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Thread ID: 19870	2002-05-24 10:03:00	cleaning CD-ROM lens?	Guest (0)	Press F1

Post ID	Timestamp	Content	User
50562	2009-01-29 01:07:00	From RepairFAQ: Laser (CD): The laser in a CD player is infra red, near IR - 780 nm - border of visible range but for all intents and purposes invisible . However, it is very low power (generally under 1 mW at the lens) and due to the optics, extremely unlikely that you could be in any danger . Nonetheless, don't go out of your way to look closely into the lens while the unit is on! As long as the lens is intact, the beam is highly divergent and at anything beyond a few inches, especially at an oblique angle, is quite safe . The only possibility of risk would be if the lens fell out and you were looking directly into a collimated beam from above . While the power is less than that of most laser pointers, there would be no aversion reflex to the nearly invisible IR . And, yes, some models of CD players are known to drop their lenses! CAUTION: There is usually a very low intensity (in appearance) emission from an IR laser which appears deep red . It will be visible as a spot the size of the period at the end of this sentence when the lens is viewed from an oblique angle . This is just your eye's response to the near IR energy of the main beam . (Some people apparently cannot see this at all . ) Do not be mislead into thinking that the laser is weak as a result of how dim this is . The main beam is up to 10,000 times more intense than it appears! It's power output is generally around 1 mW - comparable to a laser pointer . Take care . However, the red dot is an indication that the laser is being powered and probably functional, though it is no guarantee of the latter . You really need a laser power meter or at least an IR detector to confirm the existence of an IR laser beam . Whenever a full size (5-1/4") CD is in place, there is absolutely no danger of exposure to the laser beam . Reflections of laser light at these power levels are harmless . However, if you are testing with a 3-1/2" 'single' or homemade cut-down test CD (see the section: Useful ways to mangle CDs, avoid staring into the lens if there is any chance the laser is powered . If you don't want to take even the minimal risk of looking into the lens at all, project the beam onto a piece of paper held close to the lens . In a dark room, it should be possible to detect a red spot on the paper when the laser is powered .	Agent_24 (57)
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