Electronically translocatable optical stylet

Information

  • Patent Grant
  • 6269066
  • Patent Number
    6,269,066
  • Date Filed
    Friday, March 6, 1998
    26 years ago
  • Date Issued
    Tuesday, July 31, 2001
    23 years ago
  • Inventors
  • Original Assignees
    • (Banner Elk, NC, US)
  • Examiners
    • Dinh; Tan
    • Chu; Kim-Kwok
    Agents
    • Lalos & Keegan
    • Lau; Michael N.
Abstract
A composite interferometer and electro-optical prism provide a means to control the position of a spot of light to read and write data on an optical disc. In this invention each light ray from a spectral source of a cone of light rays is regenerated into a plurality of light rays by an interferometer. These rays are transmitted through an electro-optic crystal and focused by a lens into a constructive interference fringe on an optical disc. A voltage across the electro-optical crystal and magnetic field inside the spectral source define the position of the constructive interference fringe on the disc.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




Fields of the inventions are: Data Storage, Compact Disc, and Optical Storage




Fields of search are: 235/375, 462; 250/201.5; 350/166, 355, 356, 375, 381, 383, 385, 386, 387, 388, 392; 359/245, 248, 250, 276, 281; 360/18, 24, 32, 33.1, 39, 72.01, 72.02; 369/44.23, 44.41, 44.42, 44.37, 59, 102, 111, 112, 124, 275.1, 275.3,




2. Description of the Prior Art




Current optical disc data pickup systems employ an electro-mechanical gimbal optical system to track and read the data band spiral. These gimbal systems use a single diode laser. In the more conventional system the laser beam is diffracted into three beams. In this approach the center beam reads the data while the outer beams track the spiral. Tracking errors generated by the tracking beams produce a mechanical torque to swivel the optical system so as to bring the reading beam to the center of the data spiral.




Techniques are also known wherein the light probe employed to track and read the data band spiral is delivered to the surface of the disc by an optical fiber. In this approach the fiber is in a permanent magnet inside an electro-magnet. An electrical current in the electro-magnet causes the permanent magnet to move. This causes the fiber to move thus translating the light probe across the surface of the disc.




Techniques are known whereby a constructive interference fringe can be produced and its position controlled by an electric field:



















3,506,334




Apr., 1970




A. Korpel






5,071,253




Dec., 1991




R. Chase














Techniques are known whereby digital data can be recorded on and read from an optical compact disc:



















5,587,983




Dec., 1996




J. Bailey






5,646,920




Jul., 1997




W. Raczynski














SUMMARY OF THE INVENTION




This invention uses an interferometer in combination with an electro-optic prism to generate an Electronically translocatable Optical Stylet. A converging pencil of light rays is injected into the interferometer where it is regenerated into a plurality of diverging pencils of light rays. These diverging pencils are collected and converged into a constructive interference fringe on the surface of an optical data storage disc. The location of this fringe on the disc is controlled by controlling the wavelength of the light and the voltage applied across the electro-optic prism.




It is the prime objective of this invention to provide a precision electronically controlled spot of light to track and read data from an optical data storage disc.




It is another objective of this invention to provide a precision electronically controlled spot of light to write data on an optical data storage disc.




It is a further objective of this invention to provide precision control of a spot of light that has no moving mechanical components.




It is an additional objective of this invention to provide an optical probe compatible with a multitude of optical data storage disc formats such as the compact disc and the digital viedo disc.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

shows a perspective view of the Electronically Translocatable Optical Stylet produced by a spectral point source generator


100


, stylet generator


200


, and focusing lens


300


reading and writing data on optical disc


400


.





FIG. 1



a


shows an optical ray trace of FIG.


1


.





FIG. 1



b


shows a typical spectral point source generator


10


shown in

FIG. 1

employing laser


110


.





FIG. 1



c


shows the point source of

FIG. 1



b


with an electrical coil


105


encircling laser


110


.





FIG. 2

shows a perspective view of a stylet generator


200


with an input pencil of light rays


195


and an output bundle of light rays


295


.





FIG. 2



a


shows a cross-sectional view of the components of stylet generator


200


shown in

FIG. 2

identifying the individual elements.





FIG. 2



b


shows an optical ray trace through stylet generator


200


shown in

FIG. 2







FIG. 3

is a cross-sectional view of disc


400


at radii


410


showing data bands


450




a,




450




b,




450




c.







FIG. 4

shows fringe


500


reconstructed in the center of a pit at band


450




c.







FIG. 4



a


shows fringe


500


reconstructed in the center of a pit at band


450




a.







FIG. 4



b


shows fringe


500


reconstructed on the left edge of a pit at band


450




a.







FIG. 4



c


shows fringe


500


reconstructed on the right edge of a pit at band


450




a.













DESCRIPTION OF THE PREFERRED EMBODIMENTS




Basic configuration of the Electronically Translocatable Optical Stylet is seen in FIG.


1


. Configured herein to the specifications of the Digital Video Disc (DVD) it comprises a point source optical system


100


, an stylet generator


200


, a converging lens


300


to form constructive interference fringe


500


at data band


450


on optical disc


400


. Lens


600


is provided to collect and focus light from data band


450


on photo detector


700


. The intersection of the plane of incidence of stylet generator


200


and disc


400


is shown as line


410


.





FIG. 1



b


shows a typical point source optical system


100


that produces a converging cone of light rays


195


. Cone


195


is technically referred to as pencil of light rays


195


or simply “pencil


195


” and produces point source


199


.




In this embodiment, source


100


employs a Helium-Neon laser spectral source


110


to produce a beam of parallel light rays


115


. The wavelength of these rays is 632.8 nanometers. Beam


115


is collected by lens


120


and converted to diverging pencil


125


. Pencil


125


is collected by lens


130


and converted to beam


135


. Beam


135


is collected by lens


190


and converted to converging pencil


195


that produces point of light


199


. The converging input cone angle of pencil


195


as 10.710 milliradians (36′49.1″).




In addition,

FIG. 1

shows the central ray


191




c


and an off axis ray


191




x


of pencil


195


.





FIG. 2

shows a three dimensional view of style generator


200


that regenerates pencil


195


into a plurality of pencils of rays


295


. This plurality of pencils, having transited stylet generator


200


, is technically known as bundle


295


.




