Silicon infrared diffuser for wireless communication.
We show what we believe to be a novel way to use silicon in infrared radio communication as a suitable material for the realization of optical diffusers in the range of 850-1600 nm. A crystalline silicon wafer is made porous by means of electrochemical etching. The porous silicon produced is optically characterized, and measurements report a high reflectance in the band of interest. We also study the angular distribution of diffused radiation by the porous silicon surface at different angles of incident radiation. Measurements show that radiation diffuses in a quasi-Lambertian manner, confirming the good performance of this material as an incident radiation diffuser.
Integrating-sphere diffuser for wireless infrared communication
The application of an integrating sphere (IS) as a diffuser in a wireless infrared (IR) network is investigated. Going beyond the simplified analytical model, it is shown that ray-tracing simulations provide realistic data for the optical insertion loss: the transfer function and the far-field light distribution. As an example, a sphere diffuser for a 155 Mbit/s 16-PPM IR transmitter is investigated with an insertion loss of 0.66 dB, a cutoff frequency of 570 MHz and a 104/spl deg/ full width at half-maximum (FWHM) angle of the intensity distribution. The device has also been manufactured using a proprietary material and good agreement between simulation and experimental data is found. A method to increase the FWHM angle and some aspects of eye safety are discussed.
Vertebral Fusion in Two Early Jurassic Sauropodomorph Dinosaurs from the Lufeng Formation of Yunnan, China
Here we describe two instances of pathological vertebral fusion in two genera of sauropodomorph dinosaurs from the Early Jurassic Lufeng Formation in Yunnan, China. The first is a specimen, of Lufengosaurus huenei with two fused cervical vertebrae, and the other is a specimen of the Lufeng basal sauropod, with two fused caudal vertebrae. Both pathologies are consistent with spondyloarthropathy and represent the earliest known occurrence of that disease in dinosaurs. The two specimens affirm that early dinosaurs suffered from the same bone diseases as living vertebrates. Spondyloarthropathy in these dinosaurs may have been induced by long-term mechanical stress, such as weight bearing, and/or limited motion at the joint that would otherwise have inhibited such remodeling. In both cases, surface remodeling suggests that the animals survived well beyond the initiation of spondyloarthropathy.