Abstract

We demonstrate the fabrication of binary, multilevel, and blazed diffractive structures by a fast and flexible direct-write process by using an excimer-laser-based tabletop micromachining workstation with an integrated optical surface profiler.

© 1997 Optical Society of America

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References

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  1. M. W. Farn, W. B. Veldkamp, “Binary optics: trends and limitations,” in Conference on Binary Optics, H. J. Cole, W. C. Pittman, eds., (NASA, Greenbelt, Md., 1993), pp. 19–29.
  2. A. Nelson, L. Domash, “Low cost paths to binary optics,” in Conference on Binary Optics, H. J. Cole, W. C. Pittman, eds., (NASA, Greenbelt, Md., 1993), pp. 283–302.
  3. T. J. Suleski, D. C. O’Shea, “Fidelity of postscript-generated masks for diffractive optics fabrication,” Appl. Opt. 34, 627–635 (1995).
    [CrossRef] [PubMed]
  4. M. T. Gale, M. Rossi, J. Pederson, H. Schutz, “Fabrication of continuous-relief micro-optical elements by direct laser writing in photoresists,” Opt. Eng. 33, 3556–3566 (1994).
    [CrossRef]
  5. W. Daschner, R. Stein, P. Long, S. H. Lee, “One-step lithography for mass production of multilevel diffractive optical elements using high energy beam sensitive gray-level mask,” in Diffractive Optics and Micro-Optics, Vol. 9 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 322–324.
  6. X. Wang, R. H. Rediker, J. R. Leger, “Rapid fabrication of diffractive microlenses using excimer laser ablation,” in Diffactive Optics and Micro-Optics, Vol. 9 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 310–313.
  7. F. von Alvensleben, M. Gonschior, H. Kappel, P. Heekenjann, “Lasers for micromachining,” Opt. Photonics News 6(8), 23–27 (1995).
    [CrossRef]
  8. M. T. Duignan, “Micromachining of diffractive optics with excimer lasers,” in Diffractive Optics, Vol. 11 of 1994 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1994), pp. 129–132.
  9. M. T. Duignan, G. P. Behrmann, “Excimer laser micromachining for rapid fabrication of binary and blazed diffractive optical elements,” in Diffractive Optics and Micro-Optics, Vol. 9 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 314–317.
  10. P. J. Caber, “Interferometric profiler for rough surfaces,” Appl. Opt. 32, 3438–3441 (1993).
    [CrossRef] [PubMed]
  11. R. Srinivasan, B. Braren, “Ablative photodecomposition of polymers by UV laser radiation,” in Lasers in Polymer Science and Technology: Applications, Vol. III, J-P. Fouassier, J. F. Rabek, eds. (CRC, Boca Raton, Fla., 1990), pp. 133–179.
  12. Y. Nakayama, T. Matsuda, “Surface microarchitectural design in biomedical applications: preparation of microporous polymer surfaces by an excimer laser ablation technique,” J. Biomed. Mater. Res. 29, 1295–1301 (1995).
    [CrossRef] [PubMed]
  13. G. H. Pettit, M. N. Ediger, R. P. Weiblinger, “Excimer laser ablation of the cornea,” Opt. Eng. 34, 661–667 (1995).
    [CrossRef]
  14. A. B. Frazier, M. G. Allen, “Metallic microstructures fabricated using photosensitive poly(imide) electroplating molds,” J. Microelectromech. Syst. 2, 87–94 (1993).
    [CrossRef]
  15. G. J. Swanson, “Binary optics technology: the theory and design of multilevel diffractive optical elements,” (MIT, Cambridge, Mass., 1989).
  16. F. S. Roux, “Wavelength dependence of thin diffractive lenses,” Opt. Eng. 33, 2843–2848 (1994).
    [CrossRef]
  17. J. A. Cox, T. Werner, J. Lee, S. Nelson, B. Fritz, J. Bergstrom, “Diffraction efficiency of binary optical elements,” in Computer and Optically Formed Holographic Optics, I. Cindrich, S. H. Lee, eds., Proc. SPIE1211, 116–124 (1990).
    [CrossRef]
  18. G. Tricoles, “Computer generated holograms: an historical review,” Appl. Opt. 26, 4351–4360 (1987).
    [CrossRef] [PubMed]
  19. J. Ojeda-Castaneda, G. Ramiez, “Zone plates for zero axial irradiance,” Opt. Lett. 18, 87–89 (1993).
    [CrossRef] [PubMed]
  20. E. Pawlowski, B. Kuhlow, “Antireflection-coated diffractive optical elements fabricated by thin-film deposition,” Opt. Eng. 33, 3537–3546 (1994).
    [CrossRef]
  21. E. C. Harvey, P. T. Rumsby, M. C. Gower, J. L. Remnant, “Microstructuring by excimer lasers,” in Micromachining and Microfabrication Process Technology, K. W. Markus, ed., Proc. SPIE2639, 266–277 (1995).

