VCSEL Array Ladar Sensor Beam Steering
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Solution Overview
Problem
Existing LADAR sensors face challenges in operating effectively with low power semiconductor laser arrays, particularly in achieving accurate 3D imaging and object tracking for applications like road hazard avoidance and autonomous navigation.
Innovation Solution
The implementation of a LADAR sensor system that incorporates a pulsed semiconductor laser, optically diffused across the field of view, combined with improved sensitivity of the receiver or spatial concentration of the laser output, and a focal plane array with a readout integrated circuit to measure range to reflective surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a low power semiconductor laser array is used to illuminate the field of view, then cost and device complexity are reduced, but the illumination intensity and detection range deteriorate
Solution Approach 1:
The patent divides the laser illumination system into multiple independent VCSELs arranged in an array, where each VCSEL illuminates a specific portion of the field of view. This segmentation allows the use of low-power individual lasers while collectively covering the entire field, resolving the contradiction between using low-power lasers and maintaining sufficient illumination intensity.
Solution Approach 2:
The patent transitions from a single-point laser source to a two-dimensional array of VCSELs, enabling spatial distribution of illumination across the field of view. This dimensional change allows low-power lasers to collectively provide sufficient illumination coverage without requiring high power from individual sources.
2Illumination intensity
If a single powerful laser pulse is diffused across the entire field of view, then illumination intensity is sufficient, but device complexity and power requirements increase
Solution Approach 1:
Instead of using a single powerful laser with diffusing optics, the patent segments the illumination function across multiple VCSELs in an array. Each VCSEL provides localized illumination without requiring complex diffusing optics, thereby reducing overall device complexity while maintaining sufficient illumination intensity.
Solution Approach 2:
The patent replaces the mechanical/optical diffusing system with an electronically controllable array of VCSELs. This substitution eliminates the need for complex diffusing optics and reduces mechanical moving parts, simplifying the overall system while providing adequate illumination.
3Use of energy by moving object
If the laser output is spatially concentrated and swept across the field of view, then low power can be used, but the system complexity and operation difficulty increase
Solution Approach 1:
The patent divides the field of view into multiple zones, each illuminated by a dedicated VCSEL in the array. This segmentation eliminates the need for beam sweeping mechanisms, allowing low-power lasers to illuminate the entire field simultaneously without complex steering control, thereby maintaining ease of operation.
Solution Approach 2:
Instead of periodically sweeping a concentrated beam across the field, the patent uses continuous simultaneous illumination from multiple VCSELs. This eliminates periodic sweeping actions and the associated control complexity, while maintaining low power consumption through efficient VCSEL 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 solution enables the LADAR sensor to effectively map the surrounding area, avoid obstacles, and maintain accurate range measurements despite the limitations of low power semiconductor lasers, thereby enhancing safety and navigation capabilities.
Implementation Method 1
A beam steering LADAR sensor incorporates a VCSEL array as a pulsed laser transmitter
Implementation Method 2
A microlens array is positioned in front of the photodetector array, with each microlens corresponding to a particular VCSEL and focused on a particular element of the photodetector array
Implementation Method 3
A focal plane array of optical detectors is positioned behind a light receiving and focusing lens
Implementation Method 4
a processor to calculate the round-trip time of flight of the laser pulse to reflective features on the object of interest
Data Source
AI summary
In one embodiment, a ladar system includes a laser transmitter with at least one semiconductor laser having a pulsed laser light output. A laser drive circuit is connected to said at least one semiconductor laser and adapted to electrically drive said at least one semiconductor laser in a predetermined sequence. A laser beam steering mechanism is adapted to scan the pulsed laser light output sequentially through the field of view. A two-dimensional array of light sensitive detectors receive reflected light and an integrated circuit calculates a direct time of flight distance measurement.