The cornea is the transparent connective tissue window at the front of the eye.The physiological role of the cornea is to conduct external light into the eye,focus it,together with the lens,onto the retina,and to prov...The cornea is the transparent connective tissue window at the front of the eye.The physiological role of the cornea is to conduct external light into the eye,focus it,together with the lens,onto the retina,and to provide rigidity to the entire eyeball.Therefore,good vision requires maintenance of the transparency and proper refractive shape of the cornea.The surface structures irregularities can be associated with wavefront aberrations and scattering errors.Light scattering in the human cornea causes a reduction of visual quality.In fact,the cornea must be transparent and maintain a smooth and stable curvature since it contributes to the major part of the focusing power of the eye.In most cases,a simple examination of visual acuity cannot demonstrate the reduction of visual quality secondary light scattering.In fact,clinical techniques for examining the human cornea in vivo have greatly expanded over the last few decades.The measurement of corneal back scattering qualifies the degree of corneal transparency.The measurement of corneal forward-scattering quantifies the amount of visual impairment that is produced by the alteration of transparency.The aim of this study was to review scattering in the human cornea and methods of measuring it.展开更多
This paper reports systematically the crystal growth and photorefractive properties of Cu-doped KNSBN, and the mechanism of the Cu ions' effects on the photorefractive properties of KNSBN. The Cu ions doped in KNS...This paper reports systematically the crystal growth and photorefractive properties of Cu-doped KNSBN, and the mechanism of the Cu ions' effects on the photorefractive properties of KNSBN. The Cu ions doped in KNSBN can form two energy levels in the band gap, thus play important roles in the photorefractive process. They increase the effective electron combination center concentration, which results in the modification of the photorefractive properties of KNSBN. The two-wave coupling gain coefficient of KNSBN: Cu is two times greater than that of KNSBN. The photorefractive sensitivity of Cudoped KNSBN is estimated to be in the order of 10^(-3) cm^2/J. Its cat-SPPC reflectivity can reach 65％ corresponding to an response time less than 8 s.展开更多
文摘The cornea is the transparent connective tissue window at the front of the eye.The physiological role of the cornea is to conduct external light into the eye,focus it,together with the lens,onto the retina,and to provide rigidity to the entire eyeball.Therefore,good vision requires maintenance of the transparency and proper refractive shape of the cornea.The surface structures irregularities can be associated with wavefront aberrations and scattering errors.Light scattering in the human cornea causes a reduction of visual quality.In fact,the cornea must be transparent and maintain a smooth and stable curvature since it contributes to the major part of the focusing power of the eye.In most cases,a simple examination of visual acuity cannot demonstrate the reduction of visual quality secondary light scattering.In fact,clinical techniques for examining the human cornea in vivo have greatly expanded over the last few decades.The measurement of corneal back scattering qualifies the degree of corneal transparency.The measurement of corneal forward-scattering quantifies the amount of visual impairment that is produced by the alteration of transparency.The aim of this study was to review scattering in the human cornea and methods of measuring it.
文摘This paper reports systematically the crystal growth and photorefractive properties of Cu-doped KNSBN, and the mechanism of the Cu ions' effects on the photorefractive properties of KNSBN. The Cu ions doped in KNSBN can form two energy levels in the band gap, thus play important roles in the photorefractive process. They increase the effective electron combination center concentration, which results in the modification of the photorefractive properties of KNSBN. The two-wave coupling gain coefficient of KNSBN: Cu is two times greater than that of KNSBN. The photorefractive sensitivity of Cudoped KNSBN is estimated to be in the order of 10^(-3) cm^2/J. Its cat-SPPC reflectivity can reach 65％ corresponding to an response time less than 8 s.
