Achromatic Diffractive Beam Scanner for Broadband LIDAR Operation
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Solution Overview
Problem
Diffraction-based beam-steering devices suffer from wavelength-dependent spatial dispersion, limiting their operation to narrow spectral bands, which is inadequate for broadband applications like hyperspectral LIDAR systems that require spectrally-broadband operation.
Innovation Solution
The method involves modifying the optical and spectral quality of a polychromatic light beam before interaction with a diffractive element to change its divergence characteristics, using a combination of passive and active diffractive elements to ensure that light at all wavelengths propagates in the same direction, thereby maintaining a broad spectral bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a diffractive element is used to steer the light beam, then the beam steering function is achieved, but wavelength-dependent spatial dispersion occurs limiting operation to narrow spectral bands
Solution Approach 1:
A passive diffractive element is placed before the active diffractive element to pre-disperse the polychromatic light beam. This preliminary dispersion counteracts the dispersion that will occur at the active element, enabling achromatic operation across broadband spectra while maintaining beam steering capability
Solution Approach 2:
The passive diffractive element acts as an intermediary component that modifies the incident polychromatic light beam by introducing wavelength-dependent angular dispersion. This intermediary element enables the active diffractive element to steer all wavelengths in the same direction, achieving broadband adaptability
2Adaptability or versatility
If passive diffractive element is added to compensate dispersion, then spectral bandwidth is improved, but device complexity increases
Solution Approach 1:
The passive diffractive element serves multiple functions: it pre-disperses the polychromatic light to counteract subsequent dispersion, maintains the spectral bandwidth, and enables achromatic operation. By combining these functions in a single element, the overall system complexity is managed despite adding another component
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 enables achromatic operation, allowing for broadband-spectrum-adapted beam-steering capable of supporting spectrally-broadband laser sources, facilitating new LIDAR applications with improved beam quality and steering efficiency.
Implementation Method 1
impinging a first polychromatic light beam having a first degree of divergence and a first wavelength spectrum onto a first diffractive element to produce a second polychromatic light beam having a second degree of divergence and a second wavelength spectrum
Data Source
AI summary
System and method utilizing a reconfigurable in real-time phase-modulating diffractive device (in a specific case—a 2D array of micro-mirror elements) in conjunction with another diffractive element (active or passive) to spatially steer a beam of polychromatic light such that light reaches the identified target without being substantially angularly dispersed.