Spatial Light Modulator for Reflectivity-Adaptive Height Mapping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Optical microscopic profilometry methods face challenges in measuring test surfaces with varying reflectivity, as existing techniques either oversaturate brighter regions or underilluminate darker regions, leading to suboptimal measurement quality and increased throughput due to the need for multiple measurements with different illumination intensities, and are prone to errors from height drift effects.
Innovation Solution
A method utilizing a multi-sensor apparatus with a pre-scan sensor and a height measuring sensor, where a spatial light modulator adjusts light intensity based on a reflectivity map to optimize illumination for the height measurement sensor, ensuring maximum signal intensity is below saturation levels, thereby improving measurement quality across varying reflectivity areas without the need for combining multiple measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the illumination intensity is set to optimise signal intensity from high reflectivity regions, then measurement quality for bright regions is improved, but measurement quality for dark regions deteriorates due to insufficient light
Solution Approach 1:
The patent applies local quality by determining an illumination intensity map that assigns different illumination intensities to different regions of the test surface based on their reflectivity characteristics. Bright regions receive lower illumination intensity to prevent saturation, while dark regions receive higher illumination intensity to ensure sufficient signal, thereby optimizing measurement quality locally for each region rather than using a uniform illumination setting
Solution Approach 2:
The patent employs preliminary action by performing a pre-scan measurement to determine the reflectivity map of the test surface before conducting the actual height measurement. This preliminary reflectivity assessment enables the system to pre-calculate the optimal illumination intensity map, allowing the illumination conditions to be optimized in advance for each region, thus avoiding the need for multiple measurements with different illumination settings
2Measurement precision
If the illumination intensity is set to optimise light intensity from low reflectivity regions, then measurement quality for dark regions is improved, but measurement quality for bright regions deteriorates due to sensor oversaturation
Solution Approach 1:
The patent applies local quality by determining an illumination intensity map that assigns different illumination intensities to different regions of the test surface based on their reflectivity characteristics. Bright regions receive lower illumination intensity to prevent saturation, while dark regions receive higher illumination intensity to ensure sufficient signal, thereby optimizing measurement quality locally for each region rather than using a uniform illumination setting
Solution Approach 2:
The patent employs feedback by using the pre-scan sensor to measure the actual light intensity reflected from different regions of the test surface. This measured reflectivity information feeds back into the calculation of the illumination intensity map, allowing the system to adjust illumination settings based on actual optical properties of the sample, thereby preventing oversaturation in bright regions while ensuring adequate illumination of dark regions
3Measurement precision
If multiple measurements with different illumination intensities are combined, then image quality is improved, but throughput of the measurement apparatus deteriorates
Solution Approach 1:
The patent employs preliminary action by performing a pre-scan measurement to determine the reflectivity map of the test surface before conducting the actual height measurement. This preliminary reflectivity assessment enables the system to pre-calculate the optimal illumination intensity map, allowing the illumination conditions to be optimized in advance for each region, thus avoiding the need for multiple measurements with different illumination settings
Solution Approach 2:
The patent applies dynamics by implementing a spatial light modulator that can dynamically adjust illumination intensity across different regions of the test surface during a single measurement. This dynamic control of illumination allows the system to adapt to varying reflectivity conditions in real-time, achieving optimal image quality in one measurement rather than requiring multiple static measurements with different illumination settings
4Measurement precision
If multiple measurements are required to combine images, then measurement quality is improved, but height drift effects between measurements introduce errors
Solution Approach 1:
The patent employs preliminary action by performing a pre-scan measurement to determine the reflectivity map of the test surface before conducting the actual height measurement. This preliminary reflectivity assessment enables the system to pre-calculate the optimal illumination intensity map, allowing the illumination conditions to be optimized in advance for each region, thus avoiding the need for multiple measurements with different illumination settings
Solution Approach 2:
The patent merges the functions of reflectivity assessment and height measurement into a single integrated measurement process. By using the pre-scan sensor data to guide the illumination settings for the height measurement sensor in real-time, the system combines what would traditionally require separate measurements into one continuous operation, thereby eliminating height drift errors that would arise from multiple sequential measurements
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 enhances measurement quality by dynamically adjusting light intensity to suit different reflectivity regions, maintaining high throughput and reducing errors, while optimizing light intensity for each pixel of the height measurement sensor to achieve optimal image quality.
Implementation Method 1
the spatial light modulator is configured to modulate light emitted from at least one of the light sources
Implementation Method 2
measuring, using the pre-scan sensor, the amount of light reflected from the test surface in a field of view of the pre-scan sensor
Data Source
AI summary
A method for measuring a height map of a test surface having a varying reflectivity using a multi-sensor apparatus including a pre-scan sensor and a height measuring sensor is disclosed. The multi-sensor apparatus further comprises one or more light sources configured to illuminate the test surface and a spatial light modulator. The spatial light modulator is placed in a light path between the one or more light sources and a measuring location of the multi-sensor apparatus and is configured to modulate light emitted from at least one of the light sources. The method comprises performing a measurement for determining an illumination intensity map of the test surface and a measurement for performing a height map of the test surface.