Optical heterodyne laser encoder for in-plane nanopositioning

Chyan Chyi Wu, Cheng Chih Hsu, Ju Yi Lee, Cheng Yang Liu

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

3 Scopus citations


Laser encoders as an optical displacement measurement technique have many applications such as modern manufacturing, scanning probe microscopy (SPM) and nanomanipulation. For the measurement scale down to the nanometer range, the stability, sensitivity and tolerance to dynamic runout are the key issues for laser encoders. This paper presents a novel laser encoder for sub-nanometer displacement measurement. It is based on optical heterodyne interferometry and conjugate optics with a symmetric and quasi-common-path optical configuration. It offers high stability, high resolution, low uncertainty displacement measurements and can break through the dynamic runout problem in laser encoders. Experimental results reveal that the laser encoder can detect a displacement variation of 26 pm, and can thus be applied to sub-nanometer or even picometer positioning.

Original languageEnglish
Title of host publicationInterferometry XIV
Subtitle of host publicationTechniques and Analysis
StatePublished - 2008
EventInterferometry XIV: Techniques and Analysis - San Diego, CA, United States
Duration: 11 Aug 200813 Aug 2008

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


ConferenceInterferometry XIV: Techniques and Analysis
Country/TerritoryUnited States
CitySan Diego, CA


  • Alignment tolerance
  • Heterodyne
  • Laser encoder
  • Sub-nanometer


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