Spectrometer Auto-Focus Using Aperture Markers for Reflective Samples
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Solution Overview
Problem
Existing spectrometers face challenges in accurately focusing on samples with highly reflective surfaces or featureless samples, leading to ghost images that hinder proper positioning and spectral data acquisition.
Innovation Solution
An auto-focusing procedure that utilizes a two-part method: first, adjusting the sample position based on an aperture marker image using a narrow-bandwidth light to achieve coarse alignment, followed by fine-tuning based on sample features using a broader light source for precise focusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional manual focusing methods are used, then the operator can visually adjust the sample position, but the focusing accuracy deteriorates for highly reflective or featureless samples due to ghost images
Solution Approach 1:
The patent introduces an aperture marker as an intermediary reference object that is projected onto the sample plane. This marker serves as a reliable focusing reference that is independent of the sample's optical properties. The marker's known geometry provides a consistent reference pattern that can be reliably detected and used to calculate the focal position, eliminating the problem of ghost images affecting focusing accuracy for reflective or featureless samples.
Solution Approach 2:
The patent utilizes the contrast between the aperture marker and the background by projecting a distinct geometric pattern (such as a crosshair or ring) that has high visual contrast. This allows the marker to be clearly distinguished from the sample and ghost images, enabling reliable automated detection and focusing calculation even when the sample itself is highly reflective or featureless.
2Productivity
If automated focusing based on sample features is used, then the focusing speed improves, but the measurement precision deteriorates for featureless samples
Solution Approach 1:
The patent performs preliminary action by projecting the aperture marker onto the sample plane before attempting to focus on the sample itself. This pre-established reference pattern provides a known geometric feature that can be immediately used for automated focusing calculations, eliminating the need to search for or identify sample features. This approach maintains high focusing speed while ensuring precision even for featureless samples.
3Reliability
If the focal point is not accurately positioned at the sample surface, then the spectral data quality improves by avoiding ghost images, but the positioning accuracy deteriorates due to manual adjustment limitations
Solution Approach 1:
The patent implements feedback by capturing an image of the aperture marker at the current focal position, comparing the observed marker position and shape with the expected marker geometry, and using this comparison to calculate the focal offset. This feedback loop allows for precise iterative adjustment of the focal position until the marker is sharply focused, ensuring the focal point is accurately positioned at the sample surface for high-quality spectral data acquisition.
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
Enables rapid and accurate focusing of the spectrometer on various sample types, including featureless or highly reflective samples, ensuring high-quality spectral data acquisition.
Implementation Method 1
direct a first light to the sample sequentially through the aperture and the objective
Implementation Method 2
adjusting a distance between the objective and the sample stage
Data Source
AI summary
Methods and systems for automatically adjusting a sample position in a spectrometer, such as a Fourier-transform infrared (FTIR) spectrometer, are described. The sample may be automatically positioned using an auto-focusing procedure. For example, images including an aperture marker are acquired by directing light towards the sample via an aperture. The sample position may be adjusted based on features extracted from the aperture marker images.