Lasermodule "jellybeaning"

[Aage]

Hi,

Can someone help with this.
I have a new module that is "jellybeaning" i think, it is pulsing when it have modulation (analog or TTL)
What can be done with this ?
Thanks for any help !

Aage

[ElektroFreak]

What color module, green or blue? If it's a blue DPSS it's pretty normal for it to flicker. It's called amplitude noise and is very common in 473nm systems. Some manufacturers spec the noise to <30%, which is quite a bit. There's really not much to be done about it since even using some form of external modulation can't change a noisy beam. This high-frequency noise is prduced by the doubling crystal during the process of converting 946nm IR light to 473nm blue.

In both green and blue DPSS lasers we get "blanking induced power loss" frequently. This is brought on by the modulation signal causing temperature fluctuations in the internal crystals. These temperature fluctuations in turn cause power fluctuations. There's nothing to be done in this case either since the cause is buried deep within the laser crystals.

DPSS lasers are inherently noisy, so don't be surprised to see these issues frequently whenever you use DPSS lasers. Some are better than others, but it's pretty much luck of the draw in general.

[Aage]

It is a Green.
I can not belive that i can live with this, maybe it is something else.(not jellybeaning)
I can try to make a movie of it.
It is pulsing very much.
Is this a warranty thing, when it is complete new ?

[ElektroFreak]

A movie wouldn't hurt. Even with they typical noise, DPSS lasers shoudn't be so bad that you just can't live with it. It does sound like a warranty RMA might be in order.

[Aage]

Here is a movie of it: http://prolight.homestead.com/pictures.html

[ElektroFreak]

Do you have a movie of it running through scanners and creating images? A modulation signal is a train of pulses or waveforms, so the laser is meant to pulse while under modulation. The high part of the pulses produce visible output which forms parts of images while the low part turns the laser off, which keeps connecting lines hidden. If the laser beam is not moving, it will appear to pulse. That movie looks normal for a stationary laser beam under modulation. If you use it to form images and the scanned lines are dotted lines then it means there's a problem with your laser or DAC. What kind of DAC/software are you using?

[Aage]

It happens when i turn down the power in Live Pro to about 50 %
My other green do not do this.
I have not put it in a projector yet.
The patern is a green line only.
I use the original DAC and Pangolin
I have only 146mW of 500mW output from it when i use modulation.

[ElektroFreak]

If you have compared it directly with another green while feeding both an identical signal, then there is a defect in this module and it should be sent back under warranty.

[mccarrot]

Your green is or a cheap Chinese laser, or the crystal tec is off,

Cheap laser manufactures tune lasers for the highest peak power but have bad modulation. If you have warranty on the laser you should return it, else you could try to tune it again, but you must be VERY VERY patient. And if you do not know what you are doing you can also mass it up and make it worse.

But first of all you need a good power-meter to tune the laser.

[Aage]

Thanks for all help !