UPDATE: So I received all of the parts a couple of days ago, and I've begun testing some simple boost circuitry.
Does anyone use bench supplies or wall adapters for their laser projects? I can quickly fab out some simple bench-sized filtering driver circuits for running laser diodes off of a wall supply. If you're really interested, I can also add some simple transformers/rectifiers for a straight 110V/220V-to-laser power supply.
I don't know much about drivers, but it seems people use dummy loads because it's unsafe to change the current with the diode attached and lasing. I'm not sure if that's because the tester wouldn't know when the max current has been reached or because messing with the pot it generates noise that kills the diode.
What I'd like to see is a driver with three holes to solder an *external* pot, which would have the knob reacheable from outside the host, so that the user could vary the current with the laser running. This video illustrates what I mean:
Perhaps it could even have another internal pot to set the max allowed current.
Of course for this to be useful the driver would have to support a wide range of currents without soldering anything.
Hope I explained myself well!
I still might be misunderstanding you, but I'll take a shot:
The drivers we use (or at least the ones I use) for laser diodes are the type that force a certain amount of current (set by a pot) through any given load. If this load is purely resistive, it will therefore also generate some sort of voltage drop across that load. Therefore, when I say "Max current set by pot", It means that that exact current will be output by the driver, regardless of the load. either that, or the driver dies.
Other forms of power sources, such as wall adapters for electronics and transformers for household devices come with a set output voltage rating (say, 5V) and a max allowable current rating. So, for example, your 5V 1A phone charger will supply a 5V potential, and the device can
draw anywhere from 0mA to 1A of current, depending on its needs.
I dont see how two pots would be of any use, if you need to dim the diode you can set the driver to a max saturation current (something that wont burn the diode) and then use the pot to lower that value when you need to dim.
With LEDs, people tend to dim in two ways. The analog way (like explained above) or the "digital" way, by adjusting the duty cycle. By turning the LED on and off in very short pulses that are faster than the human eye can percieve, you can create the illusion of "dimming". This is done by adjusting the pulses so that if every "pulse" was 100ms, the LED would be off for 80ms and on for 20ms. This creates the same effect visually as dimming the LED to 20% brightness.
We can't do this readily with Lasers, because there is both a threshold current, and the fact that sudden changes in voltage/current can damage the diode itself. You can, however, switch the diode between a "LOW" power mode (Near threshold) and a "HIGH" power mode (near usual operating point) if you are interested in doing some sort of modulation, or communications system.
So, what is the nature of the dimming that interests you? And what will you be using it for?
