This paper focuses on a micro-optoelectro-mechanical vibratory gyroscope that provides an optical output and operates in a resonant condition. A custom fabrication technology, based on a silicon-on-insulator substrate, has been considered for the development of the inertial sensor. The optical readout has been accomplished using a metal–dielectric multilayer photonic bandgap (PBG) material. Such an optical structure, composed of alternated layers of one metal and one dielectric material, is embedded in the micromachined device, thus obtaining reflection properties correlated with the displacement of the proof mass induced by the external angular velocity. The principle of the micromachined gyroscope is first introduced, and then, the microelectromechanical gyroscope structure, the materials properties, and the fabrication technology are illustrated. Numerical analyses have also been performed in order to gain insight into the micromachined device. Furthermore, the optical transduction principle that exploits metal–dielectric 1-D PBG structures has been investigated from both a theoretical and an experimental point of view.

Fabrication and Characterization of an MOEMS Gyroscope Based on Photonic Bandgap Materials

Scanning broadband light interferometry (SBLI) has been widely utilized in surface metrology due to its non-contact and high-accuracy method. In SBLI, phase evaluation through Fourier Transform (FT) is a prevalent and efficient technique, where the topography measurement can often be achieved through one interferogram. Nevertheless, the accuracy of the FT method would be significantly influenced by intensity modulation depth: “the lower the modulation of the pixel, the higher the error probability of its phase assignment”. If the structure has a large enough range along the z-axis, several areas in an individual interferogram would be weakly modulated due to the limited depth of focus (DOF). In this paper, we propose an advanced FT-based method when it comes to large-height structures. Spatial modulation depth is first calculated for each interferogram independently. After that, a binary control mask is reasonably constructed to identify the pixels that are valid for phase unwrapping. Then, a phase stitching method along the z-axis is carried out to conduct the large-height topography measurement within a giving field of view. The theoretical principle, simulation, and experimental validation are elaborated to demonstrate that the method can achieve an improved robustness for the reconstruction of large-range microstructures, the advantages of which include the elimination of stepping errors, the suppression of light fluctuations, and the freedom of a limited DOF.

https://www.mdpi.com/2072-666X/8/11/319/pdf

Topography Measurement of Large-Range Microstructures through Advanced Fourier-Transform Method and Phase Stitching in Scanning Broadband Light Interferometry

This paper is a preliminary attempt to evaluate the regulatory gap for Unmanned aerial system (UAS) operations in Sri Lanka and to propose improvements to the regulatory framework. Data were collected on the existing distribution of UAS usage in the country. A sample of users of UASs was surveyed to determine current and intended future use of UASs. Using UAS regulations applied elsewhere in the world and other scientific studies, a list of criteria was established. The relative importance of the established evaluation criteria was determined based on the perception of both UAS operators and a sample of the general public. Using the identified criteria and newly imposed UAS regulations in Sri Lanka, the regulatory gap analysis was performed to evaluate the regulatory performance.

A Microlens Reactive Ion Etching Process Study on CMOS Image Sensor - Wen-Hao Lo

We review various metrology techniques for the characterization of refractive microlenses and microlens arrays (MLAs). The limitations and strength of each technique are analyzed. The goal is to obtain more stable and repeatable metrology routines for micro-optics manufacturing. This analysis comprises both techniques for the characterization of individual microlenses and the analysis of a very large number of microlenses in array configurations. Metrology of spherical and aspherical lens profiles, surface properties, aberrations, Strehl ratio, and focal properties will be presented.

Overview of characterization and metrology techniques for microlenses and microlens arrays

Various metrology techniques for refractive microlenses and microlens arrays (MLAs) are reviewed in order to investigate the limitations and strength of each technique. Manufacturing relies more on lens profile measurements which provide the radius of curvature (ROC) and the conic constant rather than aberrations and the focal properties which are more useful indications for users. The goal of this study is to set up stable and repeatable characterization and metrology routines for micro-optics manufacturing.

Metrology techniques for refractive microlenses and microlens array manufacturing

We present several characterization techniques, which are suitable for small-size microlenses of lens diameters down to 5 μm. For an individual microlens, we apply full characterization for optical performance and surface characteristics.
First, the optical performance is characterized by using a high-resolution interference microscope (HRIM). Second, a
confocal microscope is applied to investigate the surface parameters. Third, the HRIM allows scanning the microlens
array along the optical axis by using a piezo actuator. This leads to a measurement of the 3D intensity distribution near
the focus of the lens. Such 3D intensity maps allow us to characterize the focal properties of each lens in an array. By
studying those characterization techniques, we develop a new method to characterize a large number of microlenses, for instance, over one million lenses, which is already applied to wafer-based manufacturing in a cleanroom fab.

Optical characterization method for very small microlenses(sub-50 micron) for industrial mass-production applications

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Metrology techniques for refractive microlenses and microlens array manufacturing

Overview of characterization and metrology techniques for microlenses and microlens arrays

Optical characterization method for very small microlenses(sub-50 micron) for industrial mass-production applications