The SA201 is specifically designed to control Thorlabs SA200 Series Fabry Perot Interferometers. The controller generates a voltage ramp, which is used to scan the separation between the two cavity mirrors. The controller provides adjustment of the ramp voltage and scan time, allowing the user to choose the scan range and speed. An offset control is provided to allow the spectrum displayed on the oscilloscope to be shifted right or left. Another convenient feature of the controller is a zoom capability that provides a 1X, 2X, 5X, 10X, 20X, 50X and 100X increase in the spectral display resolution. The ouput TTL level trigger allows the user to externally trigger an oscialloscope on either the beginning or midpoint of the ramp waveform.
The SA201 also includes a high precision photodetector amplifier circuit used to monitor the transmission of the cavity. The amplifier provides an adjustable transimpedance gain of 10K, 100K, and 1MV/A when driving a high impedance load, such as an oscilloscope. Using the ouput sync signal from the controller, an oscilloscope can be used to display the spectrum of the input laser. The detector circuity incorporates a blanking circuit, which disables the photodiode response during the falling edge of the sawtooth waveform
In optics, a Fabry--Pérot interferometer or etalon is typically made of a transparent plate with two reflecting surfaces, or two parallel highly reflecting mirrors.Its transmission spectrum as a function of wavelength exhibits peaks of large transmission corresponding to resonances of the etalon. It is named after Charles Fabry and Alfred Perot.
The SA200 and SA210 Series of Scanning Fabry-Perot (FP) Interferometers are high-finesse spectrum analyzers that are frequently used to examine the fine structure of the spectral characteristics of CW lasers. The confocal FP cavity acts as a very narrow bandpass filter. The transmission wavelength of the cavity is tuned by adjusting the length of the cavity using piezoelectric transducers, which are driven using the SA201 controller or an equivalent function generator. The transmitted light intensity is measured using a photodiode, amplified by the transimpedence amplifier in the SA201 (or equivalent amplifier) and then displayed / recorded by an oscilloscope or data acquisition card. For more information on confocal Fabry-Perot cavities, please see Thorlabs' online tutorial.
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This model is: SA201
Control Box for the SA200 Scanning Fabry Perot
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