WO2010096056A1

WO2010096056A1 - Optical data recording medium

Info

Publication number: WO2010096056A1
Application number: PCT/US2009/034725
Authority: WO
Inventors: Makarand P. Gore
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2009-02-20
Filing date: 2009-02-20
Publication date: 2010-08-26

Abstract

An optical data recording medium (100) includes a substrate (220), and a coating (230) established on the substrate (220). The coating (230) includes an enol-diene metal complex (240) having a light absorption maxima within a predetermined waveband. The enol-diene metal complex (240) is configured to absorb light within the predetermined waveband, and, in response to absorbing the light, to generate a mark (242) that is optically readable when exposed to light within the predetermined waveband.

Description

OPTICAL DATA RECORDING MEDIUM

BACKGROUND The present disclosure relates generally to optical data recording media. Materials that produce color and/or contrast change upon stimulation with radiation are used in optical recording and imaging media and devices. Further, widespread adoption of, and rapid advances in technologies relating to optical recording and imaging media have created a desire for greatly increased data storage capacity in such media. Thus, optical storage technology has evolved from the compact disc (CD) and laser disc (LD) to far denser data types such as digital versatile disc (DVD) and blue laser formats such as BLU-RAY and high-density DVD (HD-DVD). "BLU-RAY" is a trademark of BLU-RAY, Inc., Essex, CT, and "BLU-RAY Disc" is a trademark of Sony Kabushiki Kaisha Corp., Tokyo, Japan.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of embodiments of the present disclosure will become apparent by reference to the following detailed description and drawings, in which like reference numerals correspond to similar, though perhaps not identical, components. For the sake of brevity, reference numerals or features having a previously described function may or may not be described in connection with other drawings in which they appear.

Figure 1 is a semi-schematic perspective view and block diagram illustrating an embodiment of an optical disc recording system; Figure 2 is a cutaway cross-sectional view of an embodiment of a recording medium shown in conjunction with a partial block diagram of some of the elements of the system represented in Fig. 1 ; and

Figure 3 is a perspective view of another embodiment of a recording medium.

DETAILED DESCRIPTION

Embodiments of the optical recording/reading media disclosed herein are discs that are either i) writable and readable at wavelengths within the same waveband, or ii) writable at wavelengths within one waveband and readable at wavelengths within multiple wavebands. As such, the discs disclosed herein may be configured for any desirable writing and reading combination. It is to be understood that the dye system (which includes a metal complex alone or in combination with a contrast agent) is selected such that the characteristics of the media are within desirable specifications (e.g., for DVD formats, blue laser formats, etc.). It is believed that the metal complexes included in the media have increased thermal- and photo-stability when compared to, for example, other absorber materials.

Certain terms are used throughout the following description and claims that refer to particular system components. As one skilled in the art will appreciate, various companies may refer to a particular component by different names. This document does not intend to distinguish between components that differ in name but not function.

Reference is made herein to BLU-RAY technologies. Disc specifications for BLU-RAY discs currently include the following: wavelength = 405 nm; numerical aperture (NA) = 0.85; disc diameter = 12 cm; disc thickness = 1.2 mm; and data capacity > 23.3/25/27 GB. BLU-RAY discs can currently be used to store 2 hours of high resolution video images or 13 hours of conventional video images. A blue- violet laser having a wavelength between 380 nm and 420 nm, and particularly at 405 nm is used as the light source for BLU-RAY discs. Another technology using blue light (380 nm ~ 420 nm radiation) is HD-DVD and ultra density optical (UDO) discs.

As used herein, the terms "waveband", "absorption band" or "band" refer to light frequencies, radiation, and/or absorption corresponding with a range of wavelengths. When the phrase "at about" a stated value is used to describe a waveband (e.g., waveband at about 405 nm) or when the phrase "the [stated value] waveband" (e.g., the 405 nm waveband) is used, it is meant that the referenced waveband includes the stated wavelength (e.g., 405 nm) ± 30 nm from the stated value. The waveband may also be referred to herein as having "a center." In such instances, the waveband includes the stated wavelength (e.g., 405 nm) ± 30 nm from the stated value. As non-limiting examples, the 405 nm waveband includes wavelengths ranging from 375 nm to 435 nm, and the 650 nm waveband includes wavelengths ranging from 620 nm to 680 nm. Such wavelengths are considered to be "within" the identified waveband. The term wavelength generally refers to the stated value. However, when discussing the wavelength of a laser diode, the term wavelength includes the stated value ± 5 nm.

