Laser Radar Low Drift Reference Using Fabry-Perot Resonator
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional laser radar systems face limitations in beam scan rates and distance calibration, which can drift over time, and are costly, necessitating improved methods for accurate and efficient distance measurement.
Innovation Solution
The implementation of a scanning reflector system with two reflective surfaces positioned at angles like 45 or 135 degrees, coupled with a signal processor that uses frequency chirped optical beams and a corner-cube configuration to estimate target distances based on the difference frequency between the return and secondary beams, along with a calibration system employing a Fabry-Perot resonator for precise distance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional laser radar systems use encoder-based beam scanning, then distance measurement capability is provided, but beam scan rates are limited and distance calibration drifts over time
Solution Approach 1:
The patent replaces the mechanical encoder-based scanning system with an optical resonator-based reference system. The Fabry-Perot resonator provides a non-mechanical reference frequency that is used to modulate the laser beam, eliminating the need for mechanical encoders and their associated drift problems while enabling higher scan rates.
Solution Approach 2:
The patent changes the reference from mechanical encoder positions to optical resonator frequencies. By using the resonator's natural frequency modes as the reference, the system achieves higher scan rates and eliminates calibration drift, as the optical frequency reference is inherently more stable than mechanical encoders.
2Measurement precision
If conventional laser radar systems use mechanical scanning components, then distance measurement is achieved, but system cost increases
Solution Approach 1:
The patent eliminates expensive mechanical scanning components by using optical resonance phenomena. The Fabry-Perot resonator provides precise frequency reference without requiring mechanical encoders, motors, or complex positioning systems, thereby reducing system cost while maintaining measurement precision.
Solution Approach 2:
The optical resonator serves as its own reference standard, using its natural resonant frequencies to provide the timing and positioning reference. This self-referencing approach eliminates the need for separate calibration systems and expensive mechanical reference components.
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 approach enhances the accuracy and reliability of distance measurements by stabilizing the optical path and using advanced signal processing to account for beam drift, while reducing costs through improved calibration and measurement precision.
Implementation Method 1
an optical path length based on a physical dimension of an ultralow thermal expansion (ULE) support structure
Implementation Method 2
a laser source configured to provide a frequency chirped optical beam
Implementation Method 3
a corner-cube configured to receive the measurement beam from the end surface of the optical fiber and reflect the measurement beam back through the optical fiber
Implementation Method 4
an optical fiber configured to receive the measurement beam from the laser source and direct to the measurement beam to the corner-cube from a fiber end surface, and to receive the return beam at the end surface
Implementation Method 5
A beam focusing optic is configured to receive the measurement beam from the corner cube and focus the measurement beam at a target surface
Data Source
AI summary
Laser radar systems include a pentaprism configured to scan a measurement beam with respect to a target surface. A focusing optical assembly includes a corner cube that is used to adjust measurement beam focus. Target distance is estimated based on heterodyne frequencies between a return beam and a local oscillator beam. The local oscillator beam is configured to propagate to and from the focusing optical assembly before mixing with the return beam. In some examples, heterodyne frequencies are calibrated with respect to target distance using a Fabry-Perot interferometer having mirrors fixed to a lithium aluminosilicate glass-ceramic tube.