Abstract

The fabrication and principal characteristics of an electrically calibrated absolute radiometer are described. The receiver substrate incorporates an evaporated chromium–nickel thermopile, an electrical shield, a copper thermal diffuser disk, an evaporated chromium electrical heating element, and a goldblack absorber. All insulating layers are evaporated silicon monoxide; the thermopile and heater are made by a photoetching process. The performances of several radiometers are discussed. For example, a 28-junction version has a responsivity and NEP of 93 mV/W and 50 nW, respectively, in air, with a time constant of 15 sec and a surface responsivity uniform to better than 1%. The radiometers require only a few corrections of small magnitude. An analysis of sources of error and residual uncertainties shows that the over-all precision of this type of radiometer is at least 0.5% for a power level of 50 μW. Comparative radiometric measurements are described that support this claim.

© 1978 Optical Society of America

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References

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  1. J. S. Preston, Proc. R. Soc. London Ser. A: 272, 133 (1963).
    [CrossRef]
  2. W. R. Blevin, B. Steiner, Metrologia 11, 97 (1975).
    [CrossRef]
  3. E. J. Gillham, Proc. R. Soc. London Ser. A: 269, 249 (1962).
    [CrossRef]
  4. W. R. Blevin, W. J. Brown, Aust. J. Phys. 20, 567 (1967).
    [CrossRef]
  5. R. J. Phelan, A. R. Cook, Appl. Opt. 12, 2494 (1973).
    [CrossRef] [PubMed]
  6. J. Geist, W. R. Blevin, Appl. Opt. 12, 2532 (1973).
    [CrossRef] [PubMed]
  7. N. Ooba, CCPR 6eSession (Gauthier-Villars, Paris, 1965).
  8. F. Hengstberger, CSIR Research Report 331, Pretoria, South Africa (1977).
  9. R. A. Smith, F. E. Jones, R. P. Chasmar, The Detection and Measurement of Infra-Red Radiation (Oxford U., London, 1975), Chap. 3.
  10. L. I. Maissel, R. Glang, Handbook of Thin Film Technology (McGraw-Hill, New York, 1970), Chap. 7.
  11. L. Harris, R. T. McGinnies, B. M. Siegel, J. Opt. Soc. Am. 38, 582 (1948).
    [CrossRef]
  12. W. R. Blevin, W. J. Brown, Metrologia 2, 139 (1966).
    [CrossRef]
  13. J. Geist, NBS Technical Note 594-1 (U.S. Government Printing Office, Washington D.C., 1972).
  14. R. D. Saunders, W. R. Ott, J. M. Bridges, Appl. Opt. 17, 593 (1978).
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  15. M. Suzuki, N. Ooba, Metrologia 12, 123 (1976).
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  16. L. P. Boivin, Appl. Opt. 15, 1204 (1976).
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  17. W. R. Blevin, Metrologia 6, 39 (1970).
    [CrossRef]
  18. W. H. Steel, M. De, J. A. Bell, J. Opt. Soc. Am. 62, 1099 (1972).
    [CrossRef]

1978

1976

L. P. Boivin, Appl. Opt. 15, 1204 (1976).
[CrossRef] [PubMed]

M. Suzuki, N. Ooba, Metrologia 12, 123 (1976).
[CrossRef]

1975

W. R. Blevin, B. Steiner, Metrologia 11, 97 (1975).
[CrossRef]

1973

1972

1970

W. R. Blevin, Metrologia 6, 39 (1970).
[CrossRef]

1967

W. R. Blevin, W. J. Brown, Aust. J. Phys. 20, 567 (1967).
[CrossRef]

1966

W. R. Blevin, W. J. Brown, Metrologia 2, 139 (1966).
[CrossRef]

1963

J. S. Preston, Proc. R. Soc. London Ser. A: 272, 133 (1963).
[CrossRef]

1962

E. J. Gillham, Proc. R. Soc. London Ser. A: 269, 249 (1962).
[CrossRef]

1948

Bell, J. A.

Blevin, W. R.

