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Optical Metrology

Optical metrology includes interferometry and other sophisticated techniques that can be used for assessing dimensions, surface properties, temperature, and alignment with accuracy and efficiency. Many industries and applications rely on these light-based non-contact measurement techniques for quality control, product design, and process optimization.

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What does an optical metrology system look like, and how does it work?

Optical metrology encompasses numerous techniques that use light to measure and analyze various properties of objects or materials. Precise measurements, inspections, and analyses for various scientific, industrial, and technological applications are possible because of the unique way that light interacts with materials.

Generally, optical metrology approaches follow these steps:

Illumination

A light source, often a laser or other coherent light emitter, is used to illuminate the object. Optical elements like fiber optic light guides, lenses, mirrors, or beam splitters can be used to control and direct the light path used for illumination.

Interaction

When light interacts with the object, the object’s characteristics cause it to change in various ways. This can modify the way the light is reflected, refracted, or absorbed, which creates changes in the intensity, wavelength, phase, or polarization of the light.

Detection

Detectors or sensors capture the modified light after it has interacted with the object. Measuring changes in the light’s properties provides important insights into the object's properties.

Optical metrology techniques

Interferometry

Interferometry uses the interference patterns generated by light waves to determine an object’s surface profiles, flatness, thickness, optical quality, and other characteristics.

Spectroscopy

By measuring interactions between light and matter, spectroscopy can be used to identify chemical composition, molecular structures, and material properties based on the light's absorption, emission, or scattering patterns.

Optical triangulation

Optical triangulation combines the principles of geometry and optics to measure distances or assess the surface profiles of objects. This is done by projecting a light pattern onto a surface and then analyzing the geometry of the light that is reflected or scattered.

Typical applications for optical metrology

Thanks to its ability to provide precise and accurate measurements, a wide variety of industries and scientific fields rely on optical metrology. Some prominent application areas include:

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Semiconductor

Optical metrology is vital in lithography processes, where it ensures precise alignment and characterization of patterns on semiconductor wafers. Techniques such as optical critical dimension (OCD) measurement are used to preserve accuracy in the nanoscale patterns created on the wafers.

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Food production

Spectroscopy is used to provide rapid, non-destructive, and precise analyses for food production. This helps ensure food quality, safety, authenticity, and compliance with regulatory standards.

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Industrial automation

In manufacturing settings, optical metrology facilitates precise measurements, automated inspection, quality control, and process optimization. This not only helps increase efficiency, reduce errors, and improve product quality in automated production lines but is also crucial for achieving the goals of Industry 4.0 and smart manufacturing initiatives.

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Oil and energy

Optical metrology can be used for level sensing, which is key for managing inventory, optimizing production, ensuring safety, and complying with regulations in the oil industry. Accurate monitoring of oil levels enables efficient operations across the different phases of oil extraction as well as during the refining, transportation, and storage processes.

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Life sciences

In the life sciences, optical metrology techniques include optical coherence tomography (OCT) for non-invasive imaging, fluorescence microscopy for studying molecules within cells, and optical tweezers for precise manipulation of cells and particles. These methods are used to help diagnose diseases, study cells, and perform microscale biomedical research.

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Defense and aerospace

Optical metrology is crucial in defense and aerospace applications. It ensures precision in manufacturing, evaluates surface quality and aligns optical systems in critical structures such as satellites and missiles. Optical components enable non-contact measurements and contribute to the precise evaluation of distances and shapes. The technology plays a key role in testing, validation and calibration, improving the overall safety and performance of defense and aerospace equipment in different environments.

Specialty glass in optical metrology

SCHOTT’s specialty glass components and subassemblies — including fiber optic light guides, optical materials and components, and hermetic packaging — are essential in advancing optical sensing and metrology, where precision and accuracy are paramount. Our specialty glass materials are engineered to possess unique combinations of optical properties, such as low dispersion and high transmittance, which enable cutting-edge sensors and measurement instruments. By facilitating light manipulation, specialized glasses and components are empowering advanced signal detection and precise measurement.

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SCHOTT´s products for optical metrology and sensing

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Fiber optics

Fiber optic bundles play a crucial role in optical metrology by carrying light from a source to a measurement device or from an object under scrutiny to a detector. Whether guiding light and images around a corner, out of a tight space, or away from a hot, dark, or challenging area, fiber optics are critical for many of the world’s most advanced technologies.

Products
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Optical and filter glass

We have an extensive range of optical and filter glass carefully developed to improve precision and accuracy in metrology applications. Our more than 120 different optical glasses can be used to fabricate the lenses, mirrors, and other components that form the backbone of the high-precision imaging systems used in metrology. In addition, SCHOTT's specialized filter glasses — including bandpass, longpass, shortpass, multiband, and contrast enhancement filters — help control light transmission and isolate specific wavelengths.

Products
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Optical components and coatings

SCHOTT offers precision-engineered optical components and coatings that enhance measurement accuracy. Crafted lenses and mirrors ensure superb imaging quality crucial for high-precision metrology. SCHOTT´s advanced coatings can help minimize reflections, enhance light transmission, and reduce surface interference, ensuring precise measurements with minimal distortion.

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Hermetic packaging for optical sensors

Packaging and electrical components ensure reliability and functionality in optical sensors and metrology devices. Vacuum-sealed packages shield from moisture, dust, vibration, and light interference, providing precise alignment for accurate measurements. Hermetic components like connectors enable optical signal communication. SCHOTT offers custom-designed packages and optical lens caps for UV/VIS/IR sensors.

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