As high-precision measuring instruments have developed, interferometers have been widely applied in the measurement of lengths and of the shape of surfaces, with nanometer precision. The emergence of the laser is one of the revolutions that has led to a well-defined traceability route to the definition of the meter via interferometry. Another change is the ever-increasing adoption of detector arrays substituting for conventional methods of recording and analyzing interferograms. New applications have also arisen from the adoption of microscopes, optical fibers, chip-level components and diffractive optical elements, developing enhanced analogues of conventional interferometers, which have the advantages of high integration, low noise levels, and complete sets of measuring instruments with a high level of automation. Since the requirements for measurement parameters and the environment are becoming more complex, we expect that the related instruments will play a progressively significant role in the progress of advanced manufacturing processes and quality control. Multi-sensor integrated flexible measurement methods have been proposed to perform measurements with holistic, more accurate and reliable information. However, most of the proposed methods are not intelligent and are highly integrated, providing only specific solutions for given measuring tasks. In this paper, the principles, progress, prospects and development trends of interferometry are reviewed.
Graphene/silicon Schottky junctions have been proven efficient for photodetection, but the existing high dark current seriously restricts applications such as weak signal detection. In this paper, a thin layer of gadolinium iron garnet (Gd3Fe5O12, GdIG) film is introduced to engineer the interface of a graphene/silicon Schottky photodetector. The novel structure shows a significant decrease in dark current by 54 times at a −2 V bias. It also exhibits high performance in a self-powered mode in terms of an Ilight/Idark ratio up to 8.2 × 106 and a specific detectivity of 1.35 × 1013 Jones at 633 nm, showing appealing potential for weak-light detection. Practical suitability characterizations reveal a broadband absorption covering ultraviolet to near-infrared light and a large linear response with a wide range of light intensities. The device holds an operation speed of 0.15 ms, a stable response for 500 continuous working cycles, and long-term environmental stability after several months. Theoretical analysis shows that the interlayer increases the barrier height and passivates the contact surface so that the dark current is suppressed. This work demonstrates the good capacity of GdIG thin films as interlayer materials and provides a new solution for high-performance photodetectors.
Photodetectors (PDs) play a crucial role in imaging, sensing, communication systems, etc. Graphene (Gr), a leading two-dimensional material, has demonstrated significant potential for photodetection in recent years. However, its relatively weak interaction with light poses challenges for practical applications. The integration of silicon (Si) and perovskite quantum dots (PQDs) has opened new avenues for Gr in the realm of next-generation optoelectronics. This review provides a comprehensive investigation of Gr/Si Schottky junction PDs and Gr/PQD hybrid PDs as well as their heterostructures. The operating principles, design, fabrication, optimization strategies, and typical applications of these devices are studied and summarized. Through these discussions, we aim to illuminate the current challenges and offer insights into future directions in this rapidly evolving field.
1 December 2021 in Sensors and Actuators A: Physical
A hybrid structure of reduced graphene oxide (rGO) sheets/ZnO nanorods was prepared and its photoluminescence intensity ratio between the UV and defect emission was enhanced up to 14 times. By controlling the reduction degree of rGO on the surface of ZnO nanorods, the UV emission was tuned with the introduction of localized surface plasmons resonance of rGO sheets. The suppression of the defect emission was ascribed to the charge transfer and decreased with the distance between the rGO and ZnO nanorods.
The traditional three-dimensional measurement system based on linear-structured light usually involves mechanical scanning platforms to perform the linear scanning, which make the structure of the system huge and complicated. The emergence of the galvanometric laser scanner solves the problem by using a galvanometer to replace the mechanical scanning platform. The employment of the galvanometer can improve the speed of scanning and simplify the structure of the system. However, there are few approaches available to calibrate this kind of system. In this paper, a high-precision calibration method is proposed to calibrate the galvanometric laser scanning three-dimensional measurement system. A precision motorized linear stage and a planar target are applied in this method. The planar target is used for the camera calibration based on Zhang’s method and the precision motorized linear stage for the laser plane calibration. The validity and accuracy of this method are evaluated by scanning the standard component. The experiments conducted suggest that the proposed method is valid and accurate for the calibration of the galvanometric laser scanning system.