Laser Imaging System Uniform Line Illumination
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Solution Overview
Problem
Conventional laser and LADAR imaging systems face challenges in achieving uniform illumination due to Gaussian irradiance, leading to difficulties in target resolution and range resolution.
Innovation Solution
A laser imaging system that uses a polarizer beam splitter and a diffraction optic beamlet generator to create a plurality of beamlets with alternating polarization states, which are closely spaced and partially overlapping, reducing destructive interference and providing uniform irradiance across a focal-plane array, thereby enhancing target and range resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional laser sources with Gaussian irradiance are used, then the system is simple to operate, but uniform illumination cannot be achieved leading to poor target resolution
Solution Approach 1:
The laser beam is divided into multiple beamlets using a diffraction optic beamlet generator. This segmentation transforms a single Gaussian beam into multiple smaller beams that can be arranged to provide uniform illumination across the target, directly addressing the target resolution issue while managing system complexity through optical element addition
Solution Approach 2:
The patent applies different polarization states to different beamlets (alternating S and P polarization). This local differentiation in polarization quality allows each beamlet to be independently controlled and combined constructively at the target plane, achieving uniform illumination intensity distribution that improves target resolution
2Manufacturing precision
If beamlets are closely spaced to improve resolution, then target resolution improves, but destructive interference occurs causing blank spots
Solution Approach 1:
Alternating polarization states (S and P) are assigned to adjacent beamlets. This local polarization differentiation prevents destructive interference between closely spaced beamlets because orthogonal polarizations do not interfere with each other, allowing beamlets to be placed closer together for improved resolution while maintaining illumination uniformity
Solution Approach 2:
The patent converts the potential harmful effect of interference between closely spaced beamlets into a beneficial outcome by using alternating polarizations. The orthogonal polarizations eliminate destructive interference (the harm) while enabling the beamlets to be closely spaced (the benefit for resolution), thus converting what would be a problem into a solution
3Manufacturing precision
If Gaussian irradiance is used, then the laser source is simple, but uniform illumination cannot be achieved leading to poor range resolution
Solution Approach 1:
The Gaussian beam is segmented into multiple beamlets with alternating polarizations. This segmentation allows the intensity distribution to be redistributed uniformly across the target area, achieving both improved range resolution and uniform illumination intensity that conventional Gaussian beams cannot provide
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 achieves improved target resolution and range resolution by eliminating blank spots and ensuring uniform illumination, overcoming the limitations of Gaussian irradiance in conventional systems.
Implementation Method 1
a polarizer beam splitter (106) to angularly separate an input laser beam (105) into a pair of overlapping cross-polarized beams (107)
Implementation Method 2
a diffraction optic (DO) beamlet generator (108) to generate a plurality of beamlets (109) of alternating polarization states
Data Source
AI summary
Embodiments of a laser imaging system with uniform line illumination and method for generating images are generally described herein. In some embodiments, the laser imaging system includes a polarizer beam splitter to angularly separate an input laser beam into a pair of overlapping cross-polarized beams having a first angular separation therebetween, and a diffraction optic beamlet generator to generate a plurality of beamlets of alternating polarization states with a second angular separation therebetween. The laser imaging system may also include a focal-plane array (FPA) having a field-of-view (FOV) to be illuminated by the plurality of beamlets.