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Дата изменения: Mon Oct 4 13:14:26 2010 Дата индексирования: Mon Oct 1 19:23:05 2012 Кодировка: Поисковые слова: microwave background |
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GRIN lenses technologyThe Refractive Index Distributions (RID) in GRIN lens preforms are made by multi-stage optimized ion-exchange diffusion between silicate mineral glasses and salt melts.
The proprietary interferometric techniques are used to optimize the diffusion procedure and to determine GRIN lens characteristics.
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Fig.1
Fig.2 |
In the LAG lenses - Low Aperture GRIN the nature of the changing of refractive index in glass via ion-exchange lies mainly in molecular volume increase. That is why in relatively high index mother glass the longitudal chromatic F-C difference of ray-trajectory pitch is very low (0.25%) and negative PF>Pd>PC (Fig.1). Special annealing treatment is used to eliminate the residual post-diffusion birefringence. LAG lenses are specially treated to create the dark anti-flick surface coating (Fig.2). The elimination of the out-of-aperture rays by this 20-mkm coating makes the image contrast significantly enhanced. The LAG resolution is not worse than 200 lines per mm in 90% zone.
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Fig.3
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In the HAG - High Aperture GRIN - imaging lenses and GTC - GRIN Tele Com - fiber collimating lenses the nature of the changing of refractive index via ion-exchange lies in polarizability difference of changing ions. Due to great dispersion difference between mother glass and ion-exchanged-glass the longitudal chromatic F-C difference of ray-trajectory pitch is comparatively high ( 3.5%) and positive PF>Pd>PC. Special achromatic length is used for HAG endoscope objective lenses (Fig.3) The resolution is not worse than 500 lines per mm in 90% diameter zone.
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