to style packages were specifically developed for use with the earliest transistors hence the name transistor outline to they are now used commonly in opto electronic applications e g for detectors etc the technology for sealing these packages is very sophisticated other novel features of the present invention include use of a gold or aluminum plated reflector gold plating is extremely desirable to reflect ir radiation in the two to fifteen 2 to 15 micrometer wavelength range it effectively increases the reflectivity by several percent over polished aluminum over this region however cost concerns may militate for use of aluminum as a satisfactory substitute as it is only slightly less reflective than gold at the wavelengths of concern in the contemplated fields of use 0097 fig4 5 show a second preferred embodiment of the present invention in this embodiment all of the physical and functional elements are identical to that of the first preferred embodiment except that the tungsten filament 140 is disposed in a glass bead 160 which is at the edge of reflector 150 rather than immediately above the focal point of the reflector the tungsten filament then extends inwardly to the focal point 155 of the reflector from the upper rim 157 of the reflector the tungsten filament is electrically connected to two filament leads 210 a 210 b which are welded or otherwise electrically connected to first and second input pins 130 a 130 b 0098 fig6 shows a third preferred embodiment 700 of the improved infrared radiation emission source of the present invention this embodiment is primarily for higher power steady state sources containing larger tungsten filaments and employs a different configuration for mounting the tungsten filament coil 710 to the electrical input feed through pins 720 730 on the.