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Department of ChemistryUniversity of Illinois – Urbana/Champaign
Joshua DiGangiYun Ding
Ben McCall
Inexpensive Interferometric Wavemeter for Visible/NIR Lasers
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MotivationsMotivations
Tunable laser systems require frequency calibrationTunable laser systems require frequency calibration
Reference cell calibration difficult without a rough Reference cell calibration difficult without a rough measurementmeasurement
Commercial wavemeters are often cost-prohibitiveCommercial wavemeters are often cost-prohibitive
Simple project for an undergraduate or a first-year Simple project for an undergraduate or a first-year graduate studentgraduate student
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Based on the design of P.J. Fox et.al.*Based on the design of P.J. Fox et.al.*– Cart Propulsion SystemCart Propulsion System– Computer InterfaceComputer Interface
Works with continuous-wave lasersWorks with continuous-wave lasers
Yields accuracy of Yields accuracy of ±1 pm±1 pm
Has an acquisition time of 3-4 secondsHas an acquisition time of 3-4 seconds
Currently usable from 400 -1000 nmCurrently usable from 400 -1000 nm
Requires an area of ~2.5’ x 2.5’Requires an area of ~2.5’ x 2.5’
Our WavemeterOur Wavemeter
* P.J. Fox, R.E. Scholten, M.R. Walkiewicz, and R.E. Drullinger, “A reliable, compact and low-cost Michelson wavemeter for laser wavelength measurement”, Am. J. Phys. 67, 624 (1999).
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* Motta, Leonardo. “Michelson Interferometer.” Eric Weisstein’s World of Physics. Ed. Eric Weisstein. 2006.
17 April 2006. <http://scienceworld.wolfram.com/physics/MichelsonInterferometer.html>
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Visible Laser at 500 nm
NIR Laser at 1000 nm
N1 / N2 = λ2 / λ1
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TTL Converters
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Computer InterfaceComputer Interface
24-channels of BCD output from the HeNe counters24-channels of BCD output from the HeNe counters
National Instruments PCI-6503 DAQ cardNational Instruments PCI-6503 DAQ card
LabWindows programLabWindows program– Translates the BCD number to an integer Translates the BCD number to an integer – Stores past readingsStores past readings– Ignores obvious misreadsIgnores obvious misreads– Sends the most recent reading to main experiment Sends the most recent reading to main experiment
computercomputer
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AcknowledgementsAcknowledgements
McCall GroupMcCall Group
University of IllinoisUniversity of Illinois
For more information:For more information:
See Joshua DiGangi’s BS thesis at See Joshua DiGangi’s BS thesis at http://bjm.scs.uiuc.edu/jdigangi/http://bjm.scs.uiuc.edu/jdigangi/