1995 (4)

T. J. Suleski, D. C. O’Shea, “Fidelity of postscript-generated masks for diffractive optics fabrication,” Appl. Opt. 34, 627–635 (1995).
[CrossRef] [PubMed]

F. von Alvensleben, M. Gonschior, H. Kappel, P. Heekenjann, “Lasers for micromachining,” Opt. Photonics News 6(8), 23–27 (1995).
[CrossRef]

Y. Nakayama, T. Matsuda, “Surface microarchitectural design in biomedical applications: preparation of microporous polymer surfaces by an excimer laser ablation technique,” J. Biomed. Mater. Res. 29, 1295–1301 (1995).
[CrossRef] [PubMed]

G. H. Pettit, M. N. Ediger, R. P. Weiblinger, “Excimer laser ablation of the cornea,” Opt. Eng. 34, 661–667 (1995).
[CrossRef]

1994 (3)

F. S. Roux, “Wavelength dependence of thin diffractive lenses,” Opt. Eng. 33, 2843–2848 (1994).
[CrossRef]

M. T. Gale, M. Rossi, J. Pederson, H. Schutz, “Fabrication of continuous-relief micro-optical elements by direct laser writing in photoresists,” Opt. Eng. 33, 3556–3566 (1994).
[CrossRef]

E. Pawlowski, B. Kuhlow, “Antireflection-coated diffractive optical elements fabricated by thin-film deposition,” Opt. Eng. 33, 3537–3546 (1994).
[CrossRef]

1993 (3)

J. Ojeda-Castaneda, G. Ramiez, “Zone plates for zero axial irradiance,” Opt. Lett. 18, 87–89 (1993).
[CrossRef] [PubMed]

P. J. Caber, “Interferometric profiler for rough surfaces,” Appl. Opt. 32, 3438–3441 (1993).
[CrossRef] [PubMed]

A. B. Frazier, M. G. Allen, “Metallic microstructures fabricated using photosensitive poly(imide) electroplating molds,” J. Microelectromech. Syst. 2, 87–94 (1993).
[CrossRef]

1987 (1)

Allen, M. G.

A. B. Frazier, M. G. Allen, “Metallic microstructures fabricated using photosensitive poly(imide) electroplating molds,” J. Microelectromech. Syst. 2, 87–94 (1993).
[CrossRef]

Behrmann, G. P.

M. T. Duignan, G. P. Behrmann, “Excimer laser micromachining for rapid fabrication of binary and blazed diffractive optical elements,” in Diffractive Optics and Micro-Optics, Vol. 9 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 314–317.

Bergstrom, J.

J. A. Cox, T. Werner, J. Lee, S. Nelson, B. Fritz, J. Bergstrom, “Diffraction efficiency of binary optical elements,” in Computer and Optically Formed Holographic Optics, I. Cindrich, S. H. Lee, eds., Proc. SPIE1211, 116–124 (1990).
[CrossRef]

Braren, B.

R. Srinivasan, B. Braren, “Ablative photodecomposition of polymers by UV laser radiation,” in Lasers in Polymer Science and Technology: Applications, Vol. III, J-P. Fouassier, J. F. Rabek, eds. (CRC, Boca Raton, Fla., 1990), pp. 133–179.

Caber, P. J.

Cox, J. A.

J. A. Cox, T. Werner, J. Lee, S. Nelson, B. Fritz, J. Bergstrom, “Diffraction efficiency of binary optical elements,” in Computer and Optically Formed Holographic Optics, I. Cindrich, S. H. Lee, eds., Proc. SPIE1211, 116–124 (1990).
[CrossRef]

Daschner, W.

W. Daschner, R. Stein, P. Long, S. H. Lee, “One-step lithography for mass production of multilevel diffractive optical elements using high energy beam sensitive gray-level mask,” in Diffractive Optics and Micro-Optics, Vol. 9 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 322–324.

