Scanning 3D Imager Using Linear Scanners for High Resolution
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Solution Overview
Problem
Current 3D imaging technologies using the time-of-flight measurement principle face challenges in achieving high resolution and high frame rates while maintaining a significant distance range, due to issues with ambient light interference, high power requirements, and mechanical limitations in mirror size and scanning frequency.
Innovation Solution
A scanning 3D imager that emits a fan-shaped pulsed light beam, using a scanning mirror to illuminate slices of the scene and a linear photosensor array, allowing for lower pulse power and longer photon collection times, enabling high resolution and extended distance range with a simple imager chip and low-frequency oscillating mirror.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rotating polygonal mirror is used for LIDAR scanning, then accurate ToF distance measurements are achieved, but imaging performance is poor and recording time is very long
Solution Approach 1:
The patent divides the scanning function into two independent linear scanners (horizontal and vertical) that scan along perpendicular axes. This segmentation allows simultaneous scanning of multiple scan lines, enabling complete 2D image acquisition much faster than sequential scanning by a single rotating mirror, while maintaining ToF measurement accuracy.
Solution Approach 2:
The patent replaces the rotating polygonal mirror mechanical system with linear scanners that move mirrors along linear guides. This substitution eliminates the rotational inertia and speed limitations of polygonal mirrors, enabling faster scanning frequencies and improved image recording speed while preserving measurement precision.
2Productivity
If oscillating mirrors are used for scanning, then complete 2D images with distance information can be recorded, but mirror size is limited by mass versus stiffness conflict
Solution Approach 1:
The patent segments the scanning function into two independent linear scanners operating along perpendicular axes. Each scanner uses a small linearly moving mirror instead of a large oscillating mirror, reducing mirror mass while maintaining the ability to record complete 2D images through coordinated operation of both scanners.
Solution Approach 2:
The patent transitions from single-axis oscillating mirror scanning to two-axis linear scanner architecture. By adding the vertical scanning dimension with a second linear scanner, the system achieves complete 2D imaging capability without requiring large mass mirrors, as each scanner operates independently with small lightweight mirrors.
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 solution achieves a reasonable frame repetition rate of 25 Hz and a distance range of over 100 meters, with resolutions above VGA format, while reducing the power requirements and improving optical aperture, allowing for accurate distance and intensity information capture.
Implementation Method 1
According to the ToF distance measurement principle, a light signal is emitted into the scene of interest and the time between the emission and the echo-return of the emitted signal is measured. The corresponding distance is proportional to the measured time-of-flight.
Implementation Method 2
The scanning mirror is arranged in the light path of the light beam to guide the light beam into the scene and to successively illuminate slices of the scene by sweeping the light beam through the scene. The scanning mirror comprises a micro-mechanical mirror (MEMS mirror) configured for oscillation at resonance.
Data Source
AI summary
A scanning 3D imager for recording images of a scene comprises a light source configured to emit a fan-shaped pulsed light beam with linear cross section, a scanning mirror arranged in the light path of the light beam to guide the light beam into the scene and to successively illuminate slices of the scene by sweeping the light beam through the scene transversally to the linear cross section thereof, and an imager chip arranged to receive light from the scene via the scanning mirror, the imager chip comprising an photosensor array disposed in such a way that the illuminated slices of the scene are successively imaged thereon.