Piezo-Actuated Helical Mirror for Variable Optical Vortex
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Solution Overview
Problem
Existing devices for generating optical vortices are limited by their inability to produce vortices with variable topological charge, continuous azimuthal phase variation, and compatibility with multiple wavelengths, particularly in high-power applications and across the visible, infrared, and ultraviolet regions.
Innovation Solution
A device comprising a circular mirror with a central hole and a radial slit, coupled with a piezo-electric actuator that undergoes azimuthally varying expansion or contraction upon voltage application, forming a single-turn helix and enabling continuous phase variation, allowing for the generation of optical vortices with variable topological charge and adaptability across different wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If computer generated hologram, spiral phase plate, or lithographically etched mirror is used to generate optical vortex, then the device structure is simple and easy to manufacture, but the topological charge is fixed and cannot be varied
Solution Approach 1:
The patent applies a piezoelectric actuator to dynamically change the shape of the mirror from flat to helical, enabling variable topological charge. The piezoelectric material deforms under applied voltage, creating a controllable helical structure that can be adjusted in real-time, thus providing adaptability while maintaining a simple overall device structure.
Solution Approach 2:
The patent changes the physical state of the mirror surface by applying voltage to the piezoelectric actuator, which alters the mirror's shape from flat to helical. This parameter change (surface curvature) directly controls the topological charge of the generated optical vortex, enabling versatile operation while keeping the device structure simple.
2Adaptability or versatility
If spatial light modulator is used to generate optical vortex of desired topological charge, then the topological charge can be varied, but the diffraction efficiency is very poor and it cannot withstand high optical power
Solution Approach 1:
The patent replaces the complex spatial light modulator system with a simpler mechanical mirror deformation approach using piezoelectric actuator. This mechanical substitution achieves variable topological charge through physical shape change rather than complex optical modulation, thereby improving diffraction efficiency and enabling high optical power handling.
Solution Approach 2:
The patent uses a curved helical mirror surface created by piezoelectric deformation to generate optical vortices. The curved geometry directly imprints the helical phase pattern on the reflected light, achieving high diffraction efficiency and variable topological charge without the losses associated with spatial light modulators.
3Adaptability or versatility
If segmented and bimorph deformable mirror is used to generate optical vortex, then the device can withstand reasonably large optical power and offers flexibility, but the azimuthal phase variation is not continuous but varies in discrete steps
Solution Approach 1:
The patent uses a radially oriented slit in the piezoelectric actuator that allows differential expansion/contraction across the mirror surface. This local quality variation creates continuous azimuthal phase variation across the mirror, achieving high manufacturing precision while maintaining the ability to handle large optical powers.
Solution Approach 2:
The patent employs a composite structure combining a piezoelectric actuator with a radially slitted mirror assembly. The piezoelectric material provides continuous deformability, and when combined with the radial slit geometry, enables continuous azimuthal phase variation while maintaining structural integrity for high optical power handling.
4Device complexity
If prior art devices are used to generate optical vortex, then the device structure is fixed for specific wavelength, but the device cannot be used for any wavelengths or range of wavelengths
Solution Approach 1:
The patent creates a universal optical vortex generator that can operate across multiple wavelengths by using a piezoelectrically controlled mirror. The mirror's helical shape, when properly formed, generates optical vortices independent of wavelength, providing multi-functionality and broad spectral coverage while maintaining a relatively simple fixed device structure.
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 device effectively generates optical vortices with continuous azimuthal phase variation and variable topological charge, overcoming previous limitations and enabling applications in high-power scenarios and across various electromagnetic spectrum regions.
Implementation Method 1
a piezo-electric actuator, comprising a hollow tube having, the inner diameter being equal to the diameter of the hole of the mirror, a through cut provided along the length of the tube extending from an inner diameter till an outer diameter of the tube, an inner electrode being formed on inner wall of the tube; and an outer electrode being formed on outer wall of the tube
Data Source
AI summary
A device for generating optical vortex of desired topological charge is disclosed. The device comprises a circular mirror having hole at its centre and a radial slit. The mirror comprises a piezoelectric actuator. The actuator comprises a hollow tube having inner diameter equal to the diameter of the hole of the mirror, a through cut extending along the length of the tube from an inner till an outer diameter, and an inner and outer electrode being formed on inner and outer wall of the tube respectively, wherein the length of the electrode increases continuously in the azimuth direction across said outer wall. The Actuator is coaxially joined to the mirror such that the slit formed between the inner and outer diameter of the tube overlaps with the radial slit. Shape of the mirror undergoes azimuthal expansion upon applying excitation voltage across electrodes forming single turn helix to generate optical vortex.