Abstract: A biomagnetometer measures the magnetic field produced by the brain as a result of a visual stimulus delivered by a display device such as a cathode ray tube (CRT). The output signal of the biomagnetometer is filtered to remove noise introduced by the operation of the display device itself, such as the repetitive scan signal of the CRT, and the CRT monitor is otherwise operated from DC power to minimize periodic variations that can interfere with the detection of brain signals. The filtering is preferably accomplished using a comb-notch filter. Cancellation coils and shielding are also preferably used to remove a portion of the noise introduced by the display device.

Abstract: An information storage device includes a magnetic recording medium, preferably supported upon a rotating disk, an electromagnetic writing device that writes magnetic patterns into the recording medium, and a superconducting quantum interference device (SQUID) that reads the magnetic patterns in the recording medium, the writing device and the SQUID preferably being mounted upon a read/write head. The SQUID as operated in its superconducting state is a highly sensitive and directional detector of the magnetic state of the recording medium, permitting it to be spaced relatively distantly from the recording medium yet read the state of small areas of the medium. Use of high temperature superconductors in the SQUID permits practical construction of the information storage device. The read/write head may support a plurality of write devices, and an array of SQUIDs can be utilized so that little or no relative movement of the read/write head is required to read and write from all tracks of the disk.

Abstract: Apparatus for making biomagnetic measurements includes a biomagnetometer for measuring magnetic fields produced by the body and an electromagnetic location measurement and recording system for automatically determining the location of the portion of the body from which the magnetic signals are being gathered. The electromagnetic location recording system permits establishing a real time body frame of reference with respect to the biomagnetometer, so that biomagnetic signals can be correlated directly with body location and structure. The electromagnetic location recording system may be operated continuously at radiation wavelengths which do not interfere with the taking of data, or intermittently with the taking of biomagnetic data, to avoid interference with the measured values of the biomagnetic data.