Abstract

The conditions for preparing evaporated Al films of highest reflectance for mirrors and gratings to be used in the vacuum ultraviolet are summarized, and an account is given of aging studies. The preparation of bloom-free, one-micron thick coatings for grating blanks is described, and the effect of thin overcoatings on the efficiency of ruled gratings is discussed. Data are presented on the reflectance and aging of other film materials, such as Pt, ZnS, and Al2O3, which are more suitable for use at wavelengths below 1200 A. A discussion is given of the preparation and the reflecting properties of various multilayer film combinations suitable for reducing the reflectance of mirrors and gratings in the visible and the near ultraviolet while at the same time preserving a high reflectance in the extreme ultraviolet. A 250-A thick layer of MgF2 evaporated onto an Al coating immediately after its deposition was found both to raise the reflectance to about 80% at wavelengths down to 1200 A, and to retard aging.

© 1959 Optical Society of America

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References

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  1. Hass, Hunter, and Tousey, J. Opt. Soc. Am. 46, 1009 (1956).
    [CrossRef]
  2. Hass, Hunter, and Tousey, J. Opt. Soc. Am. 47, 1070 (1957).
    [CrossRef]
  3. W. Walkenhorst, Z. tech. Physik 22, 14 (1941).
  4. Cabrera, Terrien, and Haman, Compt rend. 224, 1558 (1947).N. Cabrera, Phil. Mag. 40, 175 (1949).
  5. See reference 2, page 120.
  6. Walker, Samson, and Rustgi, J. Opt. Soc. Am. 48, 71 (1958).
    [CrossRef]
  7. Cox, Hunter, and Waylonis, J. Opt. Soc. Am. 48, 281 (1958).
  8. A. H. Pfund, J. Opt. Soc. Am. 24, 99 (1934).
    [CrossRef]
  9. P. R. Gleason, Proc. Am. Acad. Arts Sci. 64, 92 (1930).
  10. Hass, Schroeder, and Turner, J. Opt. Soc. Am. 46, 31 (1956).
    [CrossRef]
  11. D. Richardson, Bausch & Lomb Optical Company, Rochester, New York (private communication).

1958 (2)

Cox, Hunter, and Waylonis, J. Opt. Soc. Am. 48, 281 (1958).

Walker, Samson, and Rustgi, J. Opt. Soc. Am. 48, 71 (1958).
[CrossRef]

1957 (1)

1956 (2)

1947 (1)

Cabrera, Terrien, and Haman, Compt rend. 224, 1558 (1947).N. Cabrera, Phil. Mag. 40, 175 (1949).

1941 (1)

W. Walkenhorst, Z. tech. Physik 22, 14 (1941).

1934 (1)

1930 (1)

P. R. Gleason, Proc. Am. Acad. Arts Sci. 64, 92 (1930).

Cabrera,

Cabrera, Terrien, and Haman, Compt rend. 224, 1558 (1947).N. Cabrera, Phil. Mag. 40, 175 (1949).

Cox,

Cox, Hunter, and Waylonis, J. Opt. Soc. Am. 48, 281 (1958).

Gleason, P. R.

P. R. Gleason, Proc. Am. Acad. Arts Sci. 64, 92 (1930).

Haman,

Cabrera, Terrien, and Haman, Compt rend. 224, 1558 (1947).N. Cabrera, Phil. Mag. 40, 175 (1949).

Hass,

Hunter,

Pfund, A. H.

Richardson, D.

D. Richardson, Bausch & Lomb Optical Company, Rochester, New York (private communication).

Rustgi,

Samson,

Schroeder,

Terrien,

Cabrera, Terrien, and Haman, Compt rend. 224, 1558 (1947).N. Cabrera, Phil. Mag. 40, 175 (1949).

Tousey,

Turner,

Walkenhorst, W.

W. Walkenhorst, Z. tech. Physik 22, 14 (1941).

Walker,

Waylonis,

Cox, Hunter, and Waylonis, J. Opt. Soc. Am. 48, 281 (1958).

