| 摘要 |
A light source (27) comprises a header (30), electrical conductors (31), (32), (33), a light sensor (40), a laser (39), a can (28), a convex lens (36), and an external control circuit (34). A window (35) is defined in an inclined top of the can (28), and the convex lens (36) is mounted within the window (35). A convex surface of the inclined convex lens (36) faces away from the light sensor (40). The laser (39) and the light sensor (40) are separately mounted on the header (30). The electrical conductors (31), (32), (33) electrically connect with the control circuit (34). The convex lens (36) has a pre-determined curvature such that emitted light beams of the laser (39) reflected from the lens (36) converge onto the light sensor (40). Accordingly, the reflected light beams (52) received by the light sensor (40) are accurately proportional to the emitted light power of the laser (39). Thus the control circuit (34) can precisely control the light intensity of the laser (39) to maintain the emission power of the laser (39) at a steady level.
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