February 26, 2025

Laser from Storm

After an email conversation, Storm offered to give me a laser unit and filter that he has. The idea is to use this to illuminate fluorescent mineral samples for spectroscopy.

Storm says that the usual 405 nm LED flashlights have a broad and messay spectrum, whereas these laser modules are pretty much monochromatic 405nm light.

The filter will go in front of the collimnator lens feeding the fiber to the spectrometer and will eliminate the 405nm light.

The diode

Storm says the seller made a claim of 100 mW. But we also know that these claims, made by Chinese sellers are often optimistic (i.e. exaggerated, often inflated). So who knows.

Storm also says that there is a good chance that this is a 20 mW diode made to be used in a blue ray player. There is no way to know the actual power output without some gadget to measure laser power (which cost $250 and up). The light output power and the electrical input power have no real correlation.

Plugging the unit into 12 volts causes a "pilot light" LED on the PCB to come own and a reasonable level of purple/blue light to come out of the diode. No bright flash followed by a burned out diode, which is nice.

The diode driver

He sent me a diode driver along with the laser. It looks like this item:

This is a "buck" mode current regulator for 405, 450, 520 nm diodes at 1, 1.6, and 2 watts. You give it 12 volts (they say 8 to 14 volts AC or DC). The Amazon listing gives the maker as "Jolooya".

Amusingly, the AliExpress listing gives the most information. It shows + towards board center for all connectors on their PCB.

My unit has 3 unused 2 terminal connectors -- what are they? Another almost identical unit on Ebay labels the one near the blue pot as "TTL", and has one near the 12V barrel connector marked "fan".

Using a meter on mine, I determine that the connector immediately behind the barrel connector is just an alternate way of providing 12 volts. With the barrel connector towards you, the pin on the left is ground, on the right is 12 volts.

Behind that is another 2 pin connector. Now the ground is on the right. On the left we have DC power (via a diode from the power input). This is no doubt a fan connector.

Now just the "TTL" control is a mystery. This connector has ground on the right..

Current level is set by the blue pot. The listings say that 500 mW is the way it is shipped out. There is another tiny pot. The listing says that both voltage and current is adjustable.

There are two 8 pin chips on the board:

MP1484EN - this a a 3A buck regulator that contains a pair of MOSFET and can accept from 4.75 to 18 volt input.

9926A - a dual channel power MOSFET

Have any comments? Questions? Drop me a line!

Tom's Electronics pages / tom@mmto.org