Problem with my 50mW pointer

[hyparh]

Hi all
I've got 50mW green laser pointer (from amazon.com). When I put the batteries included, the beam and dot was very bright, but after a minute it's got drastically reduced. From a bright it becomes a very pale dot and non-visible beam. I thought that the batteries are dead, but when I put new ones (alkalines) the problem remains After a break of 10-15 minutes it starts to shine bright again, then after a minute or two- pale. What may be the problem- defect crystal or something?

 

[Jaseth]

First of all your laser is most likely bad quality since it is from amazon.
Secondly, DPPS lasers have a variable output caused mostly by temperature. It is completely normal for low quality greenies to reduce a lot in visibility when hot/cold. You just have to use it for cycles of 60 seconds on, 60 seconds off and you should be fine. Better cycle will require effective heatsinking.

 

[styropyro]

Your laser is just temperature sensitive. Turn it on until it dims, put it in a refrigerator for a few minutes (without the batteries in it) and turn on the laser again. If it isn't as dim as it was this proves that your laser like to be cold.

 

[hyparh]

Thanks for the replies, I'll try the trick with the refrigerator this evening.

 

[ElektroFreak]

Please read the stickies before you post these types of questions. There is a sticky in this section (green lasers) that answers this question (among others). That way we don't have to answer the same questions over and over..

 

[nikokapo]

Problem, OP?

Yes, it's temperature what's bugging you. Try and use it somewhere cooler than room temperature and see how that works.

 

[hyparh]

Yep, the laser definitely prefers cold. I play with it until gets dim, then put it in the fridge for about 5 min., after that when I turned it on there was not green, but very dim red dot. After a few seconds becomes green and starts to increase. It stands the full power for about 3 min., then dim again (at room temperature about 20 deg.) Then I tried the same steps, but without putting into the fridge. Leave it to cool down for 5 min. and when firing up it stands bright just a few seconds before gets dim again.
I read the FAQ about the warm-up period of 5-15 min., but that's not the problem. After all the pointer doesn't work normal at room temps, but only when it's cold. I don't think it's normal :-/

 

[ElektroFreak]

You missed the "optimum temperature" question? You must not do a very good job of reading, then.. It's even highlighted.  :-?

Also, read Sam's Laser FAQ.. It'll help you gain some understanding of DPSS lasers and how they work.. Here's a link to the DPSS section: http://www.repairfaq.org/sam/laserssl.htm#ssldps

What is happening is that you have found out that your laser's optimum teperature is a little on the cold side. As the pump diode inside the laser heats up and the rest of the laser heats up around it, the internal alignment changes due to expansion from the heat. These subtle changes are what is causing the instability in your laser. The optimum alignment for your laser occurs at a colder temperauture. At any temperature above this optimum or likely even a bit below, your laser will not be stable. It's not a problem with your laser, it is just how DPSS lasers work. If you want true stability from a DPSS pointer, you either need to spend the money to get a higher-quality unit, get lucky and find a cheapy that just happens to be stable, or buy a lab-style laser. A cheap unregulated DPSS laser is impossible to predict in terms of output, and will never be entirely stable. That's just the way it is.

 

[hyparh]

I forgot to mention that I'm not very good with english. Now I read the materials, it's a pity that these lasers are so individual even from same type... Well I purchase one 200mW from Dealextreme, I hope to be lucky this time and get more stable laser I'll get a lab-style 100mW red laser too (hope to be absolutely stable ) Thanks for the help everyone!

 

[nikokapo]

DO NOT PUT IT IN THE FRIDGE!

Doin' it wrong!



You can get condensation on the inner circuits thus elevating the chances that the laser module gets shorted ==> Laser will die.

 

[hyparh]

Yes, I figured that out when took it out of the fridge, a dew-drops was forming all over the laser...

 

[larrball]

I have a greeie that like the frige.
Now i respect niko, in the fact that not all green lasers should "chil" before use, but i have one that when i put it in the frige for 3 min's it run's fine tell it get's to room temp.

 

[Arenared]

Please read the stickies before you post these types of questions. There is a sticky in this section (green lasers) that answers this question (among others). That way we don't have to answer the same questions over and over..

You missed the "optimum temperature" question? You must not do a very good job of reading, then.. It's even highlighted. *:-?

Im sure there are also alot of posts just like yours , so im sure you dont have to repeat it everytime someone has a question... thank you

 

[Deleted member 8382]

lasers do not like hot or cold. When you put it on fridge you are doing thesame than when it goescold. This red dot is part of the IR light the crystals are not converting.

Yours,
Albert

 

[TEMA]

When we talk about the heat...do the laser drivers have temperature sensor to avoid overheating? 2 days ago my Nova X75 went one hour (accidentally), and I don't know whether the diode was damaged or not.

 

[ElektroFreak]

Im sure there are also alot of posts just like yours , so im sure you dont have to repeat it everytime someone has a question... thank you

Gosh, I'm so very sorry. [/sarcasm]