Geometric model of image formation in Scheimpflug cameras

Abstract

We present a geometric model of image formation in Scheimpflug cameras that is most general. Scheimpflug imaging is commonly used is scientific and medical imaging either to increase the depth of field of the imager or to focus on tilted object surfaces. Existing Scheimpflug imaging models do not take into account the effect of pupil magnification (i.e. the ratio of the exit pupil diameter to the entrance pupil diameter), which we have found to affect the type of distortions experienced by the image-field upon lens rotations. In this work, we have also derived the relationship between the object, lens and sensor planes in Scheimpflug configuration, which is very similar in form with the standard Gaussian imaging equation, but applicable for imaging systems in which the lens plane and the sensor plane are arbitrarily oriented with respect to each other. Since the conventional rigid camera, in which the sensor and lens planes are constrained to be parallel to each other, is a special case of the Scheimpflug camera, our model also applies to imaging with conventional cameras.

Age-specific influences of refractive error and illuminance on pupil diameter

“…Pupil magnification has been defined as “the ratio of the paraxial exit-pupil diameter to the paraxial entrance-pupil diameter,” and the entrance pupil has been defined as the “image of the stop seen through the elements preceding it is.” [36,37] Hence, we strongly believe that myopes, influenced by the different corneal power (higher) and shape (steeper), have a larger pupil (entrance pupil image) diameter than hyperopes with less corneal power and shape.…”