W. R. Blevin, B. Steiner, Metrologia 11, 97 (1975).
[CrossRef]

J. Geist, W. R. Blevin, Appl. Opt. 12, 2532 (1973).
[CrossRef] [PubMed]

W. R. Blevin, Metrologia 6, 39 (1970).
[CrossRef]

W. R. Blevin, W. J. Brown, Aust. J. Phys. 20, 567 (1967).
[CrossRef]

W. R. Blevin, W. J. Brown, Metrologia 2, 139 (1966).
[CrossRef]

Boivin, L. P.

Bridges, J. M.

Brown, W. J.

W. R. Blevin, W. J. Brown, Aust. J. Phys. 20, 567 (1967).
[CrossRef]

W. R. Blevin, W. J. Brown, Metrologia 2, 139 (1966).
[CrossRef]

Chasmar, R. P.

R. A. Smith, F. E. Jones, R. P. Chasmar, The Detection and Measurement of Infra-Red Radiation (Oxford U., London, 1975), Chap. 3.

Cook, A. R.

De, M.

Geist, J.

J. Geist, W. R. Blevin, Appl. Opt. 12, 2532 (1973).
[CrossRef] [PubMed]

J. Geist, NBS Technical Note 594-1 (U.S. Government Printing Office, Washington D.C., 1972).

Gillham, E. J.

E. J. Gillham, Proc. R. Soc. London Ser. A: 269, 249 (1962).
[CrossRef]

Glang, R.

L. I. Maissel, R. Glang, Handbook of Thin Film Technology (McGraw-Hill, New York, 1970), Chap. 7.

Harris, L.

Hengstberger, F.

F. Hengstberger, CSIR Research Report 331, Pretoria, South Africa (1977).

Jones, F. E.

R. A. Smith, F. E. Jones, R. P. Chasmar, The Detection and Measurement of Infra-Red Radiation (Oxford U., London, 1975), Chap. 3.

Maissel, L. I.

L. I. Maissel, R. Glang, Handbook of Thin Film Technology (McGraw-Hill, New York, 1970), Chap. 7.

McGinnies, R. T.

Ooba, N.

M. Suzuki, N. Ooba, Metrologia 12, 123 (1976).
[CrossRef]

N. Ooba, CCPR 6eSession (Gauthier-Villars, Paris, 1965).

Ott, W. R.

Phelan, R. J.

Preston, J. S.

J. S. Preston, Proc. R. Soc. London Ser. A: 272, 133 (1963).
[CrossRef]

Saunders, R. D.

Siegel, B. M.

Smith, R. A.

R. A. Smith, F. E. Jones, R. P. Chasmar, The Detection and Measurement of Infra-Red Radiation (Oxford U., London, 1975), Chap. 3.

Steel, W. H.

Steiner, B.

W. R. Blevin, B. Steiner, Metrologia 11, 97 (1975).
[CrossRef]

Suzuki, M.

M. Suzuki, N. Ooba, Metrologia 12, 123 (1976).
[CrossRef]

Appl. Opt.

Aust. J. Phys.

W. R. Blevin, W. J. Brown, Aust. J. Phys. 20, 567 (1967).
[CrossRef]

J. Opt. Soc. Am.

Metrologia

M. Suzuki, N. Ooba, Metrologia 12, 123 (1976).
[CrossRef]

W. R. Blevin, Metrologia 6, 39 (1970).
[CrossRef]

W. R. Blevin, B. Steiner, Metrologia 11, 97 (1975).
[CrossRef]

W. R. Blevin, W. J. Brown, Metrologia 2, 139 (1966).
[CrossRef]

Proc. R. Soc. London Ser. A

E. J. Gillham, Proc. R. Soc. London Ser. A: 269, 249 (1962).
[CrossRef]

J. S. Preston, Proc. R. Soc. London Ser. A: 272, 133 (1963).
[CrossRef]

Other

J. Geist, NBS Technical Note 594-1 (U.S. Government Printing Office, Washington D.C., 1972).

N. Ooba, CCPR 6eSession (Gauthier-Villars, Paris, 1965).

F. Hengstberger, CSIR Research Report 331, Pretoria, South Africa (1977).

R. A. Smith, F. E. Jones, R. P. Chasmar, The Detection and Measurement of Infra-Red Radiation (Oxford U., London, 1975), Chap. 3.