Stylet generator


200


consists of substrate


210


, total reflecting film


230


, waveguide


250


, partially reflecting film


270


, and electro-optic cover


290


. Pencil


195


is injected into waveguide


250


by locating point


199


at entrance face


253


. Pencil


195


is orthogonal to face


253


.




A

FIG. 2



a


shows a cross-sectional view of stylet generator


200


in the plane of incidence. Stylet generator


200


consists of a:




1. Substrate


210


is Fused Silica (SiO


2


) configured as a 4 millimeter wide, 131.1 millimeter long, and 2 millimeter thick parallelopiped.




2. Electrical conductor


210




e


of Aluminum (Al) is 0.1 nano-meters thick and vapor deposited on face


218


of Substrate


210


, a




3. Total reflection film


230


of Magnesium Fluoride (MgF


2


) whose index of refraction is 1.38. Film


230


is a 2.000 micrometers thick and vapor deposited on Electrical Conductor


210




e,


a




4. Waveguide


250


is a Zinc Selinide (ZnSe) crystal whose index of refraction is 2.5918. Waveguide


250


is configured as a chisel shaped prism with two sets of opposing parallel faces. Face


258


is the obverse face 4 millimeters wide by 131 millimeters long. It is parallel to face


253


, the reverse face, which is 4 millimeters wide by 131.1 milli-meters long. Both face


253


and face


258


are optically flat to λ/20. The spacing between face


253


and face


258


is 519.958 micrometers. In

FIG. 2



b


face


255


is beveled so as to make angle


200




a,


with respect to face


253


, equal to 608.313 milliradians (34°51′13.5″). This face is optically flat to λ/20. Beveled face


255


is the waveguide entrance face. Face


258


is the waveguide exit face. Face


253


is the total reflection face and is in optical contact with film


230


, a




5. Partial reflection film


270


is Magnesium Fluoride (MgF


2


) whose index is 1.38. Film


270


is 527.2 nanometers thick. It is vapor deposited on face


258


of waveguide


250


. This controls the amount of energy in any incident ray that leaks into cover


290


at each reflection, a




6. Cover


290


is Potassium di-Hydrogen-Deuterium Phosphate (KD*P), an electro-optical material, whose index of refraction is 1.502. In addition KD*P has a dielectric constant of 44.5 mm/mm and an electro-optic coefficient of 3.22×10


−8


mm/volt. Cover


290


is configured as a parallelopiped 4 millimeters wide by 30 millimeters long and 5.049 millimeters thick. Face


293


is the entrance face. Face


299


is the exit face. Face


293


is orthogonal to exit Face


299


. Face


293


and face


299


are optically flat to λ/20. Face


293


is in optical contact with Film


270


.




7. Electrical conductor


290




e


is Aluminum (Al) 0.100 nanometers thick. It is vapor deposited on face


298


of cover


290


.





FIG. 2



b


shows the basic interferometric process in stylet generator


200


by the action of the first three reflections of a ray inside waveguide


250


. This ray trace employs the following terms:




1. Entrance face of waveguide


250


is face


255


,




2. Normal to entrance face


255


is normal


255




n,






3. Interface between waveguide


250


and film


230


are faces


238


and


253


,




4. Normal to face


235


is normal


235




n,






5. Interface between waveguide


250


and film


270


are faces


258


and


273


,




6. Interface between film


270


and cover


290


are faces


278


and


293


,




7. Normal to face


278


is normal


278




n,






8. Normal to exit face


299


is normal


299




n,






9. The Goos-Hänchen total reflection boundary is shown as line 235.




With no electric field between film


210




e


and film


290




e


the ray trace proceeds as follows:




1. Ray


191




c


is incident normal to face


255


.




2. Ray


191




c


enters waveguide


250


to become ray


251




ra.






3. Ray


251




ra


transits waveguide


250


and is incident on face


253


at angle


251




aa


with respect to normal


235




n


generating an evanescent wave inside film


230


. Angle


251




aa


is −608.313 milliradian (−34°51′13.5″). (Note: a negative sign denotes counter-clockwise rotation)




4. Ray


251




ra


penetrates Film


230


, in accordance with the Goos-Hänchen Shift [see Kogelnik, H., “Goos-Hänchen Shift” Topics in Applied Physics Vol. 7 Integrated Optics 25, Springer-Verlag, Berlin, Germany(1979)], to boundary


235


, at a depth of 187.192 nanometers where it is totally reflected back into waveguide


250


as ray


251




rb.






5. Ray


251




rb


transits Waveguide


250


and is incident on face


258


at angle


251




ab.


(Note: angle


251




ab


equals angle


251




aa


) Here it generates an evanescent wave that penetrates film


270


. When this evanescent wave reaches face


278


, 0.5% of the energy in ray


251




rb


is transmitted into cover


290


as ray


291




ra


and 99.5% is reflected back into waveguide


250


as ray


251




rc


at angle


251




ab.


Angle


291




aa,


between ray


291




ar


and normal


278




n,


is 1.404065 radians (80°26′49.2″).




6. Ray


251




rc


transits waveguide


250


and is incident on film


230


at face


253


where it again generates an evanescent wave that penetrates film


230


to boundary


235


to be totally reflected back into waveguide


250


as ray


251




rd.






7. Ray


251




rd


transits waveguide


250


and is incident on Face


258


where it generates an evanescent wave that penetrates film


270


. When this evanescent wave reaches face


278


, 0.5% of the energy in ray


251




rd


is transmitted into cover


290


as ray


291




rb


and 99.5% is reflected back into waveguide


250


as ray


251




re.


The energy in ray


291




rb


is 0.4975% of the energy in ray


251




ra


and the energy in ray


251




re


is 99.0025% of the energy in ray


251




ra.


Thus 0.9975% of the energy in ray


251




ra


is in ray


291




ra


and ray


291




rb.






8. Ray


251




re


transits waveguide


250


and is incident on film


230


at face


253


where it generates an evanescent wave that penetrates film


230


to boundary


235


to be totally reflected back into waveguide


250


as ray


251




rf.






