Tunable Acoustic Gradient Lens Double-Pass Mirror Configuration
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Solution Overview
Problem
The limitations in optical performance, particularly focus range, of tunable acoustic gradient (TAG) lenses restrict the operational capabilities of systems used for inspection and dimensional metrology, necessitating improvements in optical performance for enhanced functionality.
Innovation Solution
A TAG lens system with a novel configuration that includes a lens casing with a mirror and window arrangement, allowing workpiece light to pass through a refractive fluid twice, thereby increasing the range of effective focus positions and optical power, along with a beam splitter and polarization management to optimize light efficiency and directionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a TAG lens uses a single-pass configuration through the refractive fluid, then the device complexity is reduced, but the focus range and optical power are limited
Solution Approach 1:
The patent introduces a reflective dimension by adding a mirror at the distal end of the lens housing, causing light to traverse the refractive fluid twice (forward and backward passes). This dimensional change in light path configuration doubles the effective optical interaction without proportionally increasing device complexity
Solution Approach 2:
The mirror acts as an intermediary element that redirects light back through the refractive fluid. This intermediate reflective component enables the double-pass configuration, effectively extending the focus range while maintaining a compact overall device structure
2Power
If a TAG lens uses a reflective configuration with a mirror, then the focus range is increased, but the device complexity increases
Solution Approach 1:
The patent merges the mirror integration directly into the lens housing structure, combining two separate components (lens housing and mirror mount) into a unified design. This merging approach increases optical power through double-pass refraction while minimizing the increase in overall device complexity
Solution Approach 2:
The distal end of the lens housing serves multiple functions: it provides structural closure, mounts the mirror, and facilitates the double-pass optical path. This multi-functionality approach increases optical power while avoiding proportional increases in device complexity
3Length of moving object
If light passes through the refractive fluid twice, then the range of effective focus positions is doubled, but the loss of energy increases
Solution Approach 1:
The patent converts the potential harm of repeated light-fluid interaction (energy loss) into a benefit by using high-reflection mirrors to ensure light returns through the fluid. The double-pass configuration, which could be seen as increasing energy loss, actually doubles the effective focus range while maintaining acceptable transmission efficiency through proper optical design
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 TAG lens system achieves a significantly increased range of effective focus positions and optical power, potentially doubling the focus range compared to single-pass configurations, while maintaining high efficiency in light transmission and utilization, thereby enhancing the performance of inspection and metrology systems.
Implementation Method 1
application of an electrical field at a TAG lens resonant frequency to a vibrating member (e.g., a piezoelectric tube) surrounding the fluid medium to create a time-varying density and index of refraction profile
Implementation Method 2
The operational volume of the refractive fluid is capable of changing its refractive index along the optical path in response to application of an acoustic wave by the acoustic wave generating element
Implementation Method 3
a second case end portion that extends generally transverse to the axial direction and comprises a centrally located mirror configuration comprising a mirror mounted along the optical path
Implementation Method 4
application of an electrical field at a TAG lens resonant frequency to a vibrating member (e.g., a piezoelectric tube) surrounding the fluid medium
Data Source
AI summary
A tunable acoustic gradient (TAG) lens includes a lens casing in which a controllable acoustic wave generating element is arranged and that surrounds a casing cavity in which an operational volume of a refractive fluid is contained. The lens casing includes a first case end portion comprising a window mounted along an optical path, and a second case end portion comprising a mirror mounted along the optical path. The TAG lens is configured to enable light to pass through the window of the TAG lens to enter the TAG lens and make a first pass through the operational volume of the refractive fluid and be reflected by the mirror of the TAG lens and make a second pass back through the operational volume of the refractive fluid and pass back out through the window of the TAG lens to exit the TAG lens and continue along the optical path.