Distance Measurement Device Using Tubular Light Blocking Member
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Solution Overview
Problem
Existing distance measurement devices using light suffer from inaccuracies due to internal stray light, which is not completely eliminated by antireflection coatings, significantly affecting the detection of reflected light, especially at longer distances.
Innovation Solution
A distance measurement device incorporating a tubular light blocking member that surrounds the optical path of the laser light to prevent internal stray light from reaching the photodetector, thereby enhancing measurement accuracy by blocking stray light from leaking inside the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If antireflection films are applied to optical system members to suppress internal stray light, then surface reflection is reduced, but internal stray light cannot be completely eliminated and still significantly affects distance measurement accuracy
Solution Approach 1:
The patent extracts and removes the harmful internal stray light from the optical system by introducing a light blocking member that physically blocks stray light paths. The light blocking member is positioned to intercept stray light before it reaches the photodetector, effectively extracting the harmful element from the measurement path. This resolves the contradiction by actively removing the harmful factor rather than merely suppressing it with coatings.
Solution Approach 2:
The light blocking member acts as an intermediary element introduced into the optical system to mediate between the optical components and the photodetector. This intermediary structure blocks stray light while allowing the intended optical path to remain functional, thus resolving the contradiction by introducing a mediating component that selectively filters harmful light without disrupting the measurement function.
2Length of stationary object
If the measured distance is increased, then the measurement range is extended, but the intensity of reflected light decreases inversely proportional to the square of the distance
Solution Approach 1:
The patent applies preliminary anti-action by proactively blocking stray light paths before they can interfere with the weak reflected light signal from distant objects. The light blocking member is positioned in advance to prevent stray light from reaching the photodetector, thus counteracting the harmful effect before it occurs. This allows the system to maintain measurement accuracy even when reflected light intensity is very low at long distances.
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 light blocking member effectively suppresses the influence of internal stray light, allowing for more accurate distance measurements by ensuring that only reflected light reaches the photodetector, reducing detection signals based on stray light to near zero levels.
Implementation Method 1
a tubular light blocking member disposed on an optical path of the laser light emitted from the light source and surrounding the optical path
Implementation Method 2
a condensing lens configured to condense the reflected light passing through the outside of the light blocking member, onto the photodetector
Implementation Method 3
a photodetector configured to detect reflected light, of the laser light, reflected at the distance measurement region
Data Source
AI summary
A distance measurement device for measuring a distance to an object that exists in a distance measurement region includes: a light source configured to emit laser light; a lens configured to converge the laser light emitted from the light source, into substantially parallel light; a tubular light blocking member disposed on an optical path of the laser light emitted from the light source and surrounding the optical path; a photodetector configured to detect reflected light, of the laser light, reflected at the distance measurement region; and a condensing lens configured to condense the reflected light passing through the outside of the light blocking member, onto the photodetector.