Freeform Mirror Deflection Unit for LiDAR Scanning Distortion
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Solution Overview
Problem
Optical detection apparatuses for motor vehicles, such as laser scanners, face inefficiencies and high losses due to distortions in the field of view caused by planar mirrors, which deviate from the intended scanning angles, leading to suboptimal coverage and detection of objects in the surrounding region.
Innovation Solution
Employing a freeform mirror with surface elements of different angles of inclination in the deflection unit to reflect the light beam, ensuring it is deflected at specific setpoint scanning angles, thereby generating a predetermined field of view with a pyramidal shape, compensating for distortions and optimizing the illumination of the surrounding region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a planar mirror is used in the deflection unit to deflect the light beam, then the device structure is simple, but the field of view is distorted and scanning accuracy deteriorates
Solution Approach 1:
The patent replaces the planar mirror with a freeform mirror that has a curved surface with varying local slopes. This curvature allows different regions of the mirror to deflect light beams at different angles, compensating for the geometric distortion inherent in planar mirror systems and achieving accurate scanning angles across the entire field of view.
Solution Approach 2:
The freeform mirror is designed with spatially varying surface properties, where each local region has a specific slope angle tailored to compensate for distortion at that particular scanning angle. This local optimization of mirror surface geometry ensures that each scanned position receives light at the precise intended angle, resolving the contradiction between structural simplicity and scanning precision.
2Area of stationary object
If the aperture angle is increased to expand the field of view, then the coverage area is improved, but the field of view shape is distorted
Solution Approach 1:
The freeform mirror's curved surface is specifically designed to maintain a rectangular field of view shape even when the aperture angle is increased. By varying the local slopes across the mirror surface, the system can expand coverage area while preventing the fan-shaped distortion that would normally occur with larger aperture angles in planar mirror systems.
Solution Approach 2:
The patent changes the geometric parameters of the mirror surface, transitioning from a planar configuration to a freeform curved configuration. This parameter change allows the system to simultaneously achieve a larger aperture angle for expanded coverage and maintain the desired rectangular field of view shape through precise control of light deflection angles across the mirror surface.
3Ease of operation
If regions with distorted field of view are used for scanning, then the device operation is simplified, but detection efficiency is reduced due to light beam losses
Solution Approach 1:
The freeform mirror eliminates the need for complex software compensation by optically correcting the field of view distortion at the hardware level. This maintains simple scanning operation while preventing light beam losses that would occur in distorted regions, thereby improving detection efficiency without complicating the operation.
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 a more efficient and low-loss optical detection system by ensuring the entire angular range is utilized effectively, enabling reliable detection of objects and reducing distortions, thus enhancing the scanning efficiency and accuracy of the optical detection apparatus.
Implementation Method 1
the freeform mirror comprises at least two surface elements having different angles of inclination and is designed to reflect the light beam in order to generate a predetermined setpoint field of view
Data Source
AI summary
The invention relates to a emitter device (8) for an optical detection apparatus (3) of a motor vehicle (1), which is designed to scan a surrounding region (4) of the motor vehicle (1) by means of a light beam (10), and which comprises a light source (13) for emitting the light beam (10) and a deflection unit (15), wherein the deflection unit (15) is designed to deflect the light beam (10) emitted onto the deflection unit (15) by the light source (13) at different scanning angles (α), wherein the deflection unit (15) comprises a freeform mirror (19). The freeform mirror (19) comprises at least two surface elements (20a, 20b) having different angles of inclination (21a, 21b) and is designed to reflect the light beam (10) in order to generate a predetermined setpoint field of view (16) of the emitter device (8) at predetermined setpoint values (−α3, −α2, −α1, α0, +α1, +α2, +α3) for the scanning angle (α), said setpoint values corresponding to the angles of inclination (21a, 21b). The invention additionally relates to an optical detection apparatus (3), a motor vehicle (1) comprising at least one optical detection apparatus (3), and to a method for generating a setpoint field of view (16) for an emitter device (8) of an optical detection apparatus (3) of a motor vehicle (1).