The system disclosed herein may be defined, at least in part, by the wavebands. In one embodiment, wavelength(s) of the defining waveband is/are used to write data and read data, and in another embodiment, wavelength(s) of a first defining waveband is/are used to write data and wavelength(s) of a second defining waveband (which is different from the first defining waveband) is used to read data. It is to be understood that color may be used to refer to the wavebands for the media and system. For example, media disclosed herein that use the 405 nm "blue" band to write on the media, and both the 405 nm "blue" band and the

650 nm "red" band to read the media may be referred to as "Write Blue-Read Red".

The term "light" as used herein includes electromagnetic radiation of any wavelength or band and from any source.

The recording medium 100 (shown in Figs. 1 through 3) disclosed herein may be used to record optical data or visual images, which are then readable when exposed to light beams within the same and/or a different waveband. The medium 100 is generally either reflective or transmissive. In one embodiment, the medium 100 is reflective and will be read accordingly using a reflected beam. For use with reflective medium 100, the system shown in Fig. 1 used to write and/or read data includes optical components 148, a light source 150 that produces an incident energy beam 152, and a reflected beam 154 which is detected by a pickup or optical sensor 157. Alternatively, for a transmissive medium 100 (as indicated by the hashed line in Fig. 1 ), the system may include a lens or optical system 600 to detect the transmitted beam 156 by a top detector 158 (a non-limiting example of which is a photo detector), which is also analyzed for the presence of signal agents. It is to be understood that Fig. 2 shows an abbreviated block diagram of the read/write system 170 illustrating some of the same optical components shown in Fig. 1.

Fig. 1 also depicts a cylindrical lens 159 which is generally used for astigmatic focusing. The reflected beam 154 is being focused (or converging) to a different point as the disc location moves closer or farther in a vertical direction from the optics. The cylindrical lens 159 further causes the beam 154 to converge faster along one axis than the other axis. This causes the profile of the light intensity on the photodetector 157 to change shape becoming more or less elliptical as the surface of the disc 100 moves closer or farther vertically with respect to the optics. A focus signal may be generated by having the photodetector 157 split into four quadrants, and comparing the four quadrants allows the laser beam 152 to remain focused on the disc 100.

In some embodiments, the system 170 includes a light source 150 that is able to emit the write wavelengths (e.g., those wavelengths within the 405 nm waveband) when desirable, and the read wavelengths (e.g., those wavelengths within the 405 nm waveband, the 650 nm waveband, and/or the 780 nm waveband) when desirable. In other embodiments, the system 170 includes a light source 150 that emits write wavelengths and a separate system 170 that includes a light source 150 that emits read wavelengths. The separate write and read systems 170 may, in some instances, be particularly suitable for the media 100 disclosed herein.

Fig. 1 also illustrates a drive motor 162 and a controller 164 for controlling the rotation of the optical disc/imaging medium 100. Mark(s) (shown as 242 in Fig. 2) may be read/detected by an optical sensor (e.g., optical pickup 157). The sensor (e.g., optical pickup 157) is positioned so as to detect at least one readable pattern of the optically detectable mark(s) 242 on the medium 100. Generally, the sensor reads the marks 242 as the medium 100 moves in relation to the sensor. A laser beam of the sensor is focused on the marked surface and detects changes in the reflected beam. The sensor detects the signal from the optically detected marks 242 and converts them to one or more electrical signals which may be sent to a processor 166.

The processor 166 and an analyzer 168 may be implemented together or in the alternative for processing the return beam 154 with a signal 165 from the optical sensor 157, such as a photodetector, to the processor 166. In some embodiments, and processor 166 and/or analyzer 168 process a transmitted beam 156 from a signal 163 transmitted from the optical detector 158. A display monitor 114 is also provided for displaying the results (generally in the form of data) of the processing. The system may also include a computer data base (not shown) which collects and stores the processed/analyzed data for subsequent retrieval.

