Prismatic Optical Sight Internal Zeroing Without Exit Pupil Shift

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Solution Overview

Problem

Existing optical systems fail to efficiently address the challenges of enhancing the performance of existing firearms, particularly in the alignment of the point-of-impact and the alignment of the point-of-impact with the point-of-impact, and the point-of-impact with the point-of-impact, and the point-of-impact with the point-of-impact, and the point-of-impact with the point-of-impact, and the point-of-impact with the point-of-impact, and the point-of-impact with the point-of-impact, and the point-of-impact with the point-of-impact, and the point-of-impact with the point-of-impact, and the optical axis.

Innovation Solution

The proposed solution is directed to an optical system comprising an aperture stop configured to direct light through the optical system, an inverting prism assembly, and a field stop configured to receive light from the prism assembly, and a field stop configured to receive light from the prism assembly, and a field stop configured to direct light through the optical system, and a field stop configured to receive light from the prism assembly, and a prism assembly configured to receive light from the field stop and direct light to the operator of the optical system. The inverting prism assembly is pivoted about the center of the aperture stop to align the point-of-impact and point-of-aim in the afocal space so that the point-of-aim is coincident with the optical axis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the inverting prism assembly is pivoted about a point other than the aperture stop center, then the point-of-impact and point-of-aim can be aligned, but the exit pupil is displaced causing vignetting and requiring increased device diameter

Engineering Contradiction:
Improvealignment precisionVSAvoiddevice diameter
Core Design Contradiction:
Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent uses the aperture stop center as an intermediary pivot point that mediates between the alignment requirement and the exit pupil position requirement. By making the aperture stop center coincide with the prism pivot point, it serves as a common reference that satisfies both alignment and optical performance requirements without requiring larger device dimensions

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the conventional mechanical zeroing system (which requires physical tilting of the entire sight assembly) with an optical internal zeroing mechanism where only the inverting prism assembly is pivoted about the aperture stop center. This substitution eliminates the need for mechanical tilting while achieving the same alignment effect, thereby maintaining compact device dimensions

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If external zeroing is used to align the optical axis, then the alignment can be achieved, but the mechanical length and diameter of the optical sighting device must be increased

Engineering Contradiction:
Improvealignment precisionVSAvoidmechanical length
Core Design Contradiction:
Measurement precisionVSLength of moving object

Solution Approach 1:

The patent extracts the zeroing function from the external mechanical structure and relocates it to the internal optical system by pivoting the inverting prism assembly about the aperture stop center. This extraction eliminates the need for external mechanical adjustment mechanisms, thereby reducing the overall mechanical length and diameter of the sighting device

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent transitions from external mechanical zeroing (operating in the mechanical dimension) to internal optical zeroing (operating in the optical dimension). By pivoting the inverting prism assembly within the optical path rather than tilting the entire mechanical assembly, the system achieves alignment without increasing mechanical dimensions

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 optical system effectively aligns the point-of-impact and point-of-aim without displacing the exit pupil, minimizing vignetting, and maintaining consistent eye position, thereby reducing the mechanical length and diameter of the optical sighting device while enhancing optical performance.

Implementation Method 1

an inverting prism assembly configured to receive light from the aperture stop and direct light through the optical system

Methodology Applied
Scientific EffectOptical reflection: Reflection

Implementation Method 2

The inverting prism assembly is configured to be pivoted about a center of the aperture stop to effect alignment of the point-of-impact and point-of-aim in the afocal space

Methodology Applied
Scientific EffectImage inversion: Prism

Data Source

PatentEP4062122B1Compact prismatic optical sight with internal zeroing method
Publication Date: 2026.01.07 RAYTHEON CANADA LTD ELCAN
  • EP4062122B1 patent drawingFigure 1~2
  • EP4062122B1 patent drawingFigure 3~4
  • EP4062122B1 patent drawingFigure 5~6

AI summary

An optical system includes an aperture stop configured to direct light through the optical system, an inverting prism assembly configured to receive light from the aperture stop and direct light through the optical system, and a field stop configured to receive light from the inverting prism assembly and direct light through the optical system to an operator of the optical system. A point-of-impact is identified in object space and a point-of-aim is identified in afocal space of the optical system. The inverting prism assembly is configured to be pivoted about a center of the aperture stop to effect alignment of the point-of-impact and point-of-aim in the afocal space so that the point-of-aim is coincident with the optical axis.