9. Ray


251




rf


transits waveguide


250


and is incident on Face


258


where it generates an evanescent wave that penetrates Film


270


. When this evanescent wave reaches face


278


, 0.5% of the energy in ray


251




rf


is transmitted into cover


290


as ray


291




rc


and 99.5% is reflected back into waveguide


250


as ray


251




rg.


The energy in ray


291




rc


is about 0.495% of the energy in ray


251




ra


and the energy in ray


251




rg


99.025% of the energy in ray


251




ra.


Thus about 0.975% of the energy in ray


251




ra


is in rays


291




ra,




291




rb,


and


291




rc.






10. Rays


291




ra,




291




rb,


and


291




rc


transit cover


290


and are incident on Face


299


. The angle between rays


291




ra,




291




rb,


and


291




rc


and normal


299




n


is


291




ab


which is 166.731 milliradians (9°33′10.8″).




11. Rays


291




ra,




291




rb,


and


291




rc


exit face


299


to become rays


295




ra,




295




rb,


and


295




rc.


The angle


295




aa


between ray


295




ra


and normal


299




n


is 251.928 milliradians (14°26′3.9″).




12. Rays


291




ra,




291




rb,


and


291




rc


are the first three of a sequence of


41


parallel phased related geometrically degraded amplitude rays regenerated from ray


191




c.


This sequence is only one of a plurality of sequences of rays that constitute bundle


295


. The optical path difference between sequential rays is 2.2148 micrometers. This is 3500 times the wavelength of the rays and is called the order number.





FIG. 1



a


is an optical ray trace of

FIG. 1

showing bundle


295


being collected by lens


300


and converted into converging pencil


395


to form constructive interference fringe


500


on disc


400


.

FIG. 3

shows a crossectional view of area


420


from disc


400


wherein pencil


395


is incident on data band


450




c.


Also see

FIG. 4

showing fringe


500


overlapping band


450




c.


Optical axis


305


, of lens


300


, orthogonal to both face


299


and disc


400


.




Lens


300


, Numerical Aperture NA 0.698, produces fringe


500


as a 406 nanometers diameter constructive interference fringe. Rays reflected from fringe


500


diverge as pencil


595


and are collected by lens


600


which converges them as pencil


695


onto photo diode


700


.




In

FIG. 3

, fringe


500


is displaced from focal point


399


. This displacement lies in the plane of incidence. The magnitude is defined by the following factors:




1. thickness of waveguide


250


,




2. angles of rays entering waveguide


250


,




3. index of refraction of waveguide


250


,




4. index of refraction of cover


290


,




5. focal length of lens


300


, and




6. wavelength of ray


191




c.






Thus the magnitude of the displacement, or location, of fringe


500


from point


399


can be changed by changing any of these parameters. In this embodiment both the index of refraction of cover


290


and the wavelength of the rays are controlled to control the location of fringe


500


.




For this configuration with zero voltage between electrical conductors


210




e


and


290




e


the displacement of fringe


500


from point


399


is 900.888 micrometers.




When the electric potential between conductors


210




e


and


290




e


is 3.687 kilovolts the index of refraction of cover


290


decreases to 1.50196 causing angle


291




aa


to increase to 1.404223 radians (80°27′21.8″). Angle


291




ab


now decrease to −166.573 milliradians (−9°22′38.2″) causing angle


295




aa


to decrease to −251.687 milliradians (−14°25′14.1″) which results in the distance between fringe


500


and point


399


becoming 899.988 micrometers.




In this manner an increase in the electrical potential between conductors


210




e


and


290




e


of 3.687 kilovolts has caused a decrease in the distance between fringe


500


and point


399


of 900 nanometers.




Alternately when the voltage between conductors


210




e


and


290




e


is zero and a 4.3566 kilogauss magnetic field is impressed on source


110


by an electric current in coil


105


, see

FIG. 1



c,


the emitted radiation is split into two wavelengths. One wavelength is 632.792 nanometers and is right circularly polarized while the other is 632.808 nanometers and is left circularly polarized.

FIG. 1



c


shows quarter wave plate


150


that serves to convert circularly polarized light into linearly polarized light. Plate


150


is oriented so that the 632.792 nanometer radiation is in the plane of incidence of interferometer


200


and the 632.808 nanometer is orthogonal to it.




Input ray 191


x


whose wavelength is 632.792 nanometers incidence on face


255


at an angle of −47.879 microradians (−9.9″) to emerge inside the waveguide at an angle −18.473 microradians (−3.84″). Ray


191




x


is incidence on face


278


at an angle of 608.331 milliradians (35°1′48.3″) so as to exit face


293


at an angle of 1.404223 radians (80°27′21.8″). Ray


191




x


is in turn incidence of face


299


at an angle of 166.573 milliradians (9°32′38.2″). Thus exiting cover


290


at an angle of −251.687 milliradians (−14°25′14.1″). This causes ray


191




x


to be regenerated as constructive interference fringe


500


at data band


450




c


which is 988.988 micrometers from point


399


. This is the same distance achieved by applying 3.687 kilovolts in the previous case.




Those rays whose wavelength is 632.808 nanometers are polarized orthogonal to the plane of incidence causing all of the energy in ray


251




rb


to be reflected back into waveguide


250


at face


258


. Thus none of the energy of the 632.808 nanometer radiation leaks into cover


290


.




A hybrid integration of the preceding electrical and magnetic techniques for changing the position of fringe


500


would employ a 2.1788 kilogauss magnetic field on source


110


and a 1.8439 kilovolt eletric field between conductors


210




e


and


290




e.


In this approach the wavelength of ray


191




x


is 632.796 nanometers and enter waveguide


250


at an angle of −24.0 nanoradians (−4.9″). Ray


191




x


is then incident on face


253


at an angle of −608.322 milliradians (−35°1′45.6″) so as to enter cover


290


at an angle of 1.404144 radians (80°27′5.5″). Ray


191




x


is then incident on face


299


at an angle of −166.652 milliradians (−9°32′54.5″) and exits cover


290


at an angle of −251.807 milliradians (−14°25′39.0″). As before this causes ray


191




x


to be regenerated as constructive interference fringe


500


at data band


450




c


which is 988.988 micrometers from point


399


.




