[54] LIGHT INTENSITY CONTROLLING DEVICE
[75] Inventors: Tadashi Minakuchi; Taminori Odano,
both of Tokyo, Japan
[73] Assignee: Asahi Kogaku Kogyo Kabushiki Kaisha, Tokyo, Japan
[21] Appl. No.: 09/106,770 [22] Filed: Jun. 30, 1998
Related U.S. Application Data
[62] Division of application No. 08/654,824, May 29, 1996.
[30] Foreign Application Priority Data
May 30, 1995 [IP] lapan 7-155180
Mar. 5, 1996 [IP] lapan 8-075182
[51] Int. CI.7 G02B 26/02; H01S 3/10
[52] U.S. CI 250/205; 250/234; 359/204
[58] Field of Search 250/205, 236,
250/234, 235; 347/236; 359/196, 204
[56] References Cited
U.S. PATENT DOCUMENTS
3,805,275 4/1974 Kiemle et al 347/326
4,581,617 4/1986 Yoshimoto et al 347/239
4,761,659 8/1988 Negishi 347/247
4,796,265 1/1989 Asada et al 372/31
4,802,179 1/1989 Negishi 372/38
4,811,348 3/1989 Aramoto et al 372/29
4,879,459 11/1989 Negishi 250/205
4,942,584 7/1990 Karaki et al 372/29
4,949,345 8/1990 Luijtjes 372/27
5,006,704 4/1991 Mochizuki et al 250/235
5,021,647 6/1991 Tatsuno et al 250/227.21
5,166,510 11/1992 Matsubara et al 250/205
5,225,850 7/1993 Egawa et al 347/246
5,270,736 12/1993 Inoue et al 347/246
5,282,217 1/1994 Yamazaki 372/31
5,305,337 4/1994 Araki et al 372/31
5,369,272 11/1994 Eguchi 250/235
5,369,630 11/1994 Hirose 369/100
5,377,213 12/1994 Honda 372/38
5,473,153 12/1995 Araki et al 250/205
5,600,126 2/1997 Appel et al 250/205
5,659,414 8/1997 Appel et al 359/196
5,844,707 12/1998 Minakuchi et al 359/204
5,892,219 4/1999 Minakuchi et al 250/205
FOREIGN PATENT DOCUMENTS
0464556 1/1982 European Pat. Off. .
0165060 12/1985 European Pat. Off. .
0418819 3/1991 European Pat. Off. .
0505156 9/1992 European Pat. Off. .
1515606 6/1978 United Kingdom .
2134351 8/1984 United Kingdom .
OTHER PUBLICATIONS
United Kingdom Search Report dated Jun. 25, 1996.
The United Kingdom Search Report dated May 8, 1997,
issued with U.K. Application No. 9611297.4.
A copy of the Preliminary Search Report issued by the
National Institude for Industrial Property, dated Feb. 6,1998
and annex.
Primary Examiner—Edward P. Westin
Assistant Examiner—-Thanh X. Luu
Attorney, Agent, or Firm—Greenblum & Bernstein, PL.C. [57] ABSTRACT
Alight intensity controlling device has a beam splitter which splits light fluxes emitted from a plurality of independently controlled semiconductor lasers, guided by optical fibers, into monitor light fluxes and main light fluxes. A gain adjusting circuit corrects the changes of output of light receiving elements depending on the polarization states of the light fluxes incident into the beam splitter. The changes result from the polarization characteristics of the optical fibers and/or the beam splitter. Alternatively, a filter is provided at one of the light receiving elements to compensate for the changes, thus providing a corrected output signal. Laser control circuits control the light emitting intensity of each semiconductor laser based on corrected output signals. The light receiving elements are set at an angle to the incoming light as so to avoid directing reflected light back toward an imaging system or the lasers.
5 Claims, 23 Drawing Sheets
