Appendix B: SR830 Lock-In Interface Program

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All pages in this lab

I. Low Light Signal Measurements

II. Staff Sign-Off Sheet (LLS)

III. Introduction to Equipment (LLS)

IV. Introduction to Noise

V. Measuring the Light Signal from a Diode

VI. Appendix A: SR760 FFT Interface Program

VII. Appendix B: SR830 Lock-In Interface Program

VIII. Appendix C: the Remote Control Box

IX. Appendix D: the Phase Sensitive (Lock-In) Detector

X. Appendix E: Interpreting the Data Sheet for the LED

Contents

Instructions for LLS SR830 Lock-In Interface Program

alt text


Shown above is a screen capture of the SR830 Interface Program. Following are descriptions of the various controls and displays grouped according to their location on the front panel.


Data Run and Save Options

  • Number of Runs Control: Specifies the number of runs the Lock-In is to complete.
  • Save Data? Check Box: If the box is checked, each data run will be saved at the end of the data run in a spreadsheet-ready file (tab delimited). If more than one run is to be performed, the data will automatically be saved.
  • Save Data To Switch: Selects whether or not each data run will be saved in its own file or if all the raw data will be saved to the same file. Note: The processed data (i.e. ) will always be saved to one file.
  • Base File Path: Displays the base file path. After entering the Data Run and Save Options, you will be asked for a base file path if the Save Data option was checked. What the base file path does:
  • Raw data saved to one file will be saved under the file name:
[base file path] (T = [time constant ] ).xls
  • Raw data saved to multiple files will be saved under file names of the form:
[base file path] (T = [time constant] Run [run number ] ).xls
  • Analyzed data will be saved under the file name:
[base file path] Analyzed Data (T = [time constant ] ).xls


Data Acquisition Options (refers to each run)

  • GPIB Address Control: Specifies the GPIB address of the SR830. Unless it is manually changed on the SR830, it should be 8.
  • Sample Mode Ring: Selects which mode will be chosen.
  • Custom mode allows the user to set both the time constant, sample rate, and span as desired (unless the total number of data points exceeds 1400).
  • Best Choice allows the user to select only the time constant. The Interface program will then automatically set the sample rate (about \frac {10}{Time Constant}) and the span (adjusts it so that 1400 data points are taken).
  • Span Control: Determines how long, in seconds, the SR830 will collect data for each run.
  • Total Number of Points Display: Displays the total number of points the SR830 will collect during each run.


Analyzed Data

  • <R> Display: Displays the average value of R (\bar {R}) for the latest set of data.
  • <dR^2>^1/2 Display: Displays the rms deviation of R for the latest set of data. I.e.
\left \langle dR^2 \right \rangle^{1/2} \leftrightarrow \sqrt {\frac {1}{N} \sum_{i=1}^N (\bar{R}-R_i)^2}=\sqrt {\bar{R}^2 - \bar{R}^2}
  • Min. R Display: Displays the smallest value of R in the latest set of data.
  • Max. R Display: Displays the largest value of R in the latest set of data.
  • <dR> Display: Displays the average deviation from <R>. I.e.
\left \langle dR \right \rangle \leftrightarrow \frac {1}{N} \sum_{i=1}^N \left | R-\bar{R} \right \vert


SR830 Status Ring

Displays the status of the SR830, the Interface program, and their link. The messages are pretty self-explanatory. During data acquisition, a fill slide will display the progress of data acquisition.


Ch. 1 Data Plot

  • The plot will display the most recent data points in cyan, the average value of the data in green, and the high and low values in dark blue.
  • The cursor control allows the user to investigate the raw data values. To use it, click on the \[+\] key on the control palette. For more information on plot displays, see LabView for Everyone.
  • The x-axis has units of data point number, while the y-axis has units of Volts.

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