave fronts that launch in unison.
* The light is very directional. A laser light has a very tight beam and is very strong and concentrated. A flashlight, on the other hand, releases light in many directions, and the light is very weak and diffuse.


To help you better understand wavelengths and lasers, click on image above. When looking at the color spectrum you can see the that colors visible to the human eye falls within the range of 400-700nm. Keeping that in mind, if you wanted to know the difference between the 635nm and 650nm you can see from the color spectrum that the 635nm is going to be more visible to the rods in your eyes then the 650nm.