Abstract

We report a study of the basic characteristics of laser polishing of fused silica with a protocol that is particularly suitable for surface smoothing of micro-optic elements fabricated by a laser ablation process. We describe a new, to our knowledge, approach based on scanning a highly controlled small size laser beam and melting areas of tens to hundreds of micrometers of glass using a computer-controlled raster scan process, which does not require beam shaping, substrate preheating, or special atmospheres. Special test samples of silica substrates with prescribed spatial frequency content were polished using a range of irradiation conditions with the beam from a well-controlled CO2 laser operating at a wavelength of 10.59μm. An analysis is presented of the laser-generated reduction in surface roughness in terms of measurements of the spatial frequency characteristics, and the results are compared with the predictions of a simple model of surface-tension-driven mass flow within the laser-melted layer. This technique is shown to be capable of smoothing silica surfaces with 1μm scale roughness down to levels <1  nm with no net effect on the as-machined net surface shape, at realistic production rates without a preheating stage, and with noncritical residual stresses.

© 2006 Optical Society of America

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References

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  1. F. Laguarta, N. Lupon, and J. Armengol, "Optical-glass polishing by controlled laser surface-heat treatment," Appl. Opt. 33, 6508-6513 (1994).
    [CrossRef] [PubMed]
  2. J. F. Monjardin, K. M. Nowak, A. R. Holdsworth, H. J. Baker, and D. R. Hall, "Brightness improvement for micro-lensed, laser diode bar stacks," presented at Advanced Solid-State Photonics Topical Meeting, San Antonio, Tex., 2-5 February 2003.
  3. R. M. Brusasco, B. M. Penetrante, J. A. Butler, and L. W. Hrubesh, "Localized CO2 laser treatment for mitigation of damage growth in fused silica," presented at the Boulder Laser Damage Symposium XXXIII, Boulder, Colo, 1-3 October 2001.
  4. E. Mendez, H. J. Baker, K. M. Nowak, F. Villarreal, and D. R. Hall, "Highly localized CO2 laser cleaning and damage repair of silica optical surfaces," presented at the Boulder Laser Damage Symposium XXXVI, Boulder, Colo, 20-22 September 2004.
  5. P. A. Temple, W. H. Lowdermilk, and D. Milam, "Carbon-dioxide laser polishing of fused-silica surfaces for increased laser-damage resistance at 1064 nm," Appl. Opt. 21, 3249-3255 (1982).
    [CrossRef] [PubMed]
  6. Y. M. Xiao and M. Bass, "Thermal-stress limitations to laser fire polishing of glasses," Appl. Opt 22, 2933-2936 (1983).
    [CrossRef] [PubMed]
  7. F. Vega, N. Lupon, J. A. Cebrian and F. Laguarta, "Laser application for optical glass polishing," Opt. Eng. 37, 272-279 (1998).
    [CrossRef]
  8. D. G. Holloway, The Physical Properties of Glasses (Wykeham Publications, 1973), pp. 19-20.
  9. J. L. Ocaña, A. Garcia-Beltran, F. Laguarta, J. Armengol, N. Lupon, and F. Vega, "Laser heat treatments driven by integrated beams: role of irradiation nonuniformities," Appl. Opt 38, 4570-4576 (1999).
    [CrossRef]
  10. J. Hentze and V. Lissotschenko, "Method and device for the production of optical lenses or the like," U.S. patent 5,504,302 (2 April 1996).
  11. V. P. Veiko, "Laser-based technology for micro-optics and photonics components fabrication," in International Symposium on Photonic Glass, C. Zhu, ed., Proc. SPIE 5061, 103-111 (2003).
    [CrossRef]
  12. G. A. J. Markillie, H. J. Baker, F. J. Villarreal, and D. R. Hall, "Effect of vaporization and melt ejection on laser machining of silica glass micro-optical components," Appl. Opt 41, 5660-5667 (2002).
    [CrossRef] [PubMed]
  13. L. K. White, N. A. Miszkowski, W. A. Kurylo, and J. M. Shaw, "Flow properties and contour modeling of fusible borophosphosilicate glasses," J. Electrochem. Soc. , 139, 822-826 (1992).
    [CrossRef]
  14. A. Paul, Chemistry of Glasses (Chapman & Hall, 1982), pp. 75, 88.
    [CrossRef]
  15. A. D. McLachlan and F. P. Meyer, "Temperature dependence of the extinction coefficient of fused silica for CO2 laser wavelengths," Appl. Opt. 26, 1728-1731 (1987).
    [CrossRef] [PubMed]
  16. L. Holland, The Properties of Glass Surfaces (Chapman & Hall, 1966).

