Mitsubishi Diodes Clarification?

Ok, so I've read a LOT of threads on these somewhat new Mitsubishi 635nm diodes. I see that some have been driven as high as 1A, and as low as around 500mA. So i was planning on building one, because I just love that color, and was wondering what would be the optimal current for a very long life. I was thinking maybe 600mA, or 700mA.





Thank you

Long life is a tough question to answer. And they've actually been driven up to 1.7A or higher.

There are a few things to balance:

- The "high point" in the power curve is at 1A
- The higher the current, the higher the heat and wavelength.
- Higher wavelengths decrease visibility.
- Higher currents also tend to cause the Mits 300s to peak high, and then drop in power (not permanently, just during your use cycle)

I set mine at 1A. Others set theirs at 700 or 800mA. In my mind, it depends largely on your use case.

I tend to use my lasers for very brief periods of time. So my preference with the Mits 300s is for a decent up-front power. If wavelength shifts upwards a tad, and power decreases a bit, by the 1-minute mark, that's cool with me - especially if it means a more visible brighter beam upfront.

If you were using this diode in a projector (if that's even possible), or some sort of longer duty cycle labby, then you'd probably want to go lower on the current.

I have one of these in a small flashlight host set (conservatively) at 700mA doing about 350mW steady. It will run for about 2 minutes before the host gets even slightly warm.
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I don't like them very much, as the multi-mode nature of the diode creates almost a 3 inch wide "bar" at less than 100 feet.

Ok. So I decided to push mine at 700mA. I have another question, should I use an AR coated acrylic or a glass lens? I see that many have used acrylic but doesn't the lens melt?

I am using glass in mine. Acrylic shouldn't degrade until about ~400mW or so (guess), but I'm not taking the chance. :beer: