Schematic representation of the wavemeter. Doublet lens focal lengths ; grating 1800 line/mm planar reflective holographic; θ1, 2 = 30°, 65°; and webcam CMOS sensor, 1920 × 1080 pixels each 3μm square (lens and IR filter removed).
Sample of spectrum. Inset shows expanded region near laser line, with Gaussian fit (solid line).
Calibration of wavelength from peak location for wavelengths between 778.8 nm to 782.8 nm. Each discrete point is an average of 100 measurements of the spectral peak location determined from a Gaussian fit to the raw spectrum. The solid line is a second-order polynomial fit, λ(nm) = λ2 x 2 + λ1 x + λ0, where x is the pixel number and λ2 = −8.42237 × 10−8, λ1 = 4.43609 × 10−3, λ0 = 777.948.
Temperature dependence of the wavelength offset calibration. Temperature changes affect the grating pitch, producing a nearly linear offset over the tested range.
Known and measured frequencies for the rubidium D2 hyperfine transitions compared to a measured saturated absorption spectrum. The horizontal error bars indicate the spectrometer wavelength uncertainty of .
Sample of spectrum for ECDL operating in multiple longitudinal modes of the semiconductor diode cavity (1 mm length, 40 GHz mode spacing). Inset detail shows clear separation of the two modes.
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