A laser diode differs from an LED in a very small crystal area. This leads to a significant concentration of power, therefore, even a short-term excess of the current through the diode junction can lead to the combustion of the crystal not by heat, but by its own radiation.
Instructions
Step 1
The most convenient red laser for experiments with an output power of about 200 milliwatts, available in every computer DVD burner. Take a drive with worn mechanics, no longer fit for its intended purpose. After making sure that the device is de-energized and not connected to anything, disassemble it and remove the two laser diodes from the moving carriage.
Step 2
Check both diodes in action. To do this, directing the lens of the device away from you onto a sheet of paper, connect a battery from the motherboard to it (not necessarily a new one, but a half-discharged one). The laser has three leads, two of which are interconnected - they are negative, the remaining lead is positive. Choose the one of the two diodes that will illuminate the sheet with a bright and saturated red color. The second device is infrared. Weak red radiation from him is a side effect, the intensity of infrared is much higher, so it also cannot be directed into the eyes.
Step 3
Install the laser, which turned out to be red, on a homemade radiator. To do this, drill a hole of such a diameter in an aluminum plate about 4 mm thick so that the device fits tightly into it. Apply a thin layer of thermal paste between the diode housing and the heatsink.
Step 4
Take a 20 ohm 5 watt ceramic wirewound resistor. Such resistors are found, in particular, in old Mustek scanners. Observing the polarity, connect the diode to the cell phone charger through this resistor. Shunt the laser itself with a ceramic capacitor of any capacity.
Step 5
Turn the laser away from you and plug the charger into the mains. A light will appear. Try using a plano-convex or biconvex lens to focus it on a sheet of fusible red-absorbing material (such as black or dark blue plastic). Hold it for a few seconds at one point, and a trace will remain in the place of its hit.
Step 6
A spectacular experiment with a laser diode can be carried out as follows. Get a thin rubber ring (you can find a set of these at office supply stores). Wrap the large-diameter felt tip tightly around the ring. Paint a small section of the tape with another felt-tip pen black. Focus the laser at this point, and after a few seconds you will burn out the ring and the marker will bounce slightly. Naturally, it will not be the light energy that will make him jump, but the kinetic energy of the stretched rubber ring, but the audience can only tell about this after the demonstration.
