Optical Chip Evanescent Field TIRF Microscopy
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Solution Overview
Problem
Conventional Total Internal Reflection Fluorescence (TIRF) microscopy requires precise adjustment of the light beam and high-numerical-aperture objectives, limiting the observation area and field homogeneity due to mechanical instability and scattering, making large-scale imaging challenging.
Innovation Solution
A compact module using an optical chip with waveguides generates an evanescent field, allowing for adjustable penetration depth and homogeneous illumination over a large area, decoupling the excitation beam path from the detection path, and enabling active control of light intensity via sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional objective-based TIRF is used with high NA objectives to achieve total internal reflection, then the evanescent field can be generated for fluorescence excitation, but the field of view is limited to a few hundred micrometers and mechanical instability affects beam placement precision
Solution Approach 1:
The patent replaces the mechanical objective lens-based TIRF system with an optical chip that uses waveguide modes to generate evanescent fields. This substitution eliminates the need for high-precision mechanical beam placement while enabling a larger field of view, as the evanescent field is generated directly at the chip-sample interface through guided modes rather than through objective lens focusing
Solution Approach 2:
The invention transitions from three-dimensional beam focusing through an objective lens to two-dimensional waveguide mode propagation on a planar optical chip. This dimensional change allows the evanescent field to be generated across a larger area without requiring precise angular control of incident beams, thereby expanding the field of view while maintaining excitation precision
2Illumination intensity
If high NA objectives are used to enable total internal reflection, then the evanescent field strength is sufficient for fluorescence excitation, but the observation area is limited and the system becomes expensive
Solution Approach 1:
The patent changes the fundamental parameter of evanescent field generation from angle-dependent total internal reflection at an objective lens interface to wavelength and geometry-dependent waveguide mode propagation. By controlling the waveguide dimensions, refractive indices, and coupling conditions, the evanescent field strength can be optimized while simultaneously expanding the field of view beyond the limitations of high NA objectives
3Manufacturing precision
If precise beam placement is required in the rear aperture of the objective to achieve TIRF, then the penetration depth can be controlled, but mechanical shifts due to temperature changes or vibrations significantly impact the evanescent field characteristics
Solution Approach 1:
The patent replaces the mechanically sensitive objective lens beam placement system with a waveguide-based optical chip where the evanescent field is generated through guided modes. This substitution eliminates the mechanical instability issues because the waveguide mode propagation is determined by the fixed geometric parameters of the chip structure rather than by dynamically adjusted beam positions that are susceptible to thermal and vibrational disturbances
Solution Approach 2:
The invention performs the evanescent field generation action in advance through the waveguide structure design, where the penetration depth and field characteristics are predetermined by the waveguide geometry and material properties. This preliminary configuration eliminates the need for real-time mechanical adjustments that would be affected by environmental fluctuations, thereby improving reliability
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
This solution provides precise and homogeneous sample excitation over a large area, improving imaging accuracy and enabling large-scale imaging without the need for high-numerical-aperture objectives, while reducing mechanical instability effects.
Implementation Method 1
an evanescent field that is generated on the sample side of the microscope substrate... the evanescent field can also be generated via a light mode propagating in a thin layer of dielectric material
Implementation Method 2
a light mode propagating in a thin layer of dielectric material... via an optical chip... at least one thin-film waveguide of the optical chip
Implementation Method 3
at least one detection unit for detecting light from at least one thin-film waveguide of the optical chip, wherein a signal relating to the light detected by the detection unit, in particular relating to its intensity
Data Source
AI summary
The present invention relates to a module for optically exciting a sample volume by means of an optical chip, comprising a control unit, a holding device for an optical chip, at least one coupling unit for guiding light into the optical chip, a positioning unit designed to position the coupling unit or at least parts thereof relative to the optical chip, and at least one detection unit for capturing light from at least one thin-film waveguide of the optical chip, a signal concerning the light captured by the detection unit, in particular concerning the intensity of said light, being transmitted to the control unit, which is designed to control the at least one light source and/or the positioning unit on the basis of the signal.