Digital Holography Optics With Restricted Illumination Spread
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Solution Overview
Problem
Existing optical measurement methods using digital holography suffer from noise caused by scattered light and unwanted light, leading to inaccuracies in measurement.
Innovation Solution
An optical measurement system that uses a beam splitter to divide light into first and second light beams, with a restriction mechanism to limit the illumination range of the sample to a predetermined area, and an image sensor to record holograms, suppressing noise and enhancing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If digital holography is used to measure sample geometry, then measurement accuracy is improved, but noise from scattered light and unwanted light increases
Solution Approach 1:
The light beam is divided into first light (for sample illumination) and second light (for reference) using a beam splitter. This segmentation separates the optical paths to reduce interference and noise from scattered light while maintaining measurement accuracy through holographic interference patterns.
Solution Approach 2:
A restriction mechanism (aperture stop) is introduced to locally control and restrict the spread of illuminated light on the sample to a predetermined range. This local quality control ensures that only light from the intended illumination area reaches the detection system, reducing noise from out-of-focus and scattered light while preserving measurement precision in the restricted region.
2Area of stationary object
If light is allowed to spread freely on the sample, then illumination coverage is improved, but measurement precision deteriorates due to noise
Solution Approach 1:
The restriction mechanism applies local quality control by defining a specific illumination area through an aperture stop. Light is restricted to spread only within this predetermined range, ensuring high measurement precision within the illuminated area while maintaining adequate coverage for the measurement task.
Solution Approach 2:
Instead of illuminating the entire sample area or allowing unlimited light spread, the system uses partial illumination by restricting light to a predetermined range that is sufficient for the measurement task. This partial action reduces noise from scattered light while providing adequate illumination coverage for accurate measurement.
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
The system effectively suppresses noise and achieves more accurate measurements by restricting the spread of light within a controlled range, improving measurement precision.
Implementation Method 1
a beam splitter that divides light from the light source into first light and second light
Implementation Method 2
obtaining a shape of a wave front of an object beam by observing interference fringes produced as a result of superimposition on a reference beam, of the object beam
Data Source
AI summary
An optical measurement system capable of suppressing noise and realizing more accurate measurement is provided. The optical measurement system includes a light source, an image sensor, and an optical system including a beam splitter that divides light from the light source into first light and second light. The optical system can configure a first optical system that records with the image sensor, a first hologram resulting from modulation of first light with second light while there is no sample, the second light being diverging light, and a second optical system that records with the image sensor, a second hologram resulting from modulation with second light, of light obtained by illumination of a sample with first light. The second optical system includes a restriction mechanism that restricts spread of the light obtained by illumination of the sample with first light to be kept within a predetermined range.