Non-contact Multi-functional Measurement System using Circular Dammann Gratings

Description

This proposal will extend the very encouraging research results obtained on the novel applications of a new type of diffractive optical elements (DOE) in our on-going GRF No. 112507 "Potential Applications of Circular Dammann Gratings" which will be completed shortly by the end of June 2010. We have investigated various types of design and fabrication of this novel DOE for optical communications and non-contact optical measurement techniques for various parameters, including focal length of lenses, wavefront collimation, angle, distance and area of distant objects. We called this DOE circular Dammann grating (CDG) as a circular pattern of equal intensities can be produced at different diffraction orders with high efficiency similar to a linear Dammann grating producing a rectangular pattern.We propose to extend this research work to design an integrated non-contact multifunctional measurement system using the CDG's design and fabrication experiences obtained in the GRF No. 112507 project, which provides not only simple, low-cost and compact configuration, but also comparable high-precision measurement capability. In this project, we will focus our research and design effort on the integrated in-situ noncontact measurement of distance, angle, area of distant objects and other appropriate parameters. In addition we plan to utilize the 3 major equipment items only recently installed in our clean room, viz. the Crestec CABL-9510C Electron beam lithography system, the Oxford ICP65 Inductively coupled plasma etching system and the Microtech LW405 Laser direct write system, to design and fabricate the CDGs. We shall therefore be able to effectively make the masks in-house, instead of outsourcing them to an outside company as the previous practice. The new ICP etching machine will hopefully produce better gratings so that the measurement system performance and accuracy can be significantly improved.