Using a linear variable filter in front of photo-detector array such as CCD or CMOS detector array, we could minimize the impact of stray light and improve the resolution of micro spectrometers. Unfortunately, this method could not exhibit the spectral resolution of a parallel filter in the same way, because the transmitted beam from a linear variable filter has broadening. The broadening becomes limited in the linear variable filter for high-resolution spectral systems. In this study, through theoretical analysis of the focused beam and the experiments, we developed a method to improve the resolution of micro spectrometer. This method was useful for practical engineering applications.
High-resolution ultrasonic imaging using an etalon detector array