Step 1: What do I need to build a laser?
Basically, you need:
laser diode (LD)
current regulator (aka driver)
something to house all the electronics (project box is ok for a first build)
then you can add other optional things:
LED for power indication
Step 2: What tools do I need?
DMM (digital multi meter, even the cheapest works fine)
some wires (the more flexible the better)
other useful tools:
Step 3: Step 1: Gathering the laser diode
Here you have 2 options:
either to get a DVD drive for pc and extract only the diode assembly (aka sled).
or buy just the laser assembly from the internet.
You can get old DVD RW drives on ebay for >15usd, or just look around and ask friends if they don't have some old unused drives.
The another option is to buy just the sled ftom internet.
My favourite e-shops for laser components:
on these sites search for LPC-815, this is the most commonly used red laser (22x write speed).
What if I can't find the LPC-815, if I have only 20x or 16x burner, or if I'm not able to determine the write speed?
First, use google to find out something about your drive (search for part numbers from the label), this should bring out enough information. Remember the write speed.
You must extract the diode from the sled. This video shows the process:
if you have other model of dvd burner, set your DMM to the DIODE TEST mode and test both diodes using the pinout below. When you see bright red light, you've got your diode :)
Step 4: Step 2: Collimation optics
The most common colimator is called Aixiz module, and it serves as the holder for both the diode and lens.
The diode is being press-fit into the module, using vice (see the pics).
You can buy it from the e-shops I mentioned in previous step