Prosthetic knee stability during the push-off phase of walking - experimental findings

Most of the energy needed for ambulation is generated during the double support phase of walking. Knee flexion during push-off is crucial to maintain the walking velocity. Since users of an above-knee prosthesis have to stabilize the knee with the hip muscles, and regular knee mechanisms are not stable during flexion, this may cost a large effort. This paper deals with experimental findings of walking with different types of knees. The results indicate that for walking with a more stable knee, the symmetry increases and the net hip moments of force, required to stabilize the knee, reduce. The mechanical work however, performed at the hip joint at the prosthetic side, remains about equa

Miniaturisation of high-NA objectives for optical recording

High-NA objectives for optical recording have received a lot of attention due to the investigation of the Blu-ray Disc system. More recently to enable optical storage in portable devices, small building height optical drives have been studied requiring miniaturised high-NA objectives. Previously reported miniaturised objectives consist of two elements and are, therefore, less suited for mass production. In this paper the design and manufacturing of a miniaturised single element high-NA objective is reported. Furthermore, with the aid of non-periodic phase structures the tolerances of the objectives can be further expanded