Abstract

A calorimeter for making absolute energy measurements of high power laser pulses is described. The calorimeter, based on volume absorption in a solid, is calibrated electrically and requires no window or vacuum environment. An error analysis is included giving the systematic and random errors of the instrument for a laser measurement. Briefly, the following performance is typical of the 32-mm × 32-mm aperture calorimeter: range 0.4–15-J; random error ±0.2% (one standard deviation); systematic error ±2.3%; and an upper operational limit of 3 J/cm2. Most of the volume absorber documentation is applicable for 1.06 μm; however, the calorimeter should be useful from the near ir through the visible. Absorbers for use with CO2 lasers in the 9–11-μm range are also discussed.

© 1976 Optical Society of America

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References

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  1. G. Birnbaum, M. Birnbaum, Proc. IEEE 55, 1026 (1967).
    [CrossRef]
  2. S. R. Gunn, J. Phys. E. 6, 105 (1973).
    [CrossRef]
  3. The CO2 TEA laser pulse consisted of a main peak 0.2–0.3μsec long followed by a tail lasting 1–2 μsec. The peak power in the pulse could be approximated from the energy by assuming a rectangular shaped pulse 0.5 μsec long. On occasions the peak power was higher since spontaneous mode locking was observed. The pulse energy to the target was varied in steps of 1.5 by dielectric coated Ge attenuators. Energy density was determined by fitting a Gaussian to the beam profile or in instances of poor TEM00 mode quality by measuring the energy at target passing through a small circular aperture.
  4. The TEM00 1.06-μm measurements were performed independently at NBS, Washington, D.C., by A. Feldman, D. Horowitz.
  5. NBS report (unpublished).
  6. J. H. Jacob, E. R. Pugh, J. D. Daugherty, D. B. Northam, Rev. Sci. Instrum. 44, 471 (1973).
    [CrossRef]
  7. J. F. Ready, Effects of High-Power Laser Radiation (Academic, New York, 1971).
  8. H. S. Carslaw, J. C. Jaeger, Conduction of Heat in Solids (Clarendon, Oxford, 1959).
  9. W. H. Reichelt, E. E. Stark, T. F. Stratton, Opt. Commun. 11, 305 (1974).
    [CrossRef]
  10. D. A. Jennings, IEEE Trans. Instrum. Meas. 15, 161 (1966).
    [CrossRef]
  11. S. R. Gunn, Rev. Sci. Instrum. 45, 936 (1974).
    [CrossRef]
  12. I. M. Winer, Appl. Opt. 12, 2809 (1973).
    [CrossRef]
  13. P. Boulanger, A. Heym, J-M. Mayor, Z. A. Pietrzyk, J. Phys. E. 6, 559 (1973).
    [CrossRef]
  14. S. R. Gunn, Lawrence Livermore Laboratory, Rept. UCRL-51854 (1975).
  15. CaF2 and MgO are also available as a Kodak Irtran material, Irtran 3 and 5, respectively.
  16. E. D. West, W. E. Case, A. L. Rasmussen, L. B. Schmidt, J. Res. Natl. Bur. Stand. Sect. A: 76, 13 (1971).
  17. E. D. West, L. B. Schmidt, to be published as NBS Technical Note.
  18. E. D. West, NBS Technical Note 396 (U.S. Government Printing Office, Washington, D.C., 1971).
  19. The pyroelectric detector was supplied by G. W. Day, C. A. Hamilton of NBS, Boulder.
  20. Statement of Uncertainty for NBS Laser Energy Standard 1, an internal report by E. G. Johnson. This error includes all systematic errors at the 99% confidence level in addition to self-consistency requirements between three C calorimeters.

