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Worked Example: Getting a Clean Calibration and Temperature Profile

This example, drawn from Microsanj application/training material on processing thermal images and taking temperature profiles, walks through the practical calibration workflow behind the Quick Start steps above and highlights what separates a usable calibration from a poor one.

Recognizing a poor calibration. Clear edge effects in a calibration image are a sign that the Alignment% setting needs improvement.

Getting a smooth calibration. To produce a calibration that looks smooth rather than showing edge artifacts:

  1. Increase Alignment% to greater than 97%.
  2. Decrease the Vibration filter setting to below 9 (ideally below 5).
  3. Be patient — it is better to spend 5–10 minutes getting one good calibration than to quickly collect ten poor ones.

Why alignment matters. Subpixel (point-by-point) calibration with proper XY thermal expansion correction significantly reduces edge artifacts compared to an uncorrected calibration. In the source material's comparison, tightening image processing narrowed the measurement scale from roughly ±1.2E-3 dR/R/°C (uncorrected) to roughly ±4E-4 dR/R/°C (after correction) — illustrating why a careful calibration pass materially improves measurement precision, particularly on sub-micron features.

Typical measurement setup. The example measurements in this material were taken under representative steady-state test conditions: 70°C base temperature, 28 V / 500 mA device bias, held at steady state for more than 30 seconds, across a range of objectives (5X, 20X, 60X, and 100X). Higher magnification objectives resolve finer spatial detail in the resulting temperature-vs-distance cross-section profiles, at the cost of a smaller field of view.

[diagram/image in source — not reproduced here: this training material is largely composed of annotated screenshots and photographs — CCD/thermal image overlays, calibration comparison images, and cross-section profile plots at various objectives — that could not be reproduced in this text-based reference]