Alternative methods for wavelength determination: interference filters and double photodiodes

Frank Bitte; Tilo Pfeifer

doi:10.1117/12.360984

9 September 1999 Alternative methods for wavelength determination: interference filters and double photodiodes

Frank Bitte, Tilo Pfeifer

Proceedings Volume 3823, Laser Metrology and Inspection; (1999) https://doi.org/10.1117/12.360984
Event: Industrial Lasers and Inspection (EUROPTO Series), 1999, Munich, Germany

Abstract

Wavelength measurements with Michelson interferometers have major disadvantages of high costs and low measurement rates. The paper shows two alternative method for wavelength measurement: one based on interference filters, the other based on double photodiodes. Interference filters are made of several optically transparent layers with different refraction indices. Within a certain wavelength range transmittance and reflectivity of the interference filter change constantly with the laser wavelength. Therefore, after calibration measurements, the wavelength can be obtained within milliseconds with a resolution of approximately plus or minus 0.01 nm by measuring the intensity of both the transmitted and the reflected beam. Double photodiodes are a combination of two single photodiodes with different spectral sensitivities in one case. Within a specified wavelength range both sensitivities are linear but have different gradients. Hence, by measuring the respective currents of each photodiode the wavelength can be obtained with a resolution of approximately plus or minus 0.1 nm also within milliseconds. Furthermore, the experimental set-up that is used for each method is illustrated, measurement results of both methods are presented, discussed and compared.

Citation Download Citation

Frank Bitte and Tilo Pfeifer "Alternative methods for wavelength determination: interference filters and double photodiodes", Proc. SPIE 3823, Laser Metrology and Inspection, (9 September 1999); https://doi.org/10.1117/12.360984

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