2003 (1)

V. P. Veiko, "Laser-based technology for micro-optics and photonics components fabrication," in International Symposium on Photonic Glass, C. Zhu, ed., Proc. SPIE 5061, 103-111 (2003).
[CrossRef]

2002 (1)

G. A. J. Markillie, H. J. Baker, F. J. Villarreal, and D. R. Hall, "Effect of vaporization and melt ejection on laser machining of silica glass micro-optical components," Appl. Opt 41, 5660-5667 (2002).
[CrossRef] [PubMed]

1999 (1)

J. L. Ocaña, A. Garcia-Beltran, F. Laguarta, J. Armengol, N. Lupon, and F. Vega, "Laser heat treatments driven by integrated beams: role of irradiation nonuniformities," Appl. Opt 38, 4570-4576 (1999).
[CrossRef]

1998 (1)

F. Vega, N. Lupon, J. A. Cebrian and F. Laguarta, "Laser application for optical glass polishing," Opt. Eng. 37, 272-279 (1998).
[CrossRef]

1994 (1)

1992 (1)

L. K. White, N. A. Miszkowski, W. A. Kurylo, and J. M. Shaw, "Flow properties and contour modeling of fusible borophosphosilicate glasses," J. Electrochem. Soc. , 139, 822-826 (1992).
[CrossRef]

1987 (1)

1983 (1)

Y. M. Xiao and M. Bass, "Thermal-stress limitations to laser fire polishing of glasses," Appl. Opt 22, 2933-2936 (1983).
[CrossRef] [PubMed]

1982 (1)

Armengol, J.

J. L. Ocaña, A. Garcia-Beltran, F. Laguarta, J. Armengol, N. Lupon, and F. Vega, "Laser heat treatments driven by integrated beams: role of irradiation nonuniformities," Appl. Opt 38, 4570-4576 (1999).
[CrossRef]

F. Laguarta, N. Lupon, and J. Armengol, "Optical-glass polishing by controlled laser surface-heat treatment," Appl. Opt. 33, 6508-6513 (1994).
[CrossRef] [PubMed]

Baker, H. J.

G. A. J. Markillie, H. J. Baker, F. J. Villarreal, and D. R. Hall, "Effect of vaporization and melt ejection on laser machining of silica glass micro-optical components," Appl. Opt 41, 5660-5667 (2002).
[CrossRef] [PubMed]

J. F. Monjardin, K. M. Nowak, A. R. Holdsworth, H. J. Baker, and D. R. Hall, "Brightness improvement for micro-lensed, laser diode bar stacks," presented at Advanced Solid-State Photonics Topical Meeting, San Antonio, Tex., 2-5 February 2003.

E. Mendez, H. J. Baker, K. M. Nowak, F. Villarreal, and D. R. Hall, "Highly localized CO2 laser cleaning and damage repair of silica optical surfaces," presented at the Boulder Laser Damage Symposium XXXVI, Boulder, Colo, 20-22 September 2004.

Bass, M.

Y. M. Xiao and M. Bass, "Thermal-stress limitations to laser fire polishing of glasses," Appl. Opt 22, 2933-2936 (1983).
[CrossRef] [PubMed]

Brusasco, R. M.

R. M. Brusasco, B. M. Penetrante, J. A. Butler, and L. W. Hrubesh, "Localized CO2 laser treatment for mitigation of damage growth in fused silica," presented at the Boulder Laser Damage Symposium XXXIII, Boulder, Colo, 1-3 October 2001.

Butler, J. A.

R. M. Brusasco, B. M. Penetrante, J. A. Butler, and L. W. Hrubesh, "Localized CO2 laser treatment for mitigation of damage growth in fused silica," presented at the Boulder Laser Damage Symposium XXXIII, Boulder, Colo, 1-3 October 2001.

Cebrian, J. A.

F. Vega, N. Lupon, J. A. Cebrian and F. Laguarta, "Laser application for optical glass polishing," Opt. Eng. 37, 272-279 (1998).
[CrossRef]

Garcia-Beltran, A.

J. L. Ocaña, A. Garcia-Beltran, F. Laguarta, J. Armengol, N. Lupon, and F. Vega, "Laser heat treatments driven by integrated beams: role of irradiation nonuniformities," Appl. Opt 38, 4570-4576 (1999).
[CrossRef]

Hall, D. R.

