Thoughts about Laser Pickup Cleaning

[oshifis]

I use a cotton bud for cleaning the laser pickup of my CD player. Now I realized that the laser diode itself does not actually move vertically, against to the common belief. It is the lightweight tiny plastic lens with coils attached to it, mounted on a flexible bronze spring that moves up and down. This is how the laser beam is focused on the pits of the disc.

So in reality, one cleans the plastic lens, not the light emitting surface of the laser. What is more, only the top surface of the lens can be cleaned. The bottom side is not accessible.

The whole thing concerns me, because I had been using an air humidifier with tap water. I observed that everything (especially the TV screen) would be covered by a very thin white powder after a few days. It goes inside everywhere, just like cigarette smoke. A CD left in the player was also covered by the white stuff (calcium carbonate?), hardly noticeable, but there is.

Since it is virtually impossible to clean the laser itself and the bottom surface of the focusing lens, this is just a warning: use distilled water in the air humidifier - and don't smoke!

Also, cleaning the focusing lens has the same effect as cleaning the lens of a camera. You don't see the dust particles or fingerprints on the photo. It is just the sharpness of the picture that gets a bit worse, but the lens must be very dirty to cause any noticeable effect.

[kevinkr]

Don't use ultrasonic humidifiers as they are the ones most likely to cause this problem. Evaporative or steam types generally don't seem to generate much residue in my admittedly limited experience.

Mold can be an issue with any of these so clean them regularly..

[Mooly]

For a CDM12.x pickup you can always try
Stripdown/Clean of CDM12.4

I have looked in the past for data on how internal contamination affects the RF signal (eye pattern) but never turned much up.
I know if you measure the before and after when cleaning a lens you can, if it was very badly contaminated see a significant increase in the amplitude of the signal.
Like you my argument is that this must be present to some extent internally. I always say, take a wine glass and clean it, then put it in a cupboard for a few years. Probably not sparkly then. But as to putting numbers in and seeing the degradation, I can't find anything. As to comparing it to a photographic lens, the problem with contamination is that it ( I believe ), absorbs the mainly infra red energy of the laser, I don't think it's anything to do with "blurring" of the returned light reflected from the disc. When I say infra red, it's just below the visible end of the spectrum.