Compact Telephoto Lens Assembly for Long Range Barcode Readers
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Solution Overview
Problem
Existing imaging devices struggle to capture sharp images of barcodes at various distances and fields of view, particularly in compact barcode readers, due to limitations in focal length and optical aberration correction.
Innovation Solution
The proposed imaging engine incorporates a telephoto lens assembly with four lenses (first, second, third, and fourth lenses) disposed along an optical axis, specifically designed to correct for pupil aberration, chromatic aberration, and optical field curvature, while maintaining a compact size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a compact imaging device uses a simple lens structure, then the device size is reduced, but imaging quality and aberration correction deteriorate
Solution Approach 1:
The imaging engine divides the optical system into four distinct lens elements (first lens with positive power, second lens with negative power, third lens with positive power, fourth lens with negative power) arranged in sequence. Each lens element is optimized for specific aberration correction, allowing compact size while maintaining high imaging quality through segmented functional specialization.
Solution Approach 2:
The patent employs a composite lens structure combining multiple materials with different optical properties. The first and third lenses use materials with higher refractive indices for convergence, while the second and fourth lenses use materials with lower refractive indices for divergence and aberration correction. This composite approach enables simultaneous correction of chromatic and spherical aberrations in a compact form factor.
2Length of moving object
If the focal length is increased for long range imaging, then the imaging distance is extended, but the device size increases
Solution Approach 1:
The patent inverts the traditional telephoto approach by using a compact four-lens configuration that achieves long effective focal length (e.g., 12mm) through strategic arrangement of positive and negative power lenses. The alternating positive-negative power sequence creates a folded optical path that extends effective focal length without proportionally increasing physical length, breaking the linear relationship between focal length and device size.
Solution Approach 2:
The patent optimizes specific parameters including the spacing between lens elements, the ratio of positive to negative power, and the refractive indices of lens materials. By carefully controlling these parameters, the system achieves an effective focal length of at least 11mm while keeping the total lens assembly length under 11mm, effectively decoupling focal length from physical dimensions through parameter optimization.
3Manufacturing precision
If multiple lenses are added to correct optical aberrations, then imaging quality is improved, but device complexity increases
Solution Approach 1:
Each lens element in the four-lens assembly serves multiple functions simultaneously. For example, the first positive power lens provides both image convergence and partial chromatic aberration correction, while the second negative power lens provides both divergence control and spherical aberration correction. This multi-functionality reduces the need for additional dedicated correction elements, maintaining simplicity while achieving comprehensive aberration correction.
Solution Approach 2:
The patent applies local quality optimization by assigning specific aberration correction tasks to specific lens positions. The first and third lenses (positive power) are optimized for chromatic aberration correction using materials with appropriate dispersion properties, while the second and fourth lenses (negative power) are optimized for spherical and coma aberration correction. This localized specialization allows each element to be simpler in design while collectively achieving superior overall correction.
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 enhances the effective focal length, improves imaging quality, and reduces the size and cost of imaging engines for barcode readers, while effectively correcting optical aberrations.
Implementation Method 1
a first lens, disposed along an optical axis to receive light from an object of interest
Implementation Method 2
a second lens, disposed along the optical axis to receive light from the first lens and further to correct for pupil aberration
Implementation Method 3
a third lens, disposed along the optical axis to receive light from the second lens and further to correct for chromatic aberration
Implementation Method 4
the fourth lens, disposed along the optical axis to receive light from the third lens and further to correct for optical field curvature
Data Source
AI summary
An imaging engine including a telephoto lens for compact long range barcode readers is disclosed herein. An example imaging engine includes an imaging sensor and a telephoto lens assembly. The example telephoto lens assembly includes a first lens, disposed along an optical axis; a second lens, disposed along the optical axis to correct for pupil aberrations of the image projected after a fourth lens onto the imaging sensor; a third lens, disposed along the optical axis to correct for chromatic aberration of the image projected after the fourth lens onto the imaging sensor; and the fourth lens, disposed along the optical axis to correct for optical field curvature of the image projected after the fourth lens onto the imaging sensor.