Abstract: An improved folded cavity laser having particular application to holographic imaging is disclosed. The laser includes a lasing medium, such as for example a ruby rod, which is optically or electronically "pumped" in order to provide laser light. The medium includes first and second optical surfaces disposed at opposite ends of the lasing medium. A retro-reflecting roof mirror is disposed in optical alignment with the second optical surface of the lasing medium. A transverse mode selector is provided in optical alignment with the first surface of the lasing medium in order to surpress all transverse modes except those of a desired character. In the present embodiment, the transverse mode selector includes two apertures of approximately two millimeters diameter in order to obtain a laser output with a TEM.sub.00 mode.