Technology Lecture: Orthogonally Polarised Lasers and Applications in Metrology

Date: 11 Feb 2009 - 11 Feb 2009

Venue: SIMTech Auditorium, Tower Block, Level 3

  The objective of this technology   lecture is to raise awareness of new developments in the advanced laser-based   dimensional metrology technology and applications. Participants will gain a   broader understanding of laser measuring techniques pertinent to research   and development of high precision dimensional measurements.  
  A high-resolution displacement sensor based on multiple feedback   effect of birefringence dual frequency lasers will be   presented. When the system operates in very strong feedback regime with   asymmetric feedback induced by the inclined external feedback reflector   in an orthogonal polarised dual frequency laser, the modulation frequency of   the laser intensity is seven times higher than that of the conventional   optical feedback system, due to multiple feedback effect.  A fringe   shift will correspond to a displacement of a fourteenth wavelength of   the external reflector. The intensity transferring periodically between the   two frequencies has been examined. A period of intensity   transfer can be divided into four states, namely o-light, o-light and   e-light, e-light, and no light, and each polarisation state corresponds   to λ/56 displacement of the external reflector. According to the   appearing sequence of the four states, the movement direction of external   reflector can be discriminated. Significantly, a novel displacement   sensor with a resolution of being as high as 11.3nm with the function of   direction discrimination is achievable.
  About the Speaker 
  Prof. Zhang Shulian is the   Director of the State Key Lab of Precision Measurement Technology &   Instruments, Department of Precision Instruments, Tsuinghua University,   Beijing. A former Director of Optic-electrical Engineering Institute of   Tsinghua University, Prof. Zhang has done extensive research on laser   technology and dimensional metrology for more than 30 years.   He holds 42 patents and is the author of 5 books with over 200   academic papers published in this field. 
  Prof. Zhang is the recipient of many national research   awards, including the Second class award of the National Science and   Technology pertaining to "Orthogonally polarised lasers and   based-on precision instruments” in 2007; the First class Award of Science and   Technology Award of National Ministry of Education for his research in Tuning   characteristics of two/three mirror lasers, 2006; the Second Class Science and Technology Award developing   “Two polarisation frequency competition displacement sensing laser system”   in 2000; the First Class Science and Technology Award in recognition   of his research in “Laser frequency splitting phenomenon and application   in metrology” in 1994; and the Second Class National Science and   Technology Award for developing “Four Frequency ring laser and angle   measurement technology”, 1985. 
  His current research interests encompass orthogonal polarisation lasers   and application in metrology, nano measurement, optical grating sensing, etc.

   9.45am  :  Registration 
  10.00am:   Presentation by Prof Zhang
                     (please click A, B, C ro view the presentation slides)
  11.00am:   Q&A
  11.15am :   Refreshment & Networking
  11.30am:    End

  Who Should Attend
  Senior management   staff, R&D managers, engineers, academic staff, researchers and   students. 
  Pre-registration for the lecture is free of charge. 
  For technical   enquiries, please contact Dr Fang Zhongping, Senior Scientist, SIMTech   Precision Measurements Group
  Email:;   Tel: 67938269
For registration and event details:
  Alice Koh, Email: