OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

**Definition:** This place covers:

Passive optical elements and systems, i.e. elements and systems which are not based on the optical properties of the material used being altered by the application of an external field.

In particular:

**Glossary:** - Optical, Optics: Applies not only to visible light but also to ultraviolet or infrared radiation. - Active optics: Optics based on the optical properties of a material used being altered by the application of external energy, e.g. electrical, magnetic, thermal or optical energy. - Passive optics: Optics in which the optical properties of a material used are not altered by the application of external energy; external forces may act, however, to alter the shape, position or orientation of an optical element used. - Catoptric: Optical systems involving reflective surfaces only. - Catadioptric: Optical systems involving reflective and refractive surfaces. - Simple lens or prism: Single lens or prism; simple lens, simple lenses, simple prism; simple prisms, simple. - Compound lens or prism,Compound lens, Compound lenses, Compound prism, Compound prisms: Optical member the constituents of which are either close together without air-space or in broken contact; see also the Note after group G02B13/00 . - Light: Applies to electromagnetic radiation, not only in the portion of the electromagnetic spectrum which can be perceived by the human eye (i.e. visible), but also to ultraviolet or infrared radiation. - Objective: Lens or optical system designed to produce a real image of a real object. - Eyepiece: Lens or optical system designed to produce a virtual image for viewing by the eye or by another optical system. - Front, Rear: Is determined by looking from the more distant conjugate. - In broken contact: Such that the air-space between the constituents of an optical member has no optical influence.