Range Finder Focal Distance Control for S/N Ratio
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Solution Overview
Problem
Range finders with variable power optical systems face issues with low signal-to-noise ratio (S/N ratio) and difficulty in ensuring laser light enters the light receiving region due to parallax problems related to power rate and focal distance.
Innovation Solution
A range finder design that includes a sighting optical system with a correcting member to address image blur, a light transmitting section for emitting measurement light, a light receiving section for receiving returned light, a distance calculating section based on timing differences, and a power changing section to control the focal distance of the light receiving section, ensuring optimal alignment and S/N ratio through focal distance adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the power rate of the variable power optical system is increased, then the light receiving region becomes smaller and more focused, but the S/N ratio decreases and laser light cannot enter the light receiving region due to parallax
Solution Approach 1:
The patent applies dynamics by making the focal distance of the light receiving optical system variable rather than fixed. The power changing section dynamically adjusts the focal distance based on the correction amount of the correcting member, allowing the system to adapt to different power rates and maintain proper alignment between the light irradiation region and light receiving region, thereby resolving the contradiction between focus precision and S/N ratio
Solution Approach 2:
The patent changes the parameter of focal distance in the light receiving optical system to match the power rate changes. By controlling the focal distance to correspond with the correction amount, the system maintains optimal alignment conditions across varying power rates, ensuring both high measurement precision and reliable S/N ratio
2Device complexity
If the focal distance of the light receiving section is fixed, then the structure is simpler, but the laser light cannot effectively enter the light receiving region when power rate changes
Solution Approach 1:
The patent transforms the fixed focal distance into a dynamic parameter that can be adjusted. The power changing section enables the focal distance to vary in response to correcting member adjustments, allowing the system to maintain precise light alignment across different operating conditions without requiring multiple fixed optical systems
Solution Approach 2:
The patent makes the light receiving optical system universally adaptable to different power rates through the power changing section. This single adjustable system replaces what would otherwise require multiple fixed focal distance configurations, achieving multi-functionality while maintaining structural simplicity
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
Improves the accuracy of distance measurement by maintaining a high S/N ratio and ensuring the laser light effectively enters the light receiving region, enhancing the range finder's performance across varying distances.
Implementation Method 1
a distance calculating section that calculates a distance to the sighting target based on a timing at which the measurement light is output and a timing at which the return light is received by the light receiving section
Data Source
AI summary
A range finder including a sighting optical system that forms an optical image of a sighting target by sighting a target object and includes a correcting member in an optical path thereof that is driven to correct image blur of an optical image; a driving section that drives the correcting member based on a shaking amount applied to the sighting optical system; a light transmitting section that emits measurement light to a sighting target; a light receiving section that receives returned light from the sighting target and outputs a received light signal; a distance calculating section that calculates distance to the sighting target based on a timing when the measurement light is output and a timing when the return light is received by the light receiving section; and a power changing section that controls a focal distance of the light receiving section according to driving of the correcting member.