AIM：To evaluate the effects of posterior corneal surface measurements on the accuracy of total estimated corneal astigmatism.METHODS：Fifty-seven patients with toric intraocular lens（IOL） implantation and posterior...AIM：To evaluate the effects of posterior corneal surface measurements on the accuracy of total estimated corneal astigmatism.METHODS：Fifty-seven patients with toric intraocular lens（IOL） implantation and posterior corneal astigmatism exceeding 0.5 diopter were enrolled in this retrospective study.The keratometric astigmatism（KA） and total corneal astigmatism（TA） were measured using a Pentacam rotating Scheimpflug camera to assess the outcomes of AcrySof IOL implantation.Toric lOLs were evaluated in 26 eyes using KA measurements and in 31 eyes using TA measurements.Preoperative corneal astigmatism and postoperative refractive astigmatism were recorded for statistical analysis.The cylindrical power of toric lOLs was estimated in all eyes.RESULTS：In all cases,the difference of toric IOL astigmatism magnitude between KA and TA measurements for the estimation of preoperative corneal astigmatism was statistically significant.Of a total of 57 cases,the 50.88%decreased from Tn to Tn-1 and 10.53%decreased from Tn to Tn-2.In all cases,5.26%increased from Tn to Tn＋1.The mean postoperative astigmatism within the TA group was significantly lower than that in the KA group.CONCLUSION：The accuracy of total corneal astigmatism calculations and the efficacy of toric IOL correction can be enhanced by measuring both the anterior and posterior corneal surfaces using a Pentacam rotating Scheimpflug camera.展开更多
This paper describes a method for estimating intrinsic and extrinsic parameters of a camera,including horizonal scale factor caused by imperfect match between computer image acquisition hardware and camera hardware,co...This paper describes a method for estimating intrinsic and extrinsic parameters of a camera,including horizonal scale factor caused by imperfect match between computer image acquisition hardware and camera hardware,coordinates of image center(c x ,c y) and lense radical distortion parameter k,which calculates extrinsic parameters by a tetrahedra pose estimation algorithm and then get all other parameters by nonlinear optimization in two steps,and simulations show this method is easy and reliable.展开更多
The fundus camera used in imaging retina includes two parts： fundus imaging path with a positive focusing lens and annular Kohler illuminating path. We present a pupil joint equation and a focus equation based on the...The fundus camera used in imaging retina includes two parts： fundus imaging path with a positive focusing lens and annular Kohler illuminating path. We present a pupil joint equation and a focus equation based on the internal focusing manner to analyze its configuration. Using these equations, the configuration of the camera is given in detail. The design result of the fundus imaging path shows compact initial configuration at a total length of about 123 mm. The focusing range is -10-10 diopter, and the movement of the focusing lens is nearly linear at displacement of more than a sub-millimeter per diopter.展开更多
A new method is proposed for the object surveillance system based on the enhanced fish-eye lens and the high speed digital signal processor （DSP）. The improved fish-eye lens images an ellipse picture on the charge-c...A new method is proposed for the object surveillance system based on the enhanced fish-eye lens and the high speed digital signal processor （DSP）. The improved fish-eye lens images an ellipse picture on the charge-coupled device （CCD） surface, which increases both the utilization rate of the 4：3 rectangular CCD and the imaging resolution, and remains the view angle of 183° The algorithm of auto-adapted renewal background subtraction （ARBS） is also explored to extract the object from the monitoring image. The experimental result shows that the ARBS algorithm has high anti-jamming ability and high resolution, leading to excellent object detecting ability from the enhanced elliptical fish-eye image under varies environments. This system has potential applications in different security monitoring fields due to its wide monitoring space, simple structure, working stability, and reliability.展开更多
