Is this laser driver analogue or just TTL (Modulation wise?)

[simonb]

Hello everyone, I hope you all had a great Christmas.
My Christmas prezzie arrived. It was supposed to be the the normal 0 to +5v analogue voltage, not the TTL 0/5v logic level type. Pulse Width Modulation for brightness/modulation won’t work with my Helios DAC & LasershowGen system. It’s a 2000mW 445nm laser module.

It was clearly labelled as analogue & the photos confirm. I cannot see any switch or solder-pad bridges to select analogue.

Before I return it, I thought I would quickly ask the experts on these forums.

It might be a fairly easy thing to just buy a suitable analogue driver. Last one I heard about was the FlexMod P3. There might even be a pin compatible one.

Thanks,
Si Bond
UK.

[absolom7691]

Hello everyone, I hope you all had a great Christmas.
My Christmas prezzie arrived. It was supposed to be the the normal 0 to +5v analogue voltage, not the TTL 0/5v logic level type. Pulse Width Modulation for brightness/modulation won’t work with my Helios DAC & LasershowGen system. It’s a 2000mW 445nm laser module.

It was clearly labelled as analogue & the photos confirm. I cannot see any switch or solder-pad bridges to select analogue.

Before I return it, I thought I would quickly ask the experts on these forums.

It might be a fairly easy thing to just buy a suitable analogue driver. Last one I heard about was the FlexMod P3. There might even be a pin compatible one.

Thanks,
Si Bond
UK.

Looks like PWM to me. The really cheap drivers on ebay are marked analog but are normally not pure analog. PWM drivers are great for TTL or lumia applications but little else. Sorry, man.

[simonb]

Good news,
i powered-up the laser & used a linear multi-turn potentiometer across my lab PSU set to +5v.

applying this analogue control voltage to the 2 pin connector marked ‘TTL’ (as advised to by supplier) worked well. So it is analogue modulation, the the PCB was incorrectly labelled.
But it might not be the case for similar products from different suppliers.

I’m very impressed with the laser. It was only £48 & seems very powerful for 2000mW. I had to be careful my beamstop didn’t catch fire when I was testing.

only thing is the beam seems a rectangular slot shape rather than a circular dot. I might need to consider beam shaping optics before I use it to replace my dead blue laser module. I’ve heard anamorphic prism pairs may help.

[buffo]

£48 for 200 mw, or 2000 mw? (Your post said 2000 mw, which is 2 watts...)

If it's really a 2 watt laser, that's a pretty good price! And yeah, a 2 watt blue diode (multi-mode) will absolutely have a rectangular beam profile, although with proper secondary correction optics you can fix that.

Truthfully even a 200 mw blue wouldn't be a bad deal at £48, but only if it had single-mode diodes in it. (Single-mode diodes would give you a lower divergence beam with a round profile and a gaussian power distribution.)

Adam

[absolom7691]

Good news,
i powered-up the laser & used a linear multi-turn potentiometer across my lab PSU set to +5v.

applying this analogue control voltage to the 2 pin connector marked ‘TTL’ (as advised to by supplier) worked well. So it is analogue modulation, the the PCB was incorrectly labelled.
But it might not be the case for similar products from different suppliers.

This could still be PWM. With the naked eye, it's is impossible to tell the difference between PWM and pure analog from a static beam. If you had an O-scope you could look at the "waveform". The other way you could tell for sure is by scanning the beam. At 25% brightness, you should just see a "dim" scan line. If it is PWM, you will see pulses.

For instance, this is what image looks like from a PWM driver. I didn't know the driver was PWM until I was scanning.