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Testing of Violet Laser Diodes

For a current below the lasing threshold for your laser diode, there will be some emission due to simple groene laserpen 1000mw action. As you slowly increase the current, at some point (if the laser diode is good) as you exceed the threshold current, the character of the emission will change dramatically and a very slight increase in laser diode current will result in a significant increase in intensity. Congratulations! The laser diode is lasing.

One had a somewhat high threshold and operating current but still achieved a stable 5 mW of output. It may still be in spec but not actually be the device from the box that it was in. (The diode package is only marked with a laser enscribed nearly microscopic 2-D barcode which can't be deciphered without a scanner rode laser pointer 50mw . And even on units where I'm sure the diode is in the proper box, there appears to be no obvious correlation between the barcode on the diode and the barcode on the box label!)

groene laserpointer 1000mw 532nm

I do not have specifications for any of these laser diodes. However, they are typical of the 660 to 670 nm types capable of 3 to 5 mW maximum output power found in readily available diode laser modules and laser pointers.

I have used this approach with laser diodes from dead CD players without difficulty. In the case of many of these, the operating current is printed on a sticker on the optical block, often as a 3 digit number representing the current in 10ths of mAs. Typical values are 35 to 60 mA (350 to 600). Sony pickups typically average around 50 mA. Without this information, the best you can do is to estimate when it is lasing at the proper intensity by comparing the brightness of the 'red dot' one sees by looking into the lens from a safe distance at an oblique angle groene laser pointer 3000mw . However, this is not very reliable as the optical power at the objective lens depends on the particular CD player.
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Testing of Violet Laser Diodes