Optoelectronic Device Speckle Reduction via Phase Modulation
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Solution Overview
Problem
Coherent light projection onto surfaces often results in undesirable speckle patterns due to surface roughness, which can cause flickering when the illumination area or observer position changes.
Innovation Solution
An optoelectronic device with a coherent radiation source, a phase-modifying element that introduces a 'rough' phase front to the beam, and a radiation-directing element to modify the beam direction, effectively changing the interference image on the surface and reducing the perception of speckle patterns through time averaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If coherent electromagnetic radiation with a smooth phase front is used to illuminate a surface, then the illumination is coherent and uniform, but a speckle pattern is produced due to interference at surface roughness
Solution Approach 1:
The patent applies local quality by modifying the phase front in a localized subzone rather than uniformly across the entire beam. The phase-modifying element introduces phase changes only in specific regions, creating local phase variations that disrupt the coherent interference pattern responsible for speckle while preserving overall beam coherence and functionality.
Solution Approach 2:
The patent changes the phase parameter of the electromagnetic radiation by introducing a phase shift between subzones of the beam. This parameter modification is achieved through the phase-modifying element, which alters the phase relationship between different parts of the wavefront, thereby changing the interference characteristics and reducing speckle pattern formation.
2Area of stationary object
If the beam is moved over the surface to illuminate different areas, then coverage is improved, but the speckle pattern flickers due to continuous changes in interference
Solution Approach 1:
The patent applies preliminary action by pre-modifying the phase front structure before the beam interacts with the surface. The phase-modifying element prepares the beam with a roughened phase front that anticipates and prevents speckle formation during surface scanning, rather than attempting to correct speckle after it forms during beam movement.
3Object-generated harmful factors
If a phase-modifying element is introduced to create a rough phase front, then speckle pattern is reduced, but device complexity increases
Solution Approach 1:
The patent introduces a phase-modifying element as an intermediary component between the coherent light source and the target surface. This mediator element transforms the smooth phase front into a roughened phase front, thereby reducing speckle pattern formation without requiring fundamental changes to the light source or the target surface.
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 minimizes the impression of speckle patterns by continuously modifying the interference image as the beam moves over the surface, utilizing a phase-modifying element with zones that alter the phase of the electromagnetic radiation, thereby reducing the speckle pattern perception through the averaging effect of the observer's persistence of vision.
Implementation Method 1
a first phase-modifying element in the beam path of the first electromagnetic radiation for modifying the phase of the first electromagnetic radiation in a subzone of the first beam
Implementation Method 2
a radiation-directing element in the beam path of the first electromagnetic radiation for modifying the beam direction of the first beam
Implementation Method 3
The speckle pattern may arise during imaging of the illuminated surface for example onto the retina of the eye or onto a spatially resolving detector system through interference effects of the light reflected at surface structures of the surface
Data Source
AI summary
An optoelectronic device for projecting a first beam (110) of coherent first electromagnetic radiation onto a surface (91) comprises a first radiation source (11), which is suitable for emitting a first beam (110) of coherent first electromagnetic radiation when in operation. The optoelectronic device additionally comprises a first phase-modifying element (21) in the beam path of the first electromagnetic radiation for changing the phase of the first electromagnetic radiation in a subzone (1102) of the first beam (110) and a radiation-directing element (4) in the beam path of the first electromagnetic radiation for changing a beam direction (P1, P2) of the first beam (110).