LIGHT INTENSITY CONTROLLER AND LIGHT INTENSITY CONTROL METHOD

• Main Authors: NUKUI MAKOTO, MIZUGUCHI NAOSHI, IIMA MITSUNORI
• Format: Patent
• Language: English
• Published: 16.03.1999
• Edition: 6
• Subjects: INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PHYSICS

PROBLEM TO BE SOLVED: To make it possible to exactly control the light quantity of a main luminous flux regardless of a change in ambient temp. by specifying the change quantity of the dependence characteristic on the polarized light of a beam splitting element for splitting a monitor luminous flux and the main luminous flux by using reference light of a specified polarization state. SOLUTION: The monitor luminous flux is separated by the beam splitter 12 to P polarized light and S polarized light. The former is detected by a light quantity detecting sensor 13 and the latter by a light quantity detecting sensor 14. The output signals of these light quantity detecting sensors 13, 14 are respectively amplified in amplifiers 20, 21 and are resynthesized by an adder circuit 22. An amplifier 23 amplifies this single at the amplification rote reflecting the dependence characteristic on the polarized light and outputs the signal as an APC signal. A light source power control circuit 18 successively and relatively operates the APC signals of a semiconductor laser with the reference voltage by a reference voltage generating circuit 19 and controls the driving current of the light source in such a manner that the intensity of the beam spot on an image plane 17 attains the intensity level set by the reference voltage, thereby maintaining the intensity level of the beam spot at a reference level.