Focusing Lens with Cylindrical Interface for Laser Beam Adaptation
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Solution Overview
Problem
Conventional light modules for motor vehicle headlights and rear lights face challenges in adapting the width of laser beams to match the dimensions of micro-mirrors and achieving a desired spot size due to non-Gaussian laser beam characteristics and protective casing constraints, which prevents efficient focusing and energy utilization.
Innovation Solution
A focusing system with a converging lens having a cylindrical input interface and a biconical output interface allows independent adaptation of the beam width along both the fast and slow axes, enabling precise adjustment to match the micro-mirror dimensions and achieving a desired spot size, even with protected light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional lens is used to focus the laser beam, then the beam width can be reduced, but it is impossible to independently adapt the beam width along both the fast and slow axes to match the micro-mirror dimensions
Solution Approach 1:
The lens is divided into two distinct optical interfaces: a first interface that focuses the beam along the fast axis and a second interface that focuses the beam along the slow axis. This segmentation allows independent control of beam width in both directions, enabling precise adaptation to the rectangular micro-mirror dimensions without requiring a complex multi-element lens system.
Solution Approach 2:
Each interface of the lens is designed with different optical properties tailored to specific needs: the first interface has curvature optimized for focusing along the fast axis, while the second interface has curvature optimized for the slow axis. This local optimization of optical quality at each interface enables independent beam width control without increasing overall device complexity.
2Use of energy by moving object
If the laser beam is focused tightly to match micro-mirror dimensions, then energy utilization is improved, but the protective casing constraints prevent achieving the desired spot size
Solution Approach 1:
The lens is positioned as close as possible to the laser source within the protective casing constraints, performing the preliminary focusing action at the earliest possible point. The two-interface lens design compensates for the limited working distance by providing strong focusing power in both axial directions, enabling tight beam confinement and high energy utilization despite the short available space.
Solution Approach 2:
The lens parameters (curvature radii, thickness, refractive index) are specifically optimized to achieve the desired spot size at the micro-mirror location given the constrained distance from the light source. By adjusting these parameters, the system achieves tight focusing and high energy utilization within the protective casing constraints.
3Area of stationary object
If the beam width is increased to cover the conversion element area, then illumination coverage is improved, but the beam extends beyond the micro-mirror edges causing energy loss and component damage
Solution Approach 1:
The focusing function is segmented into two independent interface operations: the first interface controls beam width along the fast axis to match the micro-mirror's dimension in that direction, while the second interface controls beam width along the slow axis to match the micro-mirror's dimension in that direction. This prevents beam overflow in both directions, eliminating energy loss and protecting components.
Solution Approach 2:
Instead of using mechanical apertures or stops to limit the beam width, the optical system uses the two lens interfaces to actively focus and confine the beam to the exact dimensions of the micro-mirror. This substitution of mechanical beam limiting with optical focusing achieves the same result without the associated energy losses and component protection issues.
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 system effectively adapts the laser beam width to match the micro-mirror dimensions and achieves a desired spot size on the conversion element, ensuring efficient illumination and energy utilization while accommodating protected light sources.
Implementation Method 1
The conversion element receives the light beam from the laser source and converts a portion of it, for example, into white light, before directing it to the projection optical system
Implementation Method 2
Known scanning methods include, for example, MEMS (Micro-Electro-Mechanical Systems) elements, comprising one or more micromirrors that reflect the laser beam onto the area
Implementation Method 3
a light beam focusing system, including for example a converging lens to modify the dimensions of the light beam
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a light module (1) for scanning a light beam, particularly for motor vehicles, comprising a light source (3) configured to generate a light beam (4) having a slow axis and a fast axis, a wavelength conversion element (7) having a conversion surface, and scanning means (5) arranged to scan the conversion surface with the light beam (4), the light module (1) further comprising a focusing system (2) arranged to focus the light beam (4) onto the conversion element (7) and to adapt the width of the light beam (4) to the dimensions of the scanning means (5), the focusing system (2) comprising a lens (8) converging along the fast and slow axes, the lens (8) being provided with an entrance diopter and an exit diopter for the light beam (4),the entrance diopter being substantially cylindrical so as to converge the light beam (4) along the fast axis only until it induces a point of inversion of the image of the light source (3) inside the lens (8) before the beam (4) reaches the exit diopter.