Polarization Modulator Prism Assembly for Stereoscopic Projection
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Solution Overview
Problem
Existing stereoscopic projection systems suffer from low light efficiency and image quality issues due to extra reflections causing inversed images on the screen, particularly when light rays incident obliquely on the polarization beam splitter assembly.
Innovation Solution
A polarization modulator configuration using a polarization beam splitting prism assembly composed of four prisms - one isosceles right-angled prism, two acute-angled triangular prisms, and one pentagonal prism - with specific angles and coatings, along with reflective mirrors and linear polarizers, to split and adjust light beams into P- and S-polarization states, ensuring all light rays are projected correctly onto the screen without inversed images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a polarization beam splitter assembly with three isosceles right-angled prisms is used, then the device structure is simplified, but light efficiency decreases and inversed images are formed on the screen due to extra reflections
Solution Approach 1:
The patent divides the polarization beam splitting function into multiple specialized prism components with different geometries (isosceles right-angled prisms, acute-angled triangular prisms, and pentagonal prisms). Each prism segment performs a specific function in the beam splitting process, avoiding the need for light to traverse the same optical path multiple times, thereby eliminating extra reflections and improving light efficiency while maintaining structural organization.
Solution Approach 2:
The patent introduces asymmetric prism designs, particularly the pentagonal prism with specific angle configurations (obtuse angle of 180-2α degrees, 90+α degrees, etc.), to optimize the light path geometry. This asymmetric configuration ensures that reflected light rays do not return to the incident plane, preventing the formation of inversed images and reducing energy loss from unwanted reflections.
2Adaptability or versatility
If light rays are incident obliquely on the polarization beam splitter assembly, then the system can handle real projection conditions, but extra reflections occur at the joint seam causing inversed images on the screen
Solution Approach 1:
The patent introduces the pentagonal prism as an intermediary component between the isosceles right-angled prisms and acute-angled triangular prisms. This intermediate element redirects oblique light rays through a controlled path, ensuring that reflections occur at optimized angles and do not return to form inversed images on the screen, thus mediating between oblique incidence requirements and image quality.
Solution Approach 2:
The patent uses the pentagonal prism to change the dimensional trajectory of light rays by introducing a third spatial dimension in the reflection path. By configuring the prism with specific angles (90+α degrees, 90 degrees), it redirects light in a multi-dimensional path that prevents co-linear return of reflected rays to the incident plane, eliminating inversed image formation.
3Illumination intensity
If a reflective mirror is added to reflect light rays back to the screen, then light can be directed to the screen, but the number of reflections increases to three times causing severe impact on image quality
Solution Approach 1:
The patent extracts the reflective mirror component from the optical path and replaces it with a reflective coating applied directly to the prism surfaces. This eliminates the need for separate mirror components and reduces the number of reflection interfaces. The light path is optimized so that reflections occur only at the necessary polarization beam splitting interfaces, reducing total reflections from three to two and improving image quality.
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 enhances light efficiency and image quality by preventing extra reflections, allowing all projected light rays to be directed correctly onto the screen, resulting in improved stereoscopic film projection with a compact and efficient beam superimposition.
Implementation Method 1
a second surface of the first acute-angled triangular prism facing the angle of 90−α degrees and one of two adjacent sides of the isosceles right-angled prism forming the angle of 90 degrees are attached with a first polarization beam coating layer formed therebetween
Implementation Method 2
a first reflective mirror and a second reflective mirror, each having a reflective coating positioned on a front surface thereof, the first reflective mirror being configured to adjust a propagation direction of the upper half of reflected beam
Implementation Method 3
a first linear polarizer, a second linear polarizer and a third linear polarizer, positioned respectively in a light path of the transmitted beam, a light path of the upper half of reflected beam, and a light path of the lower half of reflected beam, and configured to filter the respective beam passing therethrough
Data Source
AI summary
A polarization modulator for stereoscopic projection comprises a polarization beam splitting prism assembly for splitting an incident beam into a transmitted beam, an upper half of reflected beam, and a lower half of reflected beam, a polarization plane rotating component for rotating the polarization plane of the transmitted beam or of the upper half of reflected beam and the lower half of reflected beam by 90 degrees, a reflective mirror for adjusting a propagation direction of the upper half of reflected beam and the lower half of reflected beam, a lens group for adjusting the range of size of the transmitted beam, a linear polarizer for filtering the beam, a polarization modulator for modulating the transmitted beam, the upper half of reflected beam and the lower half of reflected beam into counter-clockwise circularly polarized light and clockwise circularly polarized light in the order of frames, and a driving circuit.