Laser pointer for an engineering project

Hi,

I have read the Newbie`s guide to buying laser pointers but
what I need to know isn't discussed there. So I`m posting this.

I need a laser pointer that will have a small, very defined beam at
distances of 2-10cm. By defined beam, I mean the beam edges must
be quite clear. And it should be safe, so either Class 1 or Class2.

Has anyone used such a laser pointer. Will appreciate some suggestions.
This is the only requirement I have so I don't mind getting a pointer
from any source, good, bad or of the worst quality. Just need to
get a precise beam at the said distance.

Thanks

Hello and welcome to the forum!:wave:

Define "small and defined" beam.
All lasers have a somewhat small and defined beams, some more than others.
Does it have to be of any specific colour?
Until you tell us more I'll say that even a dollar store red pointer does what you need.
The beam won't be visible without fog, but it is there.
If you need a visible beam, try a 5mW 532nm green pointer.
It is not class II anymore, rather class IIIA, I don't know if that is a problem for you...

It depends on how sharp you want it, but most all pointers have roughly a Gaussian beam distribution, so generally speaking you're out of luck.

If you try cutting the blurry edges off, the light will just diffract around whatever you put in the way and you're back to a blurry edge.

It might help to know your ultimate objective. See sig.

Thanks for the replies and apologies if I did not give enough info.

In my application,a laser beam will be directed at some *small* object and then I have to track the object (by actually tracking the laser beam) using image-processing techniques.

In the image processing part, I will detect the laser beam, determine its center and then use the center to track the object (the laser will always be centered onto the object and move with it).

So that I can detect the beam accurately, I need the beam to be well "defined"
Please take a look at this vid to see what I mean by well defined: http://www.youtube.com/user/dragonlasersfanman#p/u/58/dmLfw3QzNqg

At the 0.45sec to 0.50 sec marks, you will see two beams being compared.
The one on the left has a poorly defined beam edge (according to my needs)
as the beam is scattered a little. But the one on the right has a neat, precise beam. And I can detect this beam accurately (since the object I need to track will be quite small).

If I use the left laser, part of the green light falls outside the object so I will not be able to track it. The object I need to track is about the size of a US quarter coin, or even smaller, hence my need to have a small, well defined beam that will fall within it.

I would prefer a green laser, class 1 or 2.

@Anslem, you said that all lasers have small defined beams but you can see clearly in the above link the laser on the left has its beam scattered around for a few mm. This is what I do not want.

Hope u can give me a few ideas!

jameslaser said:

The one on the left has a poorly defined beam edge (according to my needs)
as the beam is scattered a little.

Click to expand...

That is just because of the blooming of the dot (it is much higher power) a lot like this image of street lamps



It looks like the lamp has blurry edges, but we all know solid objects don't have blurry edges. It is due to the camera and the brightness of the light source. Notice how the lamps look sharper as you move into the background.

For your purposes, All lasers have a well defined beam. Any low-power green will do.