Abstract

Pitch button blocking (PBB), involving attaching small pitch buttons between the back of a thin workpiece (i.e., optic) and a blocking plate, enables noncompliant convergent polishing in which the workpiece stiffness and block interface strength are maintained. This process has been optimized, and practical design criteria (number, size, and spacing of pitch buttons) have been determined both experimentally and theoretically using a thermoelastic model. The optimized PBB process has been successfully implemented on 100–265 mm sized workpieces with aspect ratios up to 45, resulting in maximum peak-to-valley heights of <|0.1|μm after blocking and polishing.

© 2012 Optical Society of America

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References

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  1. N. Brown, “Optical polishing pitch,” Lawrence Livermore National Laboratory Report UCRL-80301 (LLNL, 1977).
  2. B. Gillman and F. Tinker, “Fun facts about pitch and the pitfalls of ignorance,” Proc. SPIE 3782, 72–79 (1999).
    [CrossRef]
  3. R. Varshneya, J. E. DeGroote, L. L. Gregg, and S. D. Jacobs, “Characterizing optical polishing pitch,” Proc. SPIE TD02, 87–89 (2003).
    [CrossRef]
  4. F. W. Preston, “On the properties of pitch used in working optical glass,” Trans. Opt. Soc. 24, 117–142 (1923).
    [CrossRef]
  5. J. E. DeGroote, S. D. Jacobs, L. L. Gregg, A. E. Marino, and J. C. Hayes, “Quantitative characterization of optical polishing pitch,” Proc. SPIE 4451, 209–221 (2001).
    [CrossRef]
  6. F. Twyman, Prism and Lens Making, 2nd ed. (Adam Hilger, 1988).
  7. D. F. Horne, Optical Production Technology (Crane, Russak, 1972).
  8. H. Karow, Fabrication Methods for Precision Optics (Wiley, 1993).
  9. R. Scott, “Optical manufacturing,” in Applied Optics and Optical Engineering, R. Kingslake, ed., Vol. III (Academic, 1965), pp. 43–95.
  10. T. Suratwala, M. Feit, and J. Menapace, “Scratch forensics,” Opt. Photon. News 19, 12–15 (2008).
  11. T. Suratwala, R. Steele, M. Feit, L. Wong, P. Miller, J. Menapace, and P. Davis, “Effect of rogue particles on the sub-surface damage of fused silica during grinding/polishing,” J. Non-Cryst. Solids 354, 2023–2037 (2008).
    [CrossRef]
  12. S. Timoshenko, “Analysis of bi-metal thermostats,” J. Opt. Soc. Am. 11, 233 –255 (1925).
    [CrossRef]
  13. T. Suratwala, R. Steele, M. Feit, R. Desjardin, and D. Mason, “Convergent pad polishing of amorphous silica,” Int. J. Appl. Glass Sci. 3, 1–15 (2012).
    [CrossRef]
  14. T. Suratwala, W. Steele, M. Feit, R. Desjardin, D. Mason, R. Dylla-Spears, L. Wong, P. Miller, and P. Geraghty, “Method and system for convergent polishing,” U.S. provisional patent application 61,454,893 (21March2011).
  15. B. A. Boley and J. H. Weiner, Theory of Thermal Stresses(Wiley, 1960).
  16. R. DesJardin, “Automated pitch button dispensing station and method,” U.S. patent 6,692,573 (17February2004).

2012

T. Suratwala, R. Steele, M. Feit, R. Desjardin, and D. Mason, “Convergent pad polishing of amorphous silica,” Int. J. Appl. Glass Sci. 3, 1–15 (2012).
[CrossRef]

2008

T. Suratwala, M. Feit, and J. Menapace, “Scratch forensics,” Opt. Photon. News 19, 12–15 (2008).

T. Suratwala, R. Steele, M. Feit, L. Wong, P. Miller, J. Menapace, and P. Davis, “Effect of rogue particles on the sub-surface damage of fused silica during grinding/polishing,” J. Non-Cryst. Solids 354, 2023–2037 (2008).
[CrossRef]

2003

R. Varshneya, J. E. DeGroote, L. L. Gregg, and S. D. Jacobs, “Characterizing optical polishing pitch,” Proc. SPIE TD02, 87–89 (2003).
[CrossRef]

2001

J. E. DeGroote, S. D. Jacobs, L. L. Gregg, A. E. Marino, and J. C. Hayes, “Quantitative characterization of optical polishing pitch,” Proc. SPIE 4451, 209–221 (2001).
[CrossRef]

1999

B. Gillman and F. Tinker, “Fun facts about pitch and the pitfalls of ignorance,” Proc. SPIE 3782, 72–79 (1999).
[CrossRef]

1925

1923

F. W. Preston, “On the properties of pitch used in working optical glass,” Trans. Opt. Soc. 24, 117–142 (1923).
[CrossRef]

Boley, B. A.

