Interferometric Shape Measurement With Adjustable Beam Deflection
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Solution Overview
Problem
Existing interferometric measurement apparatuses face challenges in measuring test objects with different surface shapes due to the need for different computer-generated holograms (CGHs) and the use of specially manufactured prisms to adjust the angle of incidence, leading to high space requirements and operational inflexibility.
Innovation Solution
A measurement apparatus with a deflection element that can be positioned using a combination of tilting and translational movements, allowing for adjustable angles of incidence without requiring reconfiguration or specially adapted beam orientation elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If differently configured prisms are used to generate different angles of incidence for different CGHs, then the measurement apparatus can measure test objects with different surface shapes, but the device complexity and manufacturing costs increase due to conversion work and specially manufactured components
Solution Approach 1:
A single deflection element is designed to perform multiple functions: it can generate different angles of incidence for different CGHs and can be used across different measurement configurations. This eliminates the need for multiple specially manufactured prisms and reduces conversion work when measuring different test objects.
Solution Approach 2:
The deflection element is made adjustable and reconfigurable rather than fixed. It can be tilted and positioned at different locations to change the angle of incidence dynamically, allowing the same physical component to adapt to different measurement requirements without physical replacement or major reconfiguration.
2Volume of moving object
If the position of the test object remains substantially the same for different CGHs, then the measurement apparatus becomes more compact, but differently configured prisms are required to generate different angles of incidence
Solution Approach 1:
The deflection element serves as a universal component that can generate different angles of incidence for different CGHs while maintaining a compact interferometer design. This single multi-functional element replaces what would otherwise require multiple specially manufactured prisms and larger spatial arrangements.
Solution Approach 2:
Instead of changing the position of the test object (spatial arrangement in 3D space), the solution changes the angle of incidence by tilting the deflection element (changing orientation in a different dimensional parameter). This allows compact spatial arrangement while achieving different measurement configurations through angular adjustment rather than positional reconfiguration.
3Ease of operation
If a single deflection element is used for different CGHs, then the measurement apparatus becomes more flexible and compact, but the angle of incidence must be adjusted
Solution Approach 1:
The deflection element incorporates adjustable tilting and positioning capabilities that allow dynamic reconfiguration for different measurement tasks. This dynamic adjustment mechanism provides operational flexibility while maintaining a compact design, as the same physical element can be repositioned and reoriented rather than replaced.
Solution Approach 2:
The solution changes the operational parameters (angle of incidence, position) of the single deflection element rather than changing the physical element itself. By adjusting these parameters, the same component can be adapted to different measurement requirements, providing flexibility without requiring complex replacement or reconfiguration of physical components.
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 flexible and compact measurement of test objects with different surface shapes by maintaining the position of the test object, reducing conversion work, and eliminating the need for specially manufactured prisms.
Implementation Method 1
a diffractive optical element produces a test wave and a reference wave from an input wave
Implementation Method 2
a deflection element upstream of the diffractive optical element in the beam path of the measurement radiation
Implementation Method 3
the wavefront is substantially normally incident at every location on the target shape and is reflected back onto itself by the target shape
Implementation Method 4
Deviations from the target shape can then be determined with the aid of an interferogram formed by superposing the reflected test wave on the reference wave
Data Source
AI summary
A measuring device (10) for the interferometric shape measurement of a surface (12) of a test object (14-1; 14-2) includes (i) a diffractive optical element (26-1; 26-2) that generates a test wave (28) from incoming measurement radiation (18), wherein the diffractive optical element radiates the test wave onto the surface of the test object, (ii) a deflection element (22) that is disposed upstream of the diffractive optical element in the beam path of the measurement radiation, and (iii) a holding device (24, 124) that holds the deflection element and that changes a position of the deflection element (22) through a combination of a tilting movement and a translation movement.