CD-DVD System Simulation & Evaluation


This page demonstrates capabilities in optical design, simulation, and evaluation of single-beam and multi-beam CD and DVD systems.

The simulation is comprehensive, namely, it starts with the laser beam and ends with analyzing the actual signals that are generated by the detectors and evaluation of the jitter. The beam is traced through the system using both geometrical and physical optics so that the beams on the detectors include aberrations of the various optical elements in the system as well as diffraction effects.

In addition to the evaluation of the jitter, the simulation is also used for:

  •   Calculating the cross-talk between tracks and evaluating various cross-talk canceling methods.

  •   Calculating focusing signals and comparing various auto-focus mechanisms.

  •   Calculating tracking signals and comparing tracking methods (i.e., push-pull, differential phase delay).



For more information and to learn how you can take advantage of these capabilities contact:





Data signals

Figure 1 shows a simulation of a three-beam DVD system. Fig. 1a shows the simulated illumination spots on the disc and Fig. 1b shows the calculated spots on the detectors. Note that the central detector is divided into four segments that are used for generating the focusing and tracking signals. The signals in the left and right detectors may also be used for cross-talk cancellation.


                             (a)                                                (b)

Figure 1.  (a) Simulated illumination spots on the disc (b) Calculated image on the detectors



Segments of the signals that are generated by each of the three detectors are shown in the following plots:


               Left track                         Central track                        Right track

Figure 2. Signals on the detectors


Figure 3 shows a typical signal that is generated by the simulation. The signal is then further processed by applying a lowpass filter and an equalizer (Fig. 4). The resulted signal is then used for generating an eye-pattern from which the jitter is evaluated (Fig. 5).


Figure 3. Row signal


Figure 4. Signal after filter and equalizer



Figure 5. Eye-Pattern.  Calculated jitter = 4.6 %




The next example demonstrates how the simulator is used for generating the focusing signals. The signals received by the focusing detectors are used for calculating the S-curve.


                    (a)                               (b)                                (c)

Figure 6.  Spots on focusing detectors: (a) before focus (b) in focus (c) after focus


Figure 7.  S-curve





Here we see a simulation of the tracking system with a DVD-RAM. In this simulation the simulated spot on the grooves of a DVD-RAM is detected by a quadrant detector (Fig. 8). The signals are used to calculate a push-pull signal for generating a tracking S-curve (Fig. 9).


                                  (a)                                             (b)

Figure 8.   Tracking in DVD-RAM. (a) Simulated illumination spot on the disc grooves
(b) Calculated spot image on the quadrant detector


Figure 9. Tracking S-curve