Fabrication and Molding Testing of the Blazed Gratings for Microoptics Applications

Abstract

This paper presents the experimental investigation of the optimal hot embossing replication to prevent the nanoscale thermal deformation of microstructures replicated from the electroless Ni mold fabricated by the diamond tool-interfered scribing process. The fabricated microstructures have the blazed profile with a period of 2.0 ㎛ and a depth of 0.2 ㎛ and a thermoplastic material PMMA as the replica was used. The hot embossing molding was carried out under the several experimental conditions. In terms of a quality of surface smoothness, profile, sharp blaze edge, surface roughness, peak to valley Ry and optical performance of the replica, the PMMA microstructures replicated under the optimal conditions, were ideally identical with those in the mold in dimension, and it was found that the demolding temperature is the most important factor for replication. From optical testing, diffraction efficiency of the replica was measured, 87.6%, similar to that of the calculated value 89.6%, and the replica molded in other conditions showed the noticeable efficiency drop due to molding error.

Miniaturized two-channel broadband spectrometer based on variable-spacing concave blazed gratings

“…It has been demonstrated that ultra-precision diamond tooling is a suitable technique for processing advanced optical surfaces, 29 – 31 including the fabrication of free-form blazed gratings 32 – 34 Xu et al 35 . used ultra-precision diamond tooling to cut a convex reflective variable spacing grating with a blazed structure and a grating density of 300 lines/mm.…”

Progress in the Preparation and Characterization of Convex Blazed Gratings for Hyper-Spectral Imaging Spectrometer: A Review

“…Using the inexpensive single-point diamond turning (SPDT) method, Advanced Machine and Optical Systems (AMOS) in Belgium showed that freeform gratings (FFG), which are blazed gratings on surfaces with no rotational symmetry, are possible [ 19 ]. High-quality freeform blazed grating elements made with a diamond can even be used instead of electron beam lithography to make holograms [ 55 , 56 ].…”

Diamond turning of diffractive microstructures

“…Due to the process kinematics it is possible to machine multi focus Fresnel lenses consisting of different segments [2]. Blazed gratings are another application example, which can also be machined with linear process kinematics [3] or by diamond milling [4]. These processes enable the machining of a wide range of structure sizes ranging from few to several hundred micrometers of the groove width and a few hundred nanometers to several micrometers of the groove depth.…”