Photonics Dictionary

An image that is similar to the object but rotated 180° about the axis of the system.

A microscope designed so that the specimen is located face down above the objective.

The particular orientation of the image, such as normal, canted, inverted or reverted.

Lenses or prisms that serve to erect the image; i.e., to bring the image upright after it has been inverted by the objective.

A laser oscillator in which two mirrors are separated by an amplifying medium with an inverted population, making a Fabry-Perot cavity. Standard diode lasers are Fabry-Perot lasers.

Gain-switching is a technique used in lasers to generate short pulses of light by modulating the gain of the laser medium. This method is distinct from Q-switching and mode-locking, two other common...

See inverted image; population inversion.

The arrangement of two Porro prisms so that the inverted image formed by certain types of optical instruments is the same as the object. The first prism, which is set at 90° to the second, inverts...

A group of energy levels to which ions in the ground state are initially excited when pumping radiation is applied to a laser medium. The pumping band usually lies higher in energy than the levels...