Imaging Interferometric Microscope High Spatial Frequency Collection
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Solution Overview
Problem
Traditional microscopy is limited by the low-pass filter characteristics of optical systems, restricting resolution and spatial frequency collection, which hinders the ability to achieve high image quality beyond the classical diffraction limit.
Innovation Solution
The use of an imaging interferometric microscope with off-axis illuminations and interferometric reintroduction of zero-order reference beams on the low-NA side of the optical system, combined with signal processing techniques, allows for the collection and reconstruction of high spatial frequencies up to 2n/λ, extending the frequency space coverage beyond conventional limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional microscopy with low-NA optical systems is used, then depth-of-field and field-of-view are maintained, but spatial frequency collection is limited by the low-pass filter characteristics
Solution Approach 1:
The frequency space is segmented into multiple regions, each captured by a separate sub-image taken with different illumination angles. These sub-images are then computationally combined to reconstruct the complete high-frequency information, effectively dividing the complex high-NA measurement into multiple simpler low-NA measurements.
Solution Approach 2:
The patent extends frequency space coverage by introducing illumination angle as an additional dimension. By varying the illumination angle and capturing multiple sub-images, the system accesses different regions of frequency space that would otherwise be inaccessible with a single fixed illumination configuration.
2Measurement precision
If multiple sub-images with different illumination angles are captured and combined, then frequency space coverage is extended to (1+NA)n/λ, but the imaging process becomes more complex
Solution Approach 1:
Multiple sub-images are captured in advance with different illumination angles before the final reconstruction. This preliminary capture of all necessary frequency information allows the complex computational combining to be performed offline, simplifying the real-time imaging operation.
3Measurement precision
If the frequency space coverage is extended to 2n/λ by incorporating multiple illumination angles and object plane tilts, then resolution approaches the linear system limit, but device complexity increases
Solution Approach 1:
The patent systematically varies key parameters including illumination angles and object plane tilt angles to access different regions of frequency space. By changing these parameters across multiple measurements, the system reconstructs high-frequency information that would require a much more complex single-shot high-NA optical system.
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 enhances image resolution to the linear system limit imposed by the transmission medium, while retaining the depth-of-field, field-of-view, and working distance associated with low-NA optical systems, providing improved imaging capabilities.
Implementation Method 1
an imaging interferometric microscope and methods for providing an optical resolution approaching the linear systems limits
Implementation Method 2
Traditional microscopy approaches are restricted in resolution by the low-pass filter characteristics of the optical system. As is well-known, the bandpass of a lens is a circle of radius NA/λ
Data Source
AI summary
Exemplary embodiments provide an image interferometric microscope (IIM) and methods for image interferometric microscopy. The disclosed IIM can approach the linear systems limits of optical resolution by using a plurality of off-axis illuminations to access high spatial frequencies along with interferometric reintroduction of a zero-order reference beam on the low-NA side of the optical system. In some embodiments, a thin object can be placed normal to the optical axis and the frequency space limit can be extended to about [(1+NA)n/λ], where NA is the numerical-aperture of the objective lens used, n is the refraction index of the transmission medium and λ is an optical wavelength. In other embodiments, tilting the object plane can further allow collection of diffraction information up to the material transmission bandpass limited spatial frequency of about 2n/λ.