US 6,983,000 B2
Laser diode module
Kimio Tatsuno, Tokyo (Japan); Hiroaki Furuichi, Yokohama (Japan); Kazumi Kawamoto, Yokohama (Japan); and Katsumi Kuroguchi, Yokohama (Japan)
Assigned to Hitachi, Ltd., Tokyo (Japan)
Filed on Jul. 15, 2003, as Appl. No. 10/618,759.
Application 10/618759 is a continuation of application No. 09/934562, filed on Aug. 23, 2001, granted, now 6,597,712.
Claims priority of application No. 2001-050534 (JP), filed on Feb. 26, 2001.
Prior Publication US 2004/0228373 A1, Nov. 18, 2004
This patent is subject to a terminal disclaimer.
Int. Cl. H01S 3/00 (2006.01); G01J 4/00 (2006.01)
U.S. Cl. 372—32 8 Claims
OG exemplary drawing
 
1. A laser diode module comprising:
a laser diode device;
a first photo detector part for receiving, directly or indirectly, first divided light that is a first portion of light when at least one of light emissions of said laser diode device is divided into two portions of light each traveling a different optical path;
a second photo detector part for receiving second divided light that is a second portion of light thus divided via at least a wavelength selective member; and
means for controlling the lasing wavelength of said laser diode device on the basis of outputs of said first and second photo detector parts;
wherein a beam splitter is provided between said laser diode and said wavelength selective member for dividing light emitted from said laser diode into the first and second divided light; and
wherein at least a quarter-wave plate is provided in an optical path between said beam splitter and said wavelength selective member.