Prism Optical Assembly With TIR Interfaces for Uniform Skin Illumination
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Solution Overview
Problem
Prism-based optical waveguides in skin treatment devices face challenges such as non-uniform angular and spatial distribution of light, light leakage, and back propagation, leading to inefficient light guidance and treatment.
Innovation Solution
An optical assembly using a prism and guiding elements with total internal reflection (TIR) and refractive index variations to guide light effectively, reducing leakage and enhancing uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If prism-based waveguides are used to guide light at large angles, then light guidance capability is improved, but light leakage and non-uniform distribution occur
Solution Approach 1:
The waveguide is divided into multiple segments with progressively changing refractive indices. This segmentation allows the light to be gradually redirected through total internal reflection at each interface, preventing light leakage while maintaining uniform distribution. The segmented structure transforms the single large-angle deflection into multiple smaller angular changes.
Solution Approach 2:
Different regions of the waveguide are assigned different refractive indices to optimize local light control. The refractive index varies along the propagation direction, creating local conditions that ensure total internal reflection occurs uniformly across the beam profile, thereby eliminating non-uniform distribution while maintaining effective light guidance.
2Productivity
If prism-based waveguides bend light at large angles, then guidance efficiency is improved, but light leaks from the waveguide
Solution Approach 1:
The refractive index parameter is changed progressively along the waveguide length. By creating a gradient or stepped variation in refractive index, the conditions for total internal reflection are maintained throughout the waveguide, preventing light leakage while achieving the required large-angle light bending for effective skin treatment guidance.
3Area of stationary object
If incoherent light source is used for treatment, then treatment coverage is improved, but light propagation control becomes difficult
Solution Approach 1:
The waveguide structure is designed with spatially varying refractive indices that account for the divergent nature of incoherent light. Each region of the waveguide is optimized to handle light rays at different angles, ensuring uniform total internal reflection across the entire beam profile. This maintains excellent propagation control despite the wide angular distribution inherent to incoherent light sources.
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 solution improves light flux and uniformity, minimizing light loss and increasing the amount of light directed towards the target, enhancing treatment efficiency.
Implementation Method 1
The first surface and the second surface of the first prism are total internal reflection surfaces
Implementation Method 2
The first surface and the second surface of the first prism are separated from the first guiding element and the second guiding element, respectively, by a refractive index interface
Data Source
AI summary
Provided is an optical assembly (1) for use in a skin treatment device (2), and the use thereof in a treatment method. The optical assembly (1) comprises a light source (10), a first prism (11) and first and second guiding elements (12) and (13) with enclosed reflective faces disposed facing each other. The first prism (11) includes a first surface (111), a second surface (112) inclined with the first surface (111) and a third surface (113) adjoining the first (111) and the second (112) surfaces. The first guiding element (12) is arranged to guide the light transmitted from the light source (10) through the first surface (111) of the first prism. The second guiding element is further arranged to receive through the second surface (112) of the first prism (11), the light reflected from the third surface (113) of the first prism and output the received light for illuminating the skin. The first surface (111) and the second surface (112) of the first prism (11) are separated from the first guiding element (12) and the second guiding element (13), respectively, by a refractive index interface and act as total internal reflection surfaces.