The center of fringe


500


can now be moved±150 nanometers, from the center to the right or left side of data band


450




a,


by changing the voltage from 1.8439 kilovolts to 1.22294 kilovolts. This is ±614.5 volts oscillation about a bias of 1.8439 kilovolts. Alternately the magnetic field can changed from 1.4525 kilogauss to 2.9048 kilogauss. This would be a ±726.1 gauss oscillation about an initial 2.1788 kilogauss field.




Changing the wavelength of the input rays can be accomplished by using either of two optical phenomenon, the Stark Effect or the Zeeman Effect. Both are well documented concepts wherein an electric field (Stark effect) or a magnetic field (Zeeman effect) inside a spectral source changes the energy level (wavelength) of the emitted radiation. Employing either of these effect permits electronically tuning the wavelength of the rays of pencil


195


and thus electronically relocating fringe


500


.




The operational Electronically Translocatable Optical Stylet is configured with the plane of incidence of interferometer


200


passing through axis


401


and intercepting disc


400


along radii


410


. Interferometer


200


exit Face


299


normal


299




n


is perpendicular to disc


400


. The angle between lens


300


axis


305


and interferometer


200


normal


295




n


is −251.687 radians (−14°25′14.1″). Lens


300


has a 3.5 millimeter focal length at FN f/0.716 (NA 0.698 Numerical Aperture) with focal point


399


located at the surface of disc


400


. Spectral source


110


is a Helium-Neon laser whose wavelength is 632.8 nanometers so that the order number of sequential rays in beam


395


is 3500 waves.





FIG. 3

is a cross-sectional view of disc


400


along radii


410


showing data bands


450




a,




450




b,


and


450




c.


In this Electronically Translocatable Optical Stylet system the “center-to-center” spacing of these data bands is 740 nanometers, which is the same as the commercial Digital Video Disc. Shown here are optical axis


305


, point


399


at angle


295




aa


which is now the angle of the central ray of pencil


395


. Point


399


is located at data band


450




a.


The distance between point


399


and fringe


500


is 1.48 micrometers which is twice the pitch of the data band spiral. Thus fringe


500


has being constructed at band


450




c,


see FIG.


4


. Band


450




c


is now considered to be the fiducial band.




The Electronically Translocatable Optical Stylet can be employed in either of three operational modes. One is a relatively inexpensive single fringe system which is less accurate and but well suited to the audio and sub-professional personal computer markets. A more accurate and expensive system for the professional audio engineer and general personal computer market would employ two fringes. The most expensive system having the highest data capacity and ultimate performance capability employs three fringes.




In the first, or single fringe mode, the fringe tracks the data band spiral and reads the data. This single fringe device can also inscribe data in the disc's virgin surface.




The basic procedure involves oscillating fringe


500


over the pits of band


450




a.


Fringe oscillations generate an error voltage in the electronics. This error voltage is used to change either the electric field across cover


290


or the magnetic field impressed on source


110


. Thus should fringe


500


drift off band


450




a


the electronics would sense the error, analyze the output signal and calculate the magnitude and direction of the misalignment between the centers of the pit and fringe. The electronics would, within the time constant of the circuit, change either the electric or magnetic fields to cause fringe


500


to be centered on band


450




a


thus tracking the band. Data carried on the band would be extracted from the electronic signal by analyzing the presents or absence of an error voltage.




The single fringe mode can both track and read data as well as inscribe data on the virgin surface of an optical disc. This is accomplished by applying a bias voltage across films


210




e


and


290




e


so as to locate fringe


500


on a data band


450




a


that has data inscribed thereon. The Electronically Translocatable Optical Stylet tracks this band during the time no pit is being inscribed in the virgin surface. During the time a pit is being inscribed the voltage across films


210




e


and


290




e


is changed to relocate fringe


500


to virgin band


450




b


where the appropriate pits are “burnt in”. After one revolution of the disc this newly inscribed band


450




b


becomes band


450




a


being tracked by fringe


500


.




In the second, or dual fringe mode, one fringe tracks the data band spiral and reads the data while the second fringe inscribe data in the disc's virgin surface thus creating a new band spiral.




In this mode the first fringe, is the tracking fringe, while the second fringe, is the stylet fringe. In this mode a bias voltage is applied across films


210




e


and


290




e


so as to position both tracking fringes over band


450




a.


A magnetic field is applied to one of the sources in order to change the wavelength thus causing the stylus fringe to be positioned over band


450




b.






As before the tracking procedure involves employing an oscillating voltage across films


210




e


and


290




e


to oscillate tracking fringe over the pits in band


450




a.


This generates an error voltage that is used to change the bias electric field across films


210




e


and


290




e.






Thus should the tracking fringe


500




t


“drift off” band


450




a


the electronics would sense the error, analyze the output signal and calculate the magnitude and direction of the misalignment between the centers of the pit and the tracking fringe. The electronics would, within the time constant of the circuit, change the electric field bias to cause the tracking fringe to track band


450




a


and the stylus fringe to overlay virgin band


450




b.






The stylus fringe would now inscribe the appropriate pits in the virgin band


450




b.






Data carried on the band would be extracted from the electronic signal by analyzing the presents or absence of an error voltage.




In the third, or triple fringe mode, two fringes track and read the data band spiral. The third fringe inscribes “pits” in the disc's virgin surface.




In this mode the first two, fringes are tracking fringes, while the second, fringe is the fringe. In this mode a bias voltage is applied across films


210




e


and


290




e


so as to position all three fringes over band


450




a.


A magnetic field is applied to one of the sources in order to change its wavelength and causing fringe


500




s


to be positioned over band


450




b.






As before the tracking procedure involves employing an oscillating voltage across films


210




e


and


290




e


to oscillate tracking fringes over the pits in band


450




a.


This generates an error voltage that is used to change the bias electric field across films


210




e


and


290




e.






Thus should the tracking fringe drift off band


450




a


the electronics would sense the error, analyze the output signal and calculate the magnitude and direction of the misalignment between the centers of the pit and the center of the tracking fringes. The electronics would, within the time constant of the circuit, change the electric field to cause both tracking fringes to track band


450




a


and the stylus fringe to overlay virgin band


450




b.






The stylus fringe would now inscribe the appropriate pits in the virgin band


450




b.






