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Measurement of bifocal intraocular lens modulation transfer function using a charge-coupled device

机译：使用电荷耦合器件测量双焦点人工晶状体调制传递函数

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Abstract: The special equipment requirements and limitations for bifocal intraocular lens MTF measurement using a CCD detector are discussed. Proper MTF measurement requires that at least 90% of the energy passing through the lens aperture be imaged within the sampled area of the sensor. Spectral filtering of optical density greater than 2.5 sufficiently eliminates out-of-band radiance. Well-corrected relay optics of numerical aperture at least twice that of the lens under test and a calibrated image scale are important for accurate results. Significant modulation losses at spatial frequencies well below the Nyquist sampling occur due to pixel geometry, blooming, and charge transfer inefficiency. for a bifocal intraocular lens, where the overall blur pattern may be as large as 0.5 mm, these factors can limit the ability to accurately compute modulation at spatial frequencies greater than 100 cycles/mm. Correction of equipment-induced modulation losses can be realized through improved data processing. Use of MTF measurement for quality control of the Storz TRUE VISTA $+TM$/ bifocal intraocular lens is discussed. Results agree with theoretical expectations to within 10% modulation. Sensitivity to defects such as astigmatism and zone defects are demonstrated at low spatial frequencies. !14
机译：摘要：讨论了使用CCD检测器测量双焦点人工晶状体MTF的特殊设备要求和局限性。正确的MTF测量要求在传感器的采样区域内将至少90％通过镜头光圈的能量成像。大于2.5的光密度的光谱滤波可充分消除带外辐射。经过校正的数值孔径的中继光学器件至少是被测镜头的两倍，并且校准后的图像比例对于获得准确的结果非常重要。由于像素的几何形状，泛光和电荷转移效率低下，在远低于奈奎斯特采样的空间频率处发生了明显的调制损耗。对于双焦点人工晶状体，其中总体模糊模式可能高达0.5 mm，这些因素可能会限制在大于100个周期/ mm的空间频率下精确计算调制的能力。设备引起的调制损耗的校正可以通过改进的数据处理来实现。讨论了使用MTF测量来控制Storz TRUE VISTA $ + TM $ /双焦点人工晶状体的质量。结果与理论预期相符，调制范围在10％以内。在低空间频率下证明了对像散和区域缺陷等缺陷的敏感性。 ！14

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