1974

W. H. Reichelt, E. E. Stark, T. F. Stratton, Opt. Commun. 11, 305 (1974).
[CrossRef]

S. R. Gunn, Rev. Sci. Instrum. 45, 936 (1974).
[CrossRef]

1973

I. M. Winer, Appl. Opt. 12, 2809 (1973).
[CrossRef]

P. Boulanger, A. Heym, J-M. Mayor, Z. A. Pietrzyk, J. Phys. E. 6, 559 (1973).
[CrossRef]

S. R. Gunn, J. Phys. E. 6, 105 (1973).
[CrossRef]

J. H. Jacob, E. R. Pugh, J. D. Daugherty, D. B. Northam, Rev. Sci. Instrum. 44, 471 (1973).
[CrossRef]

1971

E. D. West, W. E. Case, A. L. Rasmussen, L. B. Schmidt, J. Res. Natl. Bur. Stand. Sect. A: 76, 13 (1971).

1967

G. Birnbaum, M. Birnbaum, Proc. IEEE 55, 1026 (1967).
[CrossRef]

1966

D. A. Jennings, IEEE Trans. Instrum. Meas. 15, 161 (1966).
[CrossRef]

Birnbaum, G.

G. Birnbaum, M. Birnbaum, Proc. IEEE 55, 1026 (1967).
[CrossRef]

Birnbaum, M.

G. Birnbaum, M. Birnbaum, Proc. IEEE 55, 1026 (1967).
[CrossRef]

Boulanger, P.

P. Boulanger, A. Heym, J-M. Mayor, Z. A. Pietrzyk, J. Phys. E. 6, 559 (1973).
[CrossRef]

Carslaw, H. S.

H. S. Carslaw, J. C. Jaeger, Conduction of Heat in Solids (Clarendon, Oxford, 1959).

Case, W. E.

E. D. West, W. E. Case, A. L. Rasmussen, L. B. Schmidt, J. Res. Natl. Bur. Stand. Sect. A: 76, 13 (1971).

Daugherty, J. D.

J. H. Jacob, E. R. Pugh, J. D. Daugherty, D. B. Northam, Rev. Sci. Instrum. 44, 471 (1973).
[CrossRef]

Day, G. W.

The pyroelectric detector was supplied by G. W. Day, C. A. Hamilton of NBS, Boulder.

Feldman, A.

The TEM00 1.06-μm measurements were performed independently at NBS, Washington, D.C., by A. Feldman, D. Horowitz.

Gunn, S. R.

S. R. Gunn, Rev. Sci. Instrum. 45, 936 (1974).
[CrossRef]

S. R. Gunn, J. Phys. E. 6, 105 (1973).
[CrossRef]

S. R. Gunn, Lawrence Livermore Laboratory, Rept. UCRL-51854 (1975).

Hamilton, C. A.

The pyroelectric detector was supplied by G. W. Day, C. A. Hamilton of NBS, Boulder.

Heym, A.

P. Boulanger, A. Heym, J-M. Mayor, Z. A. Pietrzyk, J. Phys. E. 6, 559 (1973).
[CrossRef]

Horowitz, D.

The TEM00 1.06-μm measurements were performed independently at NBS, Washington, D.C., by A. Feldman, D. Horowitz.

Jacob, J. H.

J. H. Jacob, E. R. Pugh, J. D. Daugherty, D. B. Northam, Rev. Sci. Instrum. 44, 471 (1973).
[CrossRef]

Jaeger, J. C.

H. S. Carslaw, J. C. Jaeger, Conduction of Heat in Solids (Clarendon, Oxford, 1959).

Jennings, D. A.

D. A. Jennings, IEEE Trans. Instrum. Meas. 15, 161 (1966).
[CrossRef]

Johnson, E. G.

Statement of Uncertainty for NBS Laser Energy Standard 1, an internal report by E. G. Johnson. This error includes all systematic errors at the 99% confidence level in addition to self-consistency requirements between three C calorimeters.

Mayor, J-M.

P. Boulanger, A. Heym, J-M. Mayor, Z. A. Pietrzyk, J. Phys. E. 6, 559 (1973).
[CrossRef]

Northam, D. B.

