Dot Sight Optical Path Adjustment for Close-Range Parallax

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Solution Overview

Problem

Existing dot sights suffer from parallax issues when aiming at close targets, affecting aiming accuracy due to the divergence of target light and the conversion of light from the light source into parallel light, which causes misalignment of images on the retina.

Innovation Solution

A dot sight design that includes a sight mount with adjustable light source positioning, a collimator lens set, and a beam splitter prism with a reflective film, allowing for adjustable refraction and alignment of light paths to ensure superimposition of target and light source images on the retina, regardless of aiming distance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the light source emits light to the eye side and the collimator objective converts it into parallel light, then the exposure risk of the shooter is reduced, but when aiming at close targets, the light from the light source is imaged in front of the retina causing parallax and affecting aiming accuracy

Engineering Contradiction:
Improveexposure riskVSAvoidaiming accuracy
Core Design Contradiction:
Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The light source member is made movable along the axial direction with an adjustable axial position relative to the sight mount. This dynamic adjustment capability allows the light source to be repositioned to match different focusing distances, enabling accurate aiming at both close and distant targets while maintaining the benefit of reduced exposure risk through the backward-facing light emission design

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The axial position parameter of the light source member is made variable. By changing the axial position of the light source relative to the collimator lens, the optical path and focusing characteristics are adjusted. This parameter change allows the system to adapt to different target distances, resolving the parallax issue for close targets while preserving the exposure protection benefit

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If the light source is positioned to emit light backward to reduce exposure risk, then shooter safety is improved, but the light path geometry becomes more complex requiring additional adjustment mechanisms

Engineering Contradiction:
Improveexposure riskVSAvoidadjustment mechanism complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The adjustment mechanism for the light source member is integrated with the existing sight structure. The light source member is threadedly connected to the sight mount, utilizing the same mounting interface and spatial arrangement as other components. This merging approach allows the light source to be adjusted without requiring a separate, complex adjustment system, thus reducing overall device complexity while maintaining the exposure protection benefit

Inventive Principle:
Principle #5Merging (Combining)

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 design effectively eliminates parallax and improves aiming accuracy and comfort by ensuring that light from the light source and target images are superimposed on the retina, even at varying distances, reducing exposure risk and eye fatigue.

Implementation Method 1

a collimator lens set provided in the first chamber, and provided at a side of the light source member close to the eye side

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

a beam splitter prism provided in the second chamber, where the beam splitter prism includes a first prism and a second prism cemented to each other, and a reflective film is provided on a cemented plane of the first prism and the second prism

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 3

an axial position of the light source member relative to the sight mount is adjustable... by adjusting an axial position of the light source member relative to the sight mount, a refraction effect of the collimator lens set for the light from the light source member can be adjusted

Methodology Applied
Scientific EffectOptical path adjustment: Lens

Data Source

PatentEP4394306B1Dot sight
Publication Date: 2025.07.30 ZHUHAI MEFO OPTICAL INSTR CO LTD
  • EP4394306B1 patent drawingFigure 1
  • EP4394306B1 patent drawingFigure 2
  • EP4394306B1 patent drawingFigure 3

AI summary

A red dot sight includes a sight mount (10), a sight frame (20), a light source member (30), a collimator lens set (40), a reflector (50), and a beam splitter prism (60), where a first chamber (11) is formed in the sight mount (10); the sight frame (20) is provided at a circumferential side of the sight mount (10) close to an eye side; a second chamber (21), and a through opening (22) communicating the second chamber (21) and the first chamber (11) are formed in the sight frame (20); the light source member (30) is provided at an end of the first chamber (11) close to an object side, and configured to emit light to the eye side; the collimator lens set (40) is provided in the first chamber (11); the reflector (50) is provided in the first chamber (11), and corresponding to the through opening (22); the beam splitter prism (60) is provided in the second chamber (21); and an axial position of the light source member (30) relative to the sight mount (10) is adjustable; or, the collimator lens set (40) includes a first lens (41), a second lens (42), and a third lens (43) that are sequentially arranged and have a refractive capability; and an axial position of the second lens (42) relative to the sight mount (10) is adjustable. While hiding a bright dot of a light source to lower an exposure risk of a shooter, the red dot sight can make a parallax fall within an allowed range at different aiming distances, thereby ensuring and improving an aiming accuracy.