david@epicb.UUCP (David Cook) (08/16/89)
In article <46900035@uxe.cso.uiuc.edu> mcdonald@uxe.cso.uiuc.edu writes: > >"White" krypton lasers are not really white. They contain several >lines that add together to appear whice to the eye. They do >make good color scanner sources, as the lines are in nice places. > > I am not an expert on lasers, but I came across some info that might be of > interest. On the Discovery Channel there was a piece on medical lasers. > Some surgeons needed different frequencies of lasers for different tasks, so > they were using a Dye laser. From what I could gather, a primary laser excited > a dye which emmitted a secondary laser which could be tuned to almost any > frequency. > Using such a laser maybe you could tune it to Red, Green, or Blue for color > scanning. I'm not an expert on lasers either... but I believe that dye lasers would not be a good choice for scanning... [1], they requre refreshing (ie.. the dye elements require refreshing (pumping) and [2], they tend to be too high of a power (read DANGEROUS) for most scanning applications. In general, you want LOW POWER lasers for most scanning applications. Helium-Neon produces light at 6328 anstroms (orangish-red) and can be used for the red component... several companies, as of 1985, have anounced helium-neon lasers tuned to operate in the blue-green area also. Therefore, it is possible to use several helium-neon lasers to get Red, Green and Blue. (By the way, Dye lasers are very expensive and he-ne lasers are very cheap). Besides he-ne... argon can also be used for the blue-green component, and current argon technology requires no pumping and are fairly inexpensive (as compared to other laser technology). Some recent advancements, however should be also considered... solid-state laser diodes which produce visible (red) light, could also be used as the Red component. I am not aware of any blue or green laser diodes. -- David Cook uunet!epicb!david
jeff@hpspdra.HP.COM (Jeff Gibson) (08/18/89)
Hmmmmmmmm, lasers. I just left a laser manufacturer where I worked on a "White Light" product. These systems are typically used in the Light Show industry for medium power applications such as auditorium and planetarium shows. There are low-powered versions (air-cooled, milliwatt power levels) which are also sold into this market, although they are a very small percentage of the marketplace. White light lasers are an attractive alternative for laser scanning if beam quality is not a big issue, ie; small spot sizes are not necessary. White lights run multimode which means that the various colors will have different beam diameters and Transverse Modes. Multiple laser systems as described ( A red Hene, a green Hene) are a way around the beam problem, but after all the lasers are added together the total cost may exceed that of a single white-light. I also believe that for a "balanced" RGB setup, or one which has somewhat equal power levels of red, green, and blue, one still needs to utilize a Hene for the Red and a air-cooled Argon for the green and the blue. Red HeNe's range from .5 to 20 mw, whereas green HeNe's have yet to exceed 1 mw in production quantities. And blue HeNe's simply do not exist. For more information on RGB scanners, look up the laser entertainment folk who build them and sell them as stand-alone products, both as single white-light systems, or as multiple laser systems.