B. A. Boley and J. H. Weiner, Theory of Thermal Stresses(Wiley, 1960).

Brown, N.

N. Brown, “Optical polishing pitch,” Lawrence Livermore National Laboratory Report UCRL-80301 (LLNL, 1977).

Davis, P.

T. Suratwala, R. Steele, M. Feit, L. Wong, P. Miller, J. Menapace, and P. Davis, “Effect of rogue particles on the sub-surface damage of fused silica during grinding/polishing,” J. Non-Cryst. Solids 354, 2023–2037 (2008).
[CrossRef]

DeGroote, J. E.

R. Varshneya, J. E. DeGroote, L. L. Gregg, and S. D. Jacobs, “Characterizing optical polishing pitch,” Proc. SPIE TD02, 87–89 (2003).
[CrossRef]

J. E. DeGroote, S. D. Jacobs, L. L. Gregg, A. E. Marino, and J. C. Hayes, “Quantitative characterization of optical polishing pitch,” Proc. SPIE 4451, 209–221 (2001).
[CrossRef]

Desjardin, R.

T. Suratwala, R. Steele, M. Feit, R. Desjardin, and D. Mason, “Convergent pad polishing of amorphous silica,” Int. J. Appl. Glass Sci. 3, 1–15 (2012).
[CrossRef]

R. DesJardin, “Automated pitch button dispensing station and method,” U.S. patent 6,692,573 (17February2004).

T. Suratwala, W. Steele, M. Feit, R. Desjardin, D. Mason, R. Dylla-Spears, L. Wong, P. Miller, and P. Geraghty, “Method and system for convergent polishing,” U.S. provisional patent application 61,454,893 (21March2011).

Dylla-Spears, R.

T. Suratwala, W. Steele, M. Feit, R. Desjardin, D. Mason, R. Dylla-Spears, L. Wong, P. Miller, and P. Geraghty, “Method and system for convergent polishing,” U.S. provisional patent application 61,454,893 (21March2011).

Feit, M.

T. Suratwala, R. Steele, M. Feit, R. Desjardin, and D. Mason, “Convergent pad polishing of amorphous silica,” Int. J. Appl. Glass Sci. 3, 1–15 (2012).
[CrossRef]

T. Suratwala, M. Feit, and J. Menapace, “Scratch forensics,” Opt. Photon. News 19, 12–15 (2008).

T. Suratwala, R. Steele, M. Feit, L. Wong, P. Miller, J. Menapace, and P. Davis, “Effect of rogue particles on the sub-surface damage of fused silica during grinding/polishing,” J. Non-Cryst. Solids 354, 2023–2037 (2008).
[CrossRef]

T. Suratwala, W. Steele, M. Feit, R. Desjardin, D. Mason, R. Dylla-Spears, L. Wong, P. Miller, and P. Geraghty, “Method and system for convergent polishing,” U.S. provisional patent application 61,454,893 (21March2011).

Geraghty, P.

T. Suratwala, W. Steele, M. Feit, R. Desjardin, D. Mason, R. Dylla-Spears, L. Wong, P. Miller, and P. Geraghty, “Method and system for convergent polishing,” U.S. provisional patent application 61,454,893 (21March2011).

Gillman, B.

B. Gillman and F. Tinker, “Fun facts about pitch and the pitfalls of ignorance,” Proc. SPIE 3782, 72–79 (1999).
[CrossRef]

Gregg, L. L.

R. Varshneya, J. E. DeGroote, L. L. Gregg, and S. D. Jacobs, “Characterizing optical polishing pitch,” Proc. SPIE TD02, 87–89 (2003).
[CrossRef]

J. E. DeGroote, S. D. Jacobs, L. L. Gregg, A. E. Marino, and J. C. Hayes, “Quantitative characterization of optical polishing pitch,” Proc. SPIE 4451, 209–221 (2001).
[CrossRef]

Hayes, J. C.

