16 August 2002 Optical pickup head reproduced signal from the pits on a disc affected by the beam divergence of the laser beam radiated from a semiconductor laser
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Abstract
The divergence of the laser beam radiated from a light source affects the resolving power of the optical pickup head. The high power semiconductor laser does not have Gaussian light intensity distribution, which can be easily proved by scanning the photo-detector in two directions. The optical resolving performance is directly measured by using the so-called Target Chip, which consists of gratings with different spatial frequencies ranging from 555 up to 1667 lines per millimeter on the synthesized quartz substrate, sputtered with aluminum forming a 70% reflective layer. The line depths of the gratings are constant at 0.1 micrometers and the line widths are 0.3 micrometers. The pickup head to be tested is situated on a table and light is focused on the grating through the substrate. The motion of the chip generates the corresponding output signal from the pickup head. This demonstrates the relationship between the divergence from the light source and the resolving power.
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Kenji Fukui, Ji Ping Tiang, Kenji Murakami, "Optical pickup head reproduced signal from the pits on a disc affected by the beam divergence of the laser beam radiated from a semiconductor laser", Proc. SPIE 4775, Modeling and Characterization of Light Sources, (16 August 2002); doi: 10.1117/12.479649; https://doi.org/10.1117/12.479649
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