THORLABS SA210 Series, Руководство пользователя

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Fabry-Perot Interferometer Chapter 5: Setup
Page 6 19502-D02
Chapter 5 Setup
Knowing the free spectral range (FSR) of the SA210 allows the time-base of an oscilloscope to be calibrated to
facilitate quantitative measurements of laser line shape. With a resolution of 67 MHz, the fine structure resulting
from multiple longitudinal modes of a laser line can be resolved. Note: A saw tooth wave (0 - 20 V) would provide
approximately 2 FSR.
The SA210 should be mounted, so that it can be easily adjusted. It is recommended that Thorlabs 1-inch
Kinematic Mount
KM100
be used to mount the interferometer at the 1-inch diameter flange.
The apparent beam size should be approximately 1 mm. It is recommended that a fold mirror be used to direct the
beam into the Fabry-Perot interferometer.
A lens with focal length of 100 mm can be used, with the focus set
roughly at the center of the housing, approximately 25 mm in from the flange.
The maximum voltage on the piezo (ramp in) is not to exceed 150 V.
If the detector is connected directly to the scope, a 5 k Ω terminator is needed. Offset adjustment (SA201) is used
to center the output on the scope.
5.1. Recommended Set-up
In a typical application the SA210 Interferometer is used in conjunction with a signal generator and an
oscilloscope, as shown below. A signal generator (Thorlabs SA201 Fabry-Perot Controller is used for
generating the required scan signals for obtaining the data in this document) that can produce either a
triangle or saw-tooth wave with an adjustable frequency (5 to 50 Hz), an adjustable amplitude (15 to 40 V),
and an adjustable offset. The signal generator is used to repetitively scan the length of the cavity by
λ /4 in
order to sweep through one FSR of the interferometer. An oscilloscope is typically used to view the
spectrum and make quantified measurements of spectral features.
Figure 3
This figure shows a schematic diagram of a typical setup that is used to measure the spectrum of a laser
source. Please note that for this device to be useful the linewidth of the source must be less than the FSR of the
interferometer.