Development of a fabrication process for production of diffractive optics.

In this study, a novel fabrication process, to the best of our knowledge, was developed to fabricate a glass harmonic diffractive lens. In this process, a polymethylmethacrylate master of the diffractive lens was machined using single-point diamond turning. Then an electrolytic plating process was conducted to grow a reverse nickel (Ni) mold. Precision compression molding was performed using the Ni mold to replicate the diffractive lens structures onto a glass surface. Surface measurements and optical testing show that the replicated diffractive lenses by the proposed method have high tolerances and require optical performance, demonstrating a high-volume, high-precision, and cost-effective process. The proposed method will be critical for consumer products where glass optics are increasingly used in lens assemblies.

Pseudoachalasia: a diagnostic challenge.

Here, we present a case of a 78-year-old man that underwent gastrointestinal endoscopy because of one- month history of dysphagia to liquids and solid foods with accompanying weight loss. On endoscopy, there was distal esophageal stenosis. Multiple biopsies were obtained. Histologic examination of the samples revealed normal tissue. The stenosis was treated by dilatation and abdomino pelvic computed tomography scanning was performed to search for an underlying malignant lesion that showed a mass adjacent to distal esophagus. We did endosonography- guided fine needle aspiration of the mass. It was a squamous cell carcinoma (SCC). Malignancy is a challenging diagnosis in patients with dysphagia and near normal endoscopy. To our knowledge, there are a few reports of SCC to cause it.

A novel sensor for two-degree-of-freedom motion measurement of linear nanopositioning stage using knife edge displacement sensing technique.

This paper presents a novel method for measuring two-degree-of-freedom (DOF) motion of flexure-based nanopositioning systems based on optical knife-edge sensing (OKES) technology, which utilizes the interference of two superimposed waves: a geometrical wave from the primary source of light and a boundary diffraction wave from the secondary source. This technique allows for two-DOF motion measurement of the linear and pitch motions of nanopositioning systems. Two capacitive sensors (CSs) are used for a baseline comparison with the proposed sensor by simultaneously measuring the motions of the nanopositioning system. The experimental results show that the proposed sensor closely agrees with the fundamental linear motion of the CS. However, the two-DOF OKES technology was shown to be approximately three times more sensitive to the pitch motion than the CS. The discrepancy in the two sensor outputs is discussed in terms of measuring principle, linearity, bandwidth, control effectiveness, and resolution.