Data carried on the band would be extracted from the electronic signal by analyzing the presents or absence of an error voltage.




To make the Electronically Translocatable Optical Stylet totally compatible with all of the current CD and DVD systems it is only necessary to make two simple adjustments in the electronic system. These are the:




1. bias voltage and




2. modulation voltage and/or magnetic field




Since stylet generator


200


is a hybrid Lummer-Gehrke Interferometer and an electro-optic cell it does not require a coherent light source and can be adapted to any spectral source and is thus capable of multiple spectral operations.




Further, since the Lummer-Gehrke Interferometer was originally created to study the ultra-violet region of the optical spectrum it is ideally suited for use with non-coherent ultra-violet light, such as 253.7 nanometer. A preliminary analysis shows that a 12 centimeter disc would be capable of storing well over 100 GB of data.




The following is a sequence of computation that exhibit how the Electronically Translocatable Optical Stylet is designed. They further show the effect on the position of the interference fringe due to different voltages across the electro-optic Cover and different magnetic fields inside the spectral source.




ETOS CD-ROM/R




This program designs and analysizes a CD-DVD compatable ETOS reader & writer.




Physical Constants



















C = speed of light (microns/second)





C = 3 · 10


14








n


e


= environment external index





n


e


= 1.0






of the cdxtl






n


c


= index of the Cover (KD*P)





n


c


= 1.502






n


o


= orthnogal index of the Cover





n


o


= 1.502






(KD*P)






n


g


= index of the Waveguide (ZnSe)





n


g


= 2.5918






n


r


= index of the Reflection Control





n


r


= 1.38






Film (MgF


2


)






n


S


= index of the Substrate (SiO


2


)





n


S


= 1.45845






λS = waveglength of the source





λS = .6328






(HeNe laser) (microns)













νS = frequency of the source (HeNe laser) (hertz)












V

s

=

C
λS











νS = 4.741 · 10


14















r = electro-optic coefficient





r = 3.22 · 10


−8








(mm/volts)






ε = dielectric constant





ε = 44.5






Zk = Zeeman constant





Zk = 7.142857 · 10


−7
















System Parameters


















β = bevel angle of the Entrance Face (radians)




β is TBD






ξ = angle of the ray entering the Waveguide (radians)




ξ is TBD






Φ = angle of the ray inside the Waveguide (radians)




Φ is TBD






Θ = specified angle of the ray inside the Cover (radians)




Φ is TBD






φ = angle of the ray at the before exiting the Cover (radians)




φ is TBD






ζ = angle of the ray exiting the Cover (radians)




ζ is TBD






L = length of the Waveguide (millimeters)




L := 30






Tc = thickness of the Cover (millimeters)




Tc is TBD






Tg = thickness of the Waveguide (microns)




Tg is TBD






Teff = effective thickness of the Waveguide (microns)




Teff is TBD






Tr = thickness of the Reflection Control Film (microns)




Tr := 0.5272






Ts = thickness of the Substrate (millimeters)




Ts := 2






R = reflection coefficient of the Reflection Control Film




R is TBD






W = width of the Waveguide (mm):




W := 4.0






fl = focal length of the lens (millimeters)




fl := 3.5






Tp = data track pitch (millimeters)




Tp := 0.00045




















dp = diameter of the pit (millimeters)
















dp = 0.0003































Φmax = 0.61814

























Θmax = 1.570627

























φmax = 0.000169

























ζmax = 0.000254













Dmax := fl · tan(ζmax)




Dmax = 0.000888






Dmax := fl · tan(ζmax)




Dmax = 0.000888






DRF := Dmax + 2000 · Tp




DRF = 0.900888

























ζRF = 0.251928

























φRF = 0.166731168

























ΘRF = 1.404065158

























ΦRF = 0.608312571

























tom = 0.148763477













ΨRF := 3500






Teff := ΨRF · tom




Teff = 520.672






Tc := L · cot(ΘRF)




Tc = 5.049






tc := Tc · cos(ζRF)




tc = 4.889

























FN = 0.715829

























NA = 0.698491














Depth of Ray Peneration into the Reflecting Film (Goos-Hanchen Effect)









dr
:=


λ





S


2
·
π
·




(


n
g

·

sin


(

Φ





RF

)



)

2

-

n
r
2









dr
=
0.187192






Tg
:=

Teff
-
dr
-
Tr





Tg
=
519.9578













Distance Between Sequential Rays Exiting the Waveguide (Goos-Hanchen Effect)






ds
:=




Teff
·

tan


(

Φ





RF

)



1000






ds

=
0.3262601











Number of Rays in the Array






p
:=



floor










(

L

2
·
ds


)






p

=
41











Frustrated Total Internal Reflection Constants









a
:=


n
g

·

cos


(

Φ





RF

)







a
=
2.127






b
:=




(


n
g

·

sin


(

Φ





RF

)



)

2

-

(

n
r
2

)







b
=
0.538022






c
:=


n
c

·

cos


(

Φ





RF

)







c
=
1.233






δ
:=


4
·
π
·
b
·
Tr


λ





S






δ
=
5.633






R
:=







(


e
δ

+

e

-
δ



)

·

(


(


a
2

+

b
2


)

·

(


b
2

+

c
2


)


)


+






2
·

(



(


a
2

-

b
2


)

·

(


b
2

-

c
2


)


-

4
·
a
·

b
2

·
c


)











(


e
δ

+

e

-
δ



)

·

(


(


a
2

+

b
2


)

·

(


b
2

+

c
2


)


)


+






2
·

(



(


a
2

-

b
2


)

·

(


b
2

-

c
2


)


+

4
·
a
·

b
2

·
c


)










R
=
0.995













Constructive Interference Fringe Constants









F
:=


4
·
R



(

1
-
R

)

2






F
=
159179.951243






G
:=


4
·

R
p




(

1
-

R
p


)

2






G
=
94.361174













Constructive Interference Fringe


3




db


Beam Width



















δΨ := 0.1








i := 0, 1 . . . 2000

























Ψ


0


= 3499.95




Ψ


2000


= 3500.15

























I


0


= 8.493 · 10


−4






I


2000


= 6.232568158 · 10


−4















Lim


i


:= if(I


i


< 0.5, 0, 1)


































































