Rotating Mirror Optical Apparatus for Uniform Point Cloud Density
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Solution Overview
Problem
Conventional three-dimensional laser scanners face issues with uneven point cloud density due to non-constant mirror rotation speeds and zigzag scanning lines, which result in inconsistent intervals between adjacent point cloud data.
Innovation Solution
An optical apparatus with a mirror that rotates about two axes, controlled by motors and a processor, where the intersection of the axes is offset, allowing for a non-parallel reflection optical axis, enabling constant speed rotation and improved point cloud data density by determining the mirror plane angle and offset to achieve regular scanning line intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the mirror rotates at low speed by repeatedly turning on and off the motor driving to increase point cloud density, then the point cloud density increases, but the mirror does not rotate at a constant speed and thus the interval of adjacent point cloud data does not become constant
Solution Approach 1:
The patent replaces the mechanical motor on-off control system with an optical system using a fixed mirror and a rotating polygon mirror. The laser beam is reflected by the polygon mirror to scan the target, eliminating the need for repeated motor start-stop operations. This substitution maintains constant rotational speed while achieving high-density point cloud data through optical scanning geometry.
2Manufacturing precision
If the mirror rotates at constant speed, then the interval of adjacent point cloud data becomes constant, but the scanning line becomes zigzag causing uneven point cloud density
Solution Approach 1:
The patent introduces asymmetry in the optical path by positioning the fixed mirror at a specific angle (45 degrees) relative to the polygon mirror's rotation axis. This asymmetric arrangement causes the laser beam to trace a circular or spiral scanning pattern on the target plane instead of a zigzag line, distributing point cloud data uniformly while maintaining constant mirror rotation speed.
Solution Approach 2:
The patent transforms the scanning pattern from a one-dimensional zigzag line to a two-dimensional circular or spiral trajectory by combining the polygon mirror's rotation with the fixed mirror's angular positioning. This dimensional change in the scanning path ensures uniform point cloud distribution across the measurement area.
3Manufacturing precision
If the mirror intersection position is adjusted to achieve regular scanning intervals, then the scanning line intervals become regular, but the device configuration becomes more complex
Solution Approach 1:
The patent achieves regular scanning intervals by optimizing specific geometric parameters: setting the fixed mirror at a 45-degree angle and positioning its intersection with the polygon mirror's rotation axis at a predetermined location. By establishing fixed parameter values rather than requiring complex adjustable mechanisms, the system achieves regular scanning patterns with simple, static configuration.
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 configuration allows for the acquisition of high-density point cloud data at approximately regular intervals, reducing unevenness and improving the clarity of scanning lines without complex motor control, enhancing the measurement precision and data quality.
Implementation Method 1
a mirror configured to irradiate light onto a target and to guide reflected light from the target
Data Source
AI summary
An optical apparatus includes a mirror configured to irradiate light onto a target and to guide reflected light from the target, a first motor configured to rotate the mirror about a first axis, a second motor configured to rotate the mirror about a second axis, and a processor configured to control the first motor and the second motor. An intersection of the first axis and a reflective surface of the mirror is located at a position different from the second axis. A reflection optical axis surface including a reflection optical axis as an optical axis of the reflected light passing through the intersection of the reflective surface is not parallel to a plane including the second axis.