Vortex phase transmission function as a factor to reduce the focal spot of high-aperture focusing system

摘要

An analysis was performed into the possibility of reducing the lateral size and increasing the longitudinal size of a high-aperture focal system focus using a vortex phase transmission function for different types of input polarisation (including the general vortex polarisation). We have shown both analytically and numerically that subwavelength localisation for individual components of the vector field is possible at any polarisation type. This fact can be important when considering the interaction between laser radiation and materials that are selectively sensitive to different components of an electromagnetic field. In order to form substantially subwavelength details in total intensity, specific polarisation types and additional apodisation of pupil function, such as masking by a narrow annular slit, are necessary. The optimal selection of the slit radius allows balance of the trade-off between focus depth and focal spot size.View full textDownload full textKeywordshigh-aperture focusing system, Debye approximation, subwavelength light localisation, focus length extension, vortex phase transmission function, generalised vortex polarisationRelated var addthis_config = { ui_cobrand: "Taylor & Francis Online", services_compact: "citeulike,netvibes,twitter,technorati,delicious,linkedin,facebook,stumbleupon,digg,google,more", pubid: "ra-4dff56cd6bb1830b" }; Add to shortlist Link Permalink http://dx.doi.org/10.1080/09500340.2011.568710