Safe bright green fatbeam w/TTL recommendation for writing on buildings

[Draco]

Maxcandy
I have a question that is unrelated to safety but related to how you create your shows in the analog realm, I operate an open loop galvo in my living room and right now i just feed it audio, your video from your Oscope got me thinking, how to you make the patterns that it displays? I don't do shows but i would love it if i could get that thing to make more interesting visualizations and have no clue on how to do it, i was hoping you could point me into that type of direction, my galvos though have a steep slope off past 500hz but i can drive them a bit harder if i dont have them deflect the beam as far, two of my lasers are TTL and one is analog, my green is 25mw, and my red and blue are 120mw max and are all single mode but for my enjoyment only. any info would be great

[catalanjo]

..... any info would be great

DZ - aldebaran-systems.com would be a pretty good place to start IMHO
Cheers

[Draco]

thanks for that link, interesting stuff

[catalanjo]

Most electronics circuits which start with VC you will find helpful.
VCO,VCA,VCF etc. you just use filtered music as the V.
Cheers

[maxcady]

TTL has (almost) NOTHING to do with the safety of a laser. In general, if you were going to choose a laser that could be safer you would NOT want TTL.

TTL only means that the diodes are at full power, or zero power. There is no 50% power. When you have a TTL laser the beam is either on or off. That's all it means.

The opposite of TTL is analog which means that the diodes can dim so you could reduce the power to say 30% which would make it generally safer.

You can put either a TTL or analog laser into an XY scanning system, or you can have them in a single beam pointer arrangement. Again, this has nothing to do with whether the beam is eye-safe or not.

Hmm.. I guess the person who supplied me with this said the wrong thing to me, he always told me to use the ttl input to control the intensity of the laser using pwm. the power supply has a "TTL INPUT" labeled jack, but it responds to slow lfos by dimming the laser. does that mean its analog but the input on the circuitboard is mislabeled? its very odd, both my friend and the actual powersupply say TTL.

Thanks for this. I've been absolutely slammed lately, but I do plan on contacting you about coming by, I really appreciate it.

[swamidog]

no. you're reducing apparent brightness by reducing the duty cycles as I stated earlier. that is not how analogue modulation works.

I highly suggest you disregard everything your supplier told you. he does not understand what he is telling you.

Hmm.. I guess the person who supplied me with this said the wrong thing to me, he always told me to use the ttl input to control the intensity of the laser using pwm. the power supply has a "TTL INPUT" labeled jack, but it responds to slow lfos by dimming the laser. does that mean its analog but the input on the circuitboard is mislabeled? its very odd, both my friend and the actual powersupply say TTL.

Thanks for this. I've been absolutely slammed lately, but I do plan on contacting you about coming by, I really appreciate it.

[frostypaw]

Hmm.. I guess the person who supplied me with this said the wrong thing to me, he always told me to use the ttl input to control the intensity of the laser using pwm. the power supply has a "TTL INPUT" labeled jack, but it responds to slow lfos by dimming the laser. does that mean its analog but the input on the circuitboard is mislabeled? its very odd, both my friend and the actual powersupply say TTL.

Thanks for this. I've been absolutely slammed lately, but I do plan on contacting you about coming by, I really appreciate it.

It probably is TTL. Your friend just hasn't really looked into this and I'm afraid should probably be disregarded about laser safety, start again for your own sake at least.

TTL means it's on or off, no inbetween - so no matter what rate you modulate it at with PWM it's potentially able to scan across someone's eye at full power for the time it crosses that 7mm pupil so identical to it just being full on and crossing that pupil - boom eye perhaps.

Analog dimming would mean it's not switching on and off quickly to simulate dimming - it's genuinely only outputting 10% of it's full power so when it goes across an eye it'd only deliver 10% of the irradiation you'd get from the TTL modulated or full power unmodulated beam.

[planters]

Thanks for this. I've been absolutely slammed lately, but I do plan on contacting you about coming by, I really appreciate it.

In your original post you were hoping to get a solution by the 23rd. I am hoping that with some new knowledge that you are not doing public laser work until you have obtained some safe equipment. Although we might sound a little like old ladies worried about something that doesn't SEEM too bad. it really can be and you just can't know.

[maxcady]

no. you're reducing apparent brightness by reducing the duty cycles as I stated earlier. that is not how analogue modulation works.

I highly suggest you disregard everything your supplier told you. he does not understand what he is telling you.

Understand now! My laser is in fact TTL, not mislabeled. Tested yesterday with LFOS and PWM and it's clearly just reducing apparent brightness, there is no dimming happening when using LFO's

[maxcady]

In your original post you were hoping to get a solution by the 23rd. I am hoping that with some new knowledge that you are not doing public laser work until you have obtained some safe equipment. Although we might sound a little like old ladies worried about something that doesn't SEEM too bad. it really can be and you just can't know.

I appreciate this !

I stopped doing what my original pie in the sky plan was until I can confidently do it myself and know that it's safe without relying on anyone else.

I've still done the gigs though, just very differently, with the projector completely impossible to approach by anyone but me, sandbags, high above everyones heads, hard masked laser output port, constant galvo modulation, "accidental exposure" minimum distance of 20 feet, no blue highpower just 50mw green/red fatbeams. always standing by power strip 'off' switch during the projection.

I plan on getting power meter, going by x-laser with my stuff to hopefully have them examine, and gain knowledge. until then its shows like the above description with lower power green or red fatbeams.