Eietsu Takahashi

Plastic lens array with the function of forming unit magnification erect image using roof prisms

An original plastic-lens array molded integrally as one block having a function of forming a unit-magnification erect image has been developed. The lens array consists of eight lens devices. The lens device has a roof prism, a reflecting v-groove, and a pair of convex-lens surfaces. A prototype of the lens arrays are arranged side by side. Thickness of the lens array is 4.5 mm, distance between object and image planes is 14.4 mm, array pitch is 1.3 mm, and the effective imaging region is 220 mm. The average modulation transfer function (MTF) at 41 p/mm of the lens array is 76% in the row direction (Y-direction) and 80% in the direction (X-direction) normal to Y-direction. The average F/NO in line-scanning is 1.8. The average irradience unevenness in line-scanning is 17%. The focal depth is +/- 0.6 mm in the area with the MTF being 60% or more. With this prototype a high-resolution image was attained. So, the lens arrays can be applied to imaging devices for use in a compact facsimile, image scanner, LED printer, and so on.

Plastic Optical Fiber Doped With Organic Fluorescent Material

This paper describes the development of a plastic optical fiber doped with organic fluorescent materials, the fiber consists of a polycarbonate core with a glass transition temperature of 150°C and a cladding made of a new polymer. The minimum optical attenuation is 1.0 dB/m at a 765 nm wavelength in the near infrared region. The fiber has excellent characteristics for use with a 1 mW light source with a spot size of 0.5 to 2 mm. The fiber is thermally stable up to 125 T and is very flexible. Furthermore, light can be transmitted through the fiber with the incident optical beam perpendicular to the fiber as well as at parallel to it. With these characteristics, the fiber should be useful for transmitting several wavelengths.