scholarly journals Numerical Analysis of Optical Trapping Force Affected by Lens Misalignments

Photonics ◽  
2021 ◽  
Vol 8 (12) ◽  
pp. 548
Author(s):  
Hanlin Zhang ◽  
Wenqiang Li ◽  
Nan Li ◽  
Huizhu Hu
Keyword(s):  
Numerical Calculation ◽  
Numerical Analysis ◽  
Optical Trapping ◽  
Optical Trap ◽  
Geometrical Optics ◽  
Optical Force ◽  
Optical Traps ◽  
Trapping Force ◽  
Calculation Results ◽  
The Asymmetry

Geometrical optics approximation is a classic method for calculating the optical trapping force on particles whose sizes are larger than the wavelength of the trapping light. In this study, the effect of the lens misalignment on optical force was analyzed in the geometrical optics regime. We used geometrical optics to analyze the influence of off-axis placement and the tilt of the lens on the trapping position and stiffness in an optical trap. Numerical calculation results showed that lens tilting has a greater impact on the optical trap force than the off-axis misalignments, and both misalignments will couple with each other and cause a shift of the equilibrium point and the asymmetry of the optical trap stiffness in different ways. Our research revealed the asymmetry in optical traps caused by lens misalignment and can provide guidance for optimize lens placement in future experiments.

Nonlinear Proportional Plus Integral Control of Optical Traps for Exogenous Force Estimation

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
D. G. Cole ◽  
J. G. Pickel
Keyword(s):  
Optical Trap ◽  
Open Loop ◽  
Optical Force ◽  
Optical Traps ◽  
Pi Control ◽  
Force Estimation ◽  
Nonlinear Controller ◽  
Closed Loop System ◽  
Integral Control ◽  
Servo Tracking

This article explores nonlinear proportional plus integral (PI) feedback for controlling the position of an object held in an optical trap. In general, nonlinearities in the spatial dependence of the optical force complicate feedback control for optical traps. Nonlinear PI control has been shown to provide all of the benefits of integral control: disturbance rejection, servo tracking, and force estimation. The controller also linearizes the closed-loop system. More importantly, the nonlinear controller is shown to be equivalent to an estimator of the exogenous force. The ability of nonlinear PI control to lower the measurement SNR is evaluated and compared to the variational open-loop case. A simulation demonstrating the performance of the nonlinear PI control is presented.

On Nonlinear Control of Optical Traps Using Pulling Trajectory Tracking for Single-Molecule Experiments

2011 ◽  
Author(s):  
Daniel G. Cole
Keyword(s):  
Single Molecule ◽  
Optical Trap ◽  
Static Condition ◽  
Optical Force ◽  
Optical Traps ◽  
Pi Control ◽  
Force Estimation ◽  
Integral Control ◽  
Servo Tracking ◽  
Additional Feedback

This article explores nonlinear position plus integral (PI) feedback for controlling an optical trap used in single-molecule experiments. In general, nonlinearities in the spatial dependence of the optical force complicate feedback control for optical traps. Furthermore, the extension of a molecule creates an additional feedback path that puts constraints on the PI control gains. The nonlinear PI control presented here is shown to provide all of the benefits of integral control: disturbance rejection, servo tracking, and force estimation. The ability of nonlinear PI control to lower the measurement SNR is evaluated. Finally, constraints on the pulling rate are given to ensure the system trajectory remains in a quasi-static condition, stable, and the bead remains held in the trap.

Numerical Analysis of a Pre-Stressed Bridge under Static Loads Based on ABAQUS

2013 ◽  
Vol 756-759 ◽  
pp. 194-197
Author(s):  
Quan Zhou ◽  
Jian Guo Hou ◽  
Xiao Chun Zhang
Keyword(s):  
Finite Element ◽  
Numerical Calculation ◽  
Numerical Analysis ◽  
Stress Distribution ◽  
Finite Element Model ◽  
Static Loading ◽  
Element Model ◽  
Static Loads ◽  
Finite Element Software ◽  
Calculation Results

Finite element model of a pre-stressed bridge is established using finite element software Abaqus according to the characteristics of the bridge. Three static loads are respectively applied to the model to investigate the stress distribution. Numerical calculation results of stress and displacement show that the design of the bridge meets the requirements of static loading.

