[Epidemiological and demographic analysis of indications for Baha® surgery in Poland--multicenter study]. / Analiza epidemiologiczna i demograficzna wskazan do implantacji systemu Baha® w Polsce--badanie wieloosrodkowe.

AIM OF THE STUDY: To collect and analyze epidemiological and demographical data of patients qualified for and implanted with the Baha® system in Poland. MATERIAL AND METHOD: 17 out of 28 otolaryngology departments performing Baha® implantation in Poland participated in the study. Up to date there were 286 patients registered in database. Data were obtained from the preoperative questionnaires including information such as age and gender, indications for the implantation, previous hearing aid use as well as data regarding the surgical technique. RESULTS: The most frequent indication for the Baha® system was bilateral mixed hearing loss (51%), followed by SSD (18%), bilateral conductive hearing loss (17%), unilateral mixed (8%) and conductive (6%) hearing loss. In 11% of subjects hearing impairment was congenital versus 89% cases of acquired. The mean age was 44 years with the slight prevalence of women (52%). 63% of patients did not have previous experience with hearing aids. The most frequent surgical technique was classic dermatome single stage procedure performed under general anesthesia (65%). CONCLUSIONS: Data gather in this multicentre research serve as a valuable source of information on qualifications for the Baha®, shows demographic spectrum of adult recipients in Poland. It also presents the preferences of surgical procedures. Outcomes of the study may constitute a reference for each centre participating in this research as well as for new centers starting the Baha® procedure.

Beam steering experiment with two cascaded ferroelectric liquid-crystal spatial light modulators.

The design, construction, and evaluation of a laser beam steerer that uses two binary ferroelectric liquid-crystal (FLC) spatial light modulators (SLMs) operated in conjunction are presented. The system is characterized by having few components and is in principle lossless. Experimentally, a throughput of approximately 20% was achieved. The simple system design was achieved because of the high tilt angle FLC material used in the SLMs, which were specifically designed and manufactured for this study. By coherently imaging the first SLM onto the second SLM, pixel by pixel, we obtained an effective four-level phase structure with a phase step of 90 degrees. An appropriate alignment procedure is presented. The beam steering performance of the system is reported and analyzed.