An antivalent sensor has two switching outputs (switching output); one of them is dark switching (Closed or NC), the other one is light switching (Open or NO). To use them, you need 4-wired connection cables or clamps.


Electro-sensitive protective device whose sender elements send beams to receiver elements. The active opto-electronic protective device (AOPD) detects an opaque object when the object interrupts the beam path. AOPD stands for active optoelectronic protective devices; it is used for sensors based on the active optoelectronic principles. 


Apertures are mechanic parts that limit the beam space. or is a circular opening within the lens which determines the amount of incident light. by means of which the diameter of the light beam can be changed and the depth of focus is increased.

Aperture Size / Barcode

The dimension of the opening through which the scanning beam passes. Normally used in conjunction with a wand (pen) type bar code scanning device. The aperture size will determine the bar code density which may be read with the scanning device.

Aperture stops

The aperture stop is an element of an optical system that determines the amount of light reaching the image. This stop is often the boundary of a lens or mirror, although it may be a separate diaphragm. In addition to controlling the amount of light entering the system, it also is one of the determining factors in the sizes of system aberrations. For most telescopes the primary mirror serves as the aperture stop, although in many infrared telescopes the secondary mirror is the aperture stop.

Aperture value

Synonyms :

Number which characterizes the luminous sensitivity of a lens. also known as f-stop.