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[[Image:neoscanfig_3_7.png|thumb|center|600px|<i><b>Figure 3.7</b>: NeoScan Optical Bench Manager Program.</i>]]
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[[Image:neoscanfig_3_8.png|thumb|center|600px|<i><b>Figure 3.8</b>: The total return power and the polarization power of delivered beam to the optical probe with Probe ID No. 1505 in channel 1.</i>]]
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When the program starts, the system detects the total return power and the polarization power in the channel, plots their variations over time and displays their numerical values in mW. Figure 3.8 indicates that channel 1 is selected to deliver the beam to optical probe with Probe ID No. 1505. The Probe ID No. is a four-digit integer number provided by EMAG Technologies Inc. The green âProbe Detectedâ indicator indicates that the probe is connected to the correct channel.
<center>[[Image:neoscanfig_3_9neoscanfig_3_8.png|thumb|center|600px|<i><b>Figure 3.98</b>: Selecting The total return power and the working polarization power of delivered beam to the optical probe with Probe ID No. 1505 in channel from NeoScan Optical Bench Manager window1.</i>]]</center>
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Select the channel number you want to use for the measurement using the dropdown list labeled âSelect Channelâ (Figure 3.9). âCh nâ denotes channel n where n = 1, 2, ⦠[[NeoScan]] Optical Bench Manager program opens up with the âCh 1â as the default working channel.
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<center>[[Image:neoscanfig_3_9.png|thumb|center|600px|<i><b>Figure 3.9</b>: Selecting the working channel from NeoScan Optical Bench Manager window.</i>]]</center>
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If the polarization is maintained, the total return power and the polarization power will lie within the specified optimized range (the default value is ±20%). In this case, âOptimization Indicator LEDâ becomes green. Otherwise, it start blinking and the information panel indicates: âPolarization is not maintained: Optimization is required.â A user can change the threshold from the box labeled âAuto Trigger Marginâ (see Figures 3.7 and 3.8). If the power difference is greater than 20%, the polarization state is found not to be maintained, therefore, the user will be prompted with a dialog window giving an opportunity to initiates the optimization process or skip the optimization by choosing âNo.â
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âThe âStopâ button stops the application. To close (kill) the [[NeoScan]] window click on exit button [[Image:icon_Exit.png]] on the top far right in the LabView user interface. To re-start running the program press the start button [[Image:icon_Start.png]] located on the top left in the LabView window as shown in Figure 3.10. During the run, the start button will disappear. Keep [[NeoScan]] Optical Bench Manager program running until the end of the measurement.
The âStopâ button stops the application. To close (kill) the <center>[[NeoScan]] window click on exit button on the top far right in the LabView user interfaceImage:neoscanfig_3_10. To re-start running the program press the start button located on the top left in the LabView window as shown in png|thumb|center|500px|<i><b>Figure 3.10. During the run, the start button will disappear. Keep [[</b>: Start and Stop buttons for NeoScan]] Optical Bench Manager program running until the end of the measurement. </i>]]</center>
⢠<ul><li><p>The message box in âInformation Panelâ displays messages of warnings, actions and results.⢠</p></li><li><p>âSave Plotsâ saves in folder C:\ProgramData\[[NeoScan]]\OpticalBenchHistory.⢠</p></li><li><p>A user can reset the graphs by pressing âReset Plotsâ button. The updated start time will be displayed under the power graph after âStarted atâ and in the information panel. ⢠</p></li><li><p>There are two options to display power plots: The âEntire Historyâ option displays the power plots from the time Optical Bench Manager program started (numerically is displayed as Start Project Time in information panel). The âUpdatedâ option displays the power plots after resetting the plots (pressing âReset Plotsâ button), see Figure 3.11. </p> <center>[[Image:neoscanfig_3_10b.png|thumb|center|600px|<i><b>Figure 3.10</b>: Resetting the power plots and displaying them with the Entire History and Updated options.</i>]]</center></li></ul>
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3.2.2 ==== Optimization Settings Page====
To set the optimization parameters, press âOptimization Settingsâ tab in [[NeoScan]] Optical Bench Manager program (Figure 3.11): Make sure the GPIB-USB cable from the back panel of Lock-in amplifier is connected to the [[NeoScan]] USB Hub.
1<center>[[Image:neoscanfig_3_11. Set Lock-in amplifier from âLock-in Amplifier Settingsâ section (png|thumb|center|600px|<i><b>Figure 3.12). Put down the Visa menu and select the appropriate GPIB address for Lock-11</b>: Optimization Settings page in amplifier Visa. The default is GPIB0::8::INSTNeoScan Optical Bench Manager program.</i>]]</center>>
2<ol><li><p>Set Lock-in amplifier from âLock-in Amplifier Settingsâ section (Figure 3. If you change any value, press âSet Valuesâ button to update12).Put down the Visa menu and select the appropriate GPIB address for Lock-in amplifier Visa. The default is GPIB0::8::INST.</p>
<center>[[Image:neoscanfig_3_12.png|thumb|center|500px|<i><b>Figure 3. 12</b>: Lock-in Amplifier Settings in Optimization Settings Page.</i>]]</center>></li><li><p>If you change any value, press âSet Valuesâ button to update.</p></li><li><p>Set Lock-in amplifier parameters:</p><ol type="a. "><li><p>Set Lock-in amplifier sensitivity. The sensitivity of Lock-in amplifier is the rms amplitude of an input sine (at the reference frequency) which results in a full scale DC output (10Vdc).</p></li><li><p>b. Select âTime Constantâ from the dropdown lists. The default for time constant of the output low-pass filter that determines the bandwidth of Lock-in amplifier in 10 ms.</p></li></ol></li><li><p>4. Press âSet Valuesâ button to update.</p></li>
Other parameters that should be directly set on SR844 RF Lock-in amplifier â since they are not controlled:
<ol><li>ï¾ Time constant: 24 dB/oct, Figure 3.13(a). </li><li>
ï¾ Signal Input: 50 ï Low noise, Figure 3.13(b).
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ï¾ Sensitivity: Low noise, Figure 3.13(c).
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ï¾ X display: R(dBm), Figure 3.13(d).
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ï¾ Y display: θ, Figure 3.13(e).
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ï¾ Remote: 50 ï external source, Figure 3.13(f).
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The signal levels at the Signal In port on the Lock-in amplifier are in the range of -100 dBm to -40 dBm or higher, depending on device one measures. It is important to set the sensitivity of the Lock-in amplifier greater than the expected input signal amplitude at the Signal Input port (from the IF Out of the optical mainframe). For example, if you expect a signal less than -67 dBm but greater than -87 dBm, set the sensitivity to -67 dBm and 100 μV (rms) setting. If the input signal is greater than the input signal setting, an OVERLOAD condition will occur and the red LED OVERLOAD indicators on the Lock-in amplifier will flash.
⢠<ul><li><p>If the largest tolerable noise signal (at the input) exceeds the full scale signal, the red LED OVLD indicators in lock-in indicate that the readings may be invalid due to an overload condition. In this situation, you many try increasing the time constant or to use a larger full scale sensitivity.</p>5. Keep the default values for other parameters. Table 3.1 lists the default values for the main parameters used in the optimization process, see Figure 3.14. 6. Optimization parameters are stored in C:\ProgramData\[[NeoScan]]\OptimizationParameters folder. </li></ul>
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Keep the default values for other parameters. Table 3.1 lists the default values for the main parameters used in the optimization process, see Figure 3.14.
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Optimization parameters are stored in C:\ProgramData\[[NeoScan]]\OptimizationParameters folder.
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