G. A. J. Markillie, H. J. Baker, F. J. Villarreal, and D. R. Hall, "Effect of vaporization and melt ejection on laser machining of silica glass micro-optical components," Appl. Opt 41, 5660-5667 (2002).
[CrossRef] [PubMed]

J. F. Monjardin, K. M. Nowak, A. R. Holdsworth, H. J. Baker, and D. R. Hall, "Brightness improvement for micro-lensed, laser diode bar stacks," presented at Advanced Solid-State Photonics Topical Meeting, San Antonio, Tex., 2-5 February 2003.

E. Mendez, H. J. Baker, K. M. Nowak, F. Villarreal, and D. R. Hall, "Highly localized CO2 laser cleaning and damage repair of silica optical surfaces," presented at the Boulder Laser Damage Symposium XXXVI, Boulder, Colo, 20-22 September 2004.

Hentze, J.

J. Hentze and V. Lissotschenko, "Method and device for the production of optical lenses or the like," U.S. patent 5,504,302 (2 April 1996).

Holdsworth, A. R.

J. F. Monjardin, K. M. Nowak, A. R. Holdsworth, H. J. Baker, and D. R. Hall, "Brightness improvement for micro-lensed, laser diode bar stacks," presented at Advanced Solid-State Photonics Topical Meeting, San Antonio, Tex., 2-5 February 2003.

Holland, L.

L. Holland, The Properties of Glass Surfaces (Chapman & Hall, 1966).

Holloway, D. G.

D. G. Holloway, The Physical Properties of Glasses (Wykeham Publications, 1973), pp. 19-20.

Hrubesh, L. W.

R. M. Brusasco, B. M. Penetrante, J. A. Butler, and L. W. Hrubesh, "Localized CO2 laser treatment for mitigation of damage growth in fused silica," presented at the Boulder Laser Damage Symposium XXXIII, Boulder, Colo, 1-3 October 2001.

Kurylo, W. A.

L. K. White, N. A. Miszkowski, W. A. Kurylo, and J. M. Shaw, "Flow properties and contour modeling of fusible borophosphosilicate glasses," J. Electrochem. Soc. , 139, 822-826 (1992).
[CrossRef]

Laguarta, F.

J. L. Ocaña, A. Garcia-Beltran, F. Laguarta, J. Armengol, N. Lupon, and F. Vega, "Laser heat treatments driven by integrated beams: role of irradiation nonuniformities," Appl. Opt 38, 4570-4576 (1999).
[CrossRef]

F. Vega, N. Lupon, J. A. Cebrian and F. Laguarta, "Laser application for optical glass polishing," Opt. Eng. 37, 272-279 (1998).
[CrossRef]

F. Laguarta, N. Lupon, and J. Armengol, "Optical-glass polishing by controlled laser surface-heat treatment," Appl. Opt. 33, 6508-6513 (1994).
[CrossRef] [PubMed]

Lissotschenko, V.

J. Hentze and V. Lissotschenko, "Method and device for the production of optical lenses or the like," U.S. patent 5,504,302 (2 April 1996).

Lowdermilk, W. H.

Lupon, N.

J. L. Ocaña, A. Garcia-Beltran, F. Laguarta, J. Armengol, N. Lupon, and F. Vega, "Laser heat treatments driven by integrated beams: role of irradiation nonuniformities," Appl. Opt 38, 4570-4576 (1999).
[CrossRef]

F. Vega, N. Lupon, J. A. Cebrian and F. Laguarta, "Laser application for optical glass polishing," Opt. Eng. 37, 272-279 (1998).
[CrossRef]

F. Laguarta, N. Lupon, and J. Armengol, "Optical-glass polishing by controlled laser surface-heat treatment," Appl. Opt. 33, 6508-6513 (1994).
[CrossRef] [PubMed]

Markillie, G. A. J.

G. A. J. Markillie, H. J. Baker, F. J. Villarreal, and D. R. Hall, "Effect of vaporization and melt ejection on laser machining of silica glass micro-optical components," Appl. Opt 41, 5660-5667 (2002).
[CrossRef] [PubMed]

McLachlan, A. D.

Mendez, E.

E. Mendez, H. J. Baker, K. M. Nowak, F. Villarreal, and D. R. Hall, "Highly localized CO2 laser cleaning and damage repair of silica optical surfaces," presented at the Boulder Laser Damage Symposium XXXVI, Boulder, Colo, 20-22 September 2004.

Meyer, F. P.

Milam, D.

Miszkowski, N. A.

L. K. White, N. A. Miszkowski, W. A. Kurylo, and J. M. Shaw, "Flow properties and contour modeling of fusible borophosphosilicate glasses," J. Electrochem. Soc. , 139, 822-826 (1992).
[CrossRef]

Monjardin, J. F.

