Hi all,
New to the forum, and relatively new to the 445nm diode. I recently received my first and began experimenting with it. Since I had a bad experience a while back, trying to get my first 405nm diode to lase using my DIY LM317 constant-current PS (destroyed it presumably by static and/ or failure to drain caps, arrgh), I decided to be ultra-careful, and used a 6V battery and assortment of power resistors to very gingerly test my new 445. I was extremely pleased to see it lase at currents similar to reports on this forum. I'm interested in creating a plane of light, using line-generating optics, and unlike most laser display systems, want to be able to lower the light output to very low levels-- lower than the lasing threshold of this diode. I already have a nice assortment of home-made hardware and software that allows me to PWM long strings of RGB LED's (2+amps/channel), and decided to try PWM'ing the 445nm diode's battery+resistor supply, limiting current to 200-300ma. It works beautifully-- I can produce extremely low levels of brightness, and by keeping the PWM rate >100Hz, I cannot detect flicker (I do not intend to scan the output). My PWM resolution is 1000, so the shortest on time is 10usec (at PWM rate = 100).
So now, I'd like to build a non-battery operated PS, and keep the PWM. But I'm concerned about PWMing a constant current source-- seems like that's a bit of an oxymoron. Also, I'm not interested in portability -- those tiny pointer-inspired PS's don't seem the best way to go for me. Is there a way to use PWM, and at the same time supply "safe" power to the diode? I'd like to build my own supply, but a reasonable commercial option would be OK.