Strange red laser behaviour

[lightlover]

I got a really cute cheap red laser. But this time, a quite strong version. The beam was pretty good, and actually quite visible in a dim ambient.
Quick as a flash(aholic), instead of the 4.5V as supplied, I put it on to 6V. The beam became twice as bright, much more visible, and the red point very sharp.
After about two minutes use, it stopped working ......

Once I calmed down, I tried it with 4.5V once more, and (thank the Great Spirit) it worked again. Then, after a few weeks, it suddenly began to put out a large rectangle instead of a point. At 15', it projects an approx. 1 1/2" rectangle. The batteries read at 4.34V. Using batteries reading 4.31V, the blob seems to be a little smaller, perhaps 1 3/8".

It wasn't dropped or knocked against anything, even though it seems that the focus has altered. Looking down the beam, it *seems* to be constant to about 12', and then diverges. Or maybe it just diverges at a constant rate and I'm imagining it.
Close-up, there are strong sideways red *shadows* cast as triangles on either side.

Given that rather vague evidence, can anyone say what is happening there - could it be that the *shadows* are caused by the beam catching on the sides of the body's aperture, for instance ?
And could I still boost it with a 6V battery, using it for short periods without burning it out ?

NO replies from cartoon characters, please !!

lightlover

 

[lightlover]

Nope, Darklite, can't be - it's head isn't spinning around and around ......

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by *something ridiculous ?:
... NO replies from cartoon characters, please !!

lightlover <HR></BLOCKQUOTE>

I didn't mean you, Telephony - that was kind of noticing your name change !! Have mercy on a poor seeker of the light ......

lightlover

 

[The_LED_Museum]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by *something ridiculous ?:
I got a really cute cheap red laser. But this time, a quite strong version. The beam was pretty good, and actually quite visible in a dim ambient.
Quick as a flash(aholic), instead of the 4.5V as supplied, I put it on to 6V. The beam became twice as bright, much more visible, and the red point very sharp.
After about two minutes use, it stopped working ......

Once I calmed down, I tried it with 4.5V once more, and (thank the Great Spirit) it worked again. Then, after a few weeks, it suddenly began to put out a large rectangle instead of a point. At 15', it projects an approx. 1 1/2" rectangle<HR></BLOCKQUOTE>

The collimating lens has become misaligned, or the collet holding it in place has changed position. If this collet is threaded into the laser diode holder, you should be able to fix it.

If you have a spanner wrench that will fit the two slots on each side of the lens, you can loosen or tighten this until the beam is back in proper collimation.

However, if the lens is press-fit into the aperture, getting the correct focus back may be a bit trickier, and may require banging the laser around a bit, then fixing the lens position with something like bathtub caulk or silicon adhesive. Don't try to use Torr-Seal or other epoxy compound, as you won't be able to "undo" any changes you make.

Try gently pressing on the lens with a Q-tip or similar cotton swab and see if it snaps back into place. A millimeter is all it takes to turn a nice sharp point into a golf ball sized blob.

 

[DArklite]

It's the Devil.

 

[lightlover]

Thanks Telephony, I'll check that out.

What do you think was happening with the 6V battery, the laser's ceasing to work - could I use it on 6V for just short periods without permanently damaging it ?

Having a quite visible red beam was so nice ......

lightlover

 

[**DONOTDELETE**]

I dropped my blaster once, and the beam distorted the same way. Definitely sounds like the collimating lens.