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Measuring standard

HEIDENHAIN encoders with photoelectric scanning incorporate measuring standards of periodic structures known as graduations. These graduations are applied to a glass or steel substrate. Glass scales are used primarily in encoders for speeds up to 10000 rpm or measuring length up to 4 meters. For higher speeds—up to 20000 rpm—steel drums are used. A steel scale tape is used on encoders for large diameters or measuring lengths up to 30 m.

These precision graduations are manufactured in various photolithographic processes. Graduations can be fabricated from, for example:

  extremely hard chromium lines on glass or gold-plated steel drums,
  three-dimensional grid structures on glass or steel substrates,
  semitransparent chrome lines on gold-plated glass or steel substrates,
  or matte-etched lines on gold-plated steel tape.