Toshihiko Gotoh

Diode laser noise at video frequencies in optical videodisc players

Video frequency noise in diode laser output and its influence on reproduced picture quality have been studied in an optical videodisc player. It was found that laser noise is related to an instability of oscillating longitudinal modes and has a strong correlation with picture quality. A single-mode laser easily oscillates in two or more modes by temperature change and optical feedback, which causes mode-hopping noise and results in white dots randomly appearing on a picture. A multimode laser has a consistently high noise level, and this results in a rough picture quality. Using high frequency superimposed current to power a single-mode laser enables multimode oscillation to be maintained at a steady level. This produces a relatively low noise level resulting in good picture quality. With regard to the video frequency laser noise specifications, it is determined that relative intensity noise should be <6 × 10−14 (Hz−1) in a practical player and <3 × 10−14 (Hz−1) in a pickup simulating noise measuring system.

A Color Video Printer with Sublimation Dye Transfer Method

In accordance with the recent progress in the video application sector such as video discs, still video floppy, electronic still video camera and hi-resoluti on VCR, the need for getting hard copies from these video signals is expanding.

A new concept of home use video printer in thermal dye transfer method

A high-quality video printer for home use has been developed using a thermal dye transfer (TDT) method. By using new ink, a maximum density of over 2.3 and a wide color-reproduction range have been realized. Precisely controlling the print density, tau data at any temperature are calculated by microcomputer using key data. A combination print system which cooperates with the VCR in order to catch the best shot from continuous moving pictures of the VCR has been developed. >