Precision Graduations the Foundation for High Accuracy
The heart of a HEIDENHAIN encoder is its measuring standard, usually in the form of a grating with typical line widths of 0.25 µm to 10 µm. These precision graduations are manufactured in a process invented by HEIDENHAIN (e.g. DIADUR or AURODUR) and are a decisive factor in the function and accuracy of encoders. The graduations consist of lines and gaps at defi ned intervals with very little deviation, forming structures with very high edge definition. These graduations are resistant to mechanical and chemical infl uences as well as to vibration and shock. They have a defi ned thermal behavior.
Special manufacturing processes make it possible to produce three-dimensional graduation structures, possessing special optical characteristics. The structure widths are in the range of a few microns down to quarters of a micron.
Graduations manufactured with the SUPRADUR process act optically like three-dimensional phase gratings, but they have a planar structure and are therefore particularly insensitive to contamination.
Thin magnetically active layers in the micron range are structured for very fine, magnetized graduations.
DIADUR precision graduations are composed of an extremely thin layer of chromium on a substrate usually of glass or glass ceramic. The accuracy of the graduation structure lies within the micron and submicron range.
AURODUR graduations consists of highly refl ective gold lines and matte etched gaps. AURODUR graduations are usually on steel carriers.
With its special optical composition of refl ective gold layers, METALLUR graduations show a virtually planar structure. They are therefore particularly tolerant to contamination.