Wavelength sensitivity of the speckle patterns produced by an integrating sphere

Abstract

Speckle metrology is a powerful tool in the measurement of wavelength and spectra. Recently, speckle produced by multiple reflections inside an integrating sphere has been proposed and showed high performance. However, to our knowledge, a complete characterisation of speckle sensitivity to wavelength in that geometry has not been performed to date. In this work, we derive a general model predicting the variation in a speckle pattern as a result of a generic transformation. Applying this to a shift in the incident wavelength, we show that the speckle sensitivity is mainly governed by the radius and surface reflectivity of the sphere. We show that integrating spheres offer sensitivity four orders of magnitude above that of multimode fibres of a similar size, and discuss analogies with the transmission profile of a Fabry-Pérot interferometer.

Optical Angle Barcodes Enabled by a Pixelated Metasurface for Absolute Micro‐Angle Measurement

“…This technology has been widely used in geometric measurements, and several related nanoscale components have been reported, including optical integrating spheres, multimode fibers, and metasurfaces. [16][17][18][19][20][21] Among the mentioned components, metasurfaces, as optical 2D arrays with subwavelength structures, offer the capability to manipulate electromagnetic wave beams by controlling the wavefront phase, amplitude, and polarization, thereby effectively controlling the reflection, refraction, and polarization of the light beam. Due to the independence and controllability of meta-atoms, metasurfaces are widely used in the interaction and control of waves-information-matter, and based on this, they have been developed into various intelligent sensor platforms.…”