Beam Position Feedback Sensor Using Out-of-Band Light
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Solution Overview
Problem
Existing systems for position feedback in optical systems, particularly in semiconductor manufacturing, face challenges in efficiently utilizing in-band light (IB) while maintaining throughput and sensor integrity, due to the need for IB light subtraction for positional feedback.
Innovation Solution
A system and method that utilize out-of-band light (OOB) for positional feedback, where a beam of light with both IB and OOB spectral components is directed through an aperture, and a sensor primarily receives the OOB component to determine the beam's position, allowing IB light to be fully utilized for downstream applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If in-band light is used for positional feedback, then beam position can be determined, but throughput is reduced due to light subtraction
Solution Approach 1:
The light spectrum is segmented into in-band and out-of-band components. The out-of-band light is separated and directed to a dedicated position sensing detector, while the in-band light continues to the downstream optical system. This segmentation allows independent optimization of position feedback and throughput without mutual interference.
Solution Approach 2:
An out-of-band light component serves as an intermediary for position measurement. Instead of using the primary in-band light directly for position feedback (which would reduce throughput), the system uses the out-of-band light as a mediator to carry position information without compromising the main beam's intensity for downstream applications.
2Measurement precision
If in-band light is used for positional feedback, then beam position can be determined, but sensor degradation occurs due to high energy photons
Solution Approach 1:
The out-of-band light acts as an intermediary that carries position information without the harmful high-energy characteristics of the in-band light. This mediator approach allows position measurement while protecting the sensor from degradation caused by high-energy photons.
Solution Approach 2:
The out-of-band light, which would normally be considered waste or harmful radiation, is converted into a beneficial resource for position sensing. By utilizing this previously discarded spectral component, the system achieves position feedback without exposing the sensor to the damaging high-energy in-band photons.
3Measurement precision
If in-band light is used for positional feedback, then beam position can be determined, but optical components become difficult or expensive to obtain
Solution Approach 1:
The system changes the wavelength parameter of the light used for position sensing from the in-band range to the out-of-band range. This parameter change enables the use of conventional, readily available optical components that are designed for standard wavelengths, rather than requiring specialized components for the in-band spectrum.
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 the use of nearly 100% of IB light for intended applications, reduces sensor degradation, and improves system efficiency and throughput by actively stabilizing the beam position using OOB light-based feedback.
Implementation Method 1
A sensor is positioned to primarily or only receive an out-of-band spectral component of the beam of light
Data Source
AI summary
An assembly is in a path of a beam of light, which has a first and second spectral components at different wavelengths. A first spectral component and a second spectral component of the beam of light are projected through an aperture. A sensor is disposed around the aperture to only receive a second spectral component of the beam of light. A position of the beam of light relative to the aperture can be determined using information from the sensor.