Optical Assembly Speckle Reduction via Dynamic Phase Modulation
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Solution Overview
Problem
Existing optical illumination systems for medical applications suffer from speckle formation and non-homogeneous light distribution, leading to suboptimal image quality due to coherent light sources and mechanical components prone to failure.
Innovation Solution
An optical assembly that combines multiple light sources with an optical homogenizer and synchronized optical elements to produce a speckle-free, homogeneous beam using a fiber combiner and actuated optical elements for speckle reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If coherent light sources (laser) are used for illumination, then illumination intensity and coherence are improved, but speckle formation occurs causing non-homogeneous light distribution and degraded image quality
Solution Approach 1:
The patent segments the coherent laser beam into multiple independent wavefronts using a diffractive optical element (DOE) that generates multiple diffraction orders. Each diffraction order represents an independent coherent beam that can be individually manipulated, transforming one coherent source into multiple coherent sources with different spatial characteristics.
Solution Approach 2:
The patent merges multiple scattered coherent beams from different diffraction orders and paths into a single combined beam. By superimposing these multiple coherent wavefronts that have undergone different optical paths and phase modulations, the system achieves both high illumination intensity and homogeneous light distribution, eliminating speckle while maintaining coherence.
Solution Approach 3:
The patent introduces dynamic phase modulation to the optical system using spatial light modulators (SLM) or acousto-optic modulators (AOM). These devices dynamically adjust the phase of individual diffraction orders in real-time, enabling active control and optimization of the combined beam's intensity distribution to maintain homogeneity and eliminate speckle patterns.
2Object-affected harmful factors
If mechanically moving or vibrating elements are used for speckle reduction, then speckle visibility is reduced, but reliability decreases due to wear and failure of mechanical parts
Solution Approach 1:
The patent replaces mechanical moving or vibrating elements with purely optical and electro-optical components. Instead of physically moving mirrors or vibrating diffusers, the system uses diffractive optical elements combined with spatial light modulators or acousto-optic modulators that use electrical signals to dynamically control beam phases and intensities, achieving speckle reduction without mechanical wear.
Solution Approach 2:
The patent changes the phase and amplitude parameters of multiple coherent beams dynamically using electro-optical modulators. By rapidly varying these optical parameters rather than physical positions, the system achieves time-varying speckle patterns that average out to reduce visible speckle, while maintaining system reliability through solid-state components.
3Object-affected harmful factors
If ordered or random microlens arrays or diffractive optical elements are used, then speckle reduction is achieved with incoherent or low coherence light, but these methods are ineffective with coherent light sources
Solution Approach 1:
The patent transforms static diffractive optical elements into dynamic systems by combining them with spatial light modulators or acousto-optic modulators. This allows real-time control of the phase and amplitude of each diffraction order, adapting the system's behavior to specifically address the challenges of coherent light sources while maintaining speckle reduction capabilities.
Solution Approach 2:
The patent dynamically changes the phase parameters of individual diffraction orders using electro-optical control. This enables the system to adapt to coherent light sources by actively managing the phase relationships between multiple beams, something that static microlens arrays or simple diffractive elements cannot achieve with coherent illumination.
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
Generates a speckle-free, coherent, and homogeneous combined beam for improved image quality by minimizing speckle visibility and maintaining uniform intensity distribution.
Implementation Method 1
owing to a coherent nature of light emitting from said light sources, the light undergoes constructive and destructive interferences
Implementation Method 2
the at least one optical homogenizer is configured to produce a homogeneous intensity profile of the combined beam
Implementation Method 3
the at least one optical element is actuated by the at least one actuator to modify the combined beam
Data Source
Figure 1
Figure 2A~2B
Figure 3~4B
AI summary
An optical assembly (100, 200) comprising light sources (102, 202a, 202b, 202c) emitting light beams having multiple wavelengths; fiber combiner(s) (104, 204) arranged to combine light beams into combined beam, light beams enter fiber combiner(s); optical homogenizer(s) (106, 206), combined beam having non-homogenous intensity profile received at third end (116a) and combined beam having homogeneous intensity profile exits at fourth end (116b); first optical element(s) (108, 208) second optical element(s) (110, 210), between optical homogenizer(s) and light guide(s) (118, 304, 406), first optical element(s) and second optical(s) element collectively steer combined beam towards light guide(s), when optical assembly in use, second optical element(s) is adjustable to steer combined beam; first actuator(s) (212) coupled to first optical element(s); controller (214) coupled to first actuator(s), controller generate first signal controlling first actuator(s) that combined beam is steered by first optical element(s) also causing vibration of first optical element(s) at randomized pattern.