COMPARISON OF 2 FILAMENT LAMPS BY DIFFERENCE HOLOGRAM INTERFEROMETRY

Total bulb fill pressure and density changes inside incandescent lamps can be studied by holographic interferometry. The main drawback stems from the fact that such techniques only provide information concerning the integral refractive index changes in response to a given electrical load. Difference hologram interferometry results in a direct comparison of any one of the large volume production lamps with a master lamp. A short discussion of the technique is presented and its experimental application is described where the difference interferogram is evaluated automatically.