High speed laser scanning using MEMS driven in-plane vibratory grating: Design, modeling and fabrication

2009 ◽  
Vol 156 (1) ◽  
pp. 134-144 ◽  
Author(s):  
Yu Du ◽  
Guangya Zhou ◽  
Kelvin K.L. Cheo ◽  
Qingxin Zhang ◽  
Hanhua Feng ◽  
...  
Keyword(s):  
High Speed ◽  
Laser Scanning ◽  
Grating Design

Five-Dimensional Microscopy using Widefield-Deconvolution: Practical Considerations and Biological Applications

1996 ◽  
Vol 54 ◽  
pp. 268-269
Author(s):  
W.F. Marshall ◽  
K. Oegema ◽  
J. Nunnari ◽  
A.F. Straight ◽  
D.A. Agard ◽  
...  
Keyword(s):  
Confocal Microscopy ◽  
High Speed ◽  
Laser Scanning ◽  
Ccd Camera ◽  
Image Plane ◽  
Time Lapse ◽  
Laser Scanning Confocal Microscopy ◽  
Three Dimensions ◽  
Excitation Light ◽  
Cooled Ccd

The ability to image cells in three dimensions has brought about a revolution in biological microscopy, enabling many questions to be asked which would be inaccessible without this capability. There are currently two major methods of three dimensional microscopy: laser-scanning confocal microscopy and widefield-deconvolution microscopy. The method of widefield-deconvolution uses a cooled CCD to acquire images from a standard widefield microscope, and then computationally removes out of focus blur. Using such a scheme, it is easy to acquire time-lapse 3D images of living cells without killing them, and to do so for multiple wavelengths (using computer-controlled filter wheels). Thus, it is now not only feasible, but routine, to perform five dimensional microscopy (three spatial dimensions, plus time, plus wavelength).Widefield-deconvolution has several advantages over confocal microscopy. The two main advantages are high speed of acquisition (because there is no scanning, a single optical section is acquired at a time by using a cooled CCD camera) and the use of low excitation light levels Excitation intensity can be much lower than in a confocal microscope for three reasons: 1) longer exposures can be taken since the entire 512x512 image plane is acquired in parallel, so that dwell time is not an issue, 2) the higher quantum efficiently of a CCD detect over those typically used in confocal microscopy (although this is expected to change due to advances in confocal detector technology), and 3) because no pinhole is used to reject light, a much larger fraction of the emitted light is collected. Thus we can typically acquire images with thousands of photons per pixel using a mercury lamp, instead of a laser, for illumination. The use of low excitation light is critical for living samples, and also reduces bleaching. The high speed of widefield microscopy is also essential for time-lapse 3D microscopy, since one must acquire images quickly enough to resolve interesting events.

scholarly journals High-speed volumetric two-photon fluorescence imaging of neurovascular dynamics

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiang Lan Fan ◽  
Jose A. Rivera ◽  
Wei Sun ◽  
John Peterson ◽  
Henry Haeberle ◽  
...  
Keyword(s):  
Blood Flow ◽  
High Speed ◽  
Laser Scanning ◽  
Three Dimensional ◽  
Laser Scanning Microscopy ◽  
Fluorescence Signal ◽  
Imaging Method ◽  
Spatiotemporal Resolution ◽  
Two Photon

AbstractUnderstanding the structure and function of vasculature in the brain requires us to monitor distributed hemodynamics at high spatial and temporal resolution in three-dimensional (3D) volumes in vivo. Currently, a volumetric vasculature imaging method with sub-capillary spatial resolution and blood flow-resolving speed is lacking. Here, using two-photon laser scanning microscopy (TPLSM) with an axially extended Bessel focus, we capture volumetric hemodynamics in the awake mouse brain at a spatiotemporal resolution sufficient for measuring capillary size and blood flow. With Bessel TPLSM, the fluorescence signal of a vessel becomes proportional to its size, which enables convenient intensity-based analysis of vessel dilation and constriction dynamics in large volumes. We observe entrainment of vasodilation and vasoconstriction with pupil diameter and measure 3D blood flow at 99 volumes/second. Demonstrating high-throughput monitoring of hemodynamics in the awake brain, we expect Bessel TPLSM to make broad impacts on neurovasculature research.