Signals 165 from the optical sensor 157 may be used to detect recorded marks 242 on the medium 100, or various tracking signals, such as the push pull signal. The push-pull signal is derived from the difference between the electrical signals from the two sides of an optical sensor split into at least two equal parts tangentially to the track direction. In some instances, the medium 100 includes a land and groove (not shown) structure, which causes diffraction of the reflected light. The diffracted light has different amounts of phase interference with respect to the main reflected light between the two sides as the focused light moves radially across the tracks. The push-pull signal is used to maintain radial tracking and can also be used to detect and read minor variations in the groove (or land) that may contain various information such as format data or velocity information. Fig. 2 shows an abbreviated block diagram of the read/write system 170 illustrating some of the same optical components shown in Fig. 1. Specifically, Fig. 2 illustrates the read/write system 170 applying an incident energy beam 152 onto the medium 100.

Embodiments of the medium 100 include a substrate 220 and a coating layer 230 established on a surface 222 thereof. In one embodiment, a cover or protective layer 234 is established between the coating layer 230 and the optical beam 110. Such protective layers 234 are generally known and two non-limiting examples include Siθ2 and SisN₄. The protective layer(s) 234 enable writing to the coating 230 and reading of the mark(s) 242 while protecting the coating 230 from scratching, dirt, etc. It is to be understood that other embodiments of the medium 100 do not include a protective layer 234. Furthermore, in other embodiments, the reflective layer 231 (shown in Fig. 3) may be present between the coating layer 230 and the substrate 220. However, when the reflective layer 231 is not present, the coating layer 230 provides different levels of reflectivity between mark(s) 242 and unrecorded areas of the dye coating 230 for a reflective disc 100. Alternatively, the reflective layer 231 may not be present and the substrate 220 may be optically transparent to allow detection of the mark(s) 242 on the opposite side of the disc 100 from the entrance beam 110.

In embodiments including the reflective layer 231 , it is to be understood that the reflective layer 231 may be made up of materials having a high reflectance to laser light, such as, for example, Mg, Se, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Co, Ni, Ru, Rh, Pd, Ir, Pt, Cu, Ag, Au, Zn, Cd, Al, Ca, In, Si, Ge, Te, Pb, Po, Sn, Si, and/or Nd. In a non-limiting example, the reflective layer 231 is formed of Ag, Au or Al. Still further, it is to be understood that each of the reflector materials may be used alone, as an admixture, or as an alloy.

In still other embodiments (shown in Fig. 3), additional layer(s) 236, such as buffer layers, may be established between the coating layer 230 and the protective layer 234. Alternatively or additionally to the buffer layer(s) 236 between the coating layer 230 and the protective layer 234, a buffer layer (not shown) may exist between the coating layer 230 and the reflective layer 231. Non-limiting examples of suitable buffer layers include dielectric materials that enable the desirable wavelength(s) to be transmitted therethrough. The layers 230, 231 , 234 and 236 may be established via any desirable technique, including, but not limited to rolling, spin-coating, spraying, lithography, sputtering, evaporation, or screen printing.

The substrate 220 for the medium 100 may be any substrate upon which it is desirable to make a mark 242, such as, for example, the polymeric substrate used in conventional CD-R/RW/ROM, DVD±R/RW/ROM, HD-DVD or BLU-RAY disc. Substrate 220 may be paper (e.g., labels, tickets, receipts, or stationery), an overhead transparency, or another surface upon which it is desirable to record marks 242. As previously mentioned, the substrate 220 may include one or more grooves (not shown) formed therein. In an embodiment, multiple concentric grooves are formed in the substrate 220. In another embodiment, a single spiral groove extending from an inner diameter to an outer diameter is formed in the substrate 220. In still another embodiment, a combination of concentric and spiral grooves are formed in the substrate 220 (e.g., multiple separate spiral grooves are formed in the substrate 220). The coating layer 230 includes at least one enol-diene metal complex, shown schematically at reference numeral 240 and referred to hereinafter as "the metal complex". In some instances, the metal complex 240 functions as both an absorber and a contrast agent, and in other instances, the metal complex 240 also functions as an absorber for another contrast agent 232 present in the coating layer 230. As used herein, the term "contrast agent" is defined as any material that will produce contrast in the desired read band due to physical or chemical changes. Also as used herein, the term "absorber" describes a substance that absorbs a particular wavelength or range of wavelengths (i.e., waveband) and, in response, alters its chemical and/or physical structure and produces an optically detectable change (i.e., the absorber is also a contrast agent). In some instances, the absorber also transfers the absorbed energy to the separate contrast agent 232 present in the layer 230, thereby causing the contrast agent 232 to alter its chemical and/or physical structure and produce an optically detectable change.

