Annular Prism Plate Illumination Optical System for Imaging Devices
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Solution Overview
Problem
Existing illumination optical systems for imaging devices face challenges in maintaining uniform central luminance while suppressing peripheral luminance drops, especially in deep device housings, due to excessive light scattering and uneven luminance distribution.
Innovation Solution
An illumination optical system featuring a prism plate with an annular shape, where the prism surface is tilted towards the center and includes both oblique sections and flat sections, guiding light to ensure uniform central luminance and controlled peripheral illumination, using a light guide body to manage light distribution and prevent unwanted bright lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a prism plate is used to control light emission direction, then specular reflection noise is suppressed, but peripheral luminance drops excessively
Solution Approach 1:
The prism plate incorporates different surface characteristics in different regions: the central region has a first surface with first inclination angle for controlling specular reflection, while the peripheral region has a second surface with second inclination angle for maintaining peripheral luminance. This local differentiation allows simultaneous suppression of specular reflection noise and preservation of peripheral illumination.
Solution Approach 2:
The prism plate is divided into multiple functional regions with different optical characteristics. The first surface handles central light distribution while the second surface handles peripheral light distribution, segmenting the light control function to address different luminance requirements at different positions.
2Stability of the object's composition
If light is scattered excessively to control directivity, then central luminance uniformity is improved, but peripheral luminance is reduced
Solution Approach 1:
Different regions of the prism plate have different surface inclination angles optimized for their specific functions: the central area uses steeper angles for uniform light scattering, while the peripheral area uses shallower angles to preserve light intensity, achieving local optimization of light distribution characteristics.
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 ensures uniform central luminance and improved peripheral luminance, reducing light scattering and maintaining even illuminance distribution across the object, thus enhancing imaging accuracy.
Implementation Method 1
The incident light that falls perpendicularly incident on the prism plate (more precisely, the incident light that does not have a Y-axis direction component; see the solid lines in FIG. 2), is deflected in the X-axis direction, which orthogonally intersects the ridge lines 202, as illustrated in FIGS. 3 and 4
Implementation Method 2
the emitted light is not emitted in the Y-axis direction (the ridge line direction) parallel to the ridge lines 202 at the flat surface 203 which is the emission plane
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
An illumination optical system for an imaging device includes a plurality of light sources arranged in an annular shape around an imaging unit, and a prism plate that is formed in an annular shape about an optical axis of illumination light from the light sources. The prism plate includes a prism surface upon which the illumination light from the light sources falls incident and on which prism rows containing a plurality of prisms arranged in an annular shape along a circumferential direction of the prism plate are formed, a flat section upon which the illumination light from the light sources falls incident and which is formed in an annular shape along the circumferential direction of the prism plate, and an emission plane that emits the illumination light. The prism surface is formed on an outer peripheral side outward from a predetermined radius of the prism plate that is centered on the optical axis, and the flat section is formed on an inner peripheral side inward from the predetermined radius of the prism plate that is centered on the optical axis.