Le labo de Michel | LDM #257: Magnetic Anomaly Detector AN/ASQ-81(V) - Part 1: Teardown @lelabodemichel5162 | Uploaded 2 years ago | Updated 3 minutes ago
00:00 - Intro
02:50 - Teardown
03:10 - Static pressure sensor from Paine Instruments
05:40 - Helium Optically Pumped Magnetometers
07:35 - electronic boards

This video shows the internal circuits of the Texas Instruments Magnetic Anomaly Detector (MAD) ASQ-81(V) manufactured in the beginning of the 80's.
This device permits to detect minute changes of the earth magnetic field. It was used in warfare for sub-marine detection and for geologic measurements.
It uses 6 optically pumped magnetometers using meta-stable Helium cells. The Larmor frequency is measured using a sweep of the magnetic field frequency generated by Helmholtz coils surrounding the He cells.

Theoretical information about this system can be found here:
youtube.com/watch?v=KexmStv2klQ&t=874s