Trailing 3db point of the constructive interference fringe




ψt := 3500.005






TOL := .0000001

























ΨRFt3db = 3500.01082033













Leading 3db point of the constructive interference fringe




ψl := 3499.985

























ΨRFl3db = 3499.98917967













ΔΨRF3db := ΨRFt3db − ΨRFl3db




ΔΨRF3db = 0.021640653

























ΦRFT3db = 0.608308132

























ΦRFl3db = 0.60831701

























ΘRFt3db = 1.404027

























ΘRFl3db = 1.404103

























ζRFt3db = 0.251985892

























ζRFl3db = 0.251870031













Stylus Fringe 3db beam width in disc space






ΔζRF3db := ζRFt3db − ζRFl3db




ΔζRF3db = 0.000115862











Diameter (3db) of the Stylus Fringe on the surface of the disc












df := ΔζRF3db · fl




df = 0.000406































Input Beam Angle Trailing Fringe




















ΨtRF = 3501.01082



























ΦtRF = 0.607897741



























ξtRF = 0.001075157















Input Beam Angle Leading Fringe



















ΨlRF = 3498.98918



























ΦlRF = 0.608727154



























ξlRF = −0.001074517















ΔξRF := ξtRF − ξlRF




ΔξRF = 0.002149673







Output Beam Angle Trailing Fringe



















ΘtRF = 1.400562



























ζtRF = 0.257289















Output Beam Angle Leading Fringe



















ΘlRF = 1.40764



























ζlRF = 0.246463















ΔζRF := ζtRF − ζlRF




ΔζRF = 0.010825917















Single Fringe System




Fringe Probe located at the center of the pit





















DsFP := DRF − 2 · Tp




DsFP = 0.899988



























ζsFP = 0.251687



























φsFP = 0.166573



























ΘsFP = 1.404223



























ΦsFP = 0.608331



























ηsFP = 1.50196



























VsFP = 3687.133854



























λsFP = 0.632791859



























νsFP = 4.740895 · 10


14

















ΔνsFP := νsFP − νS




ΔνsFP = 6.099 · 10


9









HsFP := Zk · (ΔνsFP)




HsFP = 4.356608 · 10


3





























λZsFP = 0.632808141















Fringe Probe located at the trailing edge of the pit

































DsFtP = 0.900138



























ζsFtP =0.251727



























φsFtP = 0.1666



























ΘsFtP = 1.404197



























ΦsFtP = 0.608328



























ηsFtP = 1.501967



























VsFtP = 3072.824311



























λsFtP = 0.632793215



























νsFtp = 4.740885 · 10


14

















ΔνsFtP := νsFtP − νS




ΔνsFtP = 5.083 · 10


9









HsFtP := Zk · (ΔνsFtP)




HsFtP = 3.630722 · 10


3





























λZsFtP = 0.632807















Fringe Probe located at the leading edge of the pit

































DsFlP = 0.899838



























ζsFlP = 0.251647



























φsFlP = 0.166547



























ΘsFlP = 1.404249



























ΦsFlP = 0.608334



























ηsFlP = 1.501954



























VsFlP = 4301.358



























λsFlP = 0.6327905



























νsFlP = 4.740906*10


14

















ΔνsFlP := νsFlP − νS




ΔνsFlP = 7.115*10


9









HsFlP := Zk · (ΔνsFlP)




HsFlP = 5.082407*10


3





























λZsFlP = 0.632809















Multiple Fringe Single Probe System





















DSF := DRF − Tp




DSF = 0.900438



























ζSF = 0.251807



























φSF = 0.166652



























ΘSF = 1.404144



























ΦSF = 0.608322



























ηSF = 1.50198



























VSF = 1843.949882















ζμδFP := ζRF + ζsFP − ζSF




ζμδFP = 0.251807



























φμδFP = 0.166652



























ΘμδFP = 1.404144



























ΦμδFP = 0.608322



























λμδFP = 0.632796



























νμδFP = 4.740865 · 10


14

















ΔνμδFP := νμδFP − νS




ΔνμδFP = 3.050358 · 10


9









HμδFP := Zk · (ΔνμδFP)




HμδFP = 2178.827142







νμδFP := νS − ΔνμδFP




νμδFP = 4.740804 · 10


14





























λZμδFP = 0.632804















Mutiple Fringe Dual Probe System




Center of the Trailing Fringe Probe located at the trailing edge of the pit

































DmFtP = 0.900588



























ζmFtP = 0.251848



























φmFtP = 0.166679



























ΘmFtP = 1.404118



























ΦmFtP = 0.608319



























ηmFtP = 1.501987



























VmFtP = 1229.385012



























λmFtP = 0.632797



























νmFtP = 4.740855 · 10


14

















ΔνmFtP := νmFtP − νS




ΔνmFtP = 2.033567 · 10


9









HmFtP := Zk · (ΔνmFtP)




HmFtP = 1452.547554















Center of the Leading Fringe Probe located at the leading edge of the pit

























DmFlP
:=

DRF
-
Tp
-

dp
2












DmF1P = 0.900288




















ζmFlP
:=

atan


(

DmFlP
fl

)












ζmF1P = 0.251767




















φmFlP
:=

asin
(



n
e

·

sin


(
ζmFlP
)




n
o


)











φmF1P = 0.166626




















ΘmFlP
:=


π
2

-
φmFlP











θmF1P = 1.40417




















ΦmFlP
:=

asin
(



n
c

·

sin


(
ΘmFlP
)




n
g


)











ΦmF1P = 0.608325




















ηmFlP
:=



n
g

·

sin


(
ΦRF
)




sin


(
ΦmFlP
)













ηmF1P = 1.501973




















VmFlP
:=


2
·

(


n
c

-
ηmFlP

)

·
Tc


r


·

n
c
3














VmF1P = 2458.429651




















λmFlP
:=



2
·
Teff
·

n
g

·
cos







(
ΦmFlP
)


ΨRF











λmF1P = 0.632795




















νmFlP
:=

C
λmFlP











vmF1P = 4.740875 · 10


14















ΔvmF1P := vmF1P − vS




ΔvmF1P = 4.06665 · 10


9








HmF1P := Zk · (ΔvmF1P)




