Multilayer dielectric stokes-lines transmitting thin film edge filters for micro Raman spectroscopy

摘要

A novel all-dielectric stokes-line transmitting multilayer filter has been designed and developed using reactive electron beam deposition for Raman spectroscopic applications. This filter consists of 33 alternate layers of TiO_2 and SiO_2 optical thin films. Reactive electron beam evaporation technique has been used for the development. The deposition parameters of the electron beam deposition technique for each component layers (TiO_2 and SiO_2) have been optimized to meet the stringent requirement of this device. Such optimized deposition parameters have been used to finally develop this device. Subsequently, the spectral transmittance characteristic of this edge filter has been studied using spectrophotometric technique. This edge filter has been used in the indigenously developed Raman imaging microscope for recording stokes lines. It has been observed that the signal to noise ratio has been substantially increased with the use of this edge filter. The results of design and development of this device have been presented in details.