Chromatic Confocal Microscopy Using Polarized Beam Splitters
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Solution Overview
Problem
Conventional confocal scanning microscopes face challenges in measurement speed due to the need to move the objective lens, which deteriorates measurement speed and requires long exposure times for insufficient light quantities, making them inefficient for precise and fast 3D measurements of small patterns in semiconductor and LCD manufacturing.
Innovation Solution
The proposed optical measuring apparatus enhances light efficiency by using a linear polarizer, polarized beam splitter, quarter wave plate, and objective lens to generate chromatic aberration, allowing for high-speed measurement without moving the objective lens, and incorporates a spectrometer or color line camera to analyze wavelengths and colors for precise height and shape analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the objective lens is moved in the optical axis direction to perform 3D measurement, then measurement capability is improved, but measurement speed deteriorates
Solution Approach 1:
The patent replaces the mechanical movement of the objective lens with an optical solution using a fixed objective lens combined with a spectrometer to analyze wavelengths. The chromatic confocal microscope uses wavelength analysis instead of mechanical scanning to achieve 3D measurement, thereby eliminating the speed limitation caused by mechanical movement while maintaining measurement capability.
Solution Approach 2:
The patent changes the measurement parameter from spatial position (requiring mechanical movement) to wavelength (analyzed by spectrometer). By using chromatic aberration to create wavelength-specific focal planes and analyzing reflected light wavelengths, the system achieves 3D measurement without moving the objective lens, thus improving measurement speed while maintaining precision.
2Use of energy by moving object
If conventional optical components are used without polarizers, then device complexity is reduced, but light efficiency deteriorates
Solution Approach 1:
The patent introduces polarizers and beam splitters as intermediary components to control and direct light paths. The linear polarizer converts unpolarized light to polarized light, and the beam splitter uses polarization properties to separate and combine light paths, thereby improving light efficiency by ensuring maximum light transmission through each optical component while maintaining manageable system complexity.
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 configuration improves measurement speed and precision by increasing light efficiency, reducing exposure time, and enabling faster 3D imaging of objects by analyzing light wavelengths and colors, thus addressing the limitations of conventional confocal scanning microscopes.
Implementation Method 1
a linear polarizer configured to linearly polarize light emitted from the light source
Implementation Method 2
a quarter wave plate configured to circularly polarize light transmitted through the first optical path from the polarized beam splitter
Implementation Method 3
the quarter wave plate configured to linearly polarize the circularly polarized light reflected from the object to be measured
Implementation Method 4
a polarized beam splitter configured to transmit the linearly polarized light to any one of a first optical path and a second optical path
Implementation Method 5
an objective lens configured to generate light having a plurality of different wavelengths by generating chromatic aberration in the circularly polarized light from the quarter wave plate
Implementation Method 6
a spectrometer disposed on the second optical path between the polarized beam splitter and the light receiver, the spectrometer being configured to produce spectral lines according to wavelengths of the linearly polarized reflected light
Data Source
AI summary
An optical measuring apparatus may include a light source, linear polarizer, polarized beam splitter, quarter wave plate, objective lens, and/or light receiver. The polarized beam splitter may be configured to transmit linearly polarized light from the linear polarizer to any one of a first and second optical path. The quarter wave plate may be configured to circularly polarize light transmitted through the first optical path from the polarized beam splitter and transmit the circularly polarized light to an object to be measured, and the quarter wave plate may be configured to linearly polarize the circularly polarized light reflected from the object to be measured and transmit the linearly polarized reflected light to the second optical path of the polarized beam splitter. The objective lens may be configured to generate light having different wavelengths by generating chromatic aberration in the circularly polarized light from the quarter wave plate.