Abstract
A NEW type of laser strainmeter is now operating in a disused railway tunnel at Queensbury, Yorkshire1. It uses two helium–neon lasers operating at 633 nm, and has extremely high resolution and linearity. The frequency of one laser, called the slave laser, is locked to the length of a Michelson interferometer attached to the ground. The other laser, used as a reference standard, is stabilised by saturated absorption in iodine vapour2–5. A similar system has been reported by Levine and Hall6 using helium–neon lasers operating at the infrared 3.39 µm wavelength. For practical reasons it is easier to use visible light.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
