Folded Optical Path Beam Generation for Thin Palm Vein Imaging
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Solution Overview
Problem
Conventional beam generation optical systems for palm-vein-image capturing apparatuses face a trade-off between thinness and beam spot size and radiance, where making the system thinner decreases sensitivity and accuracy due to increased beam spot size and reduced radiance.
Innovation Solution
A beam generation optical system with a specific configuration including a first transmissive section, a first reflection section, a second reflection section, and a second transmissive section, which allows light to be incident, reflected, and emitted in a manner that maintains low projection magnification and beam spot size while enabling a thinner design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the beam generation optical system is made thinner, then the device thickness is reduced, but the beam spot size increases and radiance decreases
Solution Approach 1:
The patent transforms the optical path from a straight linear arrangement to a folded configuration using reflection sections. Light travels through the optical element, reflects off a first reflection section, then a second reflection section, and exits through a second transmissive section. This folding of the optical path in additional spatial dimensions enables the system to achieve the equivalent optical path length of a thicker design while maintaining a thin physical profile.
Solution Approach 2:
The patent embeds multiple functional sections within a compact optical element structure. The optical element contains transmissive sections, reflection sections, and intermediate sections nested within each other in a layered configuration. This nesting allows the light to traverse multiple functional zones (incidence, reflection, intermediate path, emission) within a thin overall structure, achieving both thinness and maintained beam quality.
2Measurement precision
If the distance between the light source and the lens is increased, then the beam spot size is reduced, but the optical system becomes thicker
Solution Approach 1:
Instead of increasing the axial distance between light source and lens, the patent uses reflection sections to extend the optical path laterally and vertically. The light travels through the optical element, reflects multiple times within the element, and exits after traversing an extended effective path length. This dimensional transformation achieves the required optical path length for small beam spot size without increasing the system's overall thickness.
3Measurement precision
If the projection magnification is reduced, then the beam spot size is reduced, but the optical system becomes more complex
Solution Approach 1:
The patent combines multiple functions into a single integrated optical element. The optical element simultaneously performs light incidence, internal reflection (through first and second reflection sections), intermediate light path control, and light emission. By merging these typically separate components (lens, mirrors, beam shaping elements) into one monolithic structure, the system achieves low projection magnification and small beam spot size without proportionally increasing complexity.
Solution Approach 2:
The optical element serves multiple functions: it acts as a light source interface, contains reflection surfaces for path folding, provides beam shaping through its transmissive and intermediate sections, and functions as the emission aperture. This multi-functionality reduces the need for separate dedicated components, thereby controlling overall system complexity while achieving the desired beam 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
The optical system achieves a smaller beam spot size with maintained radiance, allowing for a thinner image capturing apparatus without compromising sensitivity and accuracy, enabling high-quality imaging data.
Implementation Method 1
a first reflection section which is located at a facing section facing the first transmissive section and from which light incident from the first transmissive section is reflected
Implementation Method 2
a second reflection section which is located around the first transmissive section and from which the light reflected from the first reflection section is reflected
Data Source
AI summary
An optical element includes: a first transmissive section 3 that causes light emitted from a light source to be incident on the optical element; a first reflection section 4 which is located at a facing section facing the first transmissive section and from which light incident from the first transmissive section is reflected; a second reflection section 5 which is located around the first transmissive section and from which the light reflected from the first reflection section is reflected; and a second transmissive section 6 that causes the light reflected from the second reflection section to be emitted out of the optical element in an optical axis direction of the light source.