We describe a system for the automated diagnosis of diabetic retinopathy and glaucoma using fundus and optical coherence tomography (OCT) images. Automatic screening will help the doctors to quickly identify the condition of the patient in a more accurate way. The macular abnormalities caused due to diabetic retinopathy can be detected by applying morphological operations, filters and thresholds on the fundus images of the patient. Early detection of glaucoma is done by estimating the Retinal Nerve Fiber Layer (RNFL) thickness from the OCT images of the patient. The RNFL thickness estimation involves the use of active contours based deformable snake algorithm for segmentation of the anterior and posterior boundaries of the retinal nerve fiber layer. The algorithm was tested on a set of 89 fundus images of which 85 were found to have at least mild retinopathy and OCT images of 31 patients out of which 13 were found to be glaucomatous. The accuracy for optical disk detection is found to be 97.75%. The proposed system therefore is accurate, reliable and robust and can be realized.

Self-assembled ${\text{In}}_{0.5}{\text{Ga}}_{0.5}\text{As}/\text{GaAs}$ quantum dot solar cell (QDSC) was grown by metal organic chemical vapor deposition. Systematic measurements of dark current versus voltage (I-V) characteristics were carried out from 30 to 310 K. Compared with the reference GaAs solar cell, the QDSC exhibits larger dark current however its ideality factor (n) was smaller, which cannot be straightly interpreted by the conventional diode models. These results are important for the fundamental understanding of QDSC properties and further implementation of new solar cell designs for improved efficiency.

We demonstrate staggered ("type-II") lineup lattice-matched GaAs/sub 0.51/Sb/sub 0.49/-InP unitraveling carrier photodiodes (UTC-PDs) for application near 1.55 /spl mu/m. The GaAsSb absorbing layer conduction band edge lines up /spl Delta/E/sub C/=0.11 eV above that of InP, and hence, allows the direct injection of photogenerated electrons into an InP collector-without any need for compositional grading around the GaAsSb-InP interface-thus simplifying epitaxial growth and device fabrication. InP-GaAsSb UTC-PDs show low dark current levels, and measurable bandwidths are limited by the test equipment. A transit-limited bandwidth of 105 GHz for a PD with a 1000-GaAsSb absorption layer (C:5/spl times/10/sup 18//cm/sup 3/) and a 2000 InP collector is inferred from the variation of photoresponse bandwidth with device area.

InGaP/GaAs/InGaAs inverted metamorphic (IMM) triple junction (TJ) solar cells were fabricated on epitaxial liftoff (ELO) 100 mm diameter GaAs wafers. These ELO IMM solar cells exhibited an efficiency of 30% at one sun AM1.5D illumination, which is the highest reported efficiency for IMM ELO thin cells to date. The TJ ELO cells had fill factor (FF) >85%, open circuit voltage (Voc) of 2.78V, and short circuit current density (Jsc) of 12.64 mA/cm ² . IMM ELO cells exhibited a peak efficiency of 36.3% at concentration of 264suns.