A practical mastering technology was developed using a blue laser optical mastering system with a wavelength of 405 nm, a numeric aperture (NA) of 0.95 and a phase-shift apodizer. The laser is shaped and collimated by a space filter with its diameter 2μm, then is split into two beams by polarizing prism. One beam is used to detection of the optical power, and the other beam is used to write data on the disc. The phase-shift mask is lay between the collimating lens and the polarizing prism to optimizing the intensity distribution of Airy point on the disc. The lens with high NA 0.95 is designed to make the image point of the laser less then the diffraction point. The air-operated focus control device is used to focalize the light on the disc. Based on the technology, the recording spot with its diameter about 223nm is achieved.
Two-photon single beam multi-layer writing and scanning confocal reading are performed in anthracene derivatives membrane by Ti:sapphire femtosecond laser and three-dimensional scanning confocal system. And a good result is achieved, Two-photon excitation can be produced inside the anthracene derivatives membrane, where is 100 μm from the surface of the recording material. The wavelength of the laser is 726 nm(363nm×2). The size of recording spot along longitidunal direction is less than 2 μm, and that along lateral direction is less than 1 μm. The signal keeps clear definition after many times of reading out, when the power of the reading laser is less than 5 mW.
One way of achieving super-resolution is to convert the Guess distribution of the object space into square distribution of that. A special phase-shifting lens is designed for attaining the function. In developing designs for the special phase-shifting lens, algebraic approximate formulas are used to obtain a general understanding of the transition between the Guess distribution and the square distribution. Computer simulation was then used to obtain a detailed performance evaluation. The evaluation results indicated the following: the Guess distribution of the laser light is converted into the square distribution by the special phase-shifting lens.
An experiment for focusing in chromatic multilayer optical storage system is presented in this paper. There laser diodes with different wavelength as respectively light sources are used in this experiment system so that focusing and servo approach are different from that in traditional optical system. Astigmatic approach is applied for defocusing detection while servo controlling and signal processing circuits are redesigned. The model of the actuator suited this chromatic multilayer optical system is established and analyzed. The static and dynamic parameters of actuator are measured. This paper specifies the design and implementation technologies of focusing and servo controlling in the chromatic multilayer experiment optical system. The preliminary result gotten from this experiment system is also given in the paper.