CD Player/CDROM Drive Laser Diode Characteristics

The laser diode in a laser printer is located inside the scanner unit which is probably a black plastic case about 6 or 8 inches on a side and a couple of inches thick with a motor protruding from the bottom. The laser diode is mounted (along with its driver board, collimating optics, and even possibly a Peltier solid state cooler on some) either near one corner or inside. There should be a laser safety sticker on it as well – but these fall off sometimes!

CD player laser diodes are infrared (IR) emitters, usually 780 nm, with a maximum power output of around 5 mW. Their emission will appear very slightly visible and deep red. This is the eye’s response to the near-IR radiation but appearing about 10,000 times weaker than the actual beam would be it it’s wavelength were centered in the visible part of the spectrum. Despite what the EM spectrum charts show 1000mw groene laser pen , the eye’s response does not drop off to zero at exactly 700 nm – there is decreasing sensitivity which may extend out beyond 820 nm depending on the individual (though some people can’t even see the 780 nm). Just realize that the main beam is IR and almost totally invisible. Take care. A collimated 5 mW beam is potentially hazardous to your eyes. Don’t be misled into thinking the laser is weak due to the dim appearance of the beam. It is not supposed to be visible at all!

However, depending on design, some of the parts may be missing or combined into one component. For example, many Sony pickups do not appear to use a collimating lens. For pickups with a collimating lens, if the objective lens is removed, you should get a more or less parallel main beam and two weaker side beams. Many newer designs have a combined laser diode/photodiode array rather than individual components krachtige 300mw groene laser pen . Mix and match parts for your needs (if you can get it apart non-destructively). Where there is no collimating lens, the objective lens may be used for this purpose if positioned closer to the laser diode.

Some of these use what are known as “hologram lasers” (a designation perhaps coined by Sharp Corporation). With these, the functions previously performed by multiple optical components. can be done by a “Holographic Optical Element” or HOE. The HOE can simply be a diffraction grating replacement or can be designed to perform some more complex beam forming. A variety of hologram lasers (as well as conventional laser diodes and photodiode arrays) are listed under Sharp Laser Diode Products Professionele Groene laser pen 5000mw . The typical Sharp hologram laser (versions for CD, DVD, and other types of optical storage devices) eliminate the normal diffraction grating in the three-beam pickup as well as the polarizing beam splitter and associated components making for a very simple, compact, low cost unit.

Some manufacturers of CD and DVD optical pickups have gone to a combined laser diode/photodiode (LD/PD) array package which looks like a large LD but with 8 to 10 pins. Aside from the objective lens assembly, the only other part may be the turning mirror, and even this is really not needed. Such a pickup can be very light in weight (which is good for fast-access drives) and extremely compact.