Modular multimodal device for dermatoscopy and videocapillaroscopy: front lens design and evaluation of prototype image quality

Subject of study. Optical systems of objective lenses with an external entrance pupil and optical systems of eyepieces in the reverse ray path are analyzed. Aim of study. The aims of this study were to design an optical lens system of a modular multimodal device operating in the modes of visual dermatoscopy, digital dermatoscopy, and videocapillaroscopy (VCS) and to develop a method for synthesizing its optical configuration. Method. Three-component basic schemes of a multimodal dermatoscope objective lens were synthesized using isoplanatic surfaces and the compositional synthesis method for optical systems. The synthesis also employed an algebraic method for calculations of optical systems based on the theory of third-order aberrations. Main results. An improved modular configuration of the device was proposed. Requirements for the optical system of a dermatoscope objective lens were formulated, and a dermatoscope optical system was developed. A method for synthesizing basic schemes of objective lenses with an external entrance pupil was determined, and new scheme variants that expand the possibilities of synthesis were obtained. Based on the calculation results, a prototype objective lens was manufactured. Practical significance. The evaluation of the image quality of the calculated objective lens of the multimodal device and its prototype confirmed its capability to operate in the visual dermatoscopy mode within a certain range of physician eye positions, in the digital dermatoscopy mode using a mobile phone camera, and in the VCS mode using a special additional module. The overall structural configuration of the device prototype is determined.