Modulation efficiency

[ElektroFreak]

445nm diodes have been mentioned in this thread. The only issue I have with diodes is that they're only single-mode up to a point (of course that's just me). If you're interested in good beam quality, diodes are out. If you don't care about beam quality (which truthfully isn't that important when doing laser shows) then diodes are a great option. It boils down to personal taste. One of the major benefits of DPSS technology is that it provides ion-like beam quality while consuming a mere fraction of the power and producing a fraction of the heat.

[danielbriggs]

445nm diodes have been mentioned in this thread. the only issue I have with diodes is that they're only single-mode up to a point. If you're interested in good beam quality, diodes are out.

Hmm... yes, to a point. However one of the 445's (1W) I have seen had really fantastic beam quality over quite a long distance if I recall correctly.
On the flip side I have also seen a 445nm module and wasn't overly impressed at all with the beam...

[ElektroFreak]

There are some very good designs out there which provide a round flat-top profile similar to, but definitely not the same as, TEM00. It beats the hell out of the rectangular mess that we see frequently with multimode diodes.

[Zoof]

Hmm... yes, to a point. However one of the 445's (1W) I have seen had really fantastic beam quality over quite a long distance if I recall correctly.
On the flip side I have also seen a 445nm module and wasn't overly impressed at all with the beam...

445nm is much less visible than 473. However, and this is a main point (!) to get the same hue as 473, a little bit of green can be mixed with 445 which also makes the mixed color much more visible than the 473nm beam would be for the same power.
There is s a thread on this here somewhere with Tocket backing this up with math.

The eye isn't that sensitive to blue wavelengths alone, but a little bit of blue has a great impact on color perception.

But as Elektrofreak says, I also like non-divergent beams better.

[DZ]

Could you scope the diode drive current? I am wondering if there might be some issue with the drivers on these Chinese DPSSes. That initial spike seems awfully high...

I'll try to get that tonight. I'm thinking that part would be fine, especially since the greens are about the same as the blues from the driver up to the pump diode. We'll see.

[ElektroFreak]

It's not at all uncommon to see a nice fat spike like that at the beginning of a pulse, especially with blue. You just never know how those crystals will react to that first bit of pump energy. That's when the crystals are going through the fasted change in temp. As you said, DZ, it's the same driver for green or blue as long as they're part of the same line from the same manufacturer.

[DZ]

Here ya go. Top trace is light output, middle trace is modulation signal, bottom trace is diode voltage(sorta).

[ElektroFreak]

There does seem to be a small voltage spike on the leading edge of those pulses, but due to the fuzzy nature of that trace it seems like it could possibly part of the noise.. hard for me to tell.

[ElektroFreak]

Very nice photos. It can be clearly seen how the crystals perform better when the duty cycle is higher. If they are allowed to maintain a fairly steady temperature, with very little time for cooling between pulses the output is steadily higher. It's the varying duty cycle that adds a lot to the instability.

[mixedgas]

Very nice photos. It can be clearly seen how the crystals perform better when the duty cycle is higher. If they are allowed to maintain a fairly steady temperature, with very little time for cooling between pulses the output is steadily higher. It's the varying duty cycle that adds a lot to the instability.

If my buddy in St Louis loaned you a adat, would you run a data gathering run on your system for for me? I dont have solid state blue.(probably not for another two years at this rate)

I'd like a tape for analysis.

Steve