Four KES-400A graphs and two destructively tested

I tested four blu-ray diodes from KES-400A modules (PS3 replacement pickups)

The first two which I tested behaved normally, and I could clearly distinguish a 'knee' with which I can deduct the sweet spot.

The next two which I tested deviated from the first two and did not show a knee at all, until they broke. Interestingly, one of those broken ones was a strange kind of 'freak' (not the normal one with the increased threshold current) and, despite being broken, is still better than the two normal ones.

This graph shows measurements of 1mA (!) increments, from the threshold current and up.

Re: Four KES-400A graphs and two destructively tes

hey hey looks good and thanks for testing. Can you descibe your testing hardware/software?

Re: Four KES-400A graphs and two destructively tes

• Lab bench power supply capable of at least 20V, with manual 10-turn voltage knob
• 100 Ohm series resistor for diode (no driver)
• Professional hand held multimeter (<3% accuracy)
• Unmodified Aixiz with acrylic lens focused at infinity
• Alpha125's/xarylx' optical power meter, 1mw resolution, calibrated with a Nova Alpha125, according to previous author.
• Diode module 3-4" away from sensor

And for the 'software': I increased the voltage, such that I make 1mA steps, until the mW reading upped one, and wrote down the mA. I did this for all mW steps until I spot a knee (I kind of keep track of how much the mA increases for several mW and if this starts diminishing, I stop). A list might look like this:

Actualy this means this, but that's implicit:
Then, I used Excel to take the average of each successive mA reading with the next (except the zero). The reason behind this is that all mA steps have their corresponding minimum mW reading, and the values in between have the mW reading of the values above. The average, however, is a good indication of the current needed on average for that amount of mW. Now the table looks like this: