Line Spectroscopic Reflectometry With Bi-Telecentric Thickness Imaging
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Solution Overview
Problem
Conventional spectroscopic reflectometry methods face limitations in high-speed, large-area measurements due to low light utilization efficiency, measurement accuracy issues, and variations in incident and reflection angles, leading to longer thickness estimation times.
Innovation Solution
Line spectroscopic reflectometry employs bi-telecentric optics to generate a line beam that is incident and reflected perpendicularly, using a line beam forming part, bi-telecentric relay optical part, and spectroscopic reflectance image acquisition part to achieve high optical utilization efficiency, uniform computational modeling, and rapid thickness estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a line measurement method is used to measure large area simultaneously, then measurement speed is improved, but light utilization efficiency becomes very low
Solution Approach 1:
The patent divides the broad spectral range into multiple narrow wavelength bands, with each band being measured sequentially. This segmentation allows the system to use a line light source efficiently for each narrow band while still achieving large-area measurement capability, thus resolving the contradiction between measurement speed and light utilization efficiency
Solution Approach 2:
The patent employs periodic switching between different narrow wavelength bands to achieve broadspectral coverage. By sequentially activating different wavelength bands in a periodic manner, the system maintains high light utilization efficiency for each band while collectively covering the full spectral range needed for accurate thickness measurement
2Area of stationary object
If line illumination is used for large-area measurement, then measurement area is increased, but measurement accuracy varies depending on position on the line
Solution Approach 1:
The patent applies local quality by optimizing the optical path for each position on the line beam. The telecentric optical system ensures that each point on the line has identical optical conditions (incident angle, reflection angle, numerical aperture), making the measurement quality uniform across the entire line rather than varying by position
3Loss of time
If line measurement method is used to improve speed, then measurement time is reduced, but computational modeling becomes complex due to angle variations
Solution Approach 1:
The patent achieves homogeneity in optical conditions across the entire line measurement area through telecentric optics. By ensuring that all positions on the line have identical incident and reflection angles, the system allows a single computational model to be applied uniformly to the entire line, dramatically reducing computational complexity compared to position-specific models
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 high-speed, large-area thickness measurement with improved accuracy and uniform computational modeling, allowing for rapid thickness estimation and measurement of specular surfaces like glass substrates and optically clear resin.
Implementation Method 1
If light with a wavelength λ is irradiated onto a measurement object, reflection occurs at each boundary surface of the medium, and due to interference phenomena, the final reflectance (R) signal varies in intensity depending on the thickness (d) and refractive index (n) of the object, as well as the light wavelength.
Implementation Method 2
a spectroscopic reflectance image acquisition part that separates the reflected line beam from the measurement object by wavelength to acquire a spectroscopic reflectance image
Data Source
AI summary
The present disclosure relates to line spectroscopic reflectometry, and the line spectroscopic reflectometry according to the present disclosure is characterized by including a line beam forming part that generates a line beam from a light source irradiating a broadband wavelength; a bi-telecentric relay optical part that uses bi-telecentric optics to enlarge the line beam generated by the line beam forming part and vertically irradiates and reflects it onto a measurement object; a spectroscopic reflectance image acquisition part that separates the reflected line beam from the measurement object by wavelength to acquire a spectroscopic reflectance image; and an image analysis processing part that obtains a thickness of the measurement object from the spectroscopic reflectance image for a region where the line beam is irradiated onto the measurement object.