Optics: measuring and testing – By light interference – Having partially reflecting plates in series
Reexamination Certificate
2005-03-22
2005-03-22
Turner, Samuel A. (Department: 2877)
Optics: measuring and testing
By light interference
Having partially reflecting plates in series
C372S032000
Reexamination Certificate
active
06870629
ABSTRACT:
The invention allows for the accurate, real-time readout of the optical frequency of a swept-wavelength laser device by counting the number of fringes of a calibrated etalon that occur as the laser is swept. The distinguishing feature of the present invention is that the etalon fringe signal is phase-locked to a slave signal of a higher multiple frequency. The higher frequency of the slave signal divides the frequency interval of the etalon fringe spacing by the additional frequency multiple. The slave signal therefore generates a scale for optical frequency that is of higher resolution than possible with the etalon alone. The phase-lock also insures that the slave signal tracks monotonic scans of the optical frequency regardless of scan profile.The invention also allows for the precise, real-time control of the optical frequency of a laser during the sweep of the laser. By comparing a signal proportional to the transmission of light through a calibrated Fabry-Perot etalon to a reference control signal, the phase difference between etalon transmission signal and the reference signal may be fed back to the laser to drive the phase difference to zero (phase-lock). The phase-lock ensures that the optical frequency profile of the sweep follows exactly the frequency profile of the reference signal. Tailoring the input reference signal controls the velocity of the optical-frequency sweep.
REFERENCES:
patent: 6331892 (2001-12-01), Green
patent: 6370169 (2002-04-01), Imajuku et al.
patent: 6552782 (2003-04-01), Colbourne et al.
Deeds Michael E.
Dinneen Timothy P.
Ensher Jason R.
Myatt Christopher J.
Vogel Kurt R.
Lyons Michael A.
Precision Photonics Corporation
Turner Samuel A.
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