Domash, L.

A. Nelson, L. Domash, “Low cost paths to binary optics,” in Conference on Binary Optics, H. J. Cole, W. C. Pittman, eds., (NASA, Greenbelt, Md., 1993), pp. 283–302.

Duignan, M. T.

M. T. Duignan, “Micromachining of diffractive optics with excimer lasers,” in Diffractive Optics, Vol. 11 of 1994 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1994), pp. 129–132.

M. T. Duignan, G. P. Behrmann, “Excimer laser micromachining for rapid fabrication of binary and blazed diffractive optical elements,” in Diffractive Optics and Micro-Optics, Vol. 9 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 314–317.

Ediger, M. N.

G. H. Pettit, M. N. Ediger, R. P. Weiblinger, “Excimer laser ablation of the cornea,” Opt. Eng. 34, 661–667 (1995).
[CrossRef]

Farn, M. W.

M. W. Farn, W. B. Veldkamp, “Binary optics: trends and limitations,” in Conference on Binary Optics, H. J. Cole, W. C. Pittman, eds., (NASA, Greenbelt, Md., 1993), pp. 19–29.

Frazier, A. B.

A. B. Frazier, M. G. Allen, “Metallic microstructures fabricated using photosensitive poly(imide) electroplating molds,” J. Microelectromech. Syst. 2, 87–94 (1993).
[CrossRef]

Fritz, B.

J. A. Cox, T. Werner, J. Lee, S. Nelson, B. Fritz, J. Bergstrom, “Diffraction efficiency of binary optical elements,” in Computer and Optically Formed Holographic Optics, I. Cindrich, S. H. Lee, eds., Proc. SPIE1211, 116–124 (1990).
[CrossRef]

Gale, M. T.

M. T. Gale, M. Rossi, J. Pederson, H. Schutz, “Fabrication of continuous-relief micro-optical elements by direct laser writing in photoresists,” Opt. Eng. 33, 3556–3566 (1994).
[CrossRef]

Gonschior, M.

F. von Alvensleben, M. Gonschior, H. Kappel, P. Heekenjann, “Lasers for micromachining,” Opt. Photonics News 6(8), 23–27 (1995).
[CrossRef]

Gower, M. C.

E. C. Harvey, P. T. Rumsby, M. C. Gower, J. L. Remnant, “Microstructuring by excimer lasers,” in Micromachining and Microfabrication Process Technology, K. W. Markus, ed., Proc. SPIE2639, 266–277 (1995).

Harvey, E. C.

E. C. Harvey, P. T. Rumsby, M. C. Gower, J. L. Remnant, “Microstructuring by excimer lasers,” in Micromachining and Microfabrication Process Technology, K. W. Markus, ed., Proc. SPIE2639, 266–277 (1995).

Heekenjann, P.

F. von Alvensleben, M. Gonschior, H. Kappel, P. Heekenjann, “Lasers for micromachining,” Opt. Photonics News 6(8), 23–27 (1995).
[CrossRef]

Kappel, H.

F. von Alvensleben, M. Gonschior, H. Kappel, P. Heekenjann, “Lasers for micromachining,” Opt. Photonics News 6(8), 23–27 (1995).
[CrossRef]

Kuhlow, B.

E. Pawlowski, B. Kuhlow, “Antireflection-coated diffractive optical elements fabricated by thin-film deposition,” Opt. Eng. 33, 3537–3546 (1994).
[CrossRef]

Lee, J.

J. A. Cox, T. Werner, J. Lee, S. Nelson, B. Fritz, J. Bergstrom, “Diffraction efficiency of binary optical elements,” in Computer and Optically Formed Holographic Optics, I. Cindrich, S. H. Lee, eds., Proc. SPIE1211, 116–124 (1990).
[CrossRef]

Lee, S. H.

W. Daschner, R. Stein, P. Long, S. H. Lee, “One-step lithography for mass production of multilevel diffractive optical elements using high energy beam sensitive gray-level mask,” in Diffractive Optics and Micro-Optics, Vol. 9 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 322–324.

Leger, J. R.

X. Wang, R. H. Rediker, J. R. Leger, “Rapid fabrication of diffractive microlenses using excimer laser ablation,” in Diffactive Optics and Micro-Optics, Vol. 9 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 310–313.

Long, P.

