an ultraminiature light source using a double - spiral shaped tungsten filament includes end contact portions which are separated to allow for radial and length - wise unwinding of the spiral . the double - spiral filament is spaced relatively far apart at the end portions thereof so that contact between portions of the filament upon expansion is avoided . the light source is made by fabricating a double - spiral ultraminiature tungsten filament from tungsten foil and housing the filament in a ceramic package having a reflective bottom and a well wherein the filament is suspended . a vacuum furnace brazing process attaches the filament to contacts of the ceramic package . finally , a cover with a transparent window is attached onto the top of the ceramic package by solder reflow in a second vacuum furnace process to form a complete hermetically sealed package .