Optical Device with Retardation Element for Uniform Flux
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Solution Overview
Problem
Existing optical devices that enlarge luminous flux diameter in two directions suffer from unevenness in optical intensity distribution due to polarization dependence of dielectric multilayered films, especially when used in scanning applications where light is incident from wide angular ranges.
Innovation Solution
An optical device comprising a first and second luminous flux diameter enlargement element with dielectric multilayered films, separated by a retardation element, where the elements are laminated in orthogonal directions to ensure even light transmission and reflection, reducing polarization-dependent transmittance variations and maintaining consistent optical intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If two optical devices with dielectric multilayered films are disposed in series with different lamination directions to enlarge luminous flux diameter in two directions, then the luminous flux diameter is enlarged in both directions, but unevenness in optical intensity distribution occurs due to polarization dependence
Solution Approach 1:
A polarization conversion element is introduced as an intermediary component between the first and second luminous flux diameter enlargement elements. This element converts the polarization state of light (e.g., from S-polarized to P-polarized or vice versa), enabling the light to pass through the second dielectric multilayered film with appropriate polarization characteristics. This mediator resolves the contradiction by maintaining uniform optical intensity distribution while still achieving luminous flux diameter enlargement in both directions.
2Illumination intensity
If a dielectric multilayered film is designed for S polarized light, then high transmittance is achieved for S polarized light, but transmittance is greatly reduced for P polarized light due to Brewster angle effects
Solution Approach 1:
The polarization state of light is changed as a parameter modification between stages. By using a polarization conversion element to transform S-polarized light to P-polarized light (or vice versa), the system adapts to the polarization requirements of subsequent dielectric multilayered films. This parameter change enables each film to operate in its optimal polarization mode, maintaining high transmittance while achieving versatility across multiple stages.
3Ease of operation
If optical devices are used to enlarge luminous flux diameter for retina scanning display, then images can be displayed, but unevenness in optical intensity becomes more significant when light from wide angular range is incident
Solution Approach 1:
The polarization conversion element serves as a mediator that corrects polarization-related intensity variations before light enters subsequent optical stages. By ensuring proper polarization alignment at each interface, the system maintains uniform optical intensity distribution even when receiving light from wide angular ranges, thereby supporting eye position tolerance without sacrificing intensity uniformity.
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 optical device effectively enlarges luminous flux diameter in two intersecting directions while minimizing unevenness in optical intensity distribution, ensuring stable light transmission across varying incidence angles, suitable for retina scanning type projection displays.
Implementation Method 1
the transmittance is reduced greatly as a result of the influence of a Brewster angle, and therefore, unevenness in optical intensity distribution and the like occurs
Implementation Method 2
the transmittance is reduced greatly as a result of the influence of a Brewster angle
Implementation Method 3
a retardation element that is disposed between the first luminous flux diameter enlargement element and the second luminous flux diameter enlargement element
Data Source
AI summary
An optical device which is disposed between a light source section of a display apparatus and a projection target member, includes a first luminous flux diameter enlargement element in which a first light-transmissive layer and a first partially reflective layer are alternately laminated in a first direction, and a second luminous flux diameter enlargement element in which a second light-transmissive layer and a second partially reflective layer are alternately laminated in a second direction intersecting the first direction. The first partially reflective layer and the second partially reflective layer are formed from dielectric multilayered films that have the same film configuration. In addition, the optical device includes a retardation element that is formed from a ½λ retardation plate between a first emission surface of the first luminous flux diameter enlargement element and a second incidence surface of the second luminous flux diameter enlargement element.