Deflectometry System for Convex Freeform Optical Components
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Solution Overview
Problem
Existing deflectometry techniques are inadequate for measuring convex or freeform optical components due to limitations in dynamic range, resolution, and accuracy, and often require expensive interferometric setups or projector systems with distortion issues.
Innovation Solution
A deflectometry system that uses a virtual source enclosure with a series of tilted light sources and a camera to create a 2π-steradian measurement range, which can be extended to 4π-steradian, allowing for full aperture surface reconstruction of optical components with arbitrary shapes by rotating the object under test in discrete or continuous steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional deflectometry techniques are used to measure convex or freeform optical components, then the measurement setup becomes prohibitively expensive and complex, but the measurement capability is limited and inaccurate
Solution Approach 1:
The light source is divided into multiple independently controllable light emitting devices (e.g., LEDs) arranged in sequences. Each light emitting device can be individually controlled to illuminate different portions of the optical component, enabling comprehensive measurement of convex and freeform surfaces without requiring complex interferometric setups
Solution Approach 2:
The patent extends measurement capability from traditional 2D surface profiles to full 3D surface reconstruction by capturing reflected light from multiple illumination angles and positions. The movable stage enables the object to be measured in three-dimensional space, allowing complete characterization of convex and freeform optical components
2Measurement precision
If interferometric techniques are used to achieve high accuracy surface measurements, then measurement precision is improved, but the system cost and complexity increase significantly
Solution Approach 1:
The patent replaces expensive interferometric systems with a cost-effective deflectometry system using inexpensive components: standard light emitting devices (LEDs), a conventional camera, and a movable stage. This provides commercial-grade surface measurement accuracy at a fraction of the cost of interferometric systems
Solution Approach 2:
The patent substitutes complex optical interferometric systems with a simpler deflectometry approach using controlled light emission and reflection. The system replaces precision mechanical interferometers with a movable stage that positions inexpensive light sources and cameras, achieving similar measurement capabilities with reduced complexity
3Area of stationary object
If the light source and detector are positioned to measure only a portion of the optical component, then the device complexity is reduced, but the measurement coverage and dynamic range are limited
Solution Approach 1:
The patent employs a movable stage that enables dynamic repositioning of the object under test relative to the light source and detector. The stage can move the object in translational and rotational directions through multiple discrete steps, allowing the measurement system to scan and capture the entire surface of large or complex optical components without requiring a large stationary illumination space
Solution Approach 2:
The patent achieves continuous measurement coverage by capturing reflected light at multiple continuous or discrete positions and angles. The movable stage enables continuous scanning or discrete sampling of the entire optical component surface, ensuring complete measurement coverage through systematic illumination and detection sequences
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
Enables accurate and cost-effective measurement of convex and freeform optical components with improved dynamic range and precision, overcoming the limitations of traditional deflectometry and interferometric methods.
Implementation Method 1
a detector positioned to receive a reflected light produced upon reflection of the incident light from the object under test
Implementation Method 2
or a transmitted light produced upon transmission of the incident light through the object under test
Data Source
AI summary
Devices, methods and systems are disclosed that enable deflectometry on a wide array of objects, including convex and freeform optical components. One example deflectometry system includes a light source with a plurality of light emitting devices to illuminate an object under test with incident light, and a detector positioned to receive a reflected or transmitted light from the object under test. The deflectometry system further includes a movable stage for holding or securing the object under test. The movable stage can move in a translational or a rotational direction to cause the object under test to translate or rotate in a plurality of steps such that the light received at the detector encompasses a portion of a full illumination space surrounding the object, and the light received at the detector from all of the plurality of steps encompasses the full illumination space that contiguously surrounds the object under test.