Prism Group Optical System for Endoscope Lens Flare Reduction
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Solution Overview
Problem
Optical systems, particularly in surgical instruments like endoscopes, suffer from image quality degradation due to light beams entering at angles beyond the field of view, causing reflections and scattering known as 'lens flares,' which existing solutions like mechanical masks cannot effectively mitigate without introducing vignetting or requiring tight manufacturing tolerances.
Innovation Solution
Incorporating a prism group within the optical system's beam path, featuring at least one prism with an interface for total reflection between optically dense and thinner media, such as glass and air, to deflect light rays outside the field of view, thereby eliminating vignetting and allowing for adjustable field of view limitation without stringent alignment demands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If mechanical masks or apertures are used to reduce light beams incident from outside the field of view, then lens flare is reduced, but strong vignetting occurs and tight manufacturing tolerances are required
Solution Approach 1:
The patent replaces mechanical masks or apertures with a prism group that uses total internal reflection to redirect stray light. This substitution eliminates the need for tight manufacturing tolerances associated with mechanical masks while still effectively reducing lens flare caused by light beams incident from outside the field of view.
Solution Approach 2:
The patent changes the optical path parameters by introducing prisms with specific refractive indices and geometries. The prism group is designed with precise angular parameters that enable total internal reflection at specific angles, effectively filtering stray light without the mechanical constraints and tolerance issues of traditional mask-based solutions.
2Object-affected harmful factors
If mechanical masks or apertures are used to reduce light beams incident from outside the field of view, then lens flare is reduced, but strong vignetting occurs
Solution Approach 1:
The patent replaces mechanical masks or apertures with a prism group that uses total internal reflection to redirect stray light. This substitution eliminates the mechanical obstruction that causes vignetting while still effectively reducing lens flare, as the prisms redirect light through optical reflection rather than physical blockage.
Solution Approach 2:
The prism group acts as an intermediary optical element that mediates between the incoming light beams and the image sensor. Instead of directly blocking stray light with masks, the prisms serve as intermediaries that redirect unwanted light paths through total internal reflection, preserving illumination uniformity while reducing lens flare.
3Object-affected harmful factors
If the field of view is limited using traditional methods, then light beams from outside the field of view are reduced, but the system becomes more complex or requires tighter alignment
Solution Approach 1:
The patent merges the field of view limitation function directly into the existing optical path by integrating a prism group among the optical elements. This consolidation approach combines stray light rejection with the normal optical transmission function, avoiding the need for separate mechanical masks or complex alignment mechanisms, thereby reducing overall system complexity.
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 significantly improves image quality by removing scattered light effects at the outset, reducing lens flare issues, and allows for flexible design with minimal production complexity and no vignetting, making the optical system more insensitive to external light and cost-effective.
Implementation Method 1
the at least one prism comprises an interface at which light rays incident from outside the field of view are reflected out of the beam path by total internal reflection
Data Source
Figure 1~2
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Figure 5~6
AI summary
The invention relates to an optical system (2) and a surgical instrument, in particular an endoscope, with such an optical system (2). The optical system (2) comprises a distal optical assembly (10), a proximal optical assembly (12) and an image sensor (18), wherein the distal and the proximal optical assembly (10, 12) define a beam path (14) and the distal optical assembly (10) couples light beams (6, 6') incident from a field of view (20) located in the object space (4) into the proximal optical assembly (12) and the proximal optical assembly (12) directs these light beams (6, 6') onto a light-sensitive surface (19) of the image sensor (18), wherein the optical system (2) is further developed by a prism group (24) arranged in the beam path (14) with at least one prism (30, 32, 34), wherein the prism group (24) limits the field of view (20) of the optical system (2) on at least one side.