Abstract

Teflon polishing is compared with pitch polishing as a method for achieving supersmooth and flat optical surfaces. Because a Teflon lap wears slowly, it will retain its surface shape to produce extremely flat optical surfaces, λ/100, consistently and reliably for extended periods of time, of the order of days. To compare the two methods, we polished 50-mm-diameter samples of various optical materials, using colloidal suspensions in water on both pitch and Teflon laps under the same polishing conditions. Flatness was maintained to better than λ/10, and roughness less than 10 Å rms was measured on all samples by two Talystep surface-profiling instruments, one in the United States and one in Australia, with excellent agreement between measurements made by the two instruments. It was possible to obtain flat and smooth surfaces (<4-Å rms roughness) on all materials (except for F4, flint glass), but only certain combinations of material, abrasive, and lap could be used to give the correct polishing conditions and surface chemistry.

© 1992 Optical Society of America

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References

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  1. A. J. Leistner, “Teflon polishers: their manufacture and use,” Appl. Opt. 15, 293–298 (1976).
  2. J. V. Ramsay, H. Kobler, E. G. V. Mugridge, “A new tunable filter with a very narrow pass-band,” Sol. Phys. 12, 492–501 (1970).
    [CrossRef]
  3. A. Lindquist, S. D. Jacobs, B. Plotsker, “Chemo-mechanical polishing of phosphate glass as a pretreatment to rapid final polishing,” in Optical Fabrication and Testing, Vol. 13 of OSA 1988 Technical Digest Series (Optical Society of America, Washington, D.C., 1988), paper WC5, pp. WC5-1–WC5-4.
  4. The FEP 856-200 and 856-301 lines of Teflon products can be obtained from the Polymer Products Department, E. I. du Pont de Nemours, 1007 Market Street, Brandywine 4213, Wilmington, Del. 19898.
  5. P. Hariharan, “Improved oblique-incidence interferometer,” Opt. Eng. 14, 257–258 (1975).
    [CrossRef]
  6. The abrasives used in this study and their suppliers are as follows: cerium oxide in the form of Liquid 85 and Vitrox R were obtained from Universal Photonics, 495 West John Street, Hicksville, N.Y. 11801; cerium oxide in the form of Microgrit was obtained from Micro Abrasives Corporation, 720 Southampton Road, P.O. Box 669, Westfield, Mass. 01086; aluminum oxide in the form of Ultra-Sol 200A and Special Ultra-Sol (not a commercial product but can be specially ordered) were obtained from Solution Technology, Inc., P.O. Box 2508, Matthews, N.C. 28106; colloidal silica in the form of Nalcoag 2350 was obtained from Rodel Products Company, 9495 East San Salvador Drive, Scotsdale, Ariz. 85258; colloidal silica in the form of Syton can be obtained from many different suppliers world wide; titanium dioxide in the form of Anatase E was obtained many years ago in Australia, but it is no longer made there.
  7. W. H. Lowdermilk, D. Milam, “Laser-induced surface and coating damage,” IEEE J. Quantum Electron. QE-17, 1888–1903 (1981).
    [CrossRef]
  8. The energy dispersing spectrometer was a Link 860 Model 5172, manufactured by Link Systems, Ltd., Halifax Road, High Wycombe, Buckinghamshire HP12 3SE, England.
  9. W. L. Silvernail, N. J. Goetzinger, “The mechanics of glass polishing,” in Secondary Manufacturing in the Glass Industry, G. Alexis Pincus, S. H. Chang, eds. (Ashlee, New York, 1978), Chap. 6, pp. 22–28.
  10. Manufactured by Wyko Corporation, 2650 E. Elvira Road, Tucson, Ariz. 85706.
  11. Talystep Step Height Measuring Instrument, manufactured by Rank Taylor Hobson, Ltd., P.O. Box 36, Leicester LE4 7JQ, England; U. S. supplier Rank Taylor Hobson, 411 East Jarvis Avenue, Des Plaines, Ill. 60018.
  12. One reviewer suggested that it would have been of interest to scan the surfaces in three dimensions by using an optical profiler to show the surface finish over a macroscopic region. This was not done for two reasons. First, the surfaces appeared isotropic when profiles of 1 to 2 mm were taken for different sample orientations on the China Lake Talystep; no additional structure other than the usual longer surface spatial wavelength waviness was seen. Second, optical profilers do not have as good lateral resolution as mechanical profilers when the latter are used with a sharp stylus and light loading. Therefore more fine structure could be seen in the profiles made with the mechanical profiler. The intent of the study was to look at the surface microstructure by using the profilers and to measure the overall figure (flatness) with the CSIRO interferometer.
  13. J. M. Bennett, J. H. Dancy, “Stylus profiling instrument for measuring statistical properties of smooth optical surfaces,” Appl. Opt. 20, 1785–1802 (1981).
    [CrossRef] [PubMed]
  14. Sold by Rank Taylor Hobson; see Ref. 11.
  15. Sold by Edge Technologies, Inc., 4455 West 62nd St., Indianapolis, Ind. 46268.
  16. See the discussion of stylus resolution in the tutorial by J. M. Bennett, L. Mattsson, Introduction to Surface Roughness and Scattering (Optical Society of America, Washington, D.C., 1989), pp. 21–22.
  17. Ref. 16, pp. 44–47.

