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Fundus camera is widely used in screening and diagnosis of retinal disease. It is a simple, and widely used medical equipment. Early fundus camera expands the pupil with mydriatic to increase the amount of the incoming light, which makes the patients feel vertigo and blurred. Nonmydriatic fundus camera is a trend of fundus camera. Desktop fundus camera is not easy to carry, and only suitable to be used in the hospital. However, portable nonmydriatic retinal camera is convenient for patient self-examination or medical stuff visiting a patient at home. This paper presents a portable nonmydriatic fundus camera with the field of view (FOV) of 40°, Two kinds of light source are used, 590nm is used in imaging, while 808nm light is used in observing the fundus in high resolving power. Ring lights and a hollow mirror are employed to restrain the stray light from the cornea center. The focus of the camera is adjusted by reposition the CCD along the optical axis. The range of the diopter is between -20m-1 and 20m-1.

The rheological behavior, morphologies, and tensile properties of reactively compatibilized PVDF/TPU blends are reported. Using PVDF-g-AAc as the compatibilizer, PVDF/TPU 90/10 and 10/90 blends are prepared. The carboxylic acid groups of PVDF-g-AAc react with the urethane linkages of TPU during melt blending to generate in situ PVDF-g-AAc-g-TPU which leads to compatibilization of PVDF/TPU blends. The introduction of PVDF-g-AAc into the PVDF/TPU blends causes an increase in viscosity. The rheological behavior of the compatibilized PVDF/TPU 90/10 and 10/90 blends are well described by the generalized Zener model. The addition of the compatibilizer PVDF-g-AAc reduces the dispersed-phase domain size and narrows the size distribution.

Using the comb copolymer PVDF-g-AAc as a compatibilizer, five reactively compatibilized PVDF/TPU blends with different compositions were prepared. During melt blending, the carboxylic acid groups of PVDF-g-AAc react with the urethane the graft copolymers PVDF-g-AAc-g-TPU, which lead to linkages of TPU to generate the graft copolymers PVDF-g-AAc-g-TPU, which lead to compatibilization of the PVDF/TPU blends. The rheological behavior of the compatibilized PVDF/TPU blends can be described by a generalized Zener model. PVDF/TPU 50/50 and PVDF/TPU 30/70 blends show a particle network structure, indicating elastic interactions between the grafted shells of compatibilized PVDF domains. SEM shows that almost all compatibilized PVDF/TPU blends exhibit a dispersion-type morphology.