Folded Optical Pathway Design for Compact Laser Rangefinders
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Solution Overview
Problem
Conventional laser rangefinding instruments have complex, space-inefficient, and costly optical pathway designs that hinder the development of compact, professional rangefinders with optimal beam transmission and reception properties.
Innovation Solution
A compact folded signal transmission and image viewing pathway design utilizing a beam splitting cube in the eyepiece optical space instead of the objective space, allowing for a longer objective focal length and reduced need for expensive relay lenses, while enabling multiple visual display planes and improved photodiode power output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional lens and prism systems are used for image viewing pathway, then optical functionality is achieved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent merges the laser transmission pathway and image viewing pathway into a shared optical pathway. The objective lens serves both functions, and the eyepiece displays both the target image and laser range finding information, eliminating the need for separate complex optical systems while maintaining measurement accuracy
Solution Approach 2:
The objective lens and optical pathway are designed to serve multiple functions simultaneously: transmitting laser beams for distance measurement and transmitting visible light for target imaging. This multi-functionality reduces the number of components needed while maintaining both range finding accuracy and imaging quality
2Manufacturing precision
If relay lens system is used to achieve long objective focal length, then optical performance improves, but manufacturing cost and assembly difficulty increase
Solution Approach 1:
The patent extracts the beam splitting function from the objective optical space and relocates it to the eyepiece optical space. This allows the use of a simple beam splitting cube instead of a complex relay lens system, reducing assembly difficulty while maintaining the ability to provide long objective focal length for high optical performance
3Adaptability or versatility
If beam splitting cube is placed in objective optical space, then visual display is enabled, but expensive relay lens system is required
Solution Approach 1:
Instead of placing the beam splitting cube in the objective optical space (conventional approach), the patent inverts the approach by placing it in the eyepiece optical space. This reversal eliminates the need for expensive relay lens systems while still enabling visual display of target images and range finding information
4Length of moving object
If shorter objective focal length is used, then physical instrument length decreases, but optical performance and magnification capability deteriorate
Solution Approach 1:
The patent uses a folded optical pathway design where the optical path length is extended in a direction perpendicular to the instrument's physical length. This allows the objective focal length to be effectively doubled (e.g., 130mm optical equivalent from 65mm physical components) while keeping the instrument compact, maintaining high optical performance and magnification capability
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 design results in a more compact, cost-effective laser rangefinder with reduced parallax and enhanced optical properties, supporting accurate distance measurement across varying light conditions through adjustable contrast elements like photochromic glass and UV LEDs.
Implementation Method 1
a beam splitting cube can be utilized in the eyepiece optical space instead of in the objective optical space of the image viewing pathway
Implementation Method 2
photochromic glass may also be incorporated into the image viewing pathway which is operable in conjunction with an internally provided ultraviolet (UV) light source
Data Source
AI summary
A compact folded signal transmission and image viewing pathway design and visual display technique for laser rangefinding instruments incorporates a beam splitting cube in the eyepiece optical space and advantageously provides an objective image focal length substantially twice that of the physical length of the instrument optical components. Through the use of some of the same optical elements in both the image viewing pathway as well as the laser transmission pathway, a relatively long transmission focal length is provided which saves in both physical instrument space and component cost while also allowing for the use of reasonably sized photodiodes with improved power output over that of previous designs.