Sony dvp-s530d User Manual
50
Three Laser Beams from One Laser
Although there is one laser, there are three spots of light on the disc’s
information layer. The three spots are made by diffraction grading inside
the laser assembly.
information layer. The three spots are made by diffraction grading inside
the laser assembly.
1 S T
Order
Order
Main
Laser
B e a m
Laser
B e a m
T o
Objective
Lens
Objective
Lens
Defraction
Grading
Grading
D V D
Laser
B e a m
Laser
B e a m
1 S T
Order
Order
2 N D
Order
Order
2 N D
Order
Order
A diffraction grading is made of a glass sheet with lines etched on it form-
ing channels. The channels are represented by the spaces between the
dotted lines in the diagram. As the main laser beam passes through a
channel, secondary light beams are produced. The first order beams are
the strongest and these are the two additional (side) spots that pass through
the objective lens onto the disc. These side spots are used for CD track-
ing.
ing channels. The channels are represented by the spaces between the
dotted lines in the diagram. As the main laser beam passes through a
channel, secondary light beams are produced. The first order beams are
the strongest and these are the two additional (side) spots that pass through
the objective lens onto the disc. These side spots are used for CD track-
ing.
1 . 1 c m
Single
F o c u s
Point
F o c u s
Point
Info Layer
C D
D V D
Laser
Light
C D F O C U S C O R R E C T E D
Objective
L e n s