Prism-Free Differential Interference Contrast Microscope with Tunable Beam Shear
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Solution Overview
Problem
Existing DIC microscopes face limitations in optimizing beam-shear distance due to the use of birefringent crystal-based prisms, leading to compromised image quality and complexity in achieving variable shear distance and direction.
Innovation Solution
A beam shear distance module comprising a beamsplitter (BS), a first mirror, and a second mirror, where the mirrors are oriented to cause split light rays to undergo two-stage reflections, allowing for adjustable yaw and pitch angles to control the beam-shear distance without using birefringent crystals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If birefringent crystal-based prisms (Wollaston or Nomarski) are used to generate beam shear, then the microscope can achieve phase contrast imaging, but the beam-shear distance is restricted by the birefringent property and geometry of the prisms, limiting optimization potential
Solution Approach 1:
The patent extracts and removes the birefringent crystal-based prisms from the optical system, replacing them with a beam shear module that uses only mirrors and beamsplitters. This extraction eliminates the geometric constraints imposed by prism physics while maintaining the essential function of generating spatially sheared light rays for DIC microscopy.
Solution Approach 2:
The invention changes the fundamental parameters of the beam shear generation mechanism by transitioning from fixed geometric parameters of birefringent prisms to adjustable mirror angles and positions. This allows continuous variation of beam-shear distance and direction, enabling optimization for different imaging requirements without being constrained by crystal properties.
2Adaptability or versatility
If two Nomarski prisms are used in combination to increase beam-shear distance or alter beam-shear angle, then variable shear parameters can be achieved, but the microscopy system becomes very complex and alignment becomes difficult
Solution Approach 1:
The patent segments the beam shear generation function into independent mirror elements (first mirror and second mirror) that can be individually adjusted. This segmentation replaces the complex interaction of multiple prisms with simpler, independently controllable reflective surfaces, reducing overall system complexity while maintaining variable shear capabilities.
Solution Approach 2:
The invention introduces dynamic adjustability through rotatable mirror mounts that allow real-time modification of mirror orientations. This dynamic capability enables variable beam-shear parameters without requiring multiple fixed optical components, simplifying the system while achieving adaptability.
3Extent of automation
If liquid crystal is used with two Nomarski prisms to switch shear direction electronically, then electronic switching is achieved, but the switching time is long and limited by the liquid crystal response
Solution Approach 1:
The patent replaces the liquid crystal-based electronic switching mechanism with a mechanical rotation system for the mirrors. While this introduces mechanical movement, it eliminates the slow response time of liquid crystals by using faster mechanical rotation to achieve shear direction switching, thereby reducing the time loss associated with switching.
4Adaptability or versatility
If phase mask on the Fourier plane is used to achieve interference contrast with variable shear distance, then electronic variable shear is achieved, but highly spatially-coherent illumination is required which is difficult to achieve and spatial light modulators are expensive
Solution Approach 1:
The invention extracts and removes the phase mask component from the optical system, replacing the complex Fourier plane modulation approach with direct spatial shear generation in the object plane using mirrors. This eliminates the requirement for highly spatially-coherent illumination and expensive spatial light modulators, simplifying both the optical requirements and component costs.
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 enables real-time control and tuning of beam-shear distance, improving image quality and resolution in DIC microscopy, while simplifying the system and reducing costs compared to traditional methods.
Implementation Method 1
The BS is configured to split the first input light ray into first and second split light rays respectively propagated on first and second light paths
Implementation Method 2
The first and second mirrors are oriented to cause each of the first and second split light rays to undergo a two-stage reflection
Data Source
AI summary
A pair of light rays spatially-sheared with a controllable beam-shear distance is generated by a module having a beamsplitter (BS) and two mirrors. The BS splits an input light ray into first and second split light rays respectively propagated on first and second light paths. The two mirrors are respectively located at distal ends of the two light paths, and cause each split light ray to undergo a two-stage reflection, thereby generating first and second reflected light rays directed to the BS. The BS processes the two reflected light rays to generate the pair of spatially-sheared light rays. Orientations of the two mirrors in yaw angle, pitch angle, or both, are jointly adjustable to realize and control the beam-shear distance without using any birefringent crystal-based prism. The module is used to form differential interference contrast (DIC) microscopes providing variable shear distances, advantages of orientation independence, etc.