HmF1P = 2904.750159






ζμδmFtP := ζRF + ζsFtP − ζSF




ζμδmFtP = 0.251847572




















φμδmFtP
:=

asin
(



n
e



(
ζμδmFtP
)



n
o


)











ΦμδmFtP = 0.166679




















ΘμδmFtP
:=


π
2

-
φμδmFtP











θμδmFtP = 1.404118




















ΦμδmFtP
:=

asin
(



n
c

·

sin


(
ΘμδmFtP
)




n
g


)











ΦμδmFtP = 0.608319




















λμδmFtP
:=



2
·
Teff
·

n
g

·
cos







(
ΦμδmFtP
)


ΨRF











λμδmFtP = 0.632797285




















νμδmFtP
:=

C
λμδmFtP











vμδmFtP = 4.740855 · 10


14















ΔvμδmFtP := vμδmFtP − vS




ΔvμδmFtP = 2.033693 · 10


9








HμδmFtP := Zk · (ΔvμδmFtP)




HμδmFtP = 1452.637678






vZμδmFtP := vS + ΔvμδmFtP




vZμδmFtP = 4.740855 · 10


14






















λZμδmFtP
:=

C
νZμδmFtP











λZμδmFtP = 0.632797













ζμδmF1P := ζRF + ζsF1P − ζSF




ζμδmF1P = 0.251767




















φμδmFlP
:=

asin
(



n
e

·

sin


(
ζμδmFlP
)




n
o


)











φμδmF1P = 0.166626




















ΘμδmFlP
:=


π
2

-
φμδmFlP











θμδmF1P = 1.40417




















ΦμδmFlP
:=

asin
(



n
c

·

sin


(
ΘμδmFlP
)




n
g


)











ΦμδmF1P = 0.608325




















λμδmFlP
:=



2
·
TEFF
·

n
g

·
cos







(
ΦμδmFlP
)


ΨRF











λμδmF1P = 0.632795




















νμδmFlP
:=

C
λμδmFlP











vμδmF1P = 4.740875 · 10


14















ΔvμδmF1P := vμδmF1P − vS




ΔvμδmF1P = 4.066903 · 10


9








HμδmF1P := Zk · (ΔvμδmF1P)




HμδmF1P = 2904.930335






vZμδmF1P := vS + ΔvμδmF1P




vZμδmF1P = 4.740875 · 10


14






















λZμδmFlP
:=

C
νZμδmFlP











λZμδmF1P = 0.632795




















ξsFP
:=

asin


(



n
g

·

sin


(

ΦRF
-
ΦsFP

)




n
e


)












ξsFP = −4.787919 · 10


−5






















ξsFtP
:=

asin
(



n
g

·

sin


(

ΦRF
-
ΦsFtP

)




n
e


)











ξsFtP = −3.990187 · 10


−5






















ξsFlP
:=

asin


(



n
g

·

sin


(

ΦRF
-
ΦsFlP

)




n
e


)












ξsF1P = −5.585549 · 10


−5






















ξSF
:=

asin


(



n
g

·

sin


(

ΦRF
-
ΦSF

)




n
e


)












ξSF = −2.394417 · 10


−5






















ξφμδFP
:=

asin


(



n
g

·

sin


(

ΦRF
-
ΦφμδFP

)




n
e


)












ξφμδFP = −2.394566 · 10


−5






















ξmFtP
:=

asin


(



n
g

·

sin


(

ΦRF
-
ΦmFtP

)




n
e


)












ξmFtP = −1.59638 · 10


−5






















ξmFlP
:=

asin


(



n
g

·

sin


(

ΦRF
-
ΦmFlP

)




n
e


)












ξmF1P = −3.192353 · 10


−5






















ξμδFP
:=

asin


(



n
g

·

sin


(

ΦRF
-
ΦμδFP

)




n
e


)












ξμδFP = −2.394566 · 10


−5






















ξμδmFtP
:=

asin


(



n
g

·

sin


(

ΦRF
-
ΦμδmFtP

)




n
e


)












ξμδmFtP = −1.596479 · 10


−5






















ξμδmFlP
:=

asin


(



n
g

·

sin


(

ΦRF
-
ΦμδmFlP

)




n
e


)












