Variable-Lens 2D Vision Optics for Moving-Object Depth of Field
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Solution Overview
Problem
Existing vision system cameras face challenges in maximizing the depth of field (DOF) when imaging objects with varying heights and orientations, particularly when the optical axis is tilted, leading to difficulties in focusing on multiple ID codes on moving objects, such as boxes on a conveyor.
Innovation Solution
A system and method combining a vision system, a glass lens, a variable liquid lens, and a mechanical system to adjust the lens configuration, allowing for enhanced DOF by varying the optical path and focusing on multiple angles using steerable mirrors and folding mirrors, without detaching optics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the optical axis is tilted to image objects at different heights, then the field of view is expanded, but the depth of field is reduced making it difficult to focus on multiple ID codes
Solution Approach 1:
The patent employs a variable lens assembly that can dynamically adjust its focal length and optical characteristics in real-time. This dynamic adjustment capability allows the system to switch between wide-angle/short-focus modes for capturing large fields of view and telephoto/long-focus modes for achieving deep depth of field, thereby resolving the contradiction between expanded field of view and maintained depth of field when imaging objects at varying heights
Solution Approach 2:
The system changes optical parameters by tilting the lens assembly at different angles relative to the optical axis. By adjusting the tilt angle and focal length parameters, the system can optimize the depth of field for specific imaging scenarios while maintaining an expanded field of view, effectively resolving the contradiction between these two parameters
2Area of stationary object
If multiple cameras are used to image objects of varying sizes and positions, then complete coverage is achieved, but system complexity increases
Solution Approach 1:
The patent creates a universal camera system that can perform multiple imaging functions with a single device. The variable lens assembly with adjustable tilt angles and focal lengths enables one camera to replace multiple fixed cameras, achieving complete coverage of objects with varying sizes and positions while reducing system complexity. The system can adapt to different imaging scenarios including top-down views, side views, and angled perspectives without requiring additional cameras
3Measurement precision
If the focal distance is adjusted for different object distances, then focus accuracy is improved, but the system requires multiple fixed focal length lenses increasing complexity
Solution Approach 1:
The patent implements a dynamic focal length adjustment mechanism that allows the lens to continuously vary its focal length between wide-angle and telephoto settings. This single dynamic lens replaces multiple fixed focal length lenses, maintaining focus accuracy for objects at different distances while significantly reducing system complexity. The variable lens can be electronically controlled to switch focal lengths based on the imaging requirements
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 system effectively extends the DOF, enabling clear imaging of larger objects with multiple ID codes, reducing the number of cameras needed and system complexity, while maintaining low drift and flexibility for different applications.
Implementation Method 1
A variable lens can be arranged between the lens assembly and the image sensor to change focus in response to the processor
Implementation Method 2
The optical path can be variable between an on-axis optical path and a non-on-axis optical path in which an optical plane of the lens assembly is non-parallel with an image plane
Data Source
AI summary
This invention provides a system and method for enhanced depth of field (DOF) advantageously used in logistics applications, scanning for features and ID codes on objects. It effectively combines a vision system, a glass lens designed for on-axis and Scheimpflug configurations, a variable lens and a mechanical system to adapt the lens to the different configurations without detaching the optics. The optics can be steerable, which allows it to adjust between variable angles so as to optimize the viewing angle to optimize DOF for the object in a Scheimpflug configuration. One, or a plurality, of images can be acquired of the object at one, or differing angle settings, with the entire region of interest clearly imaged. In another implementation, the optical path can include a steerable mirror and a folding mirror overlying the region of interest, which allows different multiple images to be acquired at different locations on the object.