Dissolution Behavior of Cast WC Particles in NiCrBSi-WC Coatings by Laser Induction Hybrid Cladding

2013 ◽  
Vol 668 ◽  
pp. 283-287
Author(s):  
Sheng Feng Zhou ◽  
Xiao Qin Dai
Keyword(s):  
High Speed ◽  
Laser Scanning ◽  
Metallic Matrix ◽  
High Hardness ◽  
Scanning Speed ◽  
Eutectic Structure ◽  
Dissolution Behavior ◽  
Positive Role ◽  
Laser Scanning Speed ◽  
Laser Induction

In order to characterize the dissolution of cast WC particles in Ni-based WC coatings by laser induction hybrid rapid cladding, NiCrBSi+50 wt.% WC coatings are produced on A3 steel by low and high speed laser induction hybrid cladding (LIHC). When laser scanning speed is only 600 mm/min, the crack-free coating has pores and its dilution is as high as 45%. At the bottom of coating, the cast WC particles are dissolved completely and the herringbone M6C eutectics are precipitated. In the center of coating, the cast WC particles are also dissolved completely and the acicular, blocky and dendritic carbides with relatively low hardness are precipitated. At two sides of coating, some cast WC particles are dissolved partially and interact with Ni-based alloy to form an alloyed reaction layer, while others preserve the primary eutectic structure and high hardness. When laser scanning speed and powder feeding rate are increased to 1500 mm/min and 85.6 g/min, the coating has cracks but no pores. Its dilution can be markedly decreased to 7.8%. Moreover, a majority of WC particles are still composed of primary eutectic structure and keep their high hardness, which can play a positive role in strengthening Ni-based metallic matrix.

High-speed hybrid laser scanning recorder

1981 ◽  
Vol 17 (12) ◽  
pp. 2478-2480
Author(s):  
M. Graser
Keyword(s):  
High Speed ◽  
Laser Scanning

scholarly journals Spray deposition inside multiple-row nursery trees with a laser-guided sprayer1

2017 ◽  
Vol 35 (1) ◽  
pp. 13-23 ◽  
Author(s):  
H. Zhu ◽  
H. Liu ◽  
Y. Shen ◽  
Hengyu Liu ◽  
R. H. Zondag
Keyword(s):  
High Speed ◽  
Laser Scanning ◽  
Quercus Rubra ◽  
Spray Deposition ◽  
Field Tests ◽  
Red Oak ◽  
Northern Red Oak ◽  
Tree Structures ◽  
Speed Sensor ◽  
Tilia Tomentosa

Abstract Multiple-row container-grown trees require specially designed sprayers to achieve efficient spray delivery. A five-port air-assisted sprayer with both automatic and manual control modes was developed to discharge adequate spray deposition inside multiple-row trees. The sprayer resulted from integration of a high-speed laser-scanning sensor with a sophisticated nozzle flow control system, an embedded computer with a touch screen, a Doppler speed sensor, a specially-designed algorithm and an air-assisted sprayer base. It was able to detect target tree presence and measure target tree size, shape and leaf density. The sprayer then controlled the spray output of each nozzle to match tree structures. The sprayer was tested for its sprayer deposition quality inside canopies in a four-row sterling silver linden (Tilia tomentosa 'Sterling Silver' Moench) field and another six-row northern red oak (Quercus rubra L.) field. Tests were conducted with the sprayer in variable-rate application (VRA) and constant-rate application (CRA) modes. The average spray deposit on foliage of trees was 1.37±0.47 μL cm−2 from VRA and 1.29±0.42 μL cm−2 from CRA in linden, and was 2.15±0.57 μL cm−2 from VRA and 2.72±0.94 μL cm−2 from CRA in red oak, respectively. In comparison, spray coverage on foliage of trees was 19.8±3.0% from VRA and 20.9±4.3% from CRA in the linden trial, and was 27.9±3.7% from VRA and 30.5±5.4% from CRA, respectively, in the red oak trial. The newly developed air-assisted sprayer in both VRA and CRA modes would be able to discharge adequate spray deposition inside multiple-row tree plants while conserving pesticide. Index words: environmental protection, pest control, pesticide, precision sprayer, spray coverage. Species used in this study: sterling silver linden (Tilia tomentosa 'Sterling Silver' Moench), northern red oak (Quercus rubra L.).

