Separate Aperture Lidar for Efficient Light Collection
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Solution Overview
Problem
Existing lidar systems with shared-aperture or shared-beam designs face limitations in light-transfer efficiency for reception, which affects imaging quality and operational speed, as they constrain transmission and reception efficiencies to similar small values, particularly with MEMS beam steering.
Innovation Solution
The implementation of a lidar apparatus with separate transmitter and receiver apertures, where the receiver aperture is significantly larger than the transmitter aperture, and an auxiliary optical system for real-time calibration of scan mirror deflections, allowing for improved beam control and pointing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If shared-aperture or shared-beam design is used, then device complexity is reduced, but light-transfer efficiency for reception deteriorates
Solution Approach 1:
The system divides the aperture into two separate entities: a transmitter aperture for beam transmission and a receiver aperture for light collection. This segmentation allows each aperture to be independently optimized for its specific function, with the receiver aperture being significantly larger than the transmitter aperture to maximize light collection efficiency without compromising transmission performance.
2Loss of energy
If receiver aperture is made larger than transmitter aperture, then light collection efficiency is improved, but device complexity increases
Solution Approach 1:
An auxiliary optical system acts as an intermediary between the scan mirror and the receiver aperture. This system includes optical elements that relay and calibrate the beam path, enabling the large receiver aperture to effectively receive light while maintaining precise beam steering control through the scan mirror without direct mechanical coupling.
Solution Approach 2:
The auxiliary optical system provides real-time calibration of scan mirror deflections by monitoring the optical path and providing feedback signals. This feedback mechanism ensures that the larger receiver aperture maintains accurate pointing precision despite its increased size, compensating for any optical path variations.
3Loss of energy
If separate transmitter and receiver apertures are used, then light-transfer efficiency is improved, but device complexity increases
Solution Approach 1:
The auxiliary optical system serves multiple functions simultaneously: it calibrates scan mirror deflections, relays the optical path between the scan mirror and receiver aperture, and maintains beam steering accuracy. This multi-functionality reduces the need for separate calibration systems and simplifies the overall architecture despite using separate apertures.
4Measurement precision
If auxiliary optical system for calibration is added, then pointing accuracy is improved, but device complexity increases
Solution Approach 1:
The auxiliary optical system uses the system's own optical components (scan mirror, optical path) to perform self-calibration. By monitoring the deflection of the beam through the existing optical path and providing feedback to the scan mirror control, the system achieves high pointing accuracy without requiring external calibration equipment or additional complex subsystems.
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 enhances imaging quality and operational speed by optimizing light collection and beam steering, enabling more accurate and efficient lidar operations, particularly in applications requiring precise location determination and speed measurement.
Implementation Method 1
a laser source that produces a laser beam
Implementation Method 2
a scan mirror or scan-mirror assembly angularly adjustable to deflect the beam
Implementation Method 3
an afocal optical unit for magnifying the beam deflection
Implementation Method 4
a lidar receiver that does not share the transmitter aperture
Data Source
AI summary
Separate reception/transmission apertures enhance pointing: reception is more efficient than transmission (kept smaller for MEMS steering). Apparatus aspects of the invention include lidar transmitters emitting laser beams, and scan mirrors (or assemblies) angularly adjustable to deflect the beams in orthogonal directions. In one aspect, afocal optics magnify deflection; a transmitter aperture transmits the beam; a lidar receiver doesn't share the transmitter aperture. In another aspect, auxiliary optics calibrate the deflection.A method aspect of the invention notices and responds to a remote source—using a similar local laser, adjustable scan mirror or assembly, afocal deflection magnifier, transmission aperture and separate receiver. Method steps include operating the receiver to notice and determine location of the remote source; and controlling the transmitter to direct laser light back toward that location.Among preferences: receiver aperture exceeds five times transmitter aperture; receiver is segmented; beam expander between laser and mirror(s) controls waist or divergence, for selecting Gaussian or Rayleigh divergence and “zoom”.