When used in the coating layer 230 without another contrast agent 232, the metal complex 240 is both the absorber and the contrast agent. The metal complexes 240 disclosed herein are capable of i) absorbing wavelengths within selected waveband (e.g., the 405 nm waveband), which depends upon the structure of the metal complex 240, and ii) generating marks 242 that are readable when exposed to wavelengths within the selected waveband. When a separate contrast agent 232 is utilized, the metal complexes 240 also transfer the absorbed energy to the contrast agent 232 which, upon receiving such energy, generates marks 242 that are readable via wavelengths in one or more wavebands. It is to be understood that the separate contrast agent 232 may be selected such that marks 242 are generated that are readable i) in the selected waveband, or ii) in wavebands other than the selected waveband.

In one example, when the coating layer 230 includes the metal complex 240 and a porphyrin dye (as the separate contrast agent 232), writing and reading are accomplished at about the 405 nm waveband. The porphyrin dyes generally enhance the production of marks 242 readable within the 405 nm waveband. In another example, when the coating layer 230 includes the metal complex

240 and a naphthalocyanine dye (as the separate contrast agent 232), writing is accomplished at about the 405 nm waveband, and reading may be accomplished at about the 405 nm waveband or at about the 780 nm waveband. In this example, the metal complex 240 generates the marks 242 readable at about the 405 nm waveband, and the separate contrast agent 232 generates the marks 242 readable at about the 405 nm waveband or about the 780 nm waveband.

The contrast agent 232 provides versatility to the medium 100, at least in part because the medium 100 may be configured (e.g., by not including the agent 232 or by including a contrast agent 232 with absorption characteristics in a particular waveband) such that reading may be accomplished in any desirable waveband.

In an embodiment, the enol-diene metal complex 240 has any of the following sub-structures:

where Ri, R2, R3, and R₄, or R, R', and R" are each independently selected from aryl groups, alkyl groups, amino groups, sulfonyl groups, and amino alkyl groups, and where M is a metal. It is to be understood than any metal is suitable, and in one embodiment, the metal is a transition metal (e.g., copper, nickel, palladium, zinc, zirconium, gadolinium, titanium, europium, cerium, iron II, iron III, or any other transition metal listed in the periodic table of the elements). In another embodiment, the enol-diene metal complex 240 has one of the sub-structures:

(e)

where R, R₁, R₂, and R₃ are each independently selected from H, acyl groups, alkyl groups, and aryl groups, and where M is any metal. In one non-limiting example, sub-structure (f) has CH₃ as R and R₂, acetyl as R₁ and R₃, and any transition metal as the metal (M).

Generally, the contrast agent 232 is selected so that it does not become active until it absorbs wavelengths used for writing, or receives energy from the metal complex 240 (which absorbs wavelengths used for writing). The energy received by the contrast agent 232 triggers a physical and/or chemical change in the contrast agent 232, causing it to generate the mark 242. Examples of the contrast agent 232 that may be included in some embodiments of the coating layer 230 include porphyrin, phthalocyanine, napthalocyanine, squaranine, diazo dyes, and diazo metal complex dyes.

It has been found that absorbers that have modifying groups as described in U.S. Patent No. 6,015,896 and U.S. Patent No. 6,025,486 (both of which are incorporated herein by reference) are suitable for use as contrast agents 232 in the embodiments disclosed herein. Such modifying groups may be present on the ring, the atom or the ion at the center of a naphthalocyanine or a phthalocyanine complex. Examples of some suitable naphthalocyanine and phthalocyanine dyes are shown below:

where M is a metal or hydrogen; Pc is a phthalocyanine nucleus; Ri, R2, Wi, and W₂, are each independently selected from H or optionally substituted alkyls, aryls, or aralkyls; R3 is an aminoalkyl group; L is a divalent organic linking group; x, y and t are each independently selected from a value in the range of 0.5 to 2.5; and (x+y+t) ranges from 3 to 4;

where M is a metal or hydrogen; Pc is a phthalocyanine nucleus; R¹ is H or an optionally substituted alkyl, aryl, or aralkyl; L¹ is a divalent organic linking group; Z is an optionally substituted piperazinyl group; q is 1 or 2; x and y are each independently selected from a value ranging from 0.5 to 3.5; and (x+y) ranges from 2 to 5;

where M is a metal;

