# Calibration

# Calibration

Perform the common setup in [Quick Start Steps](#quick-start-steps), then click **Calibration** to start. Continue with the steps below.

1. **Hardware**
   1. Set Base Temp to 20 °C and click **Set Low Temp**.
      - Note: The temperature set on the 4D Nano Align should change. If it does not, make sure the Chiller is on.
   2. Set High Temp to 120 °C.
      - Note: Microscope Settings are auto-filled from Project Manager (no need to reselect them).
2. **Timing/Illumination**
   1. Set Stage Heating Time to 50.
   2. Set Image Averages to 55.
   3. Auto-select the Brightness (%).
      - Note: Brightness % is auto-filled from Project Manager (no need to reselect it).
3. **3D Alignment – Focus ROI**
   1. Select a region on the CCD image using the rectangle tool. Choose a unique feature on the sample, such as edges or scratch marks.
   2. Press **Focus ROI** to set the selected region as your ROI.
   3. Wait a few seconds until the selected region is focused as your ROI and the Focus ROI indicator turns green.
      - Note: The selected ROI region displays in green. To zoom in/out, use the magnifying glass — hold Shift to zoom out, Shift+Click to zoom in.
4. **3D Alignment – Capture Ref**
   1. After selecting the ROI, keep the same ROI or select another region with more distinct features for alignment.
   2. Press **Capture Ref** to set the newly selected region as the Reference region.
   3. Wait for the Capture Ref indicator to turn green.
   4. Set the initial parameters for Focus Tolerance, Alignment %, and Vibration Filter. The indicator lights turn green when the image is in range.
      - Note: Increasing the Alignment % value and decreasing the Vibration Filter improves alignment accuracy.
5. **Start Measurement**
   1. Once setup is complete, click **START Measurement** to begin calibration.
6. **Save Images**
   1. The calibration cycles through temperatures to reduce noise and improve accuracy. Typically after 3 cycles, the thermoreflectance error is <1E-5 (or <5% for 530 nm on gold material). The System Status bar shows progress and displays "Calibration Done" after each cycle, and counts cycles under "Loop Iterations".
      - Note: Each cycle takes about 4 minutes.
   2. Select a region on the Thermal Image View to get the Thermoreflectance Coefficient (Cth) while the measurement is running. (Example in source: the middle of the blue 5 µm x 500 µm band is selected.)
   3. Under Save Images, check that the directory and "Save Path" name are correct.
   4. Check the **Save Every Cycle** box. When ready to save the data, click **Save Image**.
      - Note: Save the image before stopping the measurement.
   5. To stop the measurement, click **STOP MEASUREMENT**, or click **File > Quit**.