MICROSCOPY: Differential-polarization technique enables precise 3-D nanoimaging

Dec. 1, 2006
A reflective optical arrangement that allows control of the properties of polarized light has enabled development of an optical-imaging technique for precise 3-D thickness, dimensional, roughness, profile and step-height measurements at the nanometer scale.

A reflective optical arrangement that allows control of the properties of polarized light has enabled development of an optical-imaging technique for precise 3-D thickness, dimensional, roughness, profile and step-height measurements at the nanometer scale. The techniquedeveloped by engineers at Nano-lane (Montfort-le-Gesnois, France), distributed by Microphotonics (Irvine, CA) in North America, and dubbed Sarfusincreases the axial sensitivity of an optical microscope by about two orders of magnitude without reducing lateral resolution. It is intended for applications such as static and dynamic visualization of items such as ultrathin films, nanotubes, and nanowires.

Sarfus visualization results from a significant increase of optical-microscope sensitivity, achieved by enhancing the contrast of the object in relation to its background, provided in this method by a contrast-enhancing sample-supporting plate referred to as a “surf.” Surfs can be used in either air or liquid environments; their specific optical properties can be manipulated by customizing the layers deposited on the substrate with specific top-layer materials such as silicon dioxide, gold, chromium, or aluminum. When a beam of white light is passed through a linear polarizer prior to hitting the sample mounted on the surf, the sample induces a change in the polarization state but the surf does not. So when the reflected light passes through an analyzer crossed with the polarizer, the light reflected from the surf is stopped, whereas the light reflected from the sample passes through.

The resulting high-contrast images allow direct observation and measurement of nanoscale film thicknesses or nanoscale object and feature dimensions, as in this copolymer crystallization. Two-dimensional images can also be converted into precise 3-D metrological images with spatial resolution below 1 nm. Roughness, profile extraction, and step-height measurements can be imaged as well. Contrast on standard surf sample supports exceeds that of silicon wafer materials by a factor of 25 for ultrathin film samples of 10 nm thickness, and by a factor of 160 for a sample of 1 nm thickness.

Current and potential applications include biomedical studies such as rapid defect visualization for soft lithography, real-time visualization and dynamic study of phospholipids, and quality control and thickness-measurement determination of DNA biochips. Thin films and surface-treatment studies include characterizing layer homogeneity of organic steps, direct visualization and height-deposition measurements of plasma, dynamic studies of crystallization and wetting applications, direct behavior and morphology characterization of nanotubes and nanowires, and direct visualization of nanolithography patterns with quality control of the deposition process.

About the Author

Hassaun A. Jones-Bey | Senior Editor and Freelance Writer

Hassaun A. Jones-Bey was a senior editor and then freelance writer for Laser Focus World.

Sponsored Recommendations

Brain Computer Interface (BCI) electrode manufacturing

Jan. 31, 2025
Learn how an industry-leading Brain Computer Interface Electrode (BCI) manufacturer used precision laser micromachining to produce high-density neural microelectrode arrays.

Electro-Optic Sensor and System Performance Verification with Motion Systems

Jan. 31, 2025
To learn how to use motion control equipment for electro-optic sensor testing, click here to read our whitepaper!

How nanopositioning helped achieve fusion ignition

Jan. 31, 2025
In December 2022, the Lawrence Livermore National Laboratory's National Ignition Facility (NIF) achieved fusion ignition. Learn how Aerotech nanopositioning contributed to this...

Nanometer Scale Industrial Automation for Optical Device Manufacturing

Jan. 31, 2025
In optical device manufacturing, choosing automation technologies at the R&D level that are also suitable for production environments is critical to bringing new devices to market...

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!