| 摘要 |
An apparatus for writing an optical record carrier (10) according to the invention comprises a write head (21) with a radiation source (22) and an optical system (23) for projecting a scanning spot (24) at the record carrier (10). The write unit (20) further comprises a first detector (25) for generating a first detection signal (Sd1) which is indicative for an intensity of the radiation source (22). It also comprises a second detector (26) for generating a second detection signal (Sd2) which is indicative for an amount of radiation reflected by the record carrier (10). The write unit (20) comprises a supply circuit (27) for modulating the intensity of the radiation source (22) between at least a first and a second value in response to a write signal (Sw). The apparatus according to the invention furthermore comprises a control circuit (30) for controlling the power of the radiation source. The control circuit (30) comprises a first feedback loop (25, 31, 32, 33) including the first detector (25) for generating a first control signal (Sc1) and a second feedback loop (25, 35, 36), including the second detector (25). A unit (35) generates a ratio signal (Sr) which is representative for the ratio between the amount of reflected radiation during writing and during erasing. The second feedback loop further comprises a signal combination unit (36) for generating a second control signal (Sc2) which is indicative for the product of the ratio signal (Sr) and the first control signal (Sc1).
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