QZFM Quick Start Guide

Previous version of the QZFM Quick Start Guide                                                                                                                                                 Last Updated on July 6, 2017

Important: Information/Discussion Page please visit “Master Slave Configuration” and “Setting heater frequency for multi-channel operation” topics before running sensors.

Figure 1: The QZFM package contains all the necessary hardware needed to run the sensors.

What’s in the box?

The QZFM package includes the following components (Figure 1):

  1. Sensor with 20 ft. cable
  2. Electronics Module
  3. Modulation cable – 3.5 mm to 3.5 mm audio cable (used only for multi-sensor operation)
  4. Analog output cable – 2.5 mm audio to 3-way BNC cable
  5. USB cable
  6. Shorting cap – For sensor cable connector to protect the laser when disconnected from the Electronics Module
  7. Power supply – 18V or 19V, 1 unit can power up to 6 sensors (using included cable splitter)

Hardware Setup

Step 1: Carefully remove the cables and the electronics module with attached sensor from the box.

  • Warning: The sensor is highly sensitive to electrostatic discharge (ESD), so please take appropriate precautions (listed below) while disconnecting and reconnecting the sensor. 
  • Note : In the event the sensor cable has to be disconnected from the electronics module, ensure a well grounded environment and immediately attach the shorting cap ( in Figure 1) to the connector of the sensor cable and tighten the screws.
  • Note: With multiple sensors, when reconnecting the sensor cables to the electronics module, check to ensure that the serial number of the sensor matches the serial number (SN) of the electronics module (located on both ends of the sensor as well as on the front and/or side of the electronics module).

Figure 2: A picture of the front (left) and back (right) of the QZFM electronics module showing all the ports.

Step 2: Make sure the power switch (1) on all electronics modules is in the OFF (down) position before connecting the power supply to ’19 V DC’ (10). Note: The electronics module can operate with an 18V or 19V power supply.

Step 3: Connect the USB cable between the sensor (‘Digital Out’ port (8) on the electronics module) and the computer. A USB hub can be used for larger number of sensors.

Figure 3: Connection of modulation cables for Master electronics (bottom) and a slave electronics (top).

Step 4: For multi-channel configurations, the modulation signal must be shared. Connect the modulation cables in the following configuration: For the Master electronics module, connect ‘Master Mod’ (6) to ‘Mod In’ (5) in Figure 2. Then connect the ‘Mod Out’ (4) from the Master, to the ‘Mod In’ (5) of a Slave electronics module. This can be repeated by connecting the ‘Mod Out’ of that Slave to the ‘Mod In’ of the next Slave until all electronics modules are receiving the Master modulation (See Figure 3).

Step 5: For monitoring or recording the analog output, connect the audio to BNC cable to the ‘Analog Out’ (7) of the electronics module to provide BNC connectivity. The red BNC is for the Z-axis signal and the white BNC is for the Y-axis signal (yellow BNC is not used).

Software Setup

Step 1: Download and run the QZFM UI v3.2 Installer.exe on a 64-bit PC with Windows 7 or later OS. Follow the standard instructions through the process, which includes the installation of LabVIEW VISA drivers and the runtime engine, other drivers, and the QZFM User Interface (UI) application.

Step 2: If connecting sensors to the QZFM UI for the first time, be sure to check that all sensors are connected to the computer via USB cables and all electronics modules are turned ON using the power switch on the front panel. Once the sensor serial numbers are all properly listed in the QZFM UI it will not matter if the electronics are powered ON before or after opening the UI.

Step 3: Run the QZFM UI through the Start menu or from the installation folder at c:\Program Files\QZFM UI\QZFM UI v3.2.exe.

Important Note: If the UI prompts for selecting the FTD2XX.dll, download the file here and add it to the QZFM UI folder.

Note: The UI may take up to a minute (5 to 10 seconds per sensor) to scan the hardware and locate the connected QZFM sensors the first time following installation or under certain conditions that are described in the next section.

This video tutorial provides an overview of the QZFM UI functions and operation.

Operating the Sensors

Once the QZFM UI is running, all sensor SNs, (1) in Figure 4, should appear along the right side of the ‘Sensors’ window next to the sensor number ‘M#’. If this is the first time running the QZFM UI on this computer, turn ON or power cycle the electronics module(s) OFF then back ON to observe that all four LEDs to the right of the Sensor list in the UI flash green/amber three times to indicate a successful startup (Note: power cycling can be done using Reboot button in the UI or power switch on front panel of electronics modules). The ‘Sensor Status’ field (2) will display “Ready” when startup is complete.

Figure 4: The top portion of the user interface for the QZFM contains all the buttons and indicators for starting, configuring, and monitoring the sensors.

Step 1: Press the [Auto Start] button (3) to bring the sensors online. The startup process takes a few minutes to complete, as indicated by the first three LEDs turning green. The ‘Laser On/Off LED’ will turn green to indicate that the laser is on. Next, the ‘Laser Lock’ LED will turn green when the laser frequency is locked. Finally, the ‘Cell T Lock’ LED will turn green when the vapor cell is at optimal temperature.

Step 2: Once the first three LEDs are green, press the [Field Zero] button (4) once to activate field zeroing. The button will turn amber color while active. When the field values for B0, By, and Bz stop fluctuating (to within a few 100 pT, usually taking between 5-10 seconds), press the [Field Zero] button a second time to stop the process and lock the compensation fields. The fourth LED turns green indicating the compensations fields are applied.

Note: It is necessary to repeat the [Field Zero] operation every time the ‘Sensitive Axis’ is switched to a different mode or the background field is expected to have changed significantly (e.g. opening and closing the shields, or moving the sensors).

