Probing the focused laser spot of the apodized light source

Yuan Hsing Fu, Wei Chih Liu, Din Ping Tsai

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

This paper deals with both theoretical and experimental studies of near-field imaging of the focused laser spot. In theoretical simulation, we calculate the intensity distribution in the focal region of the apodized light source. Size reduction of the focusing spot of an annular light beam is found to be related with various ε, which is the ratio of the obstruction radius to the radius of lens aperture. The experimental setup is based on a near-field scanning optical microscope (NSOM) system. An opaque disk is used to make an annular beam. A high numerical aperture objective lens (NA = 0.8) is used to focus incident lights of different annular light beams, and a tapered near-field optical fiber probe of the NSOM system is used to collect the intensity of the focal field. Results demonstrate that a better transverse resolution can be obtained from the reduction of the focusing spot. The intensity profile of an annular beam may have a significant influence on the size reduction of the focusing spot.

Original languageEnglish
JournalScanning
Volume26
Issue number5 SUPPL.
Publication statusPublished - 2004

Fingerprint

Light sources
near fields
light sources
Lasers
optical microscopes
light beams
lasers
lenses
radii
scanning
Lenses
Microscopes
numerical aperture
luminaires
Scanning
optical fibers
apertures
probes
Optical fibers
profiles

Keywords

  • Annular beam
  • Apodization
  • Focal point
  • Intensity Gaussian distribution
  • Near-field scanning optical microscopy

ASJC Scopus subject areas

  • Instrumentation

Cite this

Probing the focused laser spot of the apodized light source. / Fu, Yuan Hsing; Liu, Wei Chih; Tsai, Din Ping.

In: Scanning, Vol. 26, No. 5 SUPPL., 2004.

Research output: Contribution to journalArticle

Fu, YH, Liu, WC & Tsai, DP 2004, 'Probing the focused laser spot of the apodized light source', Scanning, vol. 26, no. 5 SUPPL..
Fu, Yuan Hsing ; Liu, Wei Chih ; Tsai, Din Ping. / Probing the focused laser spot of the apodized light source. In: Scanning. 2004 ; Vol. 26, No. 5 SUPPL.
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