jelly beaning blue

[oliverst14@hotmail.com]

hi

i have a f2000 laser projector and recently i think its started jelly beaning on the blue diode. the blue when looking at the wall looks a bit like static off a telly. to be honest i think when its on a tunnel effect it looks damn good and im not that bothered about it.
im just wondering if this means my bluey might pack in soon????

what actually is this jelly beaning?
is there any way of stopping it? (not that i want to)

and i think i read in another thread that someone else was having this and they thought it looked good and they asked if it was possible to make this happen then turn it normal again? i was wondering this too?

cheers ollie

[stanwax]

Ollie

Jelly beaning is basically noise in the beam If you were to see an oscilloscope representation of the output it would resemble white noise. Its caused by instability in the laser usually (but not exclusively) due to temperature. The problem with blue is to get the best power you need to be very specific with temp of internal parts. This is ok in CW mode as its predicatable but when you start modulating the stability goes out the window and the Tecs cant keep up with whats going on and can never know whats coming next. Part of the problem I believe is due to most modules having single ended tec control - which means the tec can only heat OR cool the internal parts not both. To get very accurate and stable temp even when modulationg takes a few tricks in the driver but the fundamental thing would be a tec control that can heat AND cool the xtals/diode

Rob

[GooeyGus]

What you're describing almost sounds more like a dirty collimating optic or even IR filter (whatever the final optic is on your laser module). Maybe I'm just not fully understanding what you're describing, though... do you have a picture?

As far as I understand 'jelly beaning', it's where the laser cannot keep up with the modulation signal that is coming in. DPSS lasers especially struggle with this. As you know, when you click a laser on it isn't instant. There is a ramp up/down time. If you are trying to modulate faster than the laser can rise and fall in power, you end up getting the 'jelly bean' effect where the line of the pattern being drawn looks like a bunch of jelly beans stacked together rather than a solid line.

EDIT: Ohhh... now that I re-read and 'thought' a bit more, I think I get what you're saying. Lets say you're projecting a blue circle on the wall, are there 'irregularities' or very tiny 'breaks' in the line creating circle causing it to look static-y?

[buffo]

As far as I understand 'jelly beaning', it's where the laser cannot keep up with the modulation signal that is coming in. DPSS lasers especially struggle with this.

This "blanking-induced power loss" is related to jellybeaning, as they are both normally caused by temperature instabilities in the lasing caivty. I admit that I've used the term jellybeaning to refer to blanking induced power loss before.

However, I do believe that Bill Benner originally coined the term to refer to the noise that is present in the continuous power beam when it is scanned. This looks like "static" (or little jellybeans stacked end-to-end), and is common to many DPSS designs.

I think since then the term has evolved to refer to any number of power or beam quality issues related to DPSS lasers. Just my opinion though...

Adam

[Zoof]

edit: see 2 posts down.

Does it look like that?
If it does, it is quite normal unfortunately. This is a 473 CNI that I bought about 20 months ago. I don't mind it too much, the laser is outputting twice its rated powers so that makes up for it.

[oliverst14@hotmail.com]

like what mate?

[Zoof]

uh,like this: ..............

[Anthony]

uh,like this: ..............

Looks more like NOISE... :-)

[keeperx]

clean your friken lense

[oliverst14@hotmail.com]

a little but more perfect. its like this -------------------------.

ollie