Mouse IRLEDs.

"ian field" wrote in news:UgiJl.30267$a% snipped-for-privacy@newsfe24.ams:

In green DPSS lasers the IR blocking filter is a sort of cyan colour. While an IR LED shouldn't be blocking IR entirely, it might have used a similar filter to get a narrower IR spectrum than they'd otherwise get. This might improve noise immunity in older systems made when LED's usually had broader spectra than current new ones do.

I've seen a similarly tinted LED in a payphone but it wasn't obvious what the opto-pair did as the payphone had been run over (several times) by construction site vehicles.

On Mon, 27 Apr 2009 14:18:42 +0100, "ian field" put finger to keyboard and composed:

You can get some detailed information (schematics, parts lists, operational description, user manual, internal/external photos) here:

For example, put "Memorex" in the Applicant Name box, and select a Grant Date Range of 01/01/2000 to 04/27/2009.

You will see 4 results for Memorex wireless optical mice.

I have a very old Mouse Systems model M411 serial optical mouse which uses a special metal tablet. It is covered by US patents 4364035 and

The patent documents describe how it works:

- Franc Zabkar