J. E. DeGroote, S. D. Jacobs, L. L. Gregg, A. E. Marino, and J. C. Hayes, “Quantitative characterization of optical polishing pitch,” Proc. SPIE 4451, 209–221 (2001).
[CrossRef]

Horne, D. F.

D. F. Horne, Optical Production Technology (Crane, Russak, 1972).

Jacobs, S. D.

R. Varshneya, J. E. DeGroote, L. L. Gregg, and S. D. Jacobs, “Characterizing optical polishing pitch,” Proc. SPIE TD02, 87–89 (2003).
[CrossRef]

J. E. DeGroote, S. D. Jacobs, L. L. Gregg, A. E. Marino, and J. C. Hayes, “Quantitative characterization of optical polishing pitch,” Proc. SPIE 4451, 209–221 (2001).
[CrossRef]

Karow, H.

H. Karow, Fabrication Methods for Precision Optics (Wiley, 1993).

Marino, A. E.

J. E. DeGroote, S. D. Jacobs, L. L. Gregg, A. E. Marino, and J. C. Hayes, “Quantitative characterization of optical polishing pitch,” Proc. SPIE 4451, 209–221 (2001).
[CrossRef]

Mason, D.

T. Suratwala, R. Steele, M. Feit, R. Desjardin, and D. Mason, “Convergent pad polishing of amorphous silica,” Int. J. Appl. Glass Sci. 3, 1–15 (2012).
[CrossRef]

T. Suratwala, W. Steele, M. Feit, R. Desjardin, D. Mason, R. Dylla-Spears, L. Wong, P. Miller, and P. Geraghty, “Method and system for convergent polishing,” U.S. provisional patent application 61,454,893 (21March2011).

Menapace, J.

T. Suratwala, R. Steele, M. Feit, L. Wong, P. Miller, J. Menapace, and P. Davis, “Effect of rogue particles on the sub-surface damage of fused silica during grinding/polishing,” J. Non-Cryst. Solids 354, 2023–2037 (2008).
[CrossRef]

T. Suratwala, M. Feit, and J. Menapace, “Scratch forensics,” Opt. Photon. News 19, 12–15 (2008).

Miller, P.

T. Suratwala, R. Steele, M. Feit, L. Wong, P. Miller, J. Menapace, and P. Davis, “Effect of rogue particles on the sub-surface damage of fused silica during grinding/polishing,” J. Non-Cryst. Solids 354, 2023–2037 (2008).
[CrossRef]

T. Suratwala, W. Steele, M. Feit, R. Desjardin, D. Mason, R. Dylla-Spears, L. Wong, P. Miller, and P. Geraghty, “Method and system for convergent polishing,” U.S. provisional patent application 61,454,893 (21March2011).

Preston, F. W.

F. W. Preston, “On the properties of pitch used in working optical glass,” Trans. Opt. Soc. 24, 117–142 (1923).
[CrossRef]

Scott, R.

R. Scott, “Optical manufacturing,” in Applied Optics and Optical Engineering, R. Kingslake, ed., Vol. III (Academic, 1965), pp. 43–95.

Steele, R.

T. Suratwala, R. Steele, M. Feit, R. Desjardin, and D. Mason, “Convergent pad polishing of amorphous silica,” Int. J. Appl. Glass Sci. 3, 1–15 (2012).
[CrossRef]

T. Suratwala, R. Steele, M. Feit, L. Wong, P. Miller, J. Menapace, and P. Davis, “Effect of rogue particles on the sub-surface damage of fused silica during grinding/polishing,” J. Non-Cryst. Solids 354, 2023–2037 (2008).
[CrossRef]

Steele, W.

T. Suratwala, W. Steele, M. Feit, R. Desjardin, D. Mason, R. Dylla-Spears, L. Wong, P. Miller, and P. Geraghty, “Method and system for convergent polishing,” U.S. provisional patent application 61,454,893 (21March2011).

Suratwala, T.

