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Updated: Jun 21, 2026
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Assembly, Tuning and Use of an Apertureless Near Field Infrared Microscope for Protein Imaging
Published on: November 25, 2009
Cover-layer-protected solid immersion lens-based near-field recording with an annular aperture
Yong-Joong Yoon1, Wan-Chin Kim, Kyoung-Su Park
1Center for Information Storage Device, Yonsei University, Seoul, Korea.
Summary
Novel near-field-recording (NFR) optics using annular pupil zones enhance data storage density. This technology improves optical performance and focal depth in cover-layer-protected solid immersion lens (SIL)-based NFR systems.
Area of Science:
- Optical Engineering
- Data Storage Technology
Background:
- Data recording density in near-field-recording (NFR) is limited by cover-layer materials and numerical aperture (NA) trade-offs.
- Higher NA in NFR optics often leads to poorer optical characteristics despite improved resolution.
Purpose of the Study:
- To develop novel cover-layer-protected solid immersion lens (SIL)-based NFR optics with enhanced recording density and optical performance.
- To overcome limitations associated with high-refractive-index materials and NA-dependent optical characteristics in NFR systems.
Main Methods:
- Utilized annular pupil zones to modulate amplitude and phase in the entrance pupil of SIL-based NFR optics.
- Designed a 1.45 NA cover-layer-protected SIL system with a three-concentric-annular-zone aperture.
Main Results:
- Achieved data recording density comparable to conventional 1.80 NA SIL-based NFR optics using 1.45 NA optics.
- Obtained a full-width at half-maximum (FWHM) spot size of 0.315 lambda, focal depth of 0.82 lambda, and air-gap sensitivity of 0.04 lambda.
- Demonstrated 3.5 times longer focal depth and significantly lower air-gap sensitivity compared to conventional 1.80 NA SIL-NFR optics, with sidelobe intensity below 7%.
Conclusions:
- The novel annular aperture NFR optics offer superior optical performance, higher recording density, and enhanced focal depth.
- This technology significantly reduces sensitivity to air-gap variations, paving the way for improved data capacity in multiple-recording layered NFR.
