Glossary

Checking a probe or the scales of a measuring instrument against a standard.

Abbreviation for “Charged Coupled Device” - a type of digital photo chip.

Abbreviation for “Complementary Metal Oxide Semiconductor” - a type of electronic chip.

Material constant indicating the degree of expansion of the material due to temperature rise.

If the light emitted from a filament bulb is transmitted through an optical fibre, only the emitted light will be transported, but not the emitted heat. The light emerging at the other end of the optical fibre will therefore be cold and cannot cause linear thermal expansion of the measuring instrument or the workpiece.

A term frequently used in photography. The length along the optical axis, over which the image generated by an optical system is constantly sharp. In contrast to microscopy, in most photographic applications a high depth of field is desired to achieve constantly sharp imaging of objects which are close as well as objects which are more remote (see also “depth of focus”).

The length along the optical axis, over which the image generated by an optical system is constantly sharp. As the resolving capacity increases with decreasing depth of focus, the depth of focus for microscope objectives should be as small as possible. In addition, the smaller the depth of focus, the higher the accuracy in measurement by focussing the image will be.

Electrical semiconductor element featuring the special property, similar to a valve, to allow the current flow only in one direction.

Also referred to as field of vision. The area of a workpiece viewable through a microscope. On observing an object through the eyepiece of a microscope a circular area will be viewable. If a digital camera is used, the field of view will be rectangular (due to the rectangular form of the digital photo chip).

Auxiliary equipment to fix the workpiece to the machine or measuring instrument, preventing it from shifting caused by machine motion or accidental touch.

Describes a point on the optical axis in which all light beams emerging from it are refracted by a lens into a bundle of parallel rays. Reciprocally, parallel light beams are bundled in the focal point by a lens (burning glass effect).

If an object is in the focus of a lens, the light beams emerging from any point on the object will be bundled by the lens in exactly one point in the image plane. In other words: The object will be imaged sharply.

The amount of deviation between a real and an ideal form.

The resolution of a scale is the smallest unit length which can be determined using the scale. The smaller this value, the higher the resolution of the scale.

Short for “Light Amplification by Stimulated Emmission of Radiation”. Highly energetic, almost punctiform light source.

Short for “Light Emitting Diode”. In other words: A diode emanating light, or even more simple – an illuminating diode.

This parameter enables the comparability of different measuring instruments with regard to the quality of the determined measuring results.

A parameter assigned to a measured value, stating the uncertainty of the measured value – that means, the possible deviation between the determined dimension and the real dimension.

Statistical method to determine if a certain measuring instrument is suited for the solution of a specified measuring problem. The dispersion of the values measured by the measuring instrument must be relatively small in relation to the dimensional tolerance.

Light-sensitive semiconductor element. The higher the intensity of the light falling onto a photodiode, the higher the amount of electric voltage generated in the element.

The smallest sensor element on a CCD- or CMOS-chip, consisting of a photodiode and the appendant controlling elements and conductors. Each pixel on a chip determines a brightness value, independently from the other pixels. A digital image will be generated by representing these brightness values in the same pattern in which the pixels are distributed on the chip. Therefore, the individual image point of a digital image is also called pixel.

The direction from which the probe of a measuring instrument performs the measuring point detection. A contact probe e. g. is moved in probing direction until it will touch the workpiece. Many probes will not function equally in all directions; the measuring point detection will be triggered earlier in some directions than in others. In high-accuracy measurements (e. g. for instrument calibration) this must always be considered.

A conventional video camera constantly transmits fields alternately. This means, while the camera is e. g. capturing the upper half of the image, the lower half will be output and vice versa – alternately and in quick succession. Progressive cameras, in contrast, capture and output the complete image.

Statistical value; stating the dimension in which the collected values scatter around the mean value.

Reference or master workpiece featuring a specified and known length or dimension.

Optical system using only those light beams for imaging an object that are to a large extent parallel to the optical axis.

A contact sensor functioning similarly to an electric switch. On contacting the workpiece the sensor outputs a one-time signal. Before the next signal can be emitted, the probe must retract from the workpiece.