Imaging Optical System with Birefringent Phase Modulator for Depth of Field
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Solution Overview
Problem
Existing imaging optical systems face challenges in extending the depth of field while maintaining resolution performance, particularly in medical imaging equipment where increased resolution can lead to a decrease in depth of field.
Innovation Solution
The proposed imaging optical system includes an aperture stop, an image-forming optical system, and an optical phase modulator with a birefringent mask that provides two pupil functions, allowing for extended depth of field while suppressing a decrease in resolution performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resolution is increased in medical imaging equipment, then image quality is improved, but depth of field decreases
Solution Approach 1:
The aperture stop is divided into multiple regions (first aperture region and second aperture region) with different aperture values. This segmentation allows different parts of the aperture to contribute to different depth ranges, enabling extended depth of field while maintaining high resolution through selective use of aperture regions for different object distances
Solution Approach 2:
The patent introduces a new dimension by varying the aperture value dynamically based on object distance. Instead of using a single fixed aperture, the system adjusts aperture values across different regions and time points, adding a temporal and spatial dimension to aperture control that enables simultaneous optimization of resolution and depth of field
2Length of moving object
If aperture value is decreased to extend depth of field, then depth of field is improved, but resolution performance decreases
Solution Approach 1:
The patent implements dynamic aperture control where the aperture value is adjusted based on the distance to the object being imaged. The control unit selects different aperture values from multiple available aperture values, allowing the system to optimize both depth of field and resolution performance dynamically rather than being constrained by a fixed aperture setting
Solution Approach 2:
The system changes the aperture value parameter dynamically according to object distance. By having multiple aperture values available and selecting appropriate ones based on the imaging scenario, the system can maintain high resolution performance while extending depth of field when needed, rather than being locked into a single aperture parameter
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
The system effectively extends the depth of field while maintaining resolution performance comparable to normal optical systems, and with appropriate measures against ghosting, it improves image quality and enables efficient surgical operations.
Implementation Method 1
an optical phase modulator that includes a substance having a birefringence index, and gives two pupil functions to the image-forming optical system
Data Source
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AI summary
An imaging optical system according to the present disclosure includes: an aperture stop; an image-forming optical system that causes an image to be formed toward an imaging plane of an image sensor; and an optical phase modulator that includes a substance having a birefringence index, and gives two pupil functions to the image-forming optical system. The following conditional expressions are satisfied: 1≤2×L×tanw+D/D<1.4 λ/4*0.75<Re<λ/4*1.1 where L: a distance between the aperture stop and the optical phase modulator; D: an aperture diameter (diameter) of the aperture stop; w: a maximum angle of incidence of a principal light ray that enters the aperture stop; λ: a wavelength of light; and Re: phase retardation caused by birefringence of the optical phase modulator.