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Compact Disc

Ben Chlebina Babajide Falae Leah Geyer Corey Gladieux. Compact Disc. Making the Mold: Master. Master Glass Adhesive Photoresist polymer Spin coated PGMEA solvent Even layer. DNQ- Novolac. Photoresist. Adhesive. Silica. Glass. Making the Mold: Photoresist. Polymer :

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Compact Disc

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  1. Ben Chlebina BabajideFalae Leah Geyer Corey Gladieux Compact Disc

  2. Making the Mold: Master • Master • Glass • Adhesive • Photoresist polymer • Spin coated • PGMEA solvent • Even layer DNQ-Novolac Photoresist Adhesive Silica Glass

  3. Making the Mold: Photoresist • Polymer: • Novolac (PF) • Diazonaphtholquinone (DNQ) • Region struck by light • Hydrolysis of bonds • Soluble in Alkali solution • Series of pits and lands • Spiral Out • Process • Dust free • Expensive

  4. Electroforming • Aluminum Plating • Electroforming • Master Makes a Father (red) • Father makes a Mother (Purple) • Mothermakes a Son (Green) • Son or Stamper becomes the mold • Quality assurance testing

  5. PC Chemical Structure

  6. Polycarbonate Disc Manufacturing Heated to a high temperature to remove impurities, especially water. Polymer additives are added to change the refractive index of the polymer. T Managed at 300 °C PC is injection molded into the master. Even polymer flow is crucial PC is expensive but economical!

  7. Metal Reflective Layer • Sputtering • Vacuum Chamber (10E-3 Torr) • Target Metal (typically aluminum or gold) • Heated to point of evaporation • Plasma-vapor target metal deposits on disc as it spins

  8. Protective Coating • Coat of Acrylic Lacquer is added • Cured by UV light • Maintains and stabilizes the etched pattern and protects the reflective surface

  9. Light Scattering-Laser Reflection • Interference pattern created by changes in pathlength of laser light

  10. Devices that use CDs must meet industry standard (light with specific wavelength) • Photo-electric cell receives light pattern and device translates the pattern into a digital signal that can be used to output information

  11. It’s a 3D World • Increased need for greater data storage capacity • Current information is stored in a 2D plane • Volume Homography allows data to be stored in 3 dimensions

  12. Volume Homography • Information is stored throughout the volume of a photosensitive material • Two coherent laser beams; the object beam and the reference beam • The two beams cause multiple interference patterns (holograms)

  13. Photopolymer Systems • Consist of a mixture of monomer and photoinitiator dissolved in a thick, cross-linked network • Holographic exposure causes polymerization • Generates a concentration gradient • Results in permanent compositional and density change

  14. Problems Arise • Writing induced shrinkage • The data stored has moved from its original position • Monomers must have low viscosities for efficient diffusion, do not lead to appreciable shrinkage on polymerization and possess a high refractive index • Highly Branched DendriticMacromonomers

  15. DendriticMacromonomers • Large volume to functional group ratio • Highly branched molecular architecture maintains a low viscosity • Incorporation of numerous high refractive index moieties at the chain ends increases the average refractive index of the macromonomer

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