deposited on the first silicon nitride thin film layer 32 the second silicon nitride si3n4 920 u00e5 u00b1 50 thin film layer 34 is deposited on the first silver partially reflective layer 33 the second silver ag 285 u00e5 u00b1 35 partially reflective layer 35 is deposited on the second silicon nitride thin film layer 34 and the third silicon nitride si3n4 3500 u00e5 u00b1 200 thin film layer 36 is deposited on the second silver partially reflective layer 35 by way of the manufacturing process mentioned above the single fabry perot structure can be made and constitutes a simple five layers process plus the photodetector silicon substrate 31 the conventional all dielectric thin film photometric filters require forty two layers of thin film coating the first silicon nitride thin film layer 32 is a bottom spacer layer the first silver partially reflective layer 33 is a bottom partial reflector layer the second silicon nitride thin film layer 34 is a center interferometric dielectric layer the second silver partially reflective layer 35 is a top partial reflector layer and the third silicon nitride thin film layer 36 is a top moisture protective layer the second silicon nitride thin film layer 34 is a fabry perot interferometric nitride layer for filtering a certain spectral band of light and a dielectric material such as silicon dioxide sio2 or oxy nitride may be further applied thereon the second silicon nitride thin film layer 34 can be shaped by plasma enhanced chemical vapor.