SURFACE ACOUSTIC WAVE VARIABLE DIFFRACTION GRATING

摘要

PURPOSE:To decrease the quantity of the heat accumulated in the light transparent part of a piezo-electric substrate by disposing absorbers for heat radiation which absorb surface acoustic waves and convert the same to heat on both ends of a surface acoustic wave generating surface of the substrate and passing heat radiators through the central parts of the absorbers. CONSTITUTION:A recess in parallel with the substrate 1 which is provided with the light transparent window 5 at the center and consists of a poor heat conductor is formed on the surface of the substrate 1 while the window 5 is included in the substrate. The piezo-electric substrate 2 having the width narrower than the width of the substrate is spanned on the projecting parts remaining on both ends of the recess and crossed finger type electrodes 6 orthogonal with the substrate 2 are provided thereon while the position opposite to the window 5 is averted. Both end parts thereof are bent downward and are press-welded to the substrate 1. The absorbers 3 for heat radiation which absorb the surface acoustic waves and convert the same to heat are respectively provided on both end parts of the substrate 2 positioned on the projecting part and the heat radiators 4 are embedded into the apertures provided thereto while the top end faces thereof are projected. The heat to be accumulated in the light transparent part of the substrate is decreased in such a manner, by which the grating having the high intensity of diffracted light is obtd.