T. Suratwala, R. Steele, M. Feit, R. Desjardin, and D. Mason, “Convergent pad polishing of amorphous silica,” Int. J. Appl. Glass Sci. 3, 1–15 (2012).
[CrossRef]

T. Suratwala, R. Steele, M. Feit, L. Wong, P. Miller, J. Menapace, and P. Davis, “Effect of rogue particles on the sub-surface damage of fused silica during grinding/polishing,” J. Non-Cryst. Solids 354, 2023–2037 (2008).
[CrossRef]

T. Suratwala, M. Feit, and J. Menapace, “Scratch forensics,” Opt. Photon. News 19, 12–15 (2008).

T. Suratwala, W. Steele, M. Feit, R. Desjardin, D. Mason, R. Dylla-Spears, L. Wong, P. Miller, and P. Geraghty, “Method and system for convergent polishing,” U.S. provisional patent application 61,454,893 (21March2011).

Timoshenko, S.

Tinker, F.

B. Gillman and F. Tinker, “Fun facts about pitch and the pitfalls of ignorance,” Proc. SPIE 3782, 72–79 (1999).
[CrossRef]

Twyman, F.

F. Twyman, Prism and Lens Making, 2nd ed. (Adam Hilger, 1988).

Varshneya, R.

R. Varshneya, J. E. DeGroote, L. L. Gregg, and S. D. Jacobs, “Characterizing optical polishing pitch,” Proc. SPIE TD02, 87–89 (2003).
[CrossRef]

Weiner, J. H.

B. A. Boley and J. H. Weiner, Theory of Thermal Stresses(Wiley, 1960).

Wong, L.

T. Suratwala, R. Steele, M. Feit, L. Wong, P. Miller, J. Menapace, and P. Davis, “Effect of rogue particles on the sub-surface damage of fused silica during grinding/polishing,” J. Non-Cryst. Solids 354, 2023–2037 (2008).
[CrossRef]

T. Suratwala, W. Steele, M. Feit, R. Desjardin, D. Mason, R. Dylla-Spears, L. Wong, P. Miller, and P. Geraghty, “Method and system for convergent polishing,” U.S. provisional patent application 61,454,893 (21March2011).

Int. J. Appl. Glass Sci.

T. Suratwala, R. Steele, M. Feit, R. Desjardin, and D. Mason, “Convergent pad polishing of amorphous silica,” Int. J. Appl. Glass Sci. 3, 1–15 (2012).
[CrossRef]

J. Non-Cryst. Solids

T. Suratwala, R. Steele, M. Feit, L. Wong, P. Miller, J. Menapace, and P. Davis, “Effect of rogue particles on the sub-surface damage of fused silica during grinding/polishing,” J. Non-Cryst. Solids 354, 2023–2037 (2008).
[CrossRef]

J. Opt. Soc. Am.

Opt. Photon. News

T. Suratwala, M. Feit, and J. Menapace, “Scratch forensics,” Opt. Photon. News 19, 12–15 (2008).

Proc. SPIE

B. Gillman and F. Tinker, “Fun facts about pitch and the pitfalls of ignorance,” Proc. SPIE 3782, 72–79 (1999).
[CrossRef]

R. Varshneya, J. E. DeGroote, L. L. Gregg, and S. D. Jacobs, “Characterizing optical polishing pitch,” Proc. SPIE TD02, 87–89 (2003).
[CrossRef]

J. E. DeGroote, S. D. Jacobs, L. L. Gregg, A. E. Marino, and J. C. Hayes, “Quantitative characterization of optical polishing pitch,” Proc. SPIE 4451, 209–221 (2001).
[CrossRef]

Trans. Opt. Soc.

F. W. Preston, “On the properties of pitch used in working optical glass,” Trans. Opt. Soc. 24, 117–142 (1923).
[CrossRef]

Other

N. Brown, “Optical polishing pitch,” Lawrence Livermore National Laboratory Report UCRL-80301 (LLNL, 1977).

F. Twyman, Prism and Lens Making, 2nd ed. (Adam Hilger, 1988).

D. F. Horne, Optical Production Technology (Crane, Russak, 1972).

H. Karow, Fabrication Methods for Precision Optics (Wiley, 1993).

R. Scott, “Optical manufacturing,” in Applied Optics and Optical Engineering, R. Kingslake, ed., Vol. III (Academic, 1965), pp. 43–95.

