Laser Display Speckle Reduction via Oscillating Diffuser
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional image display apparatus using laser light sources face challenges in reducing speckle noise while maintaining a compact size, as existing methods either require enlargement of the apparatus or fail to adequately reduce noise due to limitations in amplitude and frequency modulation of diffusers and diaphragms.
Innovation Solution
The apparatus incorporates a light source, an interference pattern changing optical element, and a drive unit that oscillates the element with a non-constant amplitude or frequency, creating a varying speckle pattern to inhibit accentuation and reduce noise effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light scattering object or diffuser is disposed on the light path to reduce speckle noise, then speckle noise is reduced, but the apparatus size increases
Solution Approach 1:
The patent applies dynamics by oscillating the diffuser at high frequency to dynamically change the speckle pattern over time. This temporal variation prevents the formation of a static, accentuated speckle pattern, thereby reducing perceived speckle noise without requiring additional spatial volume for noise reduction components.
Solution Approach 2:
The patent employs periodic action by oscillating the diffuser back and forth at a specific frequency (e.g., 120 Hz or higher). This periodic motion continuously varies the interference pattern, preventing speckle accentuation while maintaining a compact apparatus configuration without additional scattering objects.
2Volume of moving object
If an electromagnet is used to oscillate the diffuser without a motor, then the apparatus is downsized, but the amplitude of oscillation becomes insufficient
Solution Approach 1:
The patent changes the parameter of oscillation frequency to a high frequency range (120 Hz or higher), which allows the use of a compact electromagnet while achieving sufficient oscillation amplitude. The high frequency compensates for the limited force output of the miniaturized electromagnet, maintaining effective speckle reduction in a downsized apparatus.
Solution Approach 2:
The patent utilizes mechanical vibration by directly oscillating the diffuser using the electromagnet's magnetic field. This approach eliminates the need for motors and mechanical linkages, achieving both apparatus downsizing and sufficient oscillation amplitude through direct electromagnetic actuation at optimized frequencies.
3Object-affected harmful factors
If the amplitude of diaphragm oscillation is increased to reduce speckle noise, then speckle noise reduction improves, but the apparatus complexity increases
Solution Approach 1:
The patent merges the oscillation function directly into the diffuser assembly by mounting the diffuser on the oscillating element (such as a mirror or prism). This integration eliminates the need for separate amplitude control mechanisms, reducing apparatus complexity while achieving sufficient oscillation amplitude for effective speckle noise reduction.
Solution Approach 2:
The patent optimizes the oscillation frequency parameter to a high frequency range, which allows for smaller oscillation amplitudes to achieve the same speckle reduction effect. This parameter change simplifies the mechanical design requirements, reducing apparatus complexity while maintaining effective noise reduction performance.
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 configuration allows for a compact image display with significantly reduced speckle noise, achieving high-quality images by dynamically modulating the speckle pattern formation, thus overcoming size and noise reduction limitations of previous technologies.
Implementation Method 1
an interference pattern changing optical element for temporally changing an interference pattern that is formed with the light
Implementation Method 2
Speckle noise is an interference pattern (hereinafter referred to as the 'speckle pattern') that is created on the retina of the observer due to the high coherency of the laser
Implementation Method 3
a drive unit for driving and oscillating the interference pattern changing optical element, wherein an amplitude or a frequency of a drive signal of the drive unit is not temporally constant
Data Source
AI summary
An image display apparatus includes: a laser light source for outputting a laser beam; a diffusion optical element for diffusing the laser beam; a drive unit for oscillating the diffusion optical element; and an image conversion unit for converting the laser beam output from the diffusion optical element into an image. The diffusion optical element disposed in the drive unit is oscillated and operated in a state where an amplitude of the drive of the drive unit, which is, for example, an amplitude that is driven in a direction of the arrow X in a plane that is perpendicular to an optical axis, is not constant.