Enhancement of image sharpness and height measurement using a low-speckle light source based on a patterned quantum dot film in dual-wavelength digital holography

Abstract

A dual-wavelength single light source based on a patterned quantum dot (QD) film was developed with a 405nm LED and bandpass filters to increase color conversion efficiency as well as to decouple the two peaks of dual-wavelength emitted from the QD film. A QD film was patterned laterally with two different sizes of QDs and was combined with bandpass filters to produce a high efficiency and low-speckle dual-wavelength light source. The experimental results showed that the developed dual-wavelength light source can decrease speckle noise to improve the reconstructed image sharpness and the accuracy on height measurement in dual-wavelength digital holography.

Compact Single-Shot Dual-Wavelength Interferometry for Large Object Measurement with Rough Surfaces

“…However, single-wavelength interferometry is constrained by the nanometer wavelength of the laser source, limiting its ability to measure very small surface profiles of objects and restricting its application range. Subsequently, researchers proposed a dual-wavelength method [11][12][13] to enhance the measurement range of object surface profiles. The principle involves using lasers with wavelengths λ 1 and λ 2 to illuminate the object separately, capturing two frames of interferograms.…”