3D Shape Inspection Using Phase-Shifted Surface Tilt Measurement
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Solution Overview
Problem
Existing methods for determining the three-dimensional shape of objects, especially when mounted on substrates, face challenges with mirror surfaces and noise issues in diffraction pattern imaging, making it difficult to accurately measure tilt angles and resulting in large equipment sizes and inefficiencies.
Innovation Solution
A detachable apparatus that uses pattern lights with phase-shifting capabilities, beam splitters, and lenses to measure the tilt of an object's surface by analyzing the phase changes in reflected light, allowing for precise determination of the object's angle relative to a reference plane and subsequent correction of its three-dimensional shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a method of irradiating light on the device and inspecting the tilt by using a position where the reflected light forms an image is used, then the tilt of the upper surface can be inspected, but when the device has a mirror surface, the reflection angle changes greatly even if the device is tilted at a small angle, requiring a large space to measure the imaging position of the reflected light
Solution Approach 1:
The patent transitions from measuring tilt in the spatial domain (image position) to measuring it in the frequency domain (phase spectrum). By converting the reflected light signal into a phase spectrum through Fourier transformation, the tilt measurement is performed by analyzing phase changes at different spatial frequencies rather than tracking large physical displacements of the image position, thereby enabling compact equipment design.
Solution Approach 2:
The patent replaces the traditional optical imaging method with a phase-shifting interferometry method. Instead of using mechanical or optical systems to track the position of reflected light images, the invention uses phase modulation and spectral analysis to measure tilt, substituting a complex optical-mechanical measurement system with a more compact interferometric system that processes phase information.
2Measurement precision
If a method of irradiating structured light to the device, forming a diffraction pattern in the air above the device by the structured light, and inspecting the tilt through the use of a phase change of the diffraction pattern is used, then the tilt of the upper surface can be inspected, but a lot of noise is generated because the diffraction pattern is imaged in the air
Solution Approach 1:
The patent extracts only the phase information from the reflected light signal by performing a Fourier transformation on the intensity distribution. By taking out the phase component at the specific spatial frequency corresponding to the structured light pattern, the method eliminates noise from the magnitude information, achieving clean tilt measurement without the noise problems associated with imaging diffraction patterns in air.
3Measurement precision
If a detachable second apparatus is coupled to a first apparatus to determine the angle of the upper surface, then accurate determination of the three-dimensional shape can be achieved, but the device complexity increases
Solution Approach 1:
The patent designs the second apparatus with universal functionality that allows it to be coupled to different first apparatuses for tilt measurement. The same phase-shifting interferometry module can be integrated with various illumination and imaging systems, making the complex measurement capability reusable across different inspection scenarios and reducing overall system complexity through standardization.
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 approach enables accurate and efficient measurement of the object's tilt and three-dimensional shape, facilitating the downsizing of inspection equipment and reducing noise, thereby improving the inspection process for substrate mounting processes.
Implementation Method 1
one or more first reflected lights generated by reflecting the one or more first pattern lights from the partial region
Implementation Method 2
a beam splitter and one or more lenses configured to change optical paths of the one or more first pattern lights
Implementation Method 3
derive a phase value of each of the one or more first reflected lights from the each light amount value of the one or more first reflected lights and to determine the angle of the upper surface with respect to the reference plane based on the phase value
Data Source
AI summary
The present disclosure proposes a detachable second apparatus coupled to a first apparatus that determines a first three-dimensional shape of an object and configured to determine an angle of an upper surface of the object. The second apparatus includes a first light source configured to sequentially irradiate first pattern lights having one phase range, a beam splitter and lenses configured to change optical paths of the first pattern lights so that a beam of light corresponding to a respective phase of the phase range spreads, and arrives at each point of a partial region of the upper surface of the object, a communication interface, and a first processor configured to obtain first information on first reflected lights generated by reflecting the first pattern lights from the partial region and determine the angle of the upper surface with respect to the reference plane based on the first information.