Phase Plate Annular Region for High NA Optical Resolution
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Solution Overview
Problem
The existing phase-contrast microscopes with a phase shift film diameter on the pupil surface of the objective lens limited to half of the numerical aperture (NA) result in reduced optical resolution due to the restricted use of direct light, limiting the utilization of the objective lens's full NA.
Innovation Solution
A phase-contrast microscope design where the phase plate's annular phase-shift region receives radiation at an angle corresponding to greater than one-half of the NA of the objective lens, enhancing the optical resolution by incorporating a condenser annulus with an annular light-transmission region and a phase plate with an expanded phase-shift area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the phase shift film diameter is limited to half of the NA of the objective lens, then the phase-contrast image can be generated using both -1-order and +1-order diffraction light, but the optical resolution is reduced due to restricted use of direct light
Solution Approach 1:
The phase plate is divided into multiple distinct regions: a phase shift film region for generating phase-contrast images and a light shielding film region for controlling direct light. This segmentation allows the system to selectively process different light components (diffraction light through the phase shift film, direct light blocked by the shielding film) independently, enabling the use of a larger phase shift film diameter without compromising image quality, thereby improving optical resolution while fully utilizing the objective lens NA.
Solution Approach 2:
A light shielding film is introduced as an intermediary element between the light source and the phase shift film. This shielding film selectively blocks direct light while allowing diffraction light to pass through to the phase shift film. By introducing this intermediary, the system can use a larger phase shift film diameter to capture more diffraction light and improve resolution, while the shielding film prevents direct light from causing unwanted effects, thus resolving the contradiction between resolution and NA utilization.
2Measurement precision
If the phase shift film diameter is increased to utilize more diffraction light, then the optical resolution improves, but the direct light control becomes more difficult
Solution Approach 1:
The phase plate is segmented into a phase shift film region and a light shielding film region. The shielding film region is specifically designed to block direct light, while the phase shift film region (with larger diameter) processes diffraction light. This segmentation enables the system to use a larger phase shift film for improved resolution without compromising direct light control, as the shielding film handles that function independently.
Solution Approach 2:
Different regions of the phase plate are assigned different functions with appropriate properties: the light shielding film region has high light absorption/blocking properties to control direct light, while the phase shift film region has phase-shifting properties to process diffraction light. This local differentiation of properties allows the phase shift film to be larger in diameter for improved resolution while the shielding film maintains effective direct light control.
3Measurement precision
If the phase shift film diameter is limited to half of the NA, then the device complexity remains simple, but the optical resolution is reduced
Solution Approach 1:
The phase plate is segmented into two functional regions (phase shift film and light shielding film) that can be implemented as a single integrated structure. This segmentation allows the system to achieve improved optical resolution with a larger phase shift film diameter while maintaining relatively simple device structure, as both regions are part of the same phase plate component rather than requiring separate complex systems.
Solution Approach 2:
The light shielding film and phase shift film are merged into a single phase plate structure. This combining of functions into one component achieves the dual goals of improved optical resolution (through larger phase shift film diameter) and controlled direct light (through the shielding film region), while avoiding the complexity of separate independent systems for each function.
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 allows for higher optical resolution and improved contrast by effectively utilizing medium to high NA components, enhancing the observation of high-frequency spatial frequencies.
Implementation Method 1
When the direct light is transmitted through the phase shift film, the phase of the direct light is shifted and the intensity of the direct light is reduced.
Implementation Method 2
Illumination light (uniform light) applied from a light source passes through the slit formed on the condenser annulus, is formed in a ring shape, and is collected on the observed object by a condenser lens. It should be noted that the illumination light is split into two light beams, i.e., direct light that is transmitted through the observed object and diffraction light that is diffracted by the observed object.
Implementation Method 3
The direct light and the diffraction light interfere with each other to generate a phase-contrast image.
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A phase-contrast microscope includes a light source, an objective lens having a numerical aperture (NA), a condenser annulus having an annular light-transmission region, and a phase plate having a first annular phase-shift region. The annular phase-shift region is arranged to receive radiation from the sample region at an angle from the sample region corresponding to greater than one-half of the NA of the objective lens.