In this research we report the design and fabrication of multi-layers beamsplitter coating in  3.5-5µm & 8-12µm wavelength regions. These multi-layer coated optics can be used to separate 3.5-5µm  (in reflection channel)­­ and 8-12µm (in transmission channel) wavelength regions .The coating material combination used on Ge substrate was Ge as high index material and IR-F625 as high index material . Deposition was performed by physical vapor deposition (PVD) technique in a vacuum chamber by using electron gun and thermal boat. Quartz crystal was used for thickness control .Result achieve was 93.6% average reflection in 3.5-5µm region and 96.1% average transmission in 8-12 µm