Begginers question

[Neitrino]

Hello everybody...

Would u please help me with some qurstions...

1) On E-bay i ve seen some laser diodes with 300, 500, 1000, mW power but the prices are only a couple of dollars - no higher than 10$, but in stores or some shops relative prices for mentioned powers are too high ! So what does that mean ? why there is such desripancy ???

2) Also please have a look on some phots attached.... I was trying to run IR laser had...to track the light beam I was watching through mobile cam, when I put my cam as close as possible onto the laser diode I saw folloing little dots... what does thease dots are ? Its good its bad ?

Thanks

 

[bluuray]

the ones you saw on ebay are probably 808nm

 

[udanis]

The diodes you saw on ebay were very crude 808nm diodes. Most of those diodes can even be used in dpss systems because their wavelength is so far off.

It could be because you have several lenses in front of the camera sensor.