Optical Reflector Geometry Using Brewster Angle to Cut Side Peaks
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Solution Overview
Problem
Existing optical devices suffer from unwanted reflections and scattering at the light-egress surface, leading to deviations from desired light distribution patterns, particularly due to the refractive index mismatch between the optical device material and air, resulting in undesirable side peaks.
Innovation Solution
The optical device is designed with a reflector-section comprising a light-ingress surface, a reflector surface for total internal reflection, and a light-egress surface, where the angles of incidence are shaped to align with the Brewster's angle, minimizing reflections and scattering by ensuring that the p-polarized component of light transmits through the egress surface without reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional optical device with a light-egress surface is used to modify light distribution, then light can exit the device, but unwanted reflections and scattering occur at the egress surface due to refractive index mismatch, creating undesirable side peaks in the light distribution pattern
Solution Approach 1:
The patent changes the geometric parameters of the optical device, specifically designing the light-egress surface with a specific curvature radius R2 and the reflector surface with curvature radius R1 such that their ratio R2/R1 falls within 0.2-0.8. This parameter optimization ensures that reflected light strikes the egress surface at angles close to Brewster's angle, minimizing reflections and scattering while maintaining light exit efficiency, thereby eliminating the harmful side peaks in the light distribution pattern
Solution Approach 2:
The patent employs curved surfaces instead of flat surfaces for both the light-egress surface and the reflector surface. The light-egress surface has a curvature radius R2 and the reflector surface has a curvature radius R1, with the ratio R2/R1 optimized to 0.2-0.8. This curvature design enables the reflected light to intersect the egress surface at optimal angles, reducing unwanted reflections and scattering effects that would otherwise create side peaks in the light distribution
2Loss of energy
If the light-egress surface is designed to allow main light exit, then light transmission is achieved, but reflections occur due to refractive index difference between the optical material and air
Solution Approach 1:
The patent optimizes the geometric parameters of the optical device, specifically setting the curvature radius ratio R2/R1 within 0.2-0.8, to control the angle at which reflected light strikes the egress surface. This parameter adjustment ensures that the incident angle is close to Brewster's angle, where p-polarized light experiences minimal reflection, thereby maximizing light transmission efficiency while minimizing reflection losses
Solution Approach 2:
The patent converts the potentially harmful reflection phenomenon into a beneficial effect by designing the optical geometry such that reflections occur at Brewster's angle. At this specific angle, the reflection of p-polarized light is minimized, transforming what would normally be a source of energy loss and unwanted scattering into a condition that enhances light transmission efficiency
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 design reduces unwanted reflections and scattering, resulting in a more uniform and desired light distribution pattern with minimal side peaks, enhancing the optical device's efficacy in modifying light distribution.
Implementation Method 1
a reflector surface for reflecting the light received through the light-ingress surface so that total internal reflection 'TIR' takes place when the light arrives at the reflector surface
Implementation Method 2
an angle of incidence of the reflected light arriving at the light-egress surface is substantially a polarization angle when the light source is located at a predetermined position with respect to the optical device. The polarization angle is an angle of incidence at which a p-polarized component of the above-mentioned light is transmitted through the light-egress surface without being reflected by the light-egress surface
Implementation Method 3
The optical device 101 is made of suitable transparent material whose refractive index is greater than one
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 2c~3
AI summary
An optical device (201) comprises a reflector-section (208) that comprises a light- ingress surface (203) for receiving light from a light source(202), a reflector surface (204) for reflecting the light based on total internal reflection, and a light-egress surface (205) through which the reflected light exits the optical device. When the light source is at a predetermined position with respect to the optical device, an angle of incidence (θi) of the light at the light-egress surface is a polarization angle at which a p-polarized component of the light is transmitted through the light-egress surface without being reflected by the light-egress surface. Thus, unwanted reflections at the light-egress surface can be reduced and thereby unwanted scattering of light is reduced while having good transmitting efficacy.