NV current camera: finding the short nobody can see (3D)
About this app
A circuit board with a hidden short: visual inspection, X-ray and thermal imaging show nothing clear. A diamond layer with NV centres turns the magnetic field of the currents into an image, revealing current path and fault location. Three fault cases to search yourself, stand-off and Biot–Savart to try out.
With explain mode: an AI tutor walks you through the app, points out what matters in the scene and answers your questions.
What it is about
Every current produces a magnetic field that falls off with distance (Biot–Savart). Above a trace the vertical field component shows two stripes, positive on one side and negative on the other. A quantum diamond microscope places a diamond layer with billions of NV centres on the sample, excites them with green light and reads their red glow with a camera. Every pixel yields its own ODMR spectrum; the shift of the resonance, about 28 kHz per microtesla, gives the field.
What the app shows
A circuit board has a hidden short carrying 2 mA. Visual inspection, X-ray and thermal imaging show nothing clear: filaments a few micrometres thin are too thin for X-ray, and 6.6 mW spread into a broad spot in the thermal image. The NV image shows the magnetic field of the current; current path and fault location are reconstructed from it. Three fault cases: a dendrite under the mask, a filament in an inner layer, a short at a via.
What you can try
Switch between the inspection methods and then take an NV image. Tap where you suspect the fault and get the distance to the real one. Increase the stand-off between diamond and copper: the field gets weaker and broader, the localisation coarser. In the case with the filament in an inner layer you see why deep faults are harder to locate.
Frequently asked questions
- What is a quantum diamond microscope?
- A quantum diamond microscope (QDM) is a wide-field magnetometer made of a diamond layer with many NV centres. Green light excites them and a camera records their red glow while a microwave is swept. The shift of the resonance in every pixel yields a map of the magnetic field.
- How do magnetic field images locate a short?
- A short conducts current, and every current has a magnetic field. The field image shows along which traces current flows and where it leaves them. Software reconstructs the current density from the field; the resolution is roughly the distance between current and sensor layer.
- Why does a thermal camera show small leakage currents poorly?
- At a few milliamperes only milliwatts are released. The heat spreads through copper and laminate, leaving a faint, broad spot. Lock-in thermography is more sensitive but stays blurrier than the magnetic field, which is tied directly to the current.
- What can I try in this app?
- You compare visual inspection, X-ray and thermal imaging with the NV image, search the fault yourself in three cases, reconstruct the current paths and change the stand-off of the diamond layer. The explain mode leads step by step from the invisible fault to its location.
Subject: Quantum sensing
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