Design of ultra-compact optical system for disposable epidural spinal endoscope

摘要

We have presented the plastic based ultra-compact aspheric lens for disposable epidural spinal endoscope. We have also showed the analysis of the stray light distribution on the image plane using optical illumination system design software (Light Tools). The optical system consists of the aspheric lens with a size of 1.4mm (total track of optical system). The effective length and field of view (FOV) is 0.66mm and 90 degrees. The distortion of the optical system is below 25%. The curves of modulation transfer function (MTF) are higher than 0.3 at 80 line pairs/mm (lps/mm) in image space. For the analysis of stray light, we assumed that the 98 percent of incident light is absorbed inside lens barrel and the rest is scattered on the inner surfaces of the lens barrel. The average value of stray light is 0.16% in the image intensity. The maximum stray light and minimum stray light of the proposed optical system is 0.57% and 0.0005% in the image intensity, respectively. The effective transmission rate of the proposed optical system is 89.6%.