T. Suratwala, W. Steele, M. Feit, R. Desjardin, D. Mason, R. Dylla-Spears, L. Wong, P. Miller, and P. Geraghty, “Method and system for convergent polishing,” U.S. provisional patent application 61,454,893 (21March2011).

B. A. Boley and J. H. Weiner, Theory of Thermal Stresses(Wiley, 1960).

R. DesJardin, “Automated pitch button dispensing station and method,” U.S. patent 6,692,573 (17February2004).

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Figures (9)

Fig. 1.
Fig. 1.

Schematic illustrating the process steps for PBB.

Fig. 2.
Fig. 2.

Schematic of PBB parameters (material and geometric). Workpiece (w) and pitch (p) are each characterized by elastic modulus E, thermal expansion coefficient α, thickness t, and radius r. The spacing between pitch button centers is s while the separation between button edges is dm.

Fig. 3.
Fig. 3.

Photographs of optimized PBB pattern used (a) for 100 mm diameter round fused silica workpiece (sample S21) and (b) for a 265 mm square fused silica workpiece.

Fig. 4.
Fig. 4.

Lineouts of the measured change in surface figure of fused silica and phosphate glass (100mmdiameter×2.2mmthick) in various blocking configurations (optimized PBB, unoptimized PBB, and solid blocking).

Fig. 5.
Fig. 5.

(a) Measured change in surface figure (ΔPV) of fused silica (100mmdiameter×2.2mmthick) in various PPB configurations as a function of button spacing (dm). (b) Measured change in surface figure (ΔPV) of fused silica and phosphate glass workpieces (100mmdiameter×2.2mmthick) as a function of area fraction (Af) when dm<15mm. The points represent experimental data, and the line is the model fit using αp=2.4×106K1.

Fig. 6.
Fig. 6.

Measured linear thermal expansion of BP1 and Cycad Pitch by TMA.

Fig. 7.
Fig. 7.

Calculated change in surface figure (ΔPV) for various PBB scenarios on fused silica workpieces (dw=100mm diameter, tw=2.2mm, E=73GPa, α=5.4×107°C1). (a) Calculated ΔPV after PBB as a function of degree of undercooling of the pitch for single button (r=50mm) and three buttons (s=50mm, rp=5mm). (b) Calculated ΔPV after PBB for single-button case and various pitch moduli, thicknesses, and thermal expansion coefficients (ΔT=54°C). (c) Calculated ΔPV for various three- and nine-button PBB as a function of Af (where dm>15mm). (d) Calculated ΔPV/Af after PBB as a function of button separation distance (dm) for three- and nine-button simulations at various button sizes (ΔT=54°C, t=1mm, Ep=0.22GPa, αp=5.4×106°C1). The lines in (c) and (d) represent simple empirical curve fits of the simulation results.

Fig. 8.
Fig. 8.

Surface figure of fused silica workpiece (100mmdiameter×2.2mmthick) using pitch (stiff) button blocking (sample S21) (a) before and (b) after polishing (full scale: 18–5 μm); surface figure of a fused silica workpiece (100mmdiameter×2.2mmthick) using foam (compliant) blocking (c) before and (d) after polishing (full scale: 8.0–6.0 μm) (after [13] with permission).

Fig. 9.
Fig. 9.

Calculated number of buttons for optimized PBB using spacing dm=20mm and relative area Af=0.05 as a function of workpiece radius using Eqs. (4) and (5).

Tables (3)

Tables Icon

Table 1. Properties of the Pitch Materials Used in This Study [2,3]

Tables Icon

Table 2. Summary of PBB Experiments Showing Process Parameters Measured Change in Surface Figure (ΔPV) before and after Blocking, with All Workpieces 100 mm in Diameter and 2.2 mm Thicka

Tables Icon

Table 3. Summary of Material Properties Used in Thermoelastic Model for PBB

Equations (6)

Equations on this page are rendered with MathJax. Learn more.

(1+2v)(1+v)(12v)Eex+E2(1+v)2uE(12v)αTx=0,(1+2v)(1+v)(12v)Eey+E2(1+v)2vE(12v)αTy=0,(1+2v)(1+v)(12v)Eez+E2(1+v)2wE(12v)αTz=0,
k2T=0.
e=ux+vy+wz.
rp=dmπAf2,
N=πrw2(2rp+dm)2,
ΔPV=AfC,

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