L. I. Maissel, R. Glang, Handbook of Thin Film Technology (McGraw-Hill, New York, 1970), Chap. 7.

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Figures (16)

Fig. 1
Fig. 1

Absolute radiometer schematic diagram: exploded view.

Fig. 2
Fig. 2

Configurations of (a) the 28-junction thermopile and (b) the 12-junction thermopile; for scaling purposes the actual outside diameter of the central ring of junctions in (a) is about 9 mm.

Fig. 3
Fig. 3

Photograph of the photoresist printer. (a) The substrate is held in place on the vacuum chuck. (b) In the aligning position, the mask is held stationary close to the substrate surface, and the latter is aligned with respect to the mask using the translation and rotation stages. For exposure, the viewing telescope swings out.

Fig. 4
Fig. 4

A photoetched 28-junction Cr–Ni thermopile on a glass substrate.

Fig. 5
Fig. 5

Configuration of the thin film heater pattern. The actual diameter of the circular region is 6 mm. The zigzag heater bar has a width of 50 μm.

Fig. 6
Fig. 6

(a) The thin film heater, photoetched in a chromium layer evaporated on a SiO insulated copper–macor disk assembly. (b) The completed radiometer receiver disk assembly showing, in particular, the goldblack absorber, the current and potential lead tabs of the thin film heater, and the thermopile contact pads. The insulating SiO between the goldblack and the heater has been omitted for clarity.

Fig. 7
Fig. 7

The radiometer receiver disk mounted inside the radiometer case (a) without the cover, showing the various electrical connections, and (b) with the cover in place.

Fig. 8
Fig. 8

Spectral reflectance of a typical goldblack absorber. The reflectance is measured on the radiometer disk itself using a Zeiss DMC spectrophotometer.

Fig. 9
Fig. 9

Variation of the responsivity over the surface of the radiometer. The numbers refer to the radiometers described in TableI.

Fig. 10
Fig. 10

Variation of the responsivity as a function of the position of a 6-mm diam uniformly irradiated spot on the radiometer surface. The numbers refer to the radiometers of Table I.

Fig. 11
Fig. 11

Variation of the responsivity of radiometer 2 for an input power ranging from 1 μW to 1 mW.

Fig. 12
Fig. 12

Circuit diagram of the radiometer electrical heating element. DPDT switch position 1: normal measurements. DPDT switch position 2: lead-heating experiment.

Fig. 13
Fig. 13

Theoretical correction factors for nonuniform surface responsivity, corresponding to uniformly irradiated regions of various diameters on the radiometer surface. The numbers refer to the radiometers of Table I.

Fig. 14
Fig. 14

Schematic diagram of the setup used for making radiometric measurements with 500-W Q.B. lamps.

Fig. 15
Fig. 15

Relative transmittance of the filter used (#6) in conjunction with the Q.B. lamps. The V(λ) curve is shown for comparison. The two curves are area normalized. The maximum transmittance of the #6 filter is about 37%.

Fig. 16
Fig. 16

Relative irradiance (solid curve) on the radiometer disk surface along a diameter parallel to the long axis of the lamp filament, with the setup of Fig. 14. The dotted line shows the approximation used in calculating the correction factors for nonuniform surface responsivity.

Tables (2)

Tables Icon

Table I Principal Characteristics of the Radiometers (in Air)

Tables Icon

Table II Irradiance at 50 cm from Reference Surface, with V(λ) Filter #6

Equations (2)

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K = 2 R 2 0 R max E ( r ) r d r 0 R S ( r ) r d r 0 R max E ( r ) S ( r ) r d r ,
Δ d = ( n 1 n ) t [ 1 + ( n + 1 ) 2 n 2 tan 2 i ] .

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