Abstract: An electrodynamic loudspeaker for use in a magnetic field generated by an external source, the speaker comprising an acoustic diaphragm attachable to a non-magnetic speaker frame at one end thereof; and a voice coil wound on a bobbin attached to the opposite end thereof, the speaker frame being adapted for mounting the speaker within the external field, the speaker further comprising a magnetic field diverter for locally reshaping the external field in the area of the voice coil for improved efficiency, and including provisions for effectuating operation of the speaker in external fields which may be oriented at various angles relative to the longitudinal extent of the diaphragm.

Abstract: An optical sensor system (such as an oximeter system) for use on a patient in an electrical environment (such as an RF field) includes at least one of the following three subsystems: (A) A light input subsystem includes a first control and display module disposed remotely outside of an electrical field, and input electrical cable connected at one end to the first module and at the other end to an electrically-powered light source disposed closely adjacent but outside of the electrical field. Input fiber optic cable for the transmission of analog optical signals extends from the light source to adjacent a patient in the electrical field. (B) A light output subsystem includes output fiber optic cable for the transmission of analog optical signals extending from adjacent the patient in the electrical field to a light detector disposed closely adjacent but outside of the electrical field.

Abstract: A RF shield, for use adjacent a portion of a patient's body during a magnetic resonance examination by magnetic resonance examination apparatus, includes an electrically and thermally conductive layer having a pair of opposed surfaces, and a pair of electrically and thermally insulative layers. One of the insulative layers is disposed adjacent one of the opposed surfaces for positioning intermediate the conductive layer and the patient's body portion to insulate the patient's body from the conductive layer, and the other of the insulative layers is disposed adjacent the other of the opposed surfaces for positioning intermediate the conductive layer and the magnetic resonance examination apparatus to insulate the magnetic resonance apparatus from the conductive layer.

Abstract: A lampchanger preferably for use in a railroad signal lantern having a focusing lens which includes a horizontally rotatable turret adapted to support a plurality of lamps for indexing one of the lamps to the focal point of the lens. The turret includes a plurality of bayonet sockets for holding a lamp in which the sockets have resilient sides which taper inwardly away from the turret body for accurately securing the lamp in position. The turret includes a contact insulator having a radially extending slot adjacent each of the sockets with a power contact positioned in each of the slots. Each power contact includes a circular ridge for engaging the bottom of a lamp positioned in a socket for cleaning and making a good contact with the lamp. A power brush engages the rotatable turret and is positioned to engage the power contact and engages the slot of the insulator positioned in lamp operating position for mechanically holding the turret in position.