Microspectrometer Fabricated by the Liga Process

Abstract

The Liga process can be used to pattern light guiding polymer layers with high accuracy, enabling planar grating spectrographs with self-focusing reflection gratings consisting of step heights as small as 0·2 μm with a total structure height of 125 μm to be fabricated. These grating spectrographs can be used for optical analysis over the entire visible and near infrared (up to 1100 nm) wavelength regions; the transmitted intensity is about 25%. They can be adapted easily to a diode array by using total internal reflection at an inclined sidewall also fabricated by the Liga process. In this case the spectral resolution may be in the order of 1–4 nm per diode pixel.