1981 (2)

W. H. Lowdermilk, D. Milam, “Laser-induced surface and coating damage,” IEEE J. Quantum Electron. QE-17, 1888–1903 (1981).
[CrossRef]

J. M. Bennett, J. H. Dancy, “Stylus profiling instrument for measuring statistical properties of smooth optical surfaces,” Appl. Opt. 20, 1785–1802 (1981).
[CrossRef] [PubMed]

1976 (1)

1975 (1)

P. Hariharan, “Improved oblique-incidence interferometer,” Opt. Eng. 14, 257–258 (1975).
[CrossRef]

1970 (1)

J. V. Ramsay, H. Kobler, E. G. V. Mugridge, “A new tunable filter with a very narrow pass-band,” Sol. Phys. 12, 492–501 (1970).
[CrossRef]

Bennett, J. M.

J. M. Bennett, J. H. Dancy, “Stylus profiling instrument for measuring statistical properties of smooth optical surfaces,” Appl. Opt. 20, 1785–1802 (1981).
[CrossRef] [PubMed]

See the discussion of stylus resolution in the tutorial by J. M. Bennett, L. Mattsson, Introduction to Surface Roughness and Scattering (Optical Society of America, Washington, D.C., 1989), pp. 21–22.

Dancy, J. H.

Goetzinger, N. J.

W. L. Silvernail, N. J. Goetzinger, “The mechanics of glass polishing,” in Secondary Manufacturing in the Glass Industry, G. Alexis Pincus, S. H. Chang, eds. (Ashlee, New York, 1978), Chap. 6, pp. 22–28.

Hariharan, P.

P. Hariharan, “Improved oblique-incidence interferometer,” Opt. Eng. 14, 257–258 (1975).
[CrossRef]

Jacobs, S. D.

A. Lindquist, S. D. Jacobs, B. Plotsker, “Chemo-mechanical polishing of phosphate glass as a pretreatment to rapid final polishing,” in Optical Fabrication and Testing, Vol. 13 of OSA 1988 Technical Digest Series (Optical Society of America, Washington, D.C., 1988), paper WC5, pp. WC5-1–WC5-4.

Kobler, H.

J. V. Ramsay, H. Kobler, E. G. V. Mugridge, “A new tunable filter with a very narrow pass-band,” Sol. Phys. 12, 492–501 (1970).
[CrossRef]

Leistner, A. J.

Lindquist, A.

A. Lindquist, S. D. Jacobs, B. Plotsker, “Chemo-mechanical polishing of phosphate glass as a pretreatment to rapid final polishing,” in Optical Fabrication and Testing, Vol. 13 of OSA 1988 Technical Digest Series (Optical Society of America, Washington, D.C., 1988), paper WC5, pp. WC5-1–WC5-4.

Lowdermilk, W. H.

W. H. Lowdermilk, D. Milam, “Laser-induced surface and coating damage,” IEEE J. Quantum Electron. QE-17, 1888–1903 (1981).
[CrossRef]

Mattsson, L.

See the discussion of stylus resolution in the tutorial by J. M. Bennett, L. Mattsson, Introduction to Surface Roughness and Scattering (Optical Society of America, Washington, D.C., 1989), pp. 21–22.