Compt rend. (1)

Cabrera, Terrien, and Haman, Compt rend. 224, 1558 (1947).N. Cabrera, Phil. Mag. 40, 175 (1949).

J. Opt. Soc. Am. (6)

Proc. Am. Acad. Arts Sci. (1)

P. R. Gleason, Proc. Am. Acad. Arts Sci. 64, 92 (1930).

Z. tech. Physik (1)

W. Walkenhorst, Z. tech. Physik 22, 14 (1941).

Other (2)

D. Richardson, Bausch & Lomb Optical Company, Rochester, New York (private communication).

See reference 2, page 120.

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Figures (20)

F. 1
F. 1

High vacuum evaporator for producing films under precisely controlled conditions.

F. 2
F. 2

The effect of evaporation speed and pressure on the reflectance of aluminum films in the extreme ultraviolet.

F. 3
F. 3

The effect of aluminum purity on the reflectance of evaporated aluminum in the extreme ultraviolet. The films were 24 hr old. The main impurities were Cu, Fe, and Si.

F. 4
F. 4

The effect of substrate temperature during deposition on the reflectance of evaporated aluminum. The coatings were 2–3 hr old when measured.

F. 5
F. 5

The effect of aging on the reflectance of evaporated aluminum in the extreme ultraviolet.

F. 6
F. 6

The calculated effect of oxide thickness on the reflectance of pure aluminum for two wavelengths.

F. 7
F. 7

The effect of storage in dry air (desiccator) and normal air (30–50% humidity) on the reflectance of evaporated aluminum. The films were 63 days old when measured.

F. 8
F. 8

The effect of 20-hr exposure to the ultraviolet radiation from a quartz mercury burner on the extreme ultraviolet reflectance of evaporated aluminum. The coatings were exposed immediately following deposition.

F. 9
F. 9

The reflectance of a 2100-A thick, old aluminum film as a function of angle of incidence at two wavelengths within the region where aluminum is transparent.

F. 10
F. 10

The reflectance of a 2-hr old 1200-A thick evaporated layer of ZnS.

F. 11
F. 11

The change in the reflectance of freshly evaporated ZnS produced by different exposures to the ultraviolet radiation from a quartz mercury burner.

F. 12
F. 12

The reflectance of evaporated platinum and rhodium in the extreme ultraviolet.

F. 13
F. 13

The reflectance of ZnS on Ge coated glass in the extreme ultraviolet. In order to produce a minimum reflectance at 4000 A the deposition was controlled, by first depositing Ge until R = 50%, then ZnS until R = 0.

F. 14
F. 14

The reflectance of Al2O3 on SiO coated glass in the extreme ultraviolet. Both films were effectively λ/4 thick at 3000 A.

F. 15
F. 15

The reflectance and layer arrangement of an Al–Ge–ZnS coating designed to have a minimum reflectance at 4000 A.

F. 16
F. 16

The reflectance of a multilayer coating designed to have low reflectance between 4800 A and 2400 A, for the purpose of suppressing the stray light as seen by a blue sensitive photographic emulsion. The layer arrangement is shown together with the reflectance control values at 4000 A.

F. 17
F. 17

The reflectance of evaporated aluminum coated immediately with MgF2 before removal from the evaporator. The enhancement of reflectance produced by the MgF2 coating can be seen by comparison with the curve for aluminum. All three curves apply to 24-hr old films.

F. 18
F. 18

The calculated reflectance of a nonabsorbing surface film of n = 1.6 on an absorbing substrate for two quite different cases; substrate Ti at 4360 A, and substrate Al at 1300 A.

F. 19
F. 19

The increase in efficiency produced by flash coating aluminum onto an aluminum surfaced 600 line/mm replica grating with blaze near 1200 A.

F. 20
F. 20

The percent of incident energy returned in the first order for a 600 line/mm replica after flash coating with aluminum and then coating with a 250–A thick layer of MgF2. The replica was blazed for 1200 A.

Tables (2)

Tables Icon

Table I Calculated effect of oxide thickness on the reflectance of aluminum for various angles of incidence at λ = 585 A and 735 A.