Editing Laser diode (section)

=== Formation of laser beam ===
Due to [[diffraction]], the beam diverges (expands) rapidly after leaving the chip, typically at 30 degrees vertically by 10 degrees laterally. A [[lens (optics)|lens]] must be used in order to form a [[collimated beam]] like that produced by a laser pointer. If a circular beam is required, then cylindrical lenses and other optics are used. For single-spatial-mode lasers, using symmetrical lenses, the collimated beam ends up being elliptical in shape, due to the difference in the vertical and lateral divergences. This is easily observable with a red [[laser pointer]]. The long axis of the ellipse is at right-angles to the plane of the chip.

The simple diode described above has been heavily modified in recent years{{When|date=November 2024}} to accommodate modern technology, resulting in a variety of types of laser diodes, as described below.