A common red or blue laser pointer module contains the following components Laser diode, photo diode (in order to control output power), optics (to convert the highly divergent beam from the bare laser diode), PCB, Driver IC (optopnal) and housing.

• Laser diode. The laser modules have the laser diode in its own can package mounted (probably press-fit) in a metal casting which in addition to holding the optics also acts as a heat sink.
• Laser power driver circuit. Many of the visible laser diodes used in laser modules have very precise current requirements. Too little and they don't lase; too much and they turn into poor imitations of LEDs or die entirely. The only reliable way of regulating the current for these is by monitoring the light output. So, the laser modules usually include a laser diode driver that provides some degree of regulation based on optical feedback from the monitor photodiode inside the laser diode package. The better designs would maintain output power nearly constant until the batteries were drained; the output power for some simpler designs would vary with battery condition and the operating temperature.
• Collimating/correcting optics. At the very least, there must be a lens to convert the highly divergent beam from the bare laser diode to one that is roughly parallel. Some will also have an easy focus adjustment.

  Note that with the typical optics used in laser pointers, as much as 30% or more of the light from the diode may be wasted largely due to its high divergence.

• Some means of generating multiple patterns (optional). These permit the projected shape to be selected to be something other than a formless spot either by a built-in thumb-wheel type or by replacing end-caps.