Step 3: When all 4 LEDs are green, press the [Calibrate] button (5). Wait for calibration values to appear sequentially in each corresponding ‘Sensor Status’ box (this process takes a few seconds per sensor). Calibration values less than 1.5 are considered normal and indicate optimal performance. Calibration values above 1.5 indicate sub-optimal sensor performance, either due to large background field (> 50 nT), or a possible sensor issue.

At this point the sensors are ready for measurement.

Additional Controls

Field Settings (6):  The [X,Y,Z] (default) and the [Y,Z] buttons set the active axes for the [Field Zero] function (4). The [Y,Z] mode is used only when X (B0) compensation is not needed. Note: The B0 value is the combined applied field value for X field compensation and internal optimization. The [Field Reset] button will set the applied field values to zero (displayed as -1).

Sensitive Axis (7): The [Z], [Y], and [Dual] buttons set the active measurement axis of the sensor. The default mode is single Z-axis and the [Dual] button activates both Y and Z. Note: When switching between measurement axes, it is necessary to re-run the [Field Zero] operation followed by [Calibrate].

Analog Output Gains (8): These buttons set the voltage gain of the ‘Analog Out’ port. The default [1x] setting corresponds to 2.7 V/nT, the [0.33x] to 0.9 V/nT, and [3x] to 8.1 V/nT.

Sensor Commands (9): Refer to the command list for numbers corresponding to specific commands. Type the number in the field to the right of the [Load All] button and press [Load All] to send a command to all connected sensors. Or alternatively, send a command to a specific sensor by selecting it in the drop down menu and typing the command number in that corresponding field and then pressing [Load].

Restart Commands (10): The [Reboot] button resets all electronics (similar to power cycling) and reloads the firmware defaults. The [Rescan] button is used to reinitialize the sensor list. Note: This button should be used ONLY if sensors are added to or removed from the system. The [Rescan] functions will prompt the user to confirm and reopen the UI, which clears the previous sensor list. Re-opening the UI without a prior list will initiate a scan for connected QZFM sensors, which will take approximately 30-90 seconds.

Data Save

The QZFM UI provides data saving functionality of the digital output at 200 Hz sampling rate. Simply set the folder path for the data files in the ‘File Path (Folder)’  (1) in Figure 5. To start saving data, press the [File Save] button (3) once to activate data recording (highlighted in red while active). To stop data recording, press the [File Save] button a second time. Any comments typed in the ‘Comments’ field (2) before stopping data recording will be saved along with the data in a separate file with the added file name extension ‘_comment.txt’. Data files with .lvm extensions are saved for each sensor (and the associated comment file) in the selected folder.

Figure 5: The Data Save section provides recording capability of the digital data stream for all connected sensors at 200 samples per second. For each recording session, all notes entered in the comments box will be saved along with the data in a separate text file at the time the recording period is stopped. The data section of the UI allows for the monitoring and plotting of data (time and spectral) for up to two selected sensor.

Data Plots

The drop-down bar (4) (in Figure 5) allows the user to select a sensor and display its output in the time series chart (8) and frequency spectrum graph (9). Press the [Print] button (6) (highlighted in amber while active) to start displaying the digital output of the selected sensor. Note: while the [Print] function is active, other sensor indicators such as the LEDs and Cell T Error will not update. Press [Autoscale Once] (5) to scale the Y-axis of the chart when needed. The [Z], [Y], and [PD] buttons (6) allow for selecting the displayed output of the Z axis, Y axis, or photodiode respectively. The [Restart Avg] button (7) will clear and restart the averaging for the spectral graph.

Beta Release of Auto UI Software

We have an experimental version of our UI that will automatically read in and sort connected QZFMs. It should only require the LabVIEW 2015 Runtime engine which can be downloaded on the National Instruments website. This UI has all the same features as the current UI but has not been thoroughly tested, feedback is very much appreciated. Please direct questions and feedback to jo@quspin.com.

The UI can be downloaded here: QZFM Auto UI V5.28

Notes/known issues:

Data drops on the second chart can occur, this is usually fixed by simply turning the print off and on.

If one or more of the sensor names are displayed with an empty box, close and reopen the UI. If that does not fix it, unplug the sensors electronics and give it time to reconnect (~5-10 seconds) then reopen the UI.

All connected sensors must be powered on for UI to work properly.

Autoscaling of the charts is off by default, this can be turned on by right clicking on the chart and selecting “Autoscale Y” or pressing the AutoScale Y button to rescale the chart. The Y range can also be edited manually for convenient viewing of data. It is important that autoscaling is OFF when saving data with the File Save feature, saving data with autoscaling ON can lead to dropped data.


Select/Deselect All:

This button will select and deselect which sensors will have commands sent to them and save data. Make sure a check box is displayed next to the name of the sensor to send commands to it, or that the check box is not active if you do not want to send commands to that sensor. Boxes can also be checked or unchecked individually.


This array displays the names of the connected sensors. Click directly on the name of the sensor to make it the active sensor for plotting data or programming.


Press to rescan for changes in the connected sensors. Be sure to give new sensors time to fully connect to the computer before rescanning to avoid a blank field name. Close and reopen the UI to fix, or try also reconnecting the USB.

File Save and Sensitivity Check:

The File Save will collect data for up to 36 sensors. The data will be saved in .txt format in the selected folder, with time (s) in the first column and magnetic field data (pT) in the second column. To preform a sensitivity check, first field zero and calibrate the sensors then run file save for less than 30 seconds and observe the values that will appear next to the Sensor Status box. It is important to note that these values are only for helpful diagnostics to observe the sensors are working properly. Higher than expected values can be the result of a noisy environment and not necessarily the performance of the sensors. Press File Save once to activate saving data and again to stop saving data, all other buttons are disabled while saving data.