Radiation from laser diode....

Hi,

I need a laser pointer for my project.. so to get more accuracy i decided to choose a laser diodes available in market.... i want to know whether the radiation light produced by the diode is in visible range or infrared range.....

it depends on the wavelenght produced by the model you choose

see the Common wavelengths Laser diode - Wikipedia, the free encyclopedia
and the visible wavelengths range File:EM spectrum.svg - Wikipedia, the free encyclopedia

Alex

Buying a ready-to-use laser pointer or low cost laser module with collimator optics seems to be the most easy way. I guess, you'll understand, that they would use a visible laser wavelength, e.g. red (630-635 nm).

but in such low cost pointers it seems that the beam angle is wide causing a dispersed pattern.... but i need a concentrated point with narrow beam... and i think that's possible only by using the laser diode....
i don't know any thing about laser diodes... can you suggest any laser diodes of visible range(630-635nm)....

any visible RED laser diode is in the 630 - 635nm range nominally 633nm. its the focussing of the collimating lens on the front of the diode that determines the sharpness of the spot. laser diodes with collimating lenses already attached are readily available in stores and by the zillions on eBay.
it really depends on what your particular use for it is ... you havent stated....
even with a well focussed lens, the spot is still likely to be a metre or so in diameter after 500metres distance

cheers
Dave

Laser diodes are used in some photocopiers and laser printers.

They would certainly need to be sharp dots.

Don't know if they're visible or not.

I remember seeing them carried by at least one electronics supply house. Maybe used. Perhaps with power supplies.

I know about that... i think they are similar to those used in DVD writers.... but they have low focal length and cannot be used for long distance ... but in my project i need a long distance point....



i was not aware of the lens assembly requirement...

The so-called beam divergence mainly depends on the collimator diameter (called aperture). The other point is, that the light is emitted from a longish chip edge rather than a round area. Thus the image spot won't be round. You need an anastigmatic optic to get an almost round spot. High quality laser modules have it.
A DVD writer's laser united consists of a laser diode (without any optics), lens(es), an electrodynamic drive to adjust the focus plane and a dual detector to sense the height.

You should be basically able to change the short focus to infinity, but the lens diameter and geometry won't be optimal for this purpose.