J. F. Monjardin, K. M. Nowak, A. R. Holdsworth, H. J. Baker, and D. R. Hall, "Brightness improvement for micro-lensed, laser diode bar stacks," presented at Advanced Solid-State Photonics Topical Meeting, San Antonio, Tex., 2-5 February 2003.

Nowak, K. M.

J. F. Monjardin, K. M. Nowak, A. R. Holdsworth, H. J. Baker, and D. R. Hall, "Brightness improvement for micro-lensed, laser diode bar stacks," presented at Advanced Solid-State Photonics Topical Meeting, San Antonio, Tex., 2-5 February 2003.

E. Mendez, H. J. Baker, K. M. Nowak, F. Villarreal, and D. R. Hall, "Highly localized CO2 laser cleaning and damage repair of silica optical surfaces," presented at the Boulder Laser Damage Symposium XXXVI, Boulder, Colo, 20-22 September 2004.

Ocaña, J. L.

J. L. Ocaña, A. Garcia-Beltran, F. Laguarta, J. Armengol, N. Lupon, and F. Vega, "Laser heat treatments driven by integrated beams: role of irradiation nonuniformities," Appl. Opt 38, 4570-4576 (1999).
[CrossRef]

Paul, A.

A. Paul, Chemistry of Glasses (Chapman & Hall, 1982), pp. 75, 88.
[CrossRef]

Penetrante, B. M.

R. M. Brusasco, B. M. Penetrante, J. A. Butler, and L. W. Hrubesh, "Localized CO2 laser treatment for mitigation of damage growth in fused silica," presented at the Boulder Laser Damage Symposium XXXIII, Boulder, Colo, 1-3 October 2001.

Shaw, J. M.

L. K. White, N. A. Miszkowski, W. A. Kurylo, and J. M. Shaw, "Flow properties and contour modeling of fusible borophosphosilicate glasses," J. Electrochem. Soc. , 139, 822-826 (1992).
[CrossRef]

Temple, P. A.

Vega, F.

J. L. Ocaña, A. Garcia-Beltran, F. Laguarta, J. Armengol, N. Lupon, and F. Vega, "Laser heat treatments driven by integrated beams: role of irradiation nonuniformities," Appl. Opt 38, 4570-4576 (1999).
[CrossRef]

F. Vega, N. Lupon, J. A. Cebrian and F. Laguarta, "Laser application for optical glass polishing," Opt. Eng. 37, 272-279 (1998).
[CrossRef]

Veiko, V. P.

V. P. Veiko, "Laser-based technology for micro-optics and photonics components fabrication," in International Symposium on Photonic Glass, C. Zhu, ed., Proc. SPIE 5061, 103-111 (2003).
[CrossRef]

Villarreal, F.

E. Mendez, H. J. Baker, K. M. Nowak, F. Villarreal, and D. R. Hall, "Highly localized CO2 laser cleaning and damage repair of silica optical surfaces," presented at the Boulder Laser Damage Symposium XXXVI, Boulder, Colo, 20-22 September 2004.

Villarreal, F. J.

G. A. J. Markillie, H. J. Baker, F. J. Villarreal, and D. R. Hall, "Effect of vaporization and melt ejection on laser machining of silica glass micro-optical components," Appl. Opt 41, 5660-5667 (2002).
[CrossRef] [PubMed]

White, L. K.

L. K. White, N. A. Miszkowski, W. A. Kurylo, and J. M. Shaw, "Flow properties and contour modeling of fusible borophosphosilicate glasses," J. Electrochem. Soc. , 139, 822-826 (1992).
[CrossRef]

Xiao, Y. M.

Y. M. Xiao and M. Bass, "Thermal-stress limitations to laser fire polishing of glasses," Appl. Opt 22, 2933-2936 (1983).
[CrossRef] [PubMed]

Appl. Opt (3)

Y. M. Xiao and M. Bass, "Thermal-stress limitations to laser fire polishing of glasses," Appl. Opt 22, 2933-2936 (1983).
[CrossRef] [PubMed]

J. L. Ocaña, A. Garcia-Beltran, F. Laguarta, J. Armengol, N. Lupon, and F. Vega, "Laser heat treatments driven by integrated beams: role of irradiation nonuniformities," Appl. Opt 38, 4570-4576 (1999).
[CrossRef]

G. A. J. Markillie, H. J. Baker, F. J. Villarreal, and D. R. Hall, "Effect of vaporization and melt ejection on laser machining of silica glass micro-optical components," Appl. Opt 41, 5660-5667 (2002).
[CrossRef] [PubMed]

Appl. Opt. (3)