Optimal trap velocity in a dynamic holographic optical trap using a nematic liquid crystal spatial light modulator

2022 ◽  
Author(s):  
Karuna Sindhu Malik ◽  
Bosanta Ranjan Boruah
Keyword(s):  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Spatial Light Modulator ◽  
Optical Trap ◽  
Optical Element ◽  
Optical Traps ◽  
Light Modulator ◽  
Step Size ◽  
Microscopic Object ◽  
Optimal Velocity

Abstract A dynamic holographic optical trap uses a dynamic diffractive optical element such as a liquid crystal spatial light modulator to realize one or more optical traps with independent controls. Such holographic optical traps provide a number of flexibilities and conveniences useful in various applications. One key requirement for such a trap is the ability to move the trapped microscopic object from one point to the other with the optimal velocity. In this paper we develop a nematic liquid crystal spatial light modulator based holographic optical trap and experimentally investigate the optimal velocity feasible for trapped beads of different sizes, in such a trap. Our results show that the achievable velocity of the trapped bead is a function of size of the bead, step size, interval between two steps and power carried by the laser beam. We observe that the refresh rate of a nematic liquid crystal spatial light modulator is sufficient to achieve an optimal velocity approaching the theoretical limit in the respective holographic trap for beads with radius larger than the wavelength of light.

scholarly journals NUMERICAL ANALYSIS OF CORRUGATED STEEL PLATE BRIDGE WITH REINFORCED CONCRETE RELIEVING SLAB

2015 ◽  
Vol 22 (5) ◽  
pp. 585-596 ◽  
Author(s):  
Damian BEBEN ◽  
Adam STRYCZEK
Keyword(s):  
Reinforced Concrete ◽  
Numerical Analysis ◽  
Steel Plate ◽  
Numerical Models ◽  
Experimental Tests ◽  
Bridge Engineering ◽  
Steel Plates ◽  
The Finite Element Method ◽  
Calculation Results ◽  
Rc Slab

The paper presents a numerical analysis of corrugated steel plate (CSP) bridge with reinforced concrete (RC) relieving slab under static loads. Calculations were made based on the finite element method using Abaqus software. Two computation models were used; in the first one, RC slab was used, and the other was without it. The effect of RC slab to deformations of CSP shell was determined. Comparing the computational results from two numerical models, it can be concluded that when the relieving slab is applied, substantial reductions in displacements, stresses, bending mo­ments and axial thrusts are achieved. Relative reductions of displacements were in the range of 53–66%, and stresses of 73–82%. Maximum displacements and bending moments were obtained at the shell crown, and maximum stresses and axial thrusts at the quarter points. The calculation results were also compared to the values from experimental tests. The course of computed displacements and stresses is similar to those obtained from experimental tests, although the absolute values were generally higher than the measured ones. Results of numerical analyses can be useful for bridge engineering, with particular regard to bridges and culverts made from corrugated steel plates for the range of necessity of using additional relieving elements.

scholarly journals COMPARISON OF THREE CALCULATION METHODS OF ENERGY PERFORMANCE CERTIFICATES IN SLOVENIA

2018 ◽  
Vol 13 (1) ◽  
Author(s):  
Wadie Kidess
Keyword(s):  
Numerical Calculation ◽  
Energy Performance ◽  
Heat Losses ◽  
Calculation Methods ◽  
The Third ◽  
Simplified Method ◽  
Calculation Results ◽  
Thermal Bridges ◽  
Simplified Calculation ◽  
Family House

In order to get the authorization for issuing energy performance certificates in Slovenia, the expert candidate has to attend the prescribed course and pass the exam. The simplified method for heat losses calculation that is taught at this course neglects the thermal bridges, raising concerns whether the calculation results are reliable. In this paper we have compared three methods for calculation of thermal losses for a “typical” family house. The first is the above mentioned simplified calculation using a correctional factor; the second takes into account the thermal bridges, using linear thermal transmittances obtained by numerical calculation, and the third takes into account the thermal bridges, using default values for linear thermal transmittances. Noting that the second method returns the most exact values, we have found that the first method results are too large, yet still smaller than the third method results.

Bandwidth analysis of non-collinear fourth and fifth harmonic generation in nonlinear uniaxial crystals

2017 ◽  
Vol 26 (01) ◽  
pp. 1750014
Author(s):  
Dongsheng Song ◽  
Yuanlin Zheng ◽  
Xiaohui Zhao ◽  
Zengyan Cai ◽  
Xianfeng Chen
Keyword(s):  
Numerical Calculation ◽  
Harmonic Generation ◽  
Phase Matching ◽  
Type I ◽  
Type Ii ◽  
Optimal Angle ◽  
Fourth Harmonic ◽  
Calculation Results ◽  
Bandwidth Analysis

The optimal angle bandwidth and wavelength bandwidth of fourth-harmonic generation (FHG) and fifth-harmonic generation (FIFHG) of the 1064[Formula: see text]nm laser are analyzed based on the numerical calculation results of non-collinear type-I and type-II phase matching processes for general nonlinear uniaxial crystals with 1[Formula: see text]cm length. The non-collinear phase matching angles and effective nonlinear coefficients of FHG and FIFHG are calculated. The optimal angle bandwidth and wavelength bandwidth are obtained. The results are beneficial to broadband and efficient non-collinear phase matching FHG and FIFHG experiments and studies.

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