W. Daschner, R. Stein, P. Long, S. H. Lee, “One-step lithography for mass production of multilevel diffractive optical elements using high energy beam sensitive gray-level mask,” in Diffractive Optics and Micro-Optics, Vol. 9 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 322–324.

Matsuda, T.

Y. Nakayama, T. Matsuda, “Surface microarchitectural design in biomedical applications: preparation of microporous polymer surfaces by an excimer laser ablation technique,” J. Biomed. Mater. Res. 29, 1295–1301 (1995).
[CrossRef] [PubMed]

Nakayama, Y.

Y. Nakayama, T. Matsuda, “Surface microarchitectural design in biomedical applications: preparation of microporous polymer surfaces by an excimer laser ablation technique,” J. Biomed. Mater. Res. 29, 1295–1301 (1995).
[CrossRef] [PubMed]

Nelson, A.

A. Nelson, L. Domash, “Low cost paths to binary optics,” in Conference on Binary Optics, H. J. Cole, W. C. Pittman, eds., (NASA, Greenbelt, Md., 1993), pp. 283–302.

Nelson, S.

J. A. Cox, T. Werner, J. Lee, S. Nelson, B. Fritz, J. Bergstrom, “Diffraction efficiency of binary optical elements,” in Computer and Optically Formed Holographic Optics, I. Cindrich, S. H. Lee, eds., Proc. SPIE1211, 116–124 (1990).
[CrossRef]

O’Shea, D. C.

Ojeda-Castaneda, J.

Pawlowski, E.

E. Pawlowski, B. Kuhlow, “Antireflection-coated diffractive optical elements fabricated by thin-film deposition,” Opt. Eng. 33, 3537–3546 (1994).
[CrossRef]

Pederson, J.

M. T. Gale, M. Rossi, J. Pederson, H. Schutz, “Fabrication of continuous-relief micro-optical elements by direct laser writing in photoresists,” Opt. Eng. 33, 3556–3566 (1994).
[CrossRef]

Pettit, G. H.

G. H. Pettit, M. N. Ediger, R. P. Weiblinger, “Excimer laser ablation of the cornea,” Opt. Eng. 34, 661–667 (1995).
[CrossRef]

Ramiez, G.

Rediker, R. H.

X. Wang, R. H. Rediker, J. R. Leger, “Rapid fabrication of diffractive microlenses using excimer laser ablation,” in Diffactive Optics and Micro-Optics, Vol. 9 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 310–313.

Remnant, J. L.

E. C. Harvey, P. T. Rumsby, M. C. Gower, J. L. Remnant, “Microstructuring by excimer lasers,” in Micromachining and Microfabrication Process Technology, K. W. Markus, ed., Proc. SPIE2639, 266–277 (1995).

Rossi, M.

M. T. Gale, M. Rossi, J. Pederson, H. Schutz, “Fabrication of continuous-relief micro-optical elements by direct laser writing in photoresists,” Opt. Eng. 33, 3556–3566 (1994).
[CrossRef]

Roux, F. S.

F. S. Roux, “Wavelength dependence of thin diffractive lenses,” Opt. Eng. 33, 2843–2848 (1994).
[CrossRef]

Rumsby, P. T.

E. C. Harvey, P. T. Rumsby, M. C. Gower, J. L. Remnant, “Microstructuring by excimer lasers,” in Micromachining and Microfabrication Process Technology, K. W. Markus, ed., Proc. SPIE2639, 266–277 (1995).

Schutz, H.

M. T. Gale, M. Rossi, J. Pederson, H. Schutz, “Fabrication of continuous-relief micro-optical elements by direct laser writing in photoresists,” Opt. Eng. 33, 3556–3566 (1994).
[CrossRef]

Srinivasan, R.

R. Srinivasan, B. Braren, “Ablative photodecomposition of polymers by UV laser radiation,” in Lasers in Polymer Science and Technology: Applications, Vol. III, J-P. Fouassier, J. F. Rabek, eds. (CRC, Boca Raton, Fla., 1990), pp. 133–179.

Stein, R.

W. Daschner, R. Stein, P. Long, S. H. Lee, “One-step lithography for mass production of multilevel diffractive optical elements using high energy beam sensitive gray-level mask,” in Diffractive Optics and Micro-Optics, Vol. 9 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 322–324.

Suleski, T. J.

Swanson, G. J.

