Optical heterodyne laser encoder with sub-nanometer resolution

Chyan Chyi Wu, Cheng Chih Hsu, Ju Yi Lee, Hui Yu Chen, Ching Liang Dai

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


This paper presents a novel laser encoder for sub-nanometer displacement measurement. It is based on optical heterodyne interferometry and two sets of conjugate optics with a symmetric and quasi-common-path optical configuration. It offers displacement measurements of high stability, high resolution. The theoretical analysis shows that our method can effectively compensate misalignments resulting from the dynamic runout in laser encoders. Experimental results reveal that the laser encoder can detect a displacement variation down to sub-nanometer range.

Original languageEnglish
Article number045305
JournalMeasurement Science and Technology
Issue number4
StatePublished - 1 Apr 2008


  • Heterodyne
  • Laser encoder
  • Misalignment
  • Sub-nanometer


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