Gallium phosphide lens attains numerical aperture of 2.0

Jan. 24, 2000
Researchers at Yale University (New Haven, CT) and Digital Instruments (Santa Barbara, CA) have built a solid-immersion-lens (SIL) microscope that reaches a numerical aperture (NA) of 2.0 at visible wavelengths--33% higher than that of oil-immersion objectives and previously reported SILs.

Researchers at Yale University (New Haven, CT) and Digital Instruments (Santa Barbara, CA) have built a solid-immersion-lens (SIL) microscope that reaches a numerical aperture (NA) of 2.0 at visible wavelengths33% higher than that of oil-immersion objectives and previously reported SILs. At the core of the instrument is a hemispherical SIL made of gallium phosphide, which has a refractive index of 3.42 at 560 nm. The lens has a 500-µm radius, is virtually achromatic, and is used in conjunction with a 0.8-NA commercial microscope objective.

When imaging 40-nm fluorescent polystyrene balls at wavelengths of 560, 645, and 720 nm, the device achieves resolutions of 145, 180, and 183 nm, respectively (defined by the full width at half maximum). Deconvolving the object diameter from the measurements results in resolutions of 139, 175, and 178 nm and effective NAs of 2.05, 1.88, and 2.06, respectively. The researchers hypothesize that a 60-nm gap between the balls and the SIL surface prevents the lens from reaching its theoretical NA of 2.50. If made of higher optical quality and used with a 0.9-NA objective, a spatial resolution of 100 nm should be possible with the lens. Contact Qiang Wu at [email protected].

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

Request a free Micro 3D Printed sample part

April 11, 2024
The best way to understand the part quality we can achieve is by seeing it first-hand. Request a free 3D printed high-precision sample part.

How to Tune Servo Systems: The Basics

April 10, 2024
Learn how to tune a servo system using frequency-based tools to meet system specifications by watching our webinar!

Motion Scan and Data Collection Methods for Electro-Optic System Testing

April 10, 2024
Learn how different scanning patterns and approaches can be used in measuring an electro-optic sensor performance, by reading our whitepaper here!

How Precision Motion Systems are Shaping the Future of Semiconductor Manufacturing

March 28, 2024
This article highlights the pivotal role precision motion systems play in supporting the latest semiconductor manufacturing trends.

Voice your opinion!

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