Recording heat-mode

Optical Data Storage on Write-once Media 9.13.2.3.1 Heat-mode recording... 

In addition to heat emission, radiative decay processes may also occur, in which light is emitted due to a transition from the lowest excited singlet or triplet state to the ground state (fluorescence or phosphorescence). In order to effect rapid and efficient conversion of optical energy (the laser) to heat, dyes which exhibit low fluorescence and in which excitation primarily involves the singlet states are the most suitable for heat-mode recording.196... 

Comparison between heat-mode and photon-mode processes is given in Table I. The main differences are the superior resolution and the possibility of multiplex recording in photon-mode systems. Because of the diffusion of heat, the resolution of heat-mode recording is inferior to that of photon-mode systems. Furthermore, photons are rich in information such as energy, polarization and coherency, which can not be rivalled by heat-mode recording. 

The next stages in the development beyond 20 Gb will be to move away from heat mode recording to photon mode recording. This is discussed elsewhere in this book, under photochromies (Chapter 1, section 1.2.8.3) and under holography, optoelectronics and photonics in Chapter 5. 

Low thermal conductivity and hence high sensitivity for heat-mode recording. 

Because of the diffusion of heat, the resolution of heat-mode recording is inferior to that of photon-mode systems. 

Furthermore, photons are rich in information such as energy, polarization and coherency, which cannot be rivalled by heat-mode recording. 

LCP is a suitable candidate for this purpose. The merits of photon-mode and heat-mode recording may be combined by the aid of... 

Nematic and smectic side-chain LCP are suitable as optical data storage media. A particular technique is the heat-mode recording technique [75], By locally heating, an optical scattering center is generated. However, heat-mode recording has the disadvantages of slow response time and low resolution [19],... 

The idea to use this effect for reversible optical data storage goes back to Todorov [77,78] and Rings-dorf [79], which is now addressed as photo-mode recording. The advantage of photo-mode recording over heat-mode recording lies in superior resolution. 

The following properties are generally required for all heat-mode optical recording applications ... 

The DRAW disc which offers the facility to make one recording consists of a plastic substrate such as polycarbonate (PC) or polymethylmethacrylate (PMMA) and a recording layer made in amorphous colourants. The thickness of the recording layer is approximately 30-100 nm. The principle of the optical DRAW disc memory, called heat mode system, is shown in Fig. 1. In this system, microscopic pits in the coloured recording layer of a disc are formed by thermal energy transformed from photo energy of a... 

HEAT-MODE AND PHOTON-MODE IMAGE RECORDING (7)... 

Comparisons between heat-mode and photon-mode processes are given in TABLE 1. The main differences are the superior resolution and the possibility of multiplex recording in photon-mode systems. 

TABLE 1. Comparison between heat- and photon-mode image recording. Item Heat-mode Photon-mode... 

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