Optical Tweezers Multi-Trap Position Detection via Segmented Photodiodes
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Solution Overview
Problem
Existing optical tweezers systems struggle to accurately determine the position of multiple objects simultaneously trapped by a single laser beam, which limits their ability to measure external forces applied to these objects.
Innovation Solution
A device comprising a laser source, a three-dimensional actuation system for deflecting the laser beam between trapping points, a microscope objective, a sample chamber, and an image sensor located between the laser source and the actuation system, allowing for simultaneous tracking of multiple trapped objects and calculation of three-dimensional force information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single laser beam is used to trap multiple objects simultaneously, then the productivity and versatility of the optical tweezers system is improved, but the measurement precision of object positions and forces deteriorates
Solution Approach 1:
The patent divides the detection function into multiple independent quadrant photodiodes, each responsible for detecting positions in specific trap regions. This segmentation allows simultaneous monitoring of multiple trapped objects without cross-interference, resolving the contradiction between multi-object trapping and precise position measurement
Solution Approach 2:
The patent introduces beam splitter optics as intermediaries to direct light from different trap regions to separate quadrant photodiodes. This intermediary optical path enables independent position detection for each trapped object while using a single laser beam, maintaining measurement precision despite multiple trapping points
2Adaptability or versatility
If the laser beam is deflected to multiple trapping points using a three-dimensional actuation system, then the adaptability and functionality of the system is improved, but the device complexity increases
Solution Approach 1:
The patent employs a single deformable mirror that performs multiple functions: it deflects the laser beam to different spatial positions, controls trap depth along the optical axis, and maintains beam focusing. This multi-functional actuator reduces the number of separate components needed, managing device complexity while achieving three-dimensional multi-trap capability
Solution Approach 2:
The patent utilizes parameter changes in the deformable mirror surface geometry to dynamically control laser beam deflection angles and focal positions. By modulating the mirror surface shape through voltage control, the system achieves flexible three-dimensional trap positioning without mechanical reconfiguration, balancing adaptability with system simplicity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables precise determination of the position and force measurement for multiple traps created by a three-dimensional multi-trap actuation system, expanding the capabilities of optical tweezers for quantitative force measurements in biological and synthetic systems.
Implementation Method 1
optical tweezers (originally called single-beam gradient force trap) arescientific instruments that use a highly focused laser beam to provide an attractive or repulsive force
Implementation Method 2
Dielectric particles are attracted along the gradient to the region of strongest electric field, which is the center of the beam
Implementation Method 3
The laser light also tends to apply a force on particles in the beam along the direction of beam propagation. This is due to conservation of momentum: photons that are absorbed or scattered by the tiny dielectric particle impart momentum to the dielectric particle. This is known as the scattering force
Implementation Method 4
The laser light also tends to apply a force on particles in the beam along the direction of beam propagation. This is due to conservation of momentum: photons that are absorbed or scattered by the tiny dielectric particle impart momentum to the dielectric particle
Data Source
AI summary
The present invention relates to a device for determining the position of a plurality of objects that are simultaneously trapped by a single laser beam, characterized in that the device comprises:—a laser source for emitting a laser beam, an actuation system for a three-dimensional deflecting of the laser beam between several trapping points,—a microscope objective for focusing the laser beam coming from the actuation system on the trapping points,—a sample chamber including the objects to be trapped on the trapping points,—a light source for lighten the sample chamber, and—a camera for determining the position of each of the trapped objects, said camera being located between the laser source and the actuation system, so that the light emitted by the light source passes successively through the sample chamber, the microscope objective, the actuation system and the camera.