Detailed Study of Laser Diode Array Collimation based on Tolerancing Analysis

Abstract

This work investigates how misalignments of collimation lenses affect two performance criteria: minimum throughput within an angular window and maximum beam height. Based on these criteria, we establish an alignment concept for the first section of a LiDAR emitter. The performance criteria are derived from the overall LiDAR system requirements and applied to an optical system consisting of a laser diode array source, a microlens array for slow-axis collimation, and an acylinder for fast-axis collimation. We use raytracing-simulations to model the collimation system and characterize its performance, emphasizing the calculation and significance of the performance criteria. Defined misalignments are introduced into the optical system to study their impact. Special attention is given to whether each misalignment requires passive or active alignment. Notably, the rotation of the acylinder around the optical axis is identified as the most sensitive parameter. Finally, we present an alignment procedure based on the results of the tolerancing analysis. This study not only identifies critical misalignment factors but also offers a practical alignment solution, potentially reducing manufacturing costs and improving the reliability of micro-optical systems.