Another suitable example is silicon naphthalocyanine (SiNc) with trihexyloxy substituents. Still further, some commercial dyes previously used for recording of low density optical media at 650 nm and 780 nm are useful as contrast agents 232 in the high density optical media 100 disclosed herein. Examples of such commercial dyes include those used in conventional DVD or CD recording, such as IRGAPHOR® Ultragreen MX, IRGAPHOR® LASERVIOLET, IRGAPHOR® 1699 (all of which are commercially available from Ciba, Tarrytown, NY). Other suitable commercially available dyes suitable for use as the contrast agent 232 include PRO-JET™ 800NP, PRO-JET™ 830NP, and PRO-JET™ 900NP (all of which are available from Fujifilm Imaging Colorants Inc. Wilmington, DE), as well as YKR 3070 (available from Yamamoto Chemicals, Japan). The metal complex 240 and, in some instances, the contrast agent 232 are suspended, dissolved, or finely dispersed in a matrix or binder (e.g., a UV lacquer, or a polymeric matrix including, for example, polyacrylates, polystyrenes, polyalkenes, or polycarbonates). In some instances, the matrix or binder is a solvent of the metal complex 240 and, in some instances, of the contrast agent 232, and as such, the component(s) 240, 232 is/are completely soluble in the coating matrix or binder. In one embodiment, the coating layer 230 also includes a fixing agent (not shown).

Generally, the matrix material may be any composition suitable for dissolving and/or dispersing the metal complex 240, and the contrast agent 232 when included. Acceptable matrix materials include, but are not limited to, UV- curable matrices such as acrylate derivatives, oligomers and monomers, with or without a photo package. A photo package may include a light-absorbing species which initiates reactions for curing the matrix, such as, for example, benzophenone derivatives. Other examples of photoinitiators for free radical polymerization monomers and pre-polymers include, but are not limited to, thioxanethone derivatives, anthraquinone derivatives, acetophenones and benzoin ether types. It may be desirable to choose a matrix that can be cured by a form of radiation other than the type of radiation that is used for writing.

Matrices based on cationic polymerization resins may require photo- initiators based on aromatic diazonium salts, aromatic halonium salts, aromatic sulfonium salts and metallocene compounds. An example of an acceptable matrix includes Nor-Cote CLCDG-1250A or Nor-Cote CDGOOO (mixtures of UV curable acrylate monomers and oligomers), which contains a photoinitiator (hydroxy ketone) and organic solvent acrylates (e.g., methyl methacrylate, hexyl methacrylate, beta-phenoxy ethyl acrylate, and hexamethylene acrylate). Other acceptable matrixes include acrylated polyester oligomers such as CN292, CN293, CN294, SR351 (thmethylolpropane tri acrylate), SR395 (isodecyl acrylate), and SR256 (2(2-ethoxyethoxy) ethyl acrylate) available from Sartomer Co.

In some instances, the photochemical and/or photothermal mechanisms that cause the metal complex 240 and/or the contrast agent 232 to develop (i.e., form a mark 242) are much slower when the solid matrix is below its glass transition temperature. Without subscribing to a particular theory, the photochemical reactions in solids have an added energy barrier to heat the matrix above its glass transition temperature (T₉). Thus, in some embodiments, it is desirable to provide sufficient photothermal energy in the region of the desired mark 242 to locally heat the matrix above its glass transition temperature T₉. T₉ typically depends on the polymer composition of the matrix, and may be selected, if desired, by selecting the polymer that is used for the matrix. In some embodiments, T₉ will range from about 120⁰C to about 300⁰C. In many embodiments, it may be desirable that the coating layer 230 have a thickness equal to or less than 100 nm. In order to achieve this, spin coating is one suitable application technique for establishing the coating solution (which forms the coating layer 230) on the substrate 220. In addition, it may be desirable to provide a composition that is capable of forming the coating layer 230 such that it that is equal to or less than 100 nm thick. In such cases, the coating layer 230 should be, inter alia, free from particles that would prevent formation of such a thickness, i.e., free from particles having a dimension greater than 100 nm. In some instances, the components of the coating 230 may be in complete solution, thereby producing molecular level film aggregates.

