Browsing by Author "Martínez, Oscar"

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    Fast scanner with position monitor forlargeopticaldelays
    (2001-11-01) Constantino, Santiago; Martínez, Oscar; Torga, Jorge Román; Do Campo, P.; Libertiun, A.R.
    Wepresent a new fastscansystemthatemploys a stepper motor used in a single steposcillatingmode and a position monitor devicebasedon a diode laser. Thesetupusedgeneratesdelays as large as 105 ps at 10 Hz, with 100% dutycycle. Wealso introduce a reliabledevicebasedontheshadow of a movingcutterwith a laser diode as the light source to avoidpowerfluctuationsproblems.
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    Wide band interferometryforthicknessmeasurement
    (2003) Constantino, Santiago; Martínez, Oscar; Torga, Jorge Román
    In thisworkwepresentthe concept of wide band interferometry as opposed to white-light interferometry to introduce a thickness measurementmethodthatgainsprecisionwhenthebandwidthisreduced to anadequatecompromise in order to avoidthedistortionsarisingfromthe material dispersion. The use of thewidestpossible band is a well established dogma whenthehighestresolutionisdesired in distance measurementswithwhite-light interferometry. Wewill show thatthe dogma fallswhenthicknessmeasurementsmust be carriedoutdue to material dispersion. In factthe precise knowledge of thefrequencydependence of therefractiveindexisessentialforadequatethicknessretrievalfromthe opticalexperiments. Thedevicewepresentisalsouseful to obtainthegroup refractiveindexthatisnecessary to calculatetheabsolutethicknessvalue. As anexample, we show thespreading of a siliconeoilon a reference surface in real time.