G. J. Swanson, “Binary optics technology: the theory and design of multilevel diffractive optical elements,” (MIT, Cambridge, Mass., 1989).

Tricoles, G.

Veldkamp, W. B.

M. W. Farn, W. B. Veldkamp, “Binary optics: trends and limitations,” in Conference on Binary Optics, H. J. Cole, W. C. Pittman, eds., (NASA, Greenbelt, Md., 1993), pp. 19–29.

von Alvensleben, F.

F. von Alvensleben, M. Gonschior, H. Kappel, P. Heekenjann, “Lasers for micromachining,” Opt. Photonics News 6(8), 23–27 (1995).
[CrossRef]

Wang, X.

X. Wang, R. H. Rediker, J. R. Leger, “Rapid fabrication of diffractive microlenses using excimer laser ablation,” in Diffactive Optics and Micro-Optics, Vol. 9 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 310–313.

Weiblinger, R. P.

G. H. Pettit, M. N. Ediger, R. P. Weiblinger, “Excimer laser ablation of the cornea,” Opt. Eng. 34, 661–667 (1995).
[CrossRef]

Werner, T.

J. A. Cox, T. Werner, J. Lee, S. Nelson, B. Fritz, J. Bergstrom, “Diffraction efficiency of binary optical elements,” in Computer and Optically Formed Holographic Optics, I. Cindrich, S. H. Lee, eds., Proc. SPIE1211, 116–124 (1990).
[CrossRef]

Appl. Opt. (3)

J. Biomed. Mater. Res. (1)

Y. Nakayama, T. Matsuda, “Surface microarchitectural design in biomedical applications: preparation of microporous polymer surfaces by an excimer laser ablation technique,” J. Biomed. Mater. Res. 29, 1295–1301 (1995).
[CrossRef] [PubMed]

J. Microelectromech. Syst. (1)

A. B. Frazier, M. G. Allen, “Metallic microstructures fabricated using photosensitive poly(imide) electroplating molds,” J. Microelectromech. Syst. 2, 87–94 (1993).
[CrossRef]

Opt. Eng. (4)

F. S. Roux, “Wavelength dependence of thin diffractive lenses,” Opt. Eng. 33, 2843–2848 (1994).
[CrossRef]

G. H. Pettit, M. N. Ediger, R. P. Weiblinger, “Excimer laser ablation of the cornea,” Opt. Eng. 34, 661–667 (1995).
[CrossRef]

M. T. Gale, M. Rossi, J. Pederson, H. Schutz, “Fabrication of continuous-relief micro-optical elements by direct laser writing in photoresists,” Opt. Eng. 33, 3556–3566 (1994).
[CrossRef]

E. Pawlowski, B. Kuhlow, “Antireflection-coated diffractive optical elements fabricated by thin-film deposition,” Opt. Eng. 33, 3537–3546 (1994).
[CrossRef]

Opt. Lett. (1)

Opt. Photonics News (1)

F. von Alvensleben, M. Gonschior, H. Kappel, P. Heekenjann, “Lasers for micromachining,” Opt. Photonics News 6(8), 23–27 (1995).
[CrossRef]

Other (10)

M. T. Duignan, “Micromachining of diffractive optics with excimer lasers,” in Diffractive Optics, Vol. 11 of 1994 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1994), pp. 129–132.

M. T. Duignan, G. P. Behrmann, “Excimer laser micromachining for rapid fabrication of binary and blazed diffractive optical elements,” in Diffractive Optics and Micro-Optics, Vol. 9 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 314–317.

M. W. Farn, W. B. Veldkamp, “Binary optics: trends and limitations,” in Conference on Binary Optics, H. J. Cole, W. C. Pittman, eds., (NASA, Greenbelt, Md., 1993), pp. 19–29.

A. Nelson, L. Domash, “Low cost paths to binary optics,” in Conference on Binary Optics, H. J. Cole, W. C. Pittman, eds., (NASA, Greenbelt, Md., 1993), pp. 283–302.

W. Daschner, R. Stein, P. Long, S. H. Lee, “One-step lithography for mass production of multilevel diffractive optical elements using high energy beam sensitive gray-level mask,” in Diffractive Optics and Micro-Optics, Vol. 9 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 322–324.

X. Wang, R. H. Rediker, J. R. Leger, “Rapid fabrication of diffractive microlenses using excimer laser ablation,” in Diffactive Optics and Micro-Optics, Vol. 9 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 310–313.

