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Laser diodes from CD-RW drives can cut and burn!

Everyone certainly knows laser pointers. You can have a lot of fun with them. On the other hand the pointer only shines, has no thermal effect. Not surprisingly, when its optical power is only around 1 mW (maximal 5mW). I wanted to make a laser with higher power output, but the construction of classical laser is very difficult, so maybe sometimes...
     Recently I came across 3 broken CD-RW burners. Lasers in these drives tend to have a pulse output of about 100 - 250mW and continuous power 50 - 125mW and work in the infrared range at a wavelength of 780nm. Average operating current is about 100 to 150 mA, pulse up to 200mA. I used a supply of 100mA (it would be possible to use more, but there is a risk of destruction of diodes, because its type is difficult to identify). The voltage drop across the diode is about 2.1 - 2.15 V. As a current limiter I used simply a resistor. It's not ideal solution, but it works. Better would be a stabilised current supply with 7805 or LM317 (see here).
     In the original construction of the laser unit, the laser beam is focused at the focal length of a few mm, which is not suitable for experiments. There are two lenses: the first transforms the divergent diode light into an parallel beam, the second focuses it to a near point. There are two possible solutions:
     1) Remove the laser diode and place it into optics from another device (laser printer, metal pointer, ...). This is only possible with conventional housings 5.6 mm which fits into the optics.
     2) Leave the laser diode in the the original unit, remove one of the lenses (the one closer to CD). The second lens is shifted a little bit away from the diode to make a beam focused to a focal point at a desired distance (1cm to 1m or more).
     Laser diode must be placed exactly on the axis of the lens, otherwise you can not focus the beam. The laser diode should never be turned on if it is not placed in a sufficiently large metal cover - this serves as a heat sink!
What you can find in various drives:
- In DVD-RW drives there are 2 burning laser diodes: red for burning of DVD and infrared for burning of CD.
- The DVD-ROM drives (reading only) can only offer you a weak red diode like 1mW. they are good only to produce pointers or very faint laser-light show. They won't burn or cut anything.
- In the CD-RW / DVD-ROM combos (drive that burns CD and only reads DVD) you can find burning infrared diode and weak red diode (as in DVD-ROM)
- Finally, the diodes from CD-ROM readers are completely useless :).

Class IIIb laser

     Warning! Laser diodes from CD-RW emit invisible laser radiation and they are very dangerous! Their light can permanently damage the eyes. You must never look into the working diode even without the lens or point it on a reflective surface. Laser beam can cause burns or fire. This is usually a Class IIIb laser. Everything you do at your own risk.

The simplest connection of the laser diode. The case is "-". Better is this one.

Calculation of the series resistance of the laser diode (supply voltage U must be at least 1V higher than the laser diode voltage drop Ud). The Ud voltage drop is 2,15V for infrared and 2,5V for red diodes. Never set the current above 0,2A.

CD-RW drives that I broke down: Samsung, MSI and Hewlett Packard.

Laser unit from the Hewlet Packard CD-RW drive 10x 4x 32x.

Disassembled drive from below

Laser diode

laser diode built into the screw optics from a laser printer.

LASER I. finished and running. Focal length is adjustable from 1 cm to infinity. Laser burns into objects and cuts rubber tape over a distance of 1m.

open unit from Samsung 40x 12x 40x drive

laser burns a hole in the duct tape, the unit is in original condition, where the focal length is only few mm.

Integrated laser diode - an unusual type, it is a laser diode and sensor in one case, in such a drive there's no semitransparent mirror. The diode has 12 pins, I used only 2 (power inputs of laser).

LASER II. in a quick design cuts the rubber tape.

Letters burned by LASER II.

LASER II. in final form. I used here only one tiny lens in the square case. The focal length is fixed at 15 cm.

Laser diode from MSI 40x 12x 40x drive in the housing ...

...and without housing.

You can download the laser videos in the videos

upozornění pro lamy
Note for lamas:
If the diode is connected to any power source (even regulated) without resistance or current regulator, the diode will be destroyed! The laser diode has almost zero differential resistance. The voltage drop of 2.1 V does not mean that the diode should be connected to 2.1 V! Always use either current supply or a supply of higher voltage and a series resistance.