Milam, D.

W. H. Lowdermilk, D. Milam, “Laser-induced surface and coating damage,” IEEE J. Quantum Electron. QE-17, 1888–1903 (1981).
[CrossRef]

Mugridge, E. G. V.

J. V. Ramsay, H. Kobler, E. G. V. Mugridge, “A new tunable filter with a very narrow pass-band,” Sol. Phys. 12, 492–501 (1970).
[CrossRef]

Plotsker, B.

A. Lindquist, S. D. Jacobs, B. Plotsker, “Chemo-mechanical polishing of phosphate glass as a pretreatment to rapid final polishing,” in Optical Fabrication and Testing, Vol. 13 of OSA 1988 Technical Digest Series (Optical Society of America, Washington, D.C., 1988), paper WC5, pp. WC5-1–WC5-4.

Ramsay, J. V.

J. V. Ramsay, H. Kobler, E. G. V. Mugridge, “A new tunable filter with a very narrow pass-band,” Sol. Phys. 12, 492–501 (1970).
[CrossRef]

Silvernail, W. L.

W. L. Silvernail, N. J. Goetzinger, “The mechanics of glass polishing,” in Secondary Manufacturing in the Glass Industry, G. Alexis Pincus, S. H. Chang, eds. (Ashlee, New York, 1978), Chap. 6, pp. 22–28.

Appl. Opt. (2)

IEEE J. Quantum Electron. (1)

W. H. Lowdermilk, D. Milam, “Laser-induced surface and coating damage,” IEEE J. Quantum Electron. QE-17, 1888–1903 (1981).
[CrossRef]

Opt. Eng. (1)

P. Hariharan, “Improved oblique-incidence interferometer,” Opt. Eng. 14, 257–258 (1975).
[CrossRef]

Sol. Phys. (1)

J. V. Ramsay, H. Kobler, E. G. V. Mugridge, “A new tunable filter with a very narrow pass-band,” Sol. Phys. 12, 492–501 (1970).
[CrossRef]

Other (12)

A. Lindquist, S. D. Jacobs, B. Plotsker, “Chemo-mechanical polishing of phosphate glass as a pretreatment to rapid final polishing,” in Optical Fabrication and Testing, Vol. 13 of OSA 1988 Technical Digest Series (Optical Society of America, Washington, D.C., 1988), paper WC5, pp. WC5-1–WC5-4.

The FEP 856-200 and 856-301 lines of Teflon products can be obtained from the Polymer Products Department, E. I. du Pont de Nemours, 1007 Market Street, Brandywine 4213, Wilmington, Del. 19898.

The energy dispersing spectrometer was a Link 860 Model 5172, manufactured by Link Systems, Ltd., Halifax Road, High Wycombe, Buckinghamshire HP12 3SE, England.

W. L. Silvernail, N. J. Goetzinger, “The mechanics of glass polishing,” in Secondary Manufacturing in the Glass Industry, G. Alexis Pincus, S. H. Chang, eds. (Ashlee, New York, 1978), Chap. 6, pp. 22–28.

Manufactured by Wyko Corporation, 2650 E. Elvira Road, Tucson, Ariz. 85706.

Talystep Step Height Measuring Instrument, manufactured by Rank Taylor Hobson, Ltd., P.O. Box 36, Leicester LE4 7JQ, England; U. S. supplier Rank Taylor Hobson, 411 East Jarvis Avenue, Des Plaines, Ill. 60018.

One reviewer suggested that it would have been of interest to scan the surfaces in three dimensions by using an optical profiler to show the surface finish over a macroscopic region. This was not done for two reasons. First, the surfaces appeared isotropic when profiles of 1 to 2 mm were taken for different sample orientations on the China Lake Talystep; no additional structure other than the usual longer surface spatial wavelength waviness was seen. Second, optical profilers do not have as good lateral resolution as mechanical profilers when the latter are used with a sharp stylus and light loading. Therefore more fine structure could be seen in the profiles made with the mechanical profiler. The intent of the study was to look at the surface microstructure by using the profilers and to measure the overall figure (flatness) with the CSIRO interferometer.

