Hardware and software implementation of a novel Quantum Well Hall Effect (QWHE) sensor based 2D array Magnetic Field Camera for NDT/NDE applications

摘要

Reliable, portable, hand held instruments are a high requirement in the field of nondestructive testing (NDT). In this work we demonstrate the hardware and software implementations of a new 2D magnetic field detection camera. This is made up of a 16×16 QWHE sensor array on a 5mm sensor pitch. The sampling rate of the array (500 kHz.) allows detection of AC magnetic fields up to 20 kHz. The impact of high sampling rate on the measurements also improves the signal to noise ratio (SNR). The instrument is capable of working online and offline, i.e. as a battery powered standalone instrument or communicating with a personal computer (PC) via an Ethernet interface. A high resolution 16.7M colour TFT screen is used for the user interface. Sampled data can be processed in real time or stored for post processing. Besides the hardware features, software capabilities and digital signal processing algorithms such as super narrow band or matched filtering, image de-blurring, automatic defect detection and sensor calibration, are also implemented on a dedicated MCU/DSP, and are discussed in details.