High precision circular plane system for angular measurement

The purpose of this project is to increase the measurement accuracy of the rotation angle and measurement speed. There is one rotatable circular plane with many holes in it, the initial location of this circular plane is stored in a CCD camera and is regarded as a stationary circular plane. When the rotatable circular plane is rotated, the intensity of the light across the holes of two circular planes is changed. This intensity will represent the position of the rotatable circular plane, so the position of that plane can be measured by calculating the intensities of light access between the two planes. In this project, several methods are proposed to increase the accuracy of measurement. To prevent a non- concentricity problem between two circular planes, only one circular plane is used in this system. To reduce the dfficulties in the fabrication process, holes will be used instead of using traditional slits. To increase the reading and calculation speed, an FPGA will be used in this system. For improving sampling accuracy, a Kalman filter is used. Overall, this system can reach an accuracy of 2:2176* 10-5 degree with all angles.

High precision circular plane system for angular measurement

The purpose of this project is to increase the measurement accuracy of the rotation angle and measurement speed. There is one rotatable circular plane with many holes in it, the initial location of this circular plane is stored in a CCD camera and is regarded as a stationary circular plane. When the rotatable circular plane is rotated, the intensity of the light across the holes of two circular planes is changed. This intensity will represent the position of the rotatable circular plane, so the position of that plane can be measured by calculating the intensities of light access between the two planes. In this project, several methods are proposed to increase the accuracy of measurement. To prevent a non- concentricity problem between two circular planes, only one circular plane is used in this system. To reduce the dfficulties in the fabrication process, holes will be used instead of using traditional slits. To increase the reading and calculation speed, an FPGA will be used in this system. For improving sampling accuracy, a Kalman filter is used. Overall, this system can reach an accuracy of 2:2176* 10-5 degree with all angles.

Chiral optical fields: a unified formulation of helicity scattered from particles and dichroism enhancement

We establish a general unified formulation which, using the optical theorem of electromagnetic helicity, shows that dichorism is a phenomenon arising in any scattering—or diffraction—process, elastic or not, of chiral electromagnetic fields by objects either chiral or achiral. It is shown how this approach paves the way to overcoming well-known limitations of standard circular dichroism, like its weak signal or the difficulties of using it with magnetodielectric particles. Based on the angular spectrum, representation of optical fields with only right circular or left circular plane waves, we introduce beams with transverse elliptic polarization and possessing a longitudinal component. Then, our formulation for general optical fields shows how to enhance the extinction rate of incident helicity (and therefore the dichroism signal) versus that of energy of the light scattered or emitted by a particle, or vice versa. This article is part of the themed issue ‘New horizons for nanophotonics’.