Calibrators are device used to calibrate instruments. Calibrators vary in form and function depending on the instruments with which they are designed to work. The types of calibrators are black body calibrators, block calibrators and fluidized sand bath temperature probe calibrators. Some calibrators incorporate both temperature environment and sensor output functions.

Caliper is a device used to measure the distance between two symmetrically opposing sides. A caliper is as simple as a compass with inward or outward-facing points. The tips of the caliper are adjusted to fit across the points to be measured. They are used in the metalworking field of mechanical engineering, handloading, woodworking and woodturning. Calipers are used by glassblowers to measure outside diameters, inside diameters, wall thickness and other dimensions specified by the drawings used in fabricating glass apparatus.

Camera is a lightproof box or container fitted with a lens, which gathers incoming light and concentrates it so that it can be directed toward the film (in an optical camera) or the imaging device (in a digital camera) contained within. They are made up of the same basic parts a body (the lightproof box), a lens and a shutter to control the amount of light reaching the light-sensitive surface, a viewfinder to frame the scene, and a focusing mechanism. The 35-mm cameras, both rangefinder and reflex models, incorporate a rapid film-transport mechanism, lens interchangeability (whereby lenses of many focal lengths, such as wide-angle and telephoto, may be used with the same camera body), and a built-in light meter. Many also have an automatic exposure device whereby either the shutter speed or the aperture is regulated automatically (by means of a very sophisticated solid-state electronics system) to produce the correct exposure. Accessories include filters, which correct for deficiencies in film sensitivity, flash bulbs and flash mechanisms for supplying light and monopods & tripods for steady support.

An electron gun for a camera tube includes an anode and a cathode. The cathode is assembled in a cathode support which can very readily be adjusted relative to the anode in the non-connected condition. In particular, the cathode support and the anode are movable radially with respect to each other and with respect to an axis. An emissive cathode surface and a part of the anode extending perpendicular to the axis remain accurately parallel to each other during the radial movement. As a result of this it is possible to cause the central path of the generated electron beam and the gun axis to coincide so that extra correction coils for aligning the electron beam may be omitted.