Redstone™ Optical Spectrum Analyzer Chapter 8: Operation
Rev C, January 21, 2022 Page 38
Derivative: Calculates the derivative of a trace. A dialog box will open, in which the derivative order, method,
and input/output traces can be specified. Derivatives are available up to the fifth order.
Noise: Adds white noise to the Active trace. A dialog box will open, in which the strength of the noise can be
specified.
Convert: Opens a small calculator where the different units used in the software can be converted to each
other. Also allows for converting resolutions from one unit to another.
Resample: Changes the sample points in the Active Trace. A dialog box will open, in which it is possible to
select the resampling method between a factor, copy from another trace, or every n:th data point. The
resampling factor is the desired length of the trace divided by the current length of the trace. For example
selecting a resampling factor of 0.5 reduces the length of the trace by a factor of two and a resampling factor of
4.0 increases the length of the trace by a factor of four. The resampling is performed using a quintic spline
interpolation to make the resampled trace as similar to the original trace as possible.
8.7.7. Functional Traces (Traces Defined by a Function)
By using the function “Curve Fit” found under the Math menu it is possible to fit a mathematical function to a
trace. The calculated function will be stored in one of the traces as a mathematical function and drawn in the
data display area along with the other traces. The currently available types of functions are Gaussian,
Lorentzian, and polynomial. In the dialog which is opened when pressing the “Curve Fit” button it is possible to
select the type of function to fit, the data range to use for fitting and the trace which will hold the fitted curve. If
the fit failed, the status bar will display the error message “Fit Failed.”
Figure 37. Curve Fit Dialog
Note that the fitted function will only be defined for the x-axis range that was used to create the function.
Opening up the trace properties window of a functional trace will display the type of function stored in the trace
together with the parameter values used to define the function. Functional traces have some limitations
compared to ordinary traces, not all mathematical operations can be performed on them.
8.8. Saving and Loading Data
The Thorlabs OSA software can read and write the following spectral file formats:
• Thorlabs OSA Spectrum file format (.spf2 / .spf2x): Native file format for Thorlabs OSA Software.
• Comma separated values (.csv) with Thorlabs OSA header: Raw ASCII file format with a header
including information about the trace and acquisition settings. Columns separated by comma,
semicolon, or tab (configurable).
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