Out-of-plane speckle reduction element motion
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Solution Overview
Problem
Digital cinema projection systems face challenges with high angular light from large-etendue light sources, leading to increased complexity, cost, and reduced image quality due to speckle noise from coherent light sources like lasers, which existing speckle reduction methods fail to adequately address without compromising image resolution or increasing lens complexity.
Innovation Solution
A coherent light projection system with a relay system forming an intermediate image at an intermediate image plane, where a speckle reduction element with a curved surface or lenslet arrangement is moved to reduce speckle visibility, allowing for the use of conventional projection lenses and minimizing the complexity and cost of optical designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a speckle reduction element is moved in-plane to reduce speckle visibility, then speckle noise is reduced, but image resolution may be compromised due to motion blur or loss of focus
Solution Approach 1:
The patent transitions from in-plane motion (2D) to out-of-plane motion (1D axial movement). The speckle reduction element moves along the optical axis within the depth of focus range, changing the dimension of motion. This allows speckle reduction through axial displacement without introducing lateral motion blur that would degrade image resolution, effectively resolving the contradiction between speckle reduction and image quality maintenance.
Solution Approach 2:
The patent changes the motion parameter from lateral displacement to axial displacement. By moving the speckle reduction element along the optical axis within a controlled range (within depth of focus), the system modifies the optical path and speckle pattern while maintaining focus. This parameter change enables speckle reduction without compromising the sharpness and resolution of the projected image.
2Device complexity
If conventional projection lenses are used instead of specialized optics, then cost and complexity are reduced, but speckle noise from coherent light sources increases
Solution Approach 1:
The patent extracts the speckle reduction function from the projection lens itself and implements it through a separate, movable speckle reduction element positioned at the intermediate image plane. This separation allows the use of conventional projection lenses while adding a dedicated component for speckle management. The element can be moved independently to reduce speckle without requiring specialized optical designs in the main projection lens, thus reducing overall system complexity while addressing speckle noise.
Solution Approach 2:
The patent introduces a speckle reduction element as an intermediary component between the projection lens and the screen. This mediator manipulates the light path and speckle patterns after projection but before display. By placing this element at the intermediate image plane and moving it out-of-plane, the system effectively reduces speckle noise without requiring modifications to the conventional projection lens, maintaining lens simplicity while achieving speckle reduction.
3Use of energy by moving object
If fast optics with low f/# values are used to maximize light efficiency, then light utilization is improved, but image quality and contrast uniformity deteriorate due to high angular light
Solution Approach 1:
The patent maintains continuous light efficiency by keeping the projection lens at a fast f/# value while adding a continuous, controllable speckle reduction mechanism. The movable speckle reduction element operates continuously during projection, allowing the system to maintain both high light efficiency (from fast optics) and improved image quality (through active speckle management). The element can be moved dynamically to optimize speckle reduction without interrupting the light path or requiring slower optics.
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 system effectively reduces speckle noise while maintaining high image quality and angular diversity, enabling the use of conventional projection lenses and reducing the complexity and cost of optical designs in digital cinema systems.
Implementation Method 1
A movement generating system moves the speckle reduction element out-of-plane a distance that is within a depth of focus of the projection subsystem. The out-of-plane motion reduces visibility of the speckle without substantially impacting pixel resolution.
Implementation Method 2
A relay system forms an intermediate image at an intermediate image plane from coherent light output from the image forming system. The intermediate image is an aerial real image.
Data Source
AI summary
In a coherent light projection system including an image forming system, a relay system, a speckle reduction element, and a projection subsystem, the relay system can have a first f-number, and the projection subsystem can have a second f-number less than the first f-number. The relay system can have a first working distance, and the projection subsystem can have a second working distance less than the first working distance. The image forming system can project an initial image having a first size, and an intermediate image can have a second size greater than or equal to the first size. The speckle reduction element can have a curved surface through which the intermediate image is transferred. The speckle reduction element can include a lenslet arrangement formed on a surface thereof. The speckle reduction element can be moved in a direction parallel to an optical axis of the speckle reduction element.