Angle measurement based on the internal-reflection effect: a new method

Abstract

We describe a new method of angle measurement that is based on the internal-reflection effect at an air-glass boundary. The method uses a differential detection scheme to largely reduce the inherent nonlinearity of the reflectance versus the angle of incidence in internal reflection. With nonlinearity reduced, the displacement of the angle of incidence can be determined accurately by measuring the reflectance. The resolution and measurement range are determined by the initial angle of incidence, the polarization state of the light, and the number of reflections. Compared with interferometers and autocollimators, this method has the advantage of a simple sensor design for applications ranging from a wide measurement range to extremely high resolution. Other advantages are compact size, simple structure, and low cost. A theoretical analysis of the method and some experimental results of a prototype sensor are presented. The possible applications of the method are also discussed.

Optical Sensors for Multi-Axis Angle and Displacement Measurement Using Grating Reflectors

“…Several types of angle sensors based on the optical lever method [2,90], the critical angle method [91], the optical fiber-based method [92] or the autocollimation method [2,93] have been developed so far. Among them, the angle sensors based on the autocollimation method are suitable for the evaluation of the angular displacements of a multi-degree-of-freedom stage system, since the distance between a measurement target and the reading head will not affect the measurement of the angular displacements.…”

Spatially and Spectrally Resolved Narrowband Optical Absorber Based on 2D Grating Nanostructures on Metallic Films

“…High‐performance optical absorbers have garnered great interest because of their wide applications in solar thermophotovoltaic systems, sensors, photodetectors, photo‐thermal modulators, etc . Take the high resolution angle measurement in spatial optical sensing as an example, the widely used techniques are mainly based on autocollimators, interferometers, and total internal reflection, which involve complex optical system and optical elements such as beam splitter, right angle prism, and mirror. By applying optical absorbers in spatial optical sensing, the size as well as the weight can be significantly reduced.…”

Full-field Transmission-type Angle-deviation Optical Microscope with Reflectivity-Height Transformation

“…The ray angle is found to be proportional to the gradient of the point. The system could be used for the characterization of internal reflection effect [4] near the critical angle in a prism to measure the reflectivity, thereby leading to the computation of the ray angle and the height of surface. This method differs greatly from traditional ones such as the White-Light Interferometry, the Optical Coherence Tomography (OCT) [5][6][7], Confocal Microscopy [8,9], NSOM: Near-field Scanning Optical Microscopy [10], and Laser-scanning Angle-deviation Microscopy (ADM) [11,12].…”