Abstract

Ion beam figuring (IBF) technology for small scale optical components is discussed. Since the small removal function can be obtained in IBF, it makes computer-controlled optical surfacing technology possible to machine precision centimeter- or millimeter-scale optical components deterministically. Using a small ion beam to machine small optical components, there are some key problems, such as small ion beam positioning on the optical surface, material removal rate, ion beam scanning pitch control on the optical surface, and so on, that must be seriously considered. The main reasons for the problems are that it is more sensitive to the above problems than a big ion beam because of its small beam diameter and lower material ratio. In this paper, we discuss these problems and their influences in machining small optical components in detail. Based on the identification–compensation principle, an iterative machining compensation method is deduced for correcting the positioning error of an ion beam with the material removal rate estimated by a selected optimal scanning pitch. Experiments on ϕ10mm Zerodur planar and spherical samples are made, and the final surface errors are both smaller than λ/100 measured by a Zygo GPI interferometer.

© 2011 Optical Society of America

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References

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  1. S. C. Fawcett, “Development of an ion beam figuring system for centimeter scale optical components,” Proc. SPIE 2263, 164–167 (1994).
    [CrossRef]
  2. P. M. Shanbhag, M. R. Feinberg, G. Sandri, M. N. Horenstein, and T. G. Bifano, “Ion-beam machining of millimeter scale optics,” Appl. Opt. 39, 599–611 (2000).
    [CrossRef]
  3. T. Franz and T. Hänsel, “Ion beam figuring (IBF) solutions for the correction of surface errors of small high performance optics,” in Optical Fabrication and Testing, OSA Technical Digest (Optical Society of America, 2008), paper OThC7.
  4. X. Xie, W. Gu, and L. Zhou, “Study on machining small precision optical component using thin ion beam,” Guofang Keji Daxue Xuebao [Journal of National University of Defense Technology 31, 10–14(2009), in Chinese.

2009 (1)

X. Xie, W. Gu, and L. Zhou, “Study on machining small precision optical component using thin ion beam,” Guofang Keji Daxue Xuebao [Journal of National University of Defense Technology 31, 10–14(2009), in Chinese.

2000 (1)

1994 (1)

S. C. Fawcett, “Development of an ion beam figuring system for centimeter scale optical components,” Proc. SPIE 2263, 164–167 (1994).
[CrossRef]

Bifano, T. G.

Fawcett, S. C.

S. C. Fawcett, “Development of an ion beam figuring system for centimeter scale optical components,” Proc. SPIE 2263, 164–167 (1994).
[CrossRef]

Feinberg, M. R.

Franz, T.

T. Franz and T. Hänsel, “Ion beam figuring (IBF) solutions for the correction of surface errors of small high performance optics,” in Optical Fabrication and Testing, OSA Technical Digest (Optical Society of America, 2008), paper OThC7.

Gu, W.

X. Xie, W. Gu, and L. Zhou, “Study on machining small precision optical component using thin ion beam,” Guofang Keji Daxue Xuebao [Journal of National University of Defense Technology 31, 10–14(2009), in Chinese.

Hänsel, T.

T. Franz and T. Hänsel, “Ion beam figuring (IBF) solutions for the correction of surface errors of small high performance optics,” in Optical Fabrication and Testing, OSA Technical Digest (Optical Society of America, 2008), paper OThC7.

Horenstein, M. N.

Sandri, G.

Shanbhag, P. M.

Xie, X.

X. Xie, W. Gu, and L. Zhou, “Study on machining small precision optical component using thin ion beam,” Guofang Keji Daxue Xuebao [Journal of National University of Defense Technology 31, 10–14(2009), in Chinese.

Zhou, L.

X. Xie, W. Gu, and L. Zhou, “Study on machining small precision optical component using thin ion beam,” Guofang Keji Daxue Xuebao [Journal of National University of Defense Technology 31, 10–14(2009), in Chinese.

Appl. Opt. (1)

Guofang Keji Daxue Xuebao [Journal of National University of Defense Technology (1)

X. Xie, W. Gu, and L. Zhou, “Study on machining small precision optical component using thin ion beam,” Guofang Keji Daxue Xuebao [Journal of National University of Defense Technology 31, 10–14(2009), in Chinese.

Proc. SPIE (1)

S. C. Fawcett, “Development of an ion beam figuring system for centimeter scale optical components,” Proc. SPIE 2263, 164–167 (1994).
[CrossRef]

Other (1)

T. Franz and T. Hänsel, “Ion beam figuring (IBF) solutions for the correction of surface errors of small high performance optics,” in Optical Fabrication and Testing, OSA Technical Digest (Optical Society of America, 2008), paper OThC7.

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Figures (9)

Fig. 1
Fig. 1

Two methods to gain a small scale ion beam [4]. (a) Small scale screen grid of the ion source, (b) small scale ion diaphragm.

Fig. 2
Fig. 2

Raster scanning of IBF.

Fig. 3
Fig. 3

Simulated residual machining errors for different raster pitches. (a)  5 mm . (b)  2 mm . (c)  1 mm .

Fig. 4
Fig. 4

Simulation of pitch versus its machining error for ϕ 100 mm planar optics.

Fig. 5
Fig. 5

Curves of deviation of relative removal rate and positioning error versus residual error. (a) Deviation of estimated relative removal rate, (b) X axial positioning error, (c) Y axial positioning error.

Fig. 6
Fig. 6

Results of the first machining cycle. (a) Initial surface contour, (b) desired removal material amount, (c) deviation of theoretical and actual residual error RMS 0.034 λ (theoretical residual error PV 0.63 λ , RMS 0.139 λ ; actual residual error PV 0.752 λ , RMS 0.143 λ ).

Fig. 7
Fig. 7

Machined results in third machining cycle. (a) Machined residual error, (b) deviation of theoretical and actual residual error.

Fig. 8
Fig. 8

Surface contour of truncated ϕ 7 mm diameter of planar optics. (a) Initial surface, (b) machined surface.

Fig. 9
Fig. 9

Final machined result of spherical optics with compensation. (a)  ϕ 10 mm spherical optics, (b) machined surface contour, (c) machined error PV 0.088 λ , RMS 0.012 λ .

Tables (2)

Tables Icon

Table 1 Beam Removal Functions with Different Screen Grids

Tables Icon

Table 2 Beam Removal Functions with Different Ion Diaphragms

Equations (10)

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f c = 9 π W .
T s < 1 2 f c = π W 18 .
. τ a ( x , y ) = τ ( x Δ x , y Δ y ) .
r a ( x , y ) = τ a ( x , y ) * R ( x , y ) = τ ( x Δ x , y Δ y ) * R ( x , y ) = r ( x Δ x , y Δ y ) ,
e ( x , y ) = r ( x , y ) r ( x Δ x , y Δ y ) .
R a ( x , y ) = ( 1 + δ p ) · R ( x , y ) .
r a ( x , y ) = τ ( x , y ) * R a ( x , y ) = ( 1 + δ p ) r ( x , y ) ,
e ( x , y ) = r ( x , y ) r a ( x , y ) = δ p r ( x , y ) .
r ( x , y ) = R ( x , y ) * τ ( x , y ) .
e r = | 1 γ | · r ( x , y ) .

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