Investigation of an Experimental Laser Sensor-Guided Spray Control System for Greenhouse Variable-Rate Applications

2019 ◽  
Vol 62 (4) ◽  
pp. 899-911
Author(s):  
Tingting Yan ◽  
Heping Zhu ◽  
Li Sun ◽  
Xiaochan Wang ◽  
Peter Ling
Keyword(s):  
Control System ◽  
Delay Time ◽  
High Speed ◽  
Laser Scanning ◽  
Plant Production ◽  
Laser Sensor ◽  
Variable Rate ◽  
Spray Volume ◽  
Spray Control ◽  
Variable Rate Spraying

Abstract. Precision variable-rate spraying technology is needed for controlled-environment plant production in greenhouses. An experimental spray system for greenhouse applications was developed for real-time control of individual nozzle outputs. The system mainly consisted of a high-speed laser scanning sensor, 12 individual variable-rate nozzles, an embedded computer, a spray control unit, and a 3.6 m long mobile spray boom. Each nozzle was coupled with a pulse-width modulated solenoid valve to discharge sprays at variable rates based on target presence and plant canopy structure. Laboratory tests were conducted to evaluate the accuracy of the spray control system in respect to spray delay time, nozzle activation, and spray volume using four target objects of different regular geometrical shapes and surface textures and two artificial plants of different canopy structures. Other experimental variables included three detection heights from 0.5 to 1.0 m and five sensor travel speeds from 1.6 to 4.8 km h-1. A high-speed video camera was used to determine the delay time and nozzle activation in discharging sprays on target objects after the laser sensor had detected the objects. The detection height and travel speed were found to have slight influence on the timing of nozzle activation. The nozzles started spraying in a range between 33 and 83 mm before reaching the target objects and stopped spraying between 13 and 84 mm after passing the objects, ensuring that the objects were fully covered by the spray. Spray volume corresponded to the object sizes well, and the spray control system performed with higher accuracy at lower travel speeds. Differences between the calculated spray volume based on the sensor detection and the actual spray volume ranged from 1.9 to 2.7 mL per object among all tested objects. The variable-rate control system reduced spray volume by 29.3% to 51.4% for all the objects compared with conventional constant-rate spraying. At the same time, the nozzles could be activated precisely by the object presence. Consequently, this experimental laser-guided system was implemented on a boom system in a commercial greenhouse for future investigations of its accuracy in variable-rate spraying to save pesticides, water, and nutrients. Keywords: Automation, Intelligent sprayer, Pesticide, Precision spray technology, Boom spray equipment.

Experimental Evaluation of Blasting Near Pipelines

2018 ◽  
Author(s):  
Justin Gossard ◽  
Steven A. Waters ◽  
Shane Finneran
Keyword(s):  
High Speed ◽  
Laser Scanning ◽  
Field Experiments ◽  
Separation Distance ◽  
Primary Objective ◽  
Operating Conditions ◽  
Soil Conditions ◽  
Exterior Surface ◽  
High Speed Video ◽  
Test Segment

Construction blasting was proposed as a technique to create a trench for a new pipeline within the right-of-way (ROW) of an existing vintage pipeline where soil conditions consisted primarily of rock. Several field experiments were conducted to assess the potential loading conditions that the vintage pipeline could experience due to various blasting configurations as part of the nearby construction process. Two test pipe segments were constructed from segments removed from the vintage pipeline for use in these experiments. Each test segment contained two vintage bell-bell chill ring girth welds (GW) and were pressurized to operating conditions of the vintage pipeline for the duration of all blasting. Groups of eight resistive strain gages were bonded around the exterior surface of three distinct locations on each test segment. The three locations include one pipe body location and each of the two welds on each segment. Four separate experiments were conducted with each experiment focusing on a unique combination of trench backfill material, compaction level and separation distance from the test pipe segments and the explosive charges. The primary objective throughout these four experiments was to monitor and record the behavior of buried test pipe sections due to nearby blasting activities. Long range 3-dimentional (3D) laser scanning equipment was used to track movement of each test segment from test to test. High-speed video equipment was also employed to capture each blast. The high-speed video provided additional details on the blast energy transfer, verification of individual charge initiation as well as pipeline test segment movement where each pipeline segment was exposed. Peak particle velocity measurements were taken during each test blast. Strain data collected during each test was used to assess potential damage to the vintage pipeline test segments as a result of blasting. The combined information collected from the in-field testing showed that elevated strains and stresses may be observed during blasting activities near pipelines.

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