PHR-805 graphs

ive asked cyparagon to graph these diodes so we know a bit more about them. hope this helps..

2 diodes were tested ill see if he can post the details of his methods of testing.

he also found that the PHR-805s are case negative unlike most 405nm diodes.

Cyparagon said:

Here are the new graphs.

Cooling them raised the voltage drop and lowers the wavelength. The red drops about 4nm when cooled to ~35F and the violet drops about 3nm when cooled to ~35F. The reds start at 657nm and rise ~0.015nm/mA. The violets start at 406nm and rise ~.040nm/mA.

The "series 1" of the violet graphs was cooled but many things were changed throughout the test such as duration of each current step, TEC voltage, TEC heatsink fan voltage, and lens. Better to take "series 2" as a reference.

Click to expand...

the red diodes he mentions are the LPC-826 diodes. you can find the graph for those here: http://laserpointerforums.com/f50/lpc-826-graphs-63867.html#post913902

That's quite a shift in wavelength. I can only assume it is far more visually appealing.

ndrew2505 said:

ive asked cyparagon to graph these diodes so we know a bit more about them. hope this helps..

2 diodes were tested ill see if he can post the details of his methods of testing.

he also found that the PHR-805s are case negative unlike most 405nm diodes.



the red diodes he mentions are the LPC-826 diodes. you can find the graph for those here: http://laserpointerforums.com/f50/lpc-826-graphs-63867.html#post913902

Click to expand...

Although they definitely show a knee above 200mA. I am more concerned with the kink at around 110mA. We know from many other diodes that for predictable long life, we have to remain below the first kink. If that remains consitent, this "805" will be no different than the "803T" in performance. Granted the case-negative is different, but the IP/OP is VERY similar

What is the price of these 805's compared to our old friend the 803T's?

Peace,
dave

its the same price as a phr803 sled. you also have to note that the "series 1" factors changed a bit during testing. in the quote from him he said its better to use "series 2" as a reference.

I was fighting with condensation on the lens the whole time. Both the condensation and me trying to mitigate it by changing things... makes for power reading I'm not too sure about. I could test the last one I have. I don't have any plans for it, otherwise.

Is the voltage graph the minimum voltage?

The voltage graph is what that particular diode was drawing at that particular current. With all laser diodes, the exact voltage required to maintain a current will vary from diode to diode, as well as with temperature.

As the diodes heat up, they draw more current for a given voltage. This is why CV drivers are in general, bad ideas with laser diodes. If running a diode 'on the edge' as it were, as most hobbyists do.. which is a lot higher than manufacturer recommendations.. Thermal runaway is a certain danger when using a CV supply.