PWM instead of analog for color control

[mixedgas]

if your NOT scanning graphics,, just pointing, you can get away with PWMing the TTL. It will reduce your current draw as well.

Steve

[Laser Ben]

I'm not trying to build a projector capable of fancy graphics. Really, I'm just trying to make myself a pointer with a large, adjustable color palette. Human vision only needs 20-30 Hz for something to be perceived as fluid and not flickering. Could a green DPSS do that? Or 100 or 1000 Hz? I'm sure I could build a suitable analog driver for my laser system (with the help of my electronics guru father) but PWM seems like it would be easier.

Not true, In a recent study done by Phillips/Lumileds, AC LEDs operating at 120hz caused extreme eye strain and made it difficult to concentrate on writing. You will for sure be able to see flicker in a 30hz pulse.

[mixedgas]

he can get 1 khz, easy.
'
No blink or flicker there unless the beam is moving, which makes it a cool effect.

Steve

[maxh]

Not true, In a recent study done by Phillips/Lumileds, AC LEDs operating at 120hz caused extreme eye strain and made it difficult to concentrate on writing. You will for sure be able to see flicker in a 30hz pulse.

Maybe flicker wasn't the right word to use. Perhaps frame rate. Apparently 60hz and even 120hz flicker in lighting can be perceived, although subliminally. This guy seems to think it's pretty horrible stuff with his list of possible side effects "a feeling of being unable to focus, disorientation, confusion, attention deficit/brain fog, irritability, headache, migraine, eye or neck pain, dizziness, queasiness, or an uncomfortable feeling down through the chest." I was almost expecting to see paralysis and/or death when I got to the end of the sentence!

http://www.conradbiologic.com/articl...FlickerII.html

Luckily I'll just be playing with the laser and not lighting my office space with it.

Thank you guys for the information!

[mixedgas]

[QUOTE=maxh;93349]Maybe flicker wasn't the right word to use. Perhaps frame rate. Apparently 60hz and even 120hz flicker in lighting can be perceived, although subliminally. This guy seems to think it's pretty horrible stuff with his list of possible side effects "a feeling of being unable to focus, disorientation, confusion, attention deficit/brain fog, irritability, headache, migraine, eye or neck pain, dizziness, queasiness, or an uncomfortable feeling down through the chest." I was almost expecting to see paralysis and/or death when I got to the end of the sentence!

Some of this valid, but most is not.


We had a PhD in the lab where I used to work. 3 or so flashes of a fast strobe and he was down for the day with migranes. We had tungsten lighting on his workstation, even though lamps flicker at 120 hz, he could tolerate the tungsten inertia vs the sharp edges when the flourescents flickered on the digital ballasts. He left the room when I turned on pulsed leds we used for microscope illumination, and he left the room for any strobes, A single flash was tolerable, but turn up the rate and he was in pain. Its just a very small fraction of people who have this problem, although a lot of low cost LED drivers make it worse. Only guy in the place that liked LCDs vs CRTs for image analysis and programing, too.

Yet he would bask in the light from tungsten, the sun, and filtered xenon arc. Steady xenon arc seemed to attract him. Also he was great for some motion studies, as he saw fast enough to not need a strobe in some cases.

The sarcastic remark I just thought of, was:
Mutation happens, live with it.....

We documented his problem, it was real, not psychosomatic.

IMHO:
The real one is gonna be short wavelength blue and yellow led light with no red and green is bad for you long term. The new sources have way too much blue, and this bleaches your ability to see green in the long term. Get away from the blue light, and green vision comes back. Blue doesnt focus so well either.

The irony is 100 uF of cap across the leds and its gone. caps are cheap,

Who were the study subjects?

Steve

[maxh]

Who were the study subjects?

I don't know; the guy didn't site his source.

[heroic]

We had a PhD in the lab where I used to work. 3 or so flashes of a fast strobe and he was down for the day with migranes.

A couple seconds of an 18 Hz strobe is enough to give me an absence; any longer and it's w00t w00t all aboard the seizure train.