Wavefront Encoding Element for Extended Depth of Field in Light Sheet Microscopy
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Solution Overview
Problem
Light sheet microscopy (LSM) techniques face challenges in achieving precise alignment, maintaining image clarity due to changes in refractive index, and facilitating fast 3D imaging without mechanical disturbances, which limits their application for biological specimens and in-vivo imaging.
Innovation Solution
The integration of a Wavefront Encoding (WFE) element or system at the exit pupil of the objective lens in the collection arm of an LSM extends the depth of field, allowing for relaxed alignment requirements, compensation for refractive index changes, and enabling 3D imaging without moving the specimen or objective, by scanning the light sheet within the extended depth of field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the objective lens is placed at a fixed distance equal to its focal length from the light sheet to obtain clear 2D images, then image clarity is improved, but the alignment requirements become critical and the system lacks adaptability to refractive index changes
Solution Approach 1:
The patent segments the imaging function by placing a wavefront encoding element in the exit pupil plane of the objective lens, separating the focusing function from the depth encoding function. This allows the objective to maintain a fixed distance from the light sheet while the WFE element handles depth discrimination, reducing alignment sensitivity.
Solution Approach 2:
The wavefront encoding element acts as an intermediary between the objective lens and the detector, modifying the wavefront to extend depth of field and encode axial position information. This intermediary component enables the system to tolerate variations in objective-to-sheet distance while maintaining image quality and depth discrimination.
2Reliability
If the objective distance is adjusted to compensate for refractive index changes, then image quality is maintained, but the system complexity and adjustment requirements increase
Solution Approach 1:
The patent replaces the mechanical adjustment of objective distance with an optical solution using a wavefront encoding element in the exit pupil plane. This element optically compensates for refractive index changes by encoding depth information in the wavefront, eliminating the need for mechanical repositioning and reducing system complexity.
3Adaptability or versatility
If the light sheet and objective are scanned in the z direction to obtain 3D images, then 3D imaging capability is achieved, but mechanical movements and pressure waves interfere with the specimen
Solution Approach 1:
The patent replaces mechanical scanning of the objective and specimen with a stationary configuration where the light sheet is scanned. The wavefront encoding element enables depth discrimination without moving the objective, and the scanned light sheet positions are determined by optical scanning rather than mechanical stage movement, reducing disturbances to the specimen.
4Ease of operation
If the depth of field is extended using wavefront encoding to allow relaxed alignment, then ease of operation is improved, but additional optical elements and processing complexity are introduced
Solution Approach 1:
The wavefront encoding element in the exit pupil plane serves multiple functions simultaneously: it extends the depth of field to relax alignment requirements, encodes axial position information for depth discrimination, and maintains compatibility with standard microscopy objectives and detectors. This multi-functionality justifies the addition of the WFE element.
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 approach allows for non-invasive, fast, and stable 3D imaging with improved depth discrimination, reduced artifacts, and the ability to calibrate lateral shifts and magnification, while maintaining image quality across the extended depth of field, thus overcoming limitations of traditional LSM and WFE systems.
Implementation Method 1
a wavefront encoder element or system placed at the exit pupil of the objective lens in the collection arm of a light sheet microscope
Implementation Method 2
the fluorescence emitted from the specimen is recorded in the orthogonal direction with an image detector
Data Source
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AI summary
Light sheet microscope for recording 3D images of a specimen, comprising a light sheet generator, an objective lens, an image detector and a wavefront encoder element or system positioned between the objective lens and the image detector for extending the depth of field of the objective lens. By doing so, the restriction on the distance between the collecting objective and the light sheet is relaxed, allowing the use of a light sheet scanning unit. The resulting light sheet microscope allows for a robust, aberration insensitive, fast 3D imaging without the need to move or perturb the specimen.