autonomously kept stable during duration of holographic measurements. In order to ensure that the positioning system is intrinsically safe a novelty control approach was taken by using only adjustable friction elements [5] together with haptic feedback resulting in a non-actuated admittance control system. This non-actuated yet active system design approach renders a positioning system that is as safe as ordinary static positioner systems. This allows for the positioner to be operated in existent otology clinic settings without the need for expensive and time consuming testing that is required with similar actuated mechanisms. A proof of concept prototype positioner (PCPP) based on the new control scheme was first developed that allows for full 6 degrees of freedom (DOF) orientation of the otoscope head with respect to the patient’s ear. Based on the development and testing of the PCPP and quantification of the required DOF in real clinical examination conditions the first fully functional prototype of the MOP was developed and deployed in a real clinic environment. Initial tests shows promising results for the measurement capabilities and versatility of the system and they also suggest the system to be safe and reliable. 2. DIGITAL OPTOELECTRONIC HOLOGRAPHIC OTOSCOPE SYSTEM 2.1. Realization of DOEHS The system consists of four physically independent modules where every one of them is easily disconnectable to allow better mobility in the transportation between examination rooms and various otology clinics. (a) (b) (c) Fig. 1. Full system overview: (a) Measurement subsystem; (b) Mobile computing and control platform; (c) LaserView [6] image processing software. The otoscope optical head (OH), the sound presentation (SP) system and the mechatronic otoscope positioner (MOP) are all in one assembly that can be attached close to the patient to an existing clinical examination setup. The laser delivery system (LD) is separate from the rest of the measurement system to reduce the size and increase mobility of the measurement system. The computing platform (CP) consists of two physical parts: a driver and power unit, and PC that controls the whole system through the driver module. The examiner controls the whole system through a single unified data processing software platform [6] that allows for various measurement modes and numerous live and offline image processing techniques. 2.2. Otoscope optical head system and sound presentation system design and packaging Reconstructing an image with the DOEHS is based on the four phase stepping digital holography method [3, 4]. Technique allows for the recording of holograms without any optical elements, thus reconstructing purely numerically the object image with the help of a computer. Without the lenses and the required alignment mechanisms associated with them, the lensless system allows for much better packaging densities. This allows for a mobile and versatile system as it greatly reduces machining and packaging requirements as well as specific size and mass of the system. The implemented design of the OH achieves nearly 60% size reduction as compared to a packaging design based on a traditional holographic setups [7] thus allowing for truly handheld portability. 194
RkJQdWJsaXNoZXIy MTMzNzEzMQ==