The abrasives used in this study and their suppliers are as follows: cerium oxide in the form of Liquid 85 and Vitrox R were obtained from Universal Photonics, 495 West John Street, Hicksville, N.Y. 11801; cerium oxide in the form of Microgrit was obtained from Micro Abrasives Corporation, 720 Southampton Road, P.O. Box 669, Westfield, Mass. 01086; aluminum oxide in the form of Ultra-Sol 200A and Special Ultra-Sol (not a commercial product but can be specially ordered) were obtained from Solution Technology, Inc., P.O. Box 2508, Matthews, N.C. 28106; colloidal silica in the form of Nalcoag 2350 was obtained from Rodel Products Company, 9495 East San Salvador Drive, Scotsdale, Ariz. 85258; colloidal silica in the form of Syton can be obtained from many different suppliers world wide; titanium dioxide in the form of Anatase E was obtained many years ago in Australia, but it is no longer made there.

Sold by Rank Taylor Hobson; see Ref. 11.

Sold by Edge Technologies, Inc., 4455 West 62nd St., Indianapolis, Ind. 46268.

See the discussion of stylus resolution in the tutorial by J. M. Bennett, L. Mattsson, Introduction to Surface Roughness and Scattering (Optical Society of America, Washington, D.C., 1989), pp. 21–22.

Ref. 16, pp. 44–47.

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Figures (16)

Fig. 1
Fig. 1

Interference fringes formed between the surface of a Teflon polisher and a test flat under white light.

Fig. 2
Fig. 2

Optical diagram of the oblique incidence interferometer using reflecting diffraction gratings (from Ref. 5).

Fig. 3
Fig. 3

Photograph of the pitch lap showing the Pyrex conditioning flat.

Fig. 4
Fig. 4

Photograph of the sample holder on a Teflon lap. The polishing fluid and the weight placed on the sample are not shown.

Fig. 5
Fig. 5

Profile of the buildup of material on a surface polished with a cerium oxide abrasive.

Fig. 6
Fig. 6

Surface profile (200 μm long) of F4 flint glass polished with aluminum oxide (Ultra-Sol) on a pitch lap.

Fig. 7
Fig. 7

Surface profile (200 μm long) of F4 flint glass polished with aluminum oxide (Ultra-Sol 200 A) on a Teflon lap.

Fig. 8
Fig. 8

Surface profile (200 μm long) of BK-7 optical glass polished with aluminum oxide (Special Ultra-Sol) on a Teflon lap.

Fig. 9
Fig. 9

Surface profile (200 μm long) of BK-7 optical glass polished with aluminum oxide (Ultra-Sol 200A) on a pitch lap.

Fig. 10
Fig. 10

Surface profile (100 μm long) of BK-7 optical glass polished with cerium oxide (Vitrox R) on a pitch lap.

Fig. 11
Fig. 11

Surface profile (1000 μm long) of Zerodur M polished with aluminum oxide (Special Ultra-Sol) on a Teflon lap.

Fig. 12
Fig. 12

Surface profile (1000 μm long) of Zerodur M polished with cerium oxide (Microgrit) on a Teflon lap.

Fig. 13
Fig. 13

Autocovariance function for BK-7 optical glass polished with aluminum oxide (Special Ultra-Sol) on a Teflon lap. The surface profile is shown in Fig. 8.

Fig. 14
Fig. 14

Autocovariance function for BK-7 optical glass polished with aluminum oxide (Ultra-Sol 200A) on a pitch lap. The surface profile is shown in Fig. 9.

Fig. 15
Fig. 15

Histograms showing roughnesses of optical glasses and fused silica polished on Teflon and pitch laps with the abrasives shown. The Zerodur M sample, labeled T*, was polished with cerium oxide in the form of Liquid 85.

Fig. 16
Fig. 16

Histograms showing roughnesses of crystal quartz, magnesium fluoride, calcium fluoride, lithium niobate, and silicon polished on a Teflon lap with the abrasives shown.

Tables (5)

Tables Icon

Table I Materials, Laps, and Abrasives Used in the Polishing Studya

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Table II Initial pH of the Polishing Agents Used in the Studya

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Table III Hardness of the Substrate Materials Used in the Polishing Study

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Table IV Comparison of Instrument Parameters for the China Lake and CSIRO Talystep Profilers

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Table V Roughnesses (in angstroms) for a Profile Length of 200 μm Measured in the Polishing Study

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