ξμδmF1P = −3.192551 · 10


−5















νsFP := ΦRF − ΦsFP




νsFP = −0.000018473






νsFtP := ΦRF − ΦsFtP




νsFtP = −0.000015495






νsF1P := ΦRF − ΦsF1P




νsF1P = −0.000021551






νSF := ΦRF − ΦSF




νSF = −0.000009238






νμδFP := ΦRF − ΦμδFP




νμδFP = −0.000009239






νmFtP := ΦRF − ΦmFtP




νmFtP = −0.000006159






μmF1P := ΦRF − ΦmF1P




νmF1P = −0.000012317






νμδFP := ΦRF − ΦμδFP




νμδFP = −0.000009239






νμδFtP := ΦRF − ΦμδmFtP




νμδFtP = −0.00000616






νμδF1P := ΦRF − ΦμδmF1P




νμδF1P = −0.000012318













Claims
  • 1. An optical device to read data on an optical disc and inscribe data recorded on said optical disc comprising in combination:a) means for generating one of a cone of light rays and a pencil of rays: b) an interferometer regenerating said pencil of rays into one of a plurality of pencils of rays and a bundle of rays; c) means for deflecting said bundle of rays; d) means for converging said bundle of rays into a constructive interference fringe on said optical disc; e) means for collecting light rays from said optical disc on a light sensor.
  • 2. The apparatus of claim 1 wherein the means for generating said pencil of rays is a spectral source.
  • 3. The apparatus of claim 2 wherein the said spectral source is a visible source.
  • 4. The apparatus of claim 2 wherein the said spectral source is an ultra violet source.
  • 5. The apparatus of claim 1 wherein the interferometer is a Lummer-Gehrcke interferometer.
  • 6. The apparatus of claim 1 wherein the interferometer is a Fabry-Perot interferometer.
  • 7. The apparatus of claim 1 wherein the means for regenerating said pencil of rays is a leaky asymmetric slab waveguide.
  • 8. The apparatus of claim 1 wherein the means for deflecting said bundle of rays is an electro-optical cell means.
  • 9. The apparatus of claim 8 wherein the location of said constructive interference fringe is a function of the strength of an electric field inside said electro-optic means for deflecting said bundle of rays.
  • 10. The apparatus of claim 1 wherein the means for regenerating said pencil of rays is optically coupled to the means for deflecting said bundle of rays.
  • 11. The apparatus of claim 1 wherein the location of said constructive interference fringe is a function of the wavelength of said constructive interference fringe.
  • 12. The apparatus of claim 11 wherein the wavelength of said constructive interference fringe is controlled by the strength of a magnetic field inside the means for generating said pencil of rays.
  • 13. The apparatus of claim 11 wherein the wavelength of said set of rays is controlled by the strength of an electric field inside the means for generating said pencil of rays.
  • 14. The apparatus of claim 1 wherein the means for regenerating said pencil of rays is an electro-optic interferometer.
  • 15. The apparatus of claim 14 wherein the location of said constructive fringe is a function of the strength of an electric field inside said electro-optic interferometer.
  • 16. The apparatus of claim 1 wherein the means for deflecting said bundle of rays is a magneto-optical cell means.
  • 17. The apparatus of claim 16 wherein the location of said constructive interference fringe is a function of the strength of a magnetic field inside said magneto-optic means for deflecting said bundle of rays.
  • 18. The apparatus of claim 1 wherein said means for generating a pencil of rays are multiple means for generating multiple pencils of rays.
  • 19. The apparatus of claim 18 wherein one of the multiple pencils of rays is an optical probe employed to track and read data on said optical disc and any number of said pencils of rays are optical scribes employed to inscribe data on said optical disc.
  • 20. The apparatus of claim 19 wherein two of the pencils of rays are optical probes employed to track and read data on said optical disc and one is an optical scribe employed to inscribe data on said optical disc.
  • 21. The apparatus of claim 18 wherein the multiple pencils of rays can be independently controlled on said optical disc by separately controlling the strength of electric or magnetic fields inside means for generating said pencils of rays.
  • 22. The apparatus of claim 18 wherein all of said pencils of rays can be collectively controlled on said optical disc by controlling the strength of either an electric or magnetic field inside said means for deflecting said pencils of rays.
  • 23. The apparatus of claim 1 wherein the means for collecting light rays from said optical disc is a lens.
  • 24. The apparatus of claim 1 wherein the location of said interference fringe is a function of the angle of said rays inside said means for regenerating said pencil of rays.
  • 25. The apparatus of claim 1 wherein the means for converging the bundle of rays is a lens.
  • 26. The apparatus of claim 1 wherein the means for generating a pencil of rays are three means for generating three pencils of rays.
  • 27. The apparatus of claim 1 wherein the means for generating said pencil of rays is a laser.
  • 28. A method of tracking a data track spiral on an optical disc comprising the steps of:a) producing multiple constructive interference fringes on said optical disc; b) positioning said multiple constructive interference fringes orthogonally across said data track spiral; c) detecting and interpreting signals from said optical disc; d) defining the center of said data track spiral relative to the center of said multiple constructive interference fringes; and e) generating an error voltage to control the positions of said multiple constructive interference fringes.
  • 29. A method of reading data on an optical disc inscribed with data comprising the steps of:a) producing a constructive interference fringe on said optical disc; b) detecting said light rays from said optical disc produced by said constructive interference fringe; and c) interpreting intensity variations in said detected light rays.
  • 30. The method of claim 29, wherein the constructive interference fringe is produced by a Fabry-Perot Interferometer.
  • 31. The method of claim 29, wherein the constructive interference fringe is produced by a Lummer-Gehrcke Interferometer.
  • 32. A method of inscribing multiple data track spirals on an optical disc comprising the steps of:a) tracking an inscribed data track spiral on said optical disc; b) producing multiple variable intensity constructive interference fringes on virgin areas of said optical disc; c) controlling the distance between a tracking fringe following the inscribed data track spiral and said multiple variable intensity constructive interference fringes on said optical disc.
  • 33. A method of inscribing a data track spiral on an optical disc comprising the steps of:a) producing a variable intensity constructive interference fringe on the virgin area of said optical disc; b) controlling the radial position of said variable intensity constructive interference fringe on said optical disc. c) varying the intensity of said variable intensity constructive interference fringe to inscribe said data track spiral.
  • 34. A method of inscribing multiple data track spirals on an optical disc comprising the steps of:a) producing multiple variable intensity constructive interference fringes on virgin areas of said optical disc for inscribing said data track spirals; b) controlling the radial position of said variable intensity constructive interference fringes on said optical disc. c) varying the intensity of each said variable intensity constructive interference fringes to inscribe said data track spirals.
  • 35. A method of reading multiple data track spirals on an optical disc inscribed with data comprising the steps of:a) producing multiple constructive interference fringes on said optical disc; b) detecting light rays from said optical disc produced by said multiple constructive interference fringe; and c) interpreting intensity variations in said detected light rays.
  • 36. The method of claim 35, wherein the constructive interference fringe is produced by a Lummer-Gehrcke Interferometer.
  • 37. The method of claim 35, wherein the constructive interference fringe is produced by a Fabry-Perot Interferometer.
  • 38. A method of tracking a data track spiral on an optical disc comprising the steps of:a) generating phased related geometrically degraded amplitude rays; b) producing a constructive interference fringe from said phased related geometrically degraded amplitude rays on said optical disc; c) oscillating said constructive interference fringe orthogonally across said data track spiral; d) detecting and interpreting variations in light intensity from said optical disc; and e) generating an error voltage to change the position of said constructive interference fringe on said optical disc.
  • 39. A method of inscribing a data track spiral on an optical disc comprising the steps of:a) tracking an inscribed data track spiral on said optical disc; b) producing a variable intensity constructive interference fringe on the virgin area of said optical disc; c) controlling the distance between a tracking fringe following an inscribed data track spiral and said variable intensity constructive interference fringe on said optical disc.
Parent Case Info

This application claims the benefit of Provisional Application Ser. No. 60/053,682 filed on Jul. 24, 1997.

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Entry
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Provisional Applications (1)
Number Date Country
60/053682 Jul 1997 US