In-line Digital Holographic Microscope Lensless Design
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Solution Overview
Problem
Existing holographic microscopes face challenges in achieving high lateral and depth resolution, and reducing twin image noise due to the need for lenses and complex hardware configurations, which limits their ability to accurately observe mechanical properties of MEMS structures.
Innovation Solution
A holographic microscope with a diverging beam illumination source and an in-line digital holographic configuration that eliminates the need for lenses, using a beam splitter and a transducer to capture interference patterns, allowing for improved resolution and phase sensitivity, and incorporating a spatial light modulator for reference beam control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If lenses are used in the holographic microscope, then magnification is provided, but the hardware configuration becomes complex and size increases
Solution Approach 1:
The patent removes lenses from the optical path by using a diverging beam illumination source that directly illuminates the object. The beam splitter and transducer capture interference patterns without requiring magnifying lenses, thereby simplifying hardware configuration while maintaining measurement precision through digital holographic processing
Solution Approach 2:
The patent replaces the mechanical optical system (lenses) with a digital processing system. The transducer captures interference patterns that encode spatial information, and digital reconstruction algorithms provide magnification and resolution without physical lenses, substituting mechanical optics with computational methods
2Device complexity
If lenses are removed to simplify hardware, then numerical aperture increases, but magnification capability is reduced
Solution Approach 1:
The patent transitions from 2D optical magnification through lenses to 3D digital reconstruction. The transducer captures interference patterns containing spatial frequency information, and computational algorithms reconstruct the object at any desired magnification level, adding a computational dimension that replaces physical magnification
3Area of stationary object
If the distance from object to transducer is increased, then field of view increases, but imaging resolution decreases
Solution Approach 1:
The patent employs dynamic digital reconstruction algorithms that can adapt to different object-transducer distances. The system processes interference patterns computationally to maintain high resolution regardless of distance, allowing the field of view to expand while resolution is preserved through algorithmic enhancement rather than fixed optical parameters
4Volume of stationary object
If a reflector is provided on the beam splitter surface, then hardware becomes more compact, but alignment precision may be affected
Solution Approach 1:
The patent combines the reflector function directly into the beam splitter by providing a reflective coating on the beam splitter surface. This integration merges two separate components (beam splitter and reflector) into one, reducing hardware size and minimizing alignment issues that would arise from separate component interfaces
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 configuration simplifies hardware, increases numerical aperture, enhances lateral and depth resolution, reduces twin image noise, and provides a wider field of view, enabling more accurate observation of MEMS structures with improved imaging capabilities.
Implementation Method 1
a beam splitter configured to direct a first portion of the diverging beam towards an object and a second portion of the diverging beam towards a reflector, the beam splitter being further configured to direct an object beam from the object and a reference beam from the reflector towards a transducer
Implementation Method 2
The reflector may have a reflecting surface configured to be transverse to the diverging radiation beam to reflect the second portion as the reference beam
Implementation Method 3
the transducer being configured to provide a signal indicative of the interference pattern of the object beam and the reference beam incident on the transducer
Data Source
AI summary
A holographic microscope comprising a source configured to provide a diverging beam of radiation, a beam splitter configured to direct a first portion of the diverging beam towards an object and a second portion of the diverging beam towards a reflector, the beam splitter being further configured to direct an object beam from the object and a reference beam from the reflector towards a transducer, and the transducer being configured to provide a signal indicative of the interference pattern of the object beam and the reference beam incident on the transducer. A method of digital holography is also disclosed.