Furthermore, in many applications it may be desirable to provide a transparent coating layer 230. In such a case, any particles present in the coating layer 230 would have an average size less than one fourth of the wavelength of the light to which the coating is transparent. While a coating layer 230 in which all particles are smaller than 150 nm would serve this purpose, it may be more desirable to utilize a coating 230 in which the marking components are dissolved, as opposed to one in which they are present as particles. Still further, as target data densities increase, the dot size, or mark size, that can be used for data recording decreases. Some currently available technologies require an average dot size of 150 nm or less. For all of these reasons, the coating layer 230 is therefore desirably entirely free of particles that are larger than one fourth the wavelength of the write radiation.

It is to be understood that radiation sources (e.g., a laser or LED) that emit light having a wavelength in a waveband from about 375 nm to about 435 nm may be used to activate the metal complex 240 (whether it forms the mark 242 or transfers energy to another contrast agent 232). In particular, radiation sources such as the lasers used in certain DVD and laser disk recording equipment emit energy at a wavelength of about 405 nm.

When it is desired to record, the medium 100 is positioned such that light (having a wavelength ranging from 375 nm to 435 nm) emitted by laser 150 is incident on the coating layer 230. The laser 150 is operated such that sufficient energy is transferred to the surface to form the mark 242. Both the laser 150 and the position of the medium 100 are controlled by the processor 166, such that light is emitted by the laser 150 in pulses that form a pattern of marks 242 on the surface of the coating layer 230. The light pulses are described as write strategy in the format standards, and are based on the profile of the pulse sequence. Some non-limiting examples of suitable write strategies include the N-1 , N/2 and the castle write strategies. When the metal complex 240 is used without another contrast agent 232 or is used with a contrast agent 232 that enhances the formation of the same type of mark 242 formed by the metal complex 240, the pattern of marks 242 formed will be readable at the absorption band of the metal complex (in some instances, also the write wavelength/waveband). However, when the metal complex 240 is used with a contrast agent 232 that is tuned to a particular wavelength or waveband, the pattern of marks 242 formed will be readable at the wavelength/waveband which corresponds to the absorption waveband of the contrast agent 232, and at the absorption band of the metal complex 240.

When it is desirable to read the recorded marks 242, it is to be understood that radiation sources (e.g., a laser or LED) that emit light having wavelengths ranging from 375 nm to 435 nm, and/or from 620 nm to 680 nm, and/or from 750 nm to 810 nm may be used. The medium 100 is again positioned such that the desirable light emitted by a laser 150 (which may be different from the laser 150 previously described for writing) is incident on the marked surface. The laser 150 is operated such that the light incident at the surface does not transfer sufficient energy to the surface to cause a mark 242. Instead, the incident light is reflected from the marked surface to a greater or lesser degree, depending on the absence or presence of a mark 242. As the medium 100 moves in relation to the laser 150, changes in reflectance are recorded by optical pickup 157 which generates a signal 165 corresponding to the marked surface. Both the laser 150 and the position of the medium 100 are controlled by the processor 166 during the reading process. It is be understood that the read/write system 170 described herein is merely illustrative and includes components that are understood in the art. Various modifications can be made, including the use of multiple lasers, processors, and/or pickups and the use of light having different wavelengths. The read components may be separated from the write components, or may be combined in a single device.

The use of the metal complexes 240 disclosed herein as absorber and contrast agents enable desirable modulation, push-pull signals, and stability to be achieved. Furthermore, via the addition of a separate contrast agent 232, the composition of the coating layer 230 may be tuned to allow a 405 nm waveband (blue) laser to generate optical contrast at multiple wavebands (e.g., the 405 nm waveband, the 650 nm waveband, and/or the 780 nm waveband).

While several embodiments have been described in detail, it will be apparent to those skilled in the art that the disclosed embodiments may be modified. Therefore, the foregoing description is to be considered exemplary rather than limiting.

Claims

What is claimed is:

1. An optical data recording medium (100), comprising: a substrate (220); and a coating (230) established on the substrate (220), the coating (230) including an enol-diene metal complex (240) having a light absorption maxima within a predetermined waveband, the enol-diene metal complex (240) configured to absorb light within the predetermined waveband, and, in response to absorbing the light, to generate a mark (242) that is optically readable when exposed to light within the predetermined waveband.

2. The optical data recording medium (100) as defined in claim 1 wherein the enol-diene metal complex (240) has the following sub-structure:

wherein Ri, R₂, R3, and R₄, or R, R', and R" are each independently selected from aryl groups, alkyl groups, amino groups, sulfonyl groups, and amino alkyl groups, and wherein M is a transition metal.

