||The Panel F is a most unusual lamp which was conceived by GE and BTH Mazda during the late 1950's. GE launched it at the World's Fair in 1964-65, but it was withdrawn just a few years later due to production difficulties. BTH never put the lamps into production and followed a different approach, culminating in the famous Thorn 2D lamp 15 years later.
Panel F consists of two flat sheets of soft glass which have been specially shaped by a novel vacuum forming process, in which the heated glass panels were sucked down over a mould by vacuum. Parallel tubular sections are moulded into the back panel to contain the discharge, and thirty-six dimples are impressed into the front face to increase luminous efficacy and provide a more attractive surface. With the aid of a frit glass sealing material, the two panels are fused together all around the rim, and at several points across the centre of the panel to ensure that the discharge follows an M-shaped path over the whole area.
Electrodes are housed behind the dimples adjacent to each cap, these being standard fluorescent stick coils, complete with anode probes as found in VHO style tubes. Their dumet lead wires are sandwiched in between the two panels and sealed in the glass frit. In British lamps an exhaust tube was also sealed through the panels in the same fashion, but in this earlier American sample two exhaust tubes are affixed to the rear chambers. An external metal stripe electrode is painted onto the rear of the tube in a fork shape, and must be earthed for reliable starting. By coating the front face with a deluxe white phosphor and the rear with a high efficacy cool-white as has been done in this "Panel Deluxe" lamp, good colour rendering and high efficacy are achieved.