A real-time two-dimensional （2D） triangulation range finder is presented, which is composed of two linear complementary metal oxidation semiconductor （CMOS） chips, two camera lenses, and four light emitting diodes...A real-time two-dimensional （2D） triangulation range finder is presented, which is composed of two linear complementary metal oxidation semiconductor （CMOS） chips, two camera lenses, and four light emitting diodes （LEDs）. The high order distortion in image aberrations is the main factor responsible for the coarse errors. The theoretical prediction is in good agreement with experiments and the correction equation is used to obtain more reliable results with the unique distortion coefficient in tile whole working region.展开更多
文摘AIM：To evaluate the effects of posterior corneal surface measurements on the accuracy of total estimated corneal astigmatism.METHODS：Fifty-seven patients with toric intraocular lens（IOL） implantation and posterior corneal astigmatism exceeding 0.5 diopter were enrolled in this retrospective study.The keratometric astigmatism（KA） and total corneal astigmatism（TA） were measured using a Pentacam rotating Scheimpflug camera to assess the outcomes of AcrySof IOL implantation.Toric lOLs were evaluated in 26 eyes using KA measurements and in 31 eyes using TA measurements.Preoperative corneal astigmatism and postoperative refractive astigmatism were recorded for statistical analysis.The cylindrical power of toric lOLs was estimated in all eyes.RESULTS：In all cases,the difference of toric IOL astigmatism magnitude between KA and TA measurements for the estimation of preoperative corneal astigmatism was statistically significant.Of a total of 57 cases,the 50.88%decreased from Tn to Tn-1 and 10.53%decreased from Tn to Tn-2.In all cases,5.26%increased from Tn to Tn＋1.The mean postoperative astigmatism within the TA group was significantly lower than that in the KA group.CONCLUSION：The accuracy of total corneal astigmatism calculations and the efficacy of toric IOL correction can be enhanced by measuring both the anterior and posterior corneal surfaces using a Pentacam rotating Scheimpflug camera.
文摘This paper describes a method for estimating intrinsic and extrinsic parameters of a camera,including horizonal scale factor caused by imperfect match between computer image acquisition hardware and camera hardware,coordinates of image center(c x ,c y) and lense radical distortion parameter k,which calculates extrinsic parameters by a tetrahedra pose estimation algorithm and then get all other parameters by nonlinear optimization in two steps,and simulations show this method is easy and reliable.
基金supported by the National Natural Science Foundation of China (Nos. 60977008 and 60678048)the Natural Science Foundation of Jiangsu Province (Nos. BK2007207 and BS2007061)the "Six Elites Peak" of Jiangsu Province
文摘The fundus camera used in imaging retina includes two parts： fundus imaging path with a positive focusing lens and annular Kohler illuminating path. We present a pupil joint equation and a focus equation based on the internal focusing manner to analyze its configuration. Using these equations, the configuration of the camera is given in detail. The design result of the fundus imaging path shows compact initial configuration at a total length of about 123 mm. The focusing range is -10-10 diopter, and the movement of the focusing lens is nearly linear at displacement of more than a sub-millimeter per diopter.
文摘A new method is proposed for the object surveillance system based on the enhanced fish-eye lens and the high speed digital signal processor （DSP）. The improved fish-eye lens images an ellipse picture on the charge-coupled device （CCD） surface, which increases both the utilization rate of the 4：3 rectangular CCD and the imaging resolution, and remains the view angle of 183° The algorithm of auto-adapted renewal background subtraction （ARBS） is also explored to extract the object from the monitoring image. The experimental result shows that the ARBS algorithm has high anti-jamming ability and high resolution, leading to excellent object detecting ability from the enhanced elliptical fish-eye image under varies environments. This system has potential applications in different security monitoring fields due to its wide monitoring space, simple structure, working stability, and reliability.
文摘A real-time two-dimensional （2D） triangulation range finder is presented, which is composed of two linear complementary metal oxidation semiconductor （CMOS） chips, two camera lenses, and four light emitting diodes （LEDs）. The high order distortion in image aberrations is the main factor responsible for the coarse errors. The theoretical prediction is in good agreement with experiments and the correction equation is used to obtain more reliable results with the unique distortion coefficient in tile whole working region.