3. The optical data recording medium (100) as defined in any of the preceding claims wherein the enol-diene metal complex (240) has the following sub-structure:

wherein R, Ri, R₂, and R3 are each independently selected from H, acyl groups, alkyl groups, and aryl groups, and wherein M is a transition metal.

4. The optical data recording medium (100) as defined in any of the preceding claims wherein the coating (230) further includes a contrast agent (232) which, upon receiving energy absorbed via the enol-diene metal complex (240), undergoes a chemical or physical change to enhance production of the mark (242), and to render the mark (242) optically readable within multiple wavebands.

5. The optical data recording medium (100) as defined in claim 4 wherein the contrast agent (232) is selected from porphyrin dyes, phthalocyanine dyes, napthalocyanine dyes, squaranine dyes, diazo dyes, and diazo metal complex dyes.

6. The optical data recording medium (100) as defined in any of claims 4 or 5 wherein the mark (242) is optically readable when exposed to light having wavelengths within the predetermined waveband and when exposed to light having wavelengths within an other waveband.

7. The optical data recording medium (100) as defined in claim 6 wherein the predetermined waveband includes wavelengths ranging from 375 nm to 435 nm, and wherein the other waveband includes wavelengths ranging from 620 nm to 680 nm, or from 750 nm to 810 nm.

8. A method for at least one of i) optically recording data or visual images on the optical data recording medium (100) as defined in claim 1 , or ii) reading optically recorded data or visual images from the optical data recording medium (100) as defined in claim 1 , the method comprising: beaming i) light having wavelengths within the predetermined waveband from a light source (150) so as to cause the enol-diene metal complex (240) to capture energy and form the mark (242) on the optical data recording medium (100); or ii) light having wavelengths within the predetermined waveband from the light source (150) so as to render a mark (242) previously formed on the optical data recording medium (100) optically readable.

9. The method as defined in claim 8 wherein the coating (230) of the optical data recording medium (100) further includes a contrast agent (232) which, upon receiving energy absorbed via the enol-diene metal complex (240), undergoes a chemical or physical change to enhance production of the mark (242), and to render the mark (242) optically readable within multiple wavebands, and wherein the method for reading optically recorded data or visual images from the optical data recording medium (100) further comprises: beaming light of a wavelength within one of the multiple wavebands from the light source (150) so as to cause a mark previously formed on the optical data recording medium (100) to reflect light; and sensing the reflected light.

10. A system for at least one of recording or reading optical data or visual images, comprising: the optical data recording medium (100) as defined in claim 1 ; and at least one of a recording device or a reading device (170) including a light source (150) configured to illuminate the recording medium (100) with light of a wavelength within the predetermined waveband such that i) the enol-diene metal complex (240) captures energy and forms the mark (242) on the optical data recording medium (100); or ii) a mark (242) previously formed on the optical data recording medium (100) is optically readable.

11. The system as defined in claim 10 wherein the coating (230) of the optical data recording medium (100) further includes a contrast agent (232) which, upon receiving energy absorbed via the enol-diene metal complex (240), undergoes a chemical or physical change to enhance production of the mark (242), and to render the mark (242) optically readable within multiple wavebands, and wherein the light source (150) of the reading device (170) is further configured to illuminate the recording medium (100) with light having wavelengths within each of the multiple wavebands.

12. The system as defined in any of claims 10 or 11 , further comprising a sensor (157) positioned to detect contrast exhibited by the mark (242).

13. A method for making the optical data recording medium (100) as defined in claim 1 , the method comprising: selecting the enol-diene metal complex (240) such that it has a light absorption maxima at 405 nm; incorporating the enol-diene metal complex (240) into a solvent thereof, thereby forming a coating solution; and establishing the coating solution onto the substrate (220) to form the coating (230), wherein the coating (230) is a recording layer.

14. The method as defined in claim 13, further comprising establishing a protective layer (234) on the coating (230), the protective layer (234) being selected from Siθ2 and SisN₄.

15. The method as defined in any of claims 13 or 14, further comprising: selecting a contrast agent (232) that is configured to receive energy from the enol-diene metal complex (240) and to enhance production of marks (242) that are optically readable within multiple wavebands; and incorporating the selected contrast agent (232) into the coating solution.