Highly sensitive and selective detection of DCP vapors using pyridine-based fluorescent nanofilms.

A novel fluorescent nanofilm DBAP-ETTA has been developed for diethyl chlorophosphate (DCP) vapor detection with high sensitivity and selectivity. Its smooth, homogeneous structure and large Stokes shift enable significant fluorescence quenching upon DCP exposure. The protonation-based sensing mechanism makes it ideal for real-time, portable DCP vapor sensing.

Large-scale-adaptive fringe projection 3D measurement.

Fringe projection profilometry (FPP) faces significant challenges regarding calibration difficulty and stitching error accumulation when operating across scenes ranging from tens to hundreds of meters. This Letter presents a calibration-free 3D measurement method by integrating a binocular vision of a FPP scanner with a wide field-of-view (FoV) vision that constructs global benchmarks to unify local 3D scanning and global 3D stitching, which is adaptable to arbitrarily large-scale scenes. A posterior global optimization model is then established to determine the reconstruction parameters and stitching poses simultaneously at each scanning node with adaptively distributed benchmarks. Consequently, the integrated vision measurement system not only eliminates the large-scale pre-calibration and stitching error accumulation but also overcomes system structural instability during moving measurement. With the proposed method, we achieved 3D measurements with an accuracy of 0.25 mm and a density of 0.5 mm for over 50-m-long scenes.

Intrinsic parameter-free calibration of FPP using a ray phase mapping model.

This Letter presents a ray phase mapping model (RPM) for fringe projection profilometry (FPP) that avoids calibrating intrinsic parameters. The novelty of the RPM, to the best of our knowledge, is the ability to characterize the imaging system with independent rays for each pixel, and to associate the rays with the projected phase in the illumination field for efficient 3D mapping, which avoids complex imaging-specific modeling about lens layout and distortion. Two loss functions are constructed to flexibly optimize camera ray parameters and mapping coefficients, respectively. As a universal approach, it has the potential to calibrate different types of FPP systems with high accuracy. Experiments on wide-angle lens FPP, telecentric lens FPP, and micro-electromechanical system (MEMS)-based FPP are carried out to verify the feasibility of the proposed method.

High-efficiency 3D reconstruction with a uniaxial MEMS-based fringe projection profilometry.

Micro-Electro-Mechanical System (MEMS) scanning is increasingly popular in 3D surface measurement with the merits of the compact structure and high frame-rate. In this paper, we achieve real-time fringe structured 3D reconstruction by using a uniaxial MEMS-based projector. To overcome the limitations on uniaxial MEMS-based projector of lensless structure and unidirectional fringe projection, a novel isophase plane model is proposed, in which the laser line from MEMS-based projector is regarded as an isophase plane. Our model directly establishes the mapping relationship between phase and spatial 3D coordinates through the intersection point of camera back-projection light ray and isophase plane. Furthermore, a flexible calibration strategy to obtain 3D mapping coefficients is introduced with a specially designed planar target. Experiments demonstrated that our method can achieve high-accuracy and real-time 3D reconstruction.