J. Electrochem. Soc. (1)

L. K. White, N. A. Miszkowski, W. A. Kurylo, and J. M. Shaw, "Flow properties and contour modeling of fusible borophosphosilicate glasses," J. Electrochem. Soc. , 139, 822-826 (1992).
[CrossRef]

Opt. Eng. (1)

F. Vega, N. Lupon, J. A. Cebrian and F. Laguarta, "Laser application for optical glass polishing," Opt. Eng. 37, 272-279 (1998).
[CrossRef]

Proc. SPIE (1)

V. P. Veiko, "Laser-based technology for micro-optics and photonics components fabrication," in International Symposium on Photonic Glass, C. Zhu, ed., Proc. SPIE 5061, 103-111 (2003).
[CrossRef]

Other (7)

D. G. Holloway, The Physical Properties of Glasses (Wykeham Publications, 1973), pp. 19-20.

J. Hentze and V. Lissotschenko, "Method and device for the production of optical lenses or the like," U.S. patent 5,504,302 (2 April 1996).

A. Paul, Chemistry of Glasses (Chapman & Hall, 1982), pp. 75, 88.
[CrossRef]

J. F. Monjardin, K. M. Nowak, A. R. Holdsworth, H. J. Baker, and D. R. Hall, "Brightness improvement for micro-lensed, laser diode bar stacks," presented at Advanced Solid-State Photonics Topical Meeting, San Antonio, Tex., 2-5 February 2003.

R. M. Brusasco, B. M. Penetrante, J. A. Butler, and L. W. Hrubesh, "Localized CO2 laser treatment for mitigation of damage growth in fused silica," presented at the Boulder Laser Damage Symposium XXXIII, Boulder, Colo, 1-3 October 2001.

E. Mendez, H. J. Baker, K. M. Nowak, F. Villarreal, and D. R. Hall, "Highly localized CO2 laser cleaning and damage repair of silica optical surfaces," presented at the Boulder Laser Damage Symposium XXXVI, Boulder, Colo, 20-22 September 2004.

L. Holland, The Properties of Glass Surfaces (Chapman & Hall, 1966).

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Figures (9)

Fig. 1
Fig. 1

Theoretical prediction of the frequency response of laser-activated polishing of fused silica at different durations of melt lifetime. Calculated using Eq. (1) with melt depth h = 50 μm, average viscosity η = 105 Pa s, and a representative value of surface tension γ = 300 mJ m−2. Temporal evolution of temperature distribution in the material is not taken into account.

Fig. 2
Fig. 2

Schematic diagram of the precision laser machining station used for polishing experiments.

Fig. 3
Fig. 3

Pulse burst used for millisecond laser polishing. The preheating pulse is followed by the pulse train. The energy of the pulse train was controlled by adjusting the duty factor.

Fig. 4
Fig. 4

Micrograph of a melt zone on an abraded surface of a silica slide created by a single pulse of polishing Protocol A. Digital readout in millimeters.

Fig. 5
Fig. 5

Micrograph of the test surface used for laser polishing experiments. The dimensions are 1 × 0.5 mm. Below, a typical profile of the test surface before laser polishing.

Fig. 6
Fig. 6

Frequency response of polishing Protocol A calculated using FFT from the test surface profiles measured with a DekTak profiler. Settings for Protocol A are listed in Table 1.

Fig. 7
Fig. 7

Frequency spectra calculated using FFT from the test surface profiles measured by DekTak polishing Protocols (a) C and (b) D.

Fig. 8
Fig. 8

Comparison of frequency responses of polishing Protocols B, C, and D. The settings are shown in Table 3. A curve described by Eq. (2) has been fitted to the data. Fitting parameters can be found in Table 2.

Fig. 9
Fig. 9

Photographs showing the transition from high scatter of raw machined surface (a) to lower scatter after (b) two and (c) four polishing treatments. Reference beam (d) shown for comparison.

Tables (5)

Tables Icon

Table 1 Characteristics of Polishing Protocol A

Tables Icon

Table 2 Fitting Parameters for Optimal Frequency Response Curves of Protocols A–D

Tables Icon

Table 3 Characteristics of Polishing Protocols B, C, and D

Tables Icon

Table 4 A100 versus Pulse Energy: Protocol D

Tables Icon

Table 5 A100 versus Accumulated Melt Lifetime

Equations (3)

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

A f = A i exp ( 4 π 2 γ η h 3 1 λ 4 t ) .
A ( ν ) = exp ( K ν M t a c c ) ,
A 100 = A i ( ν = 100 ) A f ( ν = 100 ) .

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