Abstract: A method for measuring visual appearance of birefringent fibers is disclosed. The method involves emitting light, creating N polarization states of the emitted light, wherein the polarized emitted light illuminates the birefringent fibers, thereby generating internal reflection components, external reflection components, and diffusion components of the light, observing the light from the illuminated birefringent fibers, creating N polarization states of the observed light, forming N images of the observed polarized light, each image comprising a plurality of pixels, measuring the intensity in each pixel of the N images, and for each pixel, separating the internal reflection component, the external reflection component, and the diffusion component from the i-th image for the N images, wherein i=1, 2, . . . N and N?4.

Abstract: Methods and apparatus to determine the orientation of randomly arranged birefringent fibers are disclosed. One method comprises emitting light, creating Ni polarization states of the emitted light, illuminating the birefringent fibers with the emitted light so polarized, thereby generating IRi internal reflection components of the light in the birefringent fibers, observing the light from the illuminated birefringent fibers, creating Oi polarization states of the observed light, forming Ii images of the observed polarized light, each image comprising an information (Ni, Oi, IRi), wherein i=1, 2, . . . , n and n?3, separating the i-th internal reflection component from the i-th image, and calculating an angle of a neutral axis of the birefringent fibers using the IRi internal reflection components.

Abstract: Methods and apparatus to measure visual appearance of randomly arranged birefringent fibers are disclosed. One method comprises emitting light, creating Ni polarization states of the emitted light, illuminating the birefringent fibers with the emitted light so polarized, thereby generating IRi internal reflection components, ERi external reflection components, and Di diffusion components of the light in the birefringent fibers, observing the light from the illuminated birefringent fibers, creating Oi polarization states of the observed light, forming Xi images of the observed polarized light, each image comprising an information (Ni, Oi, IRi, ERi, Di), wherein i=1, 2, . . . n and n?4, measuring the intensity Ii in each pixel in the X, images, and separating the i-th internal reflection component, the i-th external reflection component, and the i-th diffusion component from the i-th image for the Xi images.

Abstract: Methods and apparatus to determine the orientation of randomly arranged birefringent fibers are disclosed. One method comprises emitting light, creating Ni polarization states of the emitted light, illuminating the birefringent fibers with the emitted light so polarized, thereby generating IRi internal reflection components of the light in the birefringent fibers, observing the light from the illuminated birefringent fibers, creating Oi polarization states of the observed light, forming Ii images of the observed polarized light, each image comprising an information (Ni, Oi, IRi), wherein i=1, 2, . . . , n and n?3, separating the i-th internal reflection component from the i-th image, and calculating an angle of a neutral axis of the birefringent fibers using the IRi internal reflection components.

Abstract: Methods and apparatus to measure visual appearance of birefringent fibers are disclosed. One method comprises emitting light, creating Ni polarization states of the emitted light, illuminating the birefringent fibers with the emitted light so polarized, thereby generating IRi internal reflection components, ERi external reflection components, and Di diffusion components of the light in the birefringent fibers, observing the light from the illuminated birefringent fibers, creating Oi polarization states of the observed light, forming Xi images of the observed polarized light, each image comprising an information (Ni, Oi, IRi, ERi, Di), wherein i=1, 2, . . . n and n?4, measuring the intensity Ii in each pixel in the Xi images, and separating the i-th internal reflection component, the i-th external reflection component, and the i-th diffusion component from the i-th image for the Xi images.