R. Srinivasan, B. Braren, “Ablative photodecomposition of polymers by UV laser radiation,” in Lasers in Polymer Science and Technology: Applications, Vol. III, J-P. Fouassier, J. F. Rabek, eds. (CRC, Boca Raton, Fla., 1990), pp. 133–179.

J. A. Cox, T. Werner, J. Lee, S. Nelson, B. Fritz, J. Bergstrom, “Diffraction efficiency of binary optical elements,” in Computer and Optically Formed Holographic Optics, I. Cindrich, S. H. Lee, eds., Proc. SPIE1211, 116–124 (1990).
[CrossRef]

G. J. Swanson, “Binary optics technology: the theory and design of multilevel diffractive optical elements,” (MIT, Cambridge, Mass., 1989).

E. C. Harvey, P. T. Rumsby, M. C. Gower, J. L. Remnant, “Microstructuring by excimer lasers,” in Micromachining and Microfabrication Process Technology, K. W. Markus, ed., Proc. SPIE2639, 266–277 (1995).

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Figures (12)

Fig. 1
Fig. 1

Schematic of the UV laser micromachining workstation used for this work. Beam size and shape are selected under computer control from an array of apertures and imaged onto the workpiece. The UV objective (Obj) with the CCD camera allows through-the-lens real-time monitoring. The integrated optical surface profiler permits rapid characterization and refinement of the micromachining process. Diffractive elements can be designed and fabricated at a single workstation. L’s, lenses; BS, beam splitter.

Fig. 2
Fig. 2

Measured average ablation depth (in nanometers) versus total dose (in millijoules per centimeter squared) at 248 nm for DuPont Pyralin Poly(imide) PI-2801. Symbols correspond to an average fluence of individual pulses used to ablate depressions: (■) 389, (●) 227, (×) 190, (○) 139, (⋄) 67 (mJ/cm2) pulse-1.

Fig. 3
Fig. 3

Fabrication process for binary (two-level) DOE’s. The polymer layer is spin coated to a thickness t that corresponds to a π-phase shift for the design wavelength λ. Selected areas are ablated to the transparent fused-silica substrate to create the diffractive structure.

Fig. 4
Fig. 4

Phase-daisy zone plate,19 1 mm in diameter, micromachined in poly(imide) on fused silica. Fabrication time <6 min.

Fig. 5
Fig. 5

CAD-generated tool paths for one quadrant of the lens in Fig. 4. Design cutting-beam kerf is 10 µm in diameter, and the maximum line spacing within a zone is 6 µm, which ensures sufficient overlap of adjacent cuts.

Fig. 6
Fig. 6

Detail from a two-level bitmapped CGH. Material is 400-nm-thick poly(imide) on fused silica. The pixel size is 10 µm.

Fig. 7
Fig. 7

CCD image of the two-level CGH in Fig. 6 reconstructed with 633-nm He–Ne laser light.

Fig. 8
Fig. 8

Figure columns illustrate three approaches to micromachining blazed gratings. The first approach requires a beam with dimensions that are small compared with the period of the grating. The beam has a uniform intensity profile, and each pulse removes a small volume of substrate material. This method is flexible and well suited to bitmapping. The second approach uses a triangular- or trapezoid-shaped beam, also of uniform intensity. When a series of adjacent pulses is laid, deeper ablation is seen in areas of greater spatial overlap, resulting in a pitched depth profile or blaze. The third approach uses a rectangular beam whose intensity profile is shaped to produce a sloping depression from a single shot.

Fig. 9
Fig. 9

3D contour plot of a detail of a four-phase-level bitmapped CGH machined into poly(imide). The pixel size is 5 µm. White areas are unablated. The plot was measured with the Wyko optical surface profilometer. Reconstruction is shown in Fig. 10.

Fig. 10
Fig. 10

CCD image of reconstruction with 633-nm light of the four-level GGH shown in Fig. 9. The CGH has a 256 × 256 × four-level unit cell that is repeated in a 2 × 2 array. Overall DOE size is 2.56 mm × 2.56 mm. Note the effective suppression of the m = -1 order when compared with the two-level version (Fig. 7).

Fig. 11
Fig. 11

40-µm-period blazed grating fabricated by the scanning-triangle method.

Fig. 12
Fig. 12

35-µm-period blazed grating fabricated by laser intensity-profile shaping.

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