J. H. Jacob, E. R. Pugh, J. D. Daugherty, D. B. Northam, Rev. Sci. Instrum. 44, 471 (1973).
[CrossRef]

Pietrzyk, Z. A.

P. Boulanger, A. Heym, J-M. Mayor, Z. A. Pietrzyk, J. Phys. E. 6, 559 (1973).
[CrossRef]

Pugh, E. R.

J. H. Jacob, E. R. Pugh, J. D. Daugherty, D. B. Northam, Rev. Sci. Instrum. 44, 471 (1973).
[CrossRef]

Rasmussen, A. L.

E. D. West, W. E. Case, A. L. Rasmussen, L. B. Schmidt, J. Res. Natl. Bur. Stand. Sect. A: 76, 13 (1971).

Ready, J. F.

J. F. Ready, Effects of High-Power Laser Radiation (Academic, New York, 1971).

Reichelt, W. H.

W. H. Reichelt, E. E. Stark, T. F. Stratton, Opt. Commun. 11, 305 (1974).
[CrossRef]

Schmidt, L. B.

E. D. West, W. E. Case, A. L. Rasmussen, L. B. Schmidt, J. Res. Natl. Bur. Stand. Sect. A: 76, 13 (1971).

E. D. West, L. B. Schmidt, to be published as NBS Technical Note.

Stark, E. E.

W. H. Reichelt, E. E. Stark, T. F. Stratton, Opt. Commun. 11, 305 (1974).
[CrossRef]

Stratton, T. F.

W. H. Reichelt, E. E. Stark, T. F. Stratton, Opt. Commun. 11, 305 (1974).
[CrossRef]

West, E. D.

E. D. West, W. E. Case, A. L. Rasmussen, L. B. Schmidt, J. Res. Natl. Bur. Stand. Sect. A: 76, 13 (1971).

E. D. West, L. B. Schmidt, to be published as NBS Technical Note.

E. D. West, NBS Technical Note 396 (U.S. Government Printing Office, Washington, D.C., 1971).

Winer, I. M.

Appl. Opt.

IEEE Trans. Instrum. Meas.

D. A. Jennings, IEEE Trans. Instrum. Meas. 15, 161 (1966).
[CrossRef]

J. Phys. E.

P. Boulanger, A. Heym, J-M. Mayor, Z. A. Pietrzyk, J. Phys. E. 6, 559 (1973).
[CrossRef]

S. R. Gunn, J. Phys. E. 6, 105 (1973).
[CrossRef]

J. Res. Natl. Bur. Stand. Sect. A

E. D. West, W. E. Case, A. L. Rasmussen, L. B. Schmidt, J. Res. Natl. Bur. Stand. Sect. A: 76, 13 (1971).

Opt. Commun.

W. H. Reichelt, E. E. Stark, T. F. Stratton, Opt. Commun. 11, 305 (1974).
[CrossRef]

Proc. IEEE

G. Birnbaum, M. Birnbaum, Proc. IEEE 55, 1026 (1967).
[CrossRef]

Rev. Sci. Instrum.

J. H. Jacob, E. R. Pugh, J. D. Daugherty, D. B. Northam, Rev. Sci. Instrum. 44, 471 (1973).
[CrossRef]

S. R. Gunn, Rev. Sci. Instrum. 45, 936 (1974).
[CrossRef]

Other

J. F. Ready, Effects of High-Power Laser Radiation (Academic, New York, 1971).

H. S. Carslaw, J. C. Jaeger, Conduction of Heat in Solids (Clarendon, Oxford, 1959).

The CO2 TEA laser pulse consisted of a main peak 0.2–0.3μsec long followed by a tail lasting 1–2 μsec. The peak power in the pulse could be approximated from the energy by assuming a rectangular shaped pulse 0.5 μsec long. On occasions the peak power was higher since spontaneous mode locking was observed. The pulse energy to the target was varied in steps of 1.5 by dielectric coated Ge attenuators. Energy density was determined by fitting a Gaussian to the beam profile or in instances of poor TEM00 mode quality by measuring the energy at target passing through a small circular aperture.

The TEM00 1.06-μm measurements were performed independently at NBS, Washington, D.C., by A. Feldman, D. Horowitz.

NBS report (unpublished).

E. D. West, L. B. Schmidt, to be published as NBS Technical Note.

E. D. West, NBS Technical Note 396 (U.S. Government Printing Office, Washington, D.C., 1971).

The pyroelectric detector was supplied by G. W. Day, C. A. Hamilton of NBS, Boulder.

Statement of Uncertainty for NBS Laser Energy Standard 1, an internal report by E. G. Johnson. This error includes all systematic errors at the 99% confidence level in addition to self-consistency requirements between three C calorimeters.

S. R. Gunn, Lawrence Livermore Laboratory, Rept. UCRL-51854 (1975).

CaF2 and MgO are also available as a Kodak Irtran material, Irtran 3 and 5, respectively.

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Figures (5)

Fig. 1
Fig. 1

Side and front cross-sectional views of the Q calorimeter absorbing cavity. Volume absorbers are epoxied inside the 0.2-mm thick electroformed cavity. An electrical calibration heater is epoxied in the groove of a copper spool soldered to the back. The path of a typical light ray is shown.

Fig. 2
Fig. 2

Cross sectional view of the Q calorimeter showing the absorbing cavity inside the constant temperature surroundings. A stable temperature for the surroundings is achieved by a servo using a Wheatstone bridge and heater epoxied in the grooves of control ring B. The constant temperature jacket is foam insulated from the room environment.

Fig. 3
Fig. 3

Calorimeter calibration constant K1 vs injected electrical energy. K1 is the injected electrical energy divided by the corrected voltage rise. The operational energy range of the calorimeter is 0.4–15 J. For the forty-two measurements between 0.4 J and 15 J, a mean of 13.030 J/mV is obtained with a standard deviation of 0.14%. One point below the operational range (12.86 J/mV at 0.2 J) was obtained and is not included in the plot. With this single exception, all electrical calibrations made on the calorimeter are indicated in this figure.

Fig. 4
Fig. 4

Calibration constant K1 and cooling constant for the Q calorimeter plotted chronologically over 6 months. More lower energy measurements were made toward the end of the 6-month period; hence, more scatter occurs at that time. A large number of laser measurements were made at times A and B.

Fig. 5
Fig. 5

Comparison of Q calorimeter to NBS C4–6 calorimeter. An average Q calibration constant K2 of 13.023 J/mV with a standard deviation of 0.1% was obtained for sixteen intercomparisons with C4–6. A discrepancy of 0.05% is indicated between K2 and the electrically determined Q calibration constant of 13.016 J/mV (K3). During the intercomparison different areas of the Q calorimeter aperture were illuminated. Measurements denoted by B, C, D, and E were offset from the center (A) by 3 mm. All measurements were made with a 5-mm diam beam. As shown, errors due to beam position are insignificant.

Tables (5)

Tables Icon

Table I Damage Threshold of Surface Absorbers

Tables Icon

Table II Damage Threshold of Volume Absorbers at 1.06 μm, 30-nsec Pulse

Tables Icon

Table III Damage Thresholds of Volume Absorbers at 10.6 μm, 0.5-μsec Pulse

Tables Icon

Table IV Systematic Errors of the Q Calorimeter

Tables Icon

Table V Specifications of the Q Calorimeter with NG-10 Main Absorber

Equations (5)

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E ( x ) = E ( o ) exp ( - α x ) .
Δ T ( o ) = α E ( o ) ρ c ,
τ = ρ c 2 α 2 K ,
F 1 = ( 6 ξ σ T s 3 α K ) f ,
F 2 = ( K ρ c K ρ c ) 1 / 2 ,

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