Abstract

Thermal emissivity of cholesteric liquid crystal films is measured as a function of the film thickness d. increases from 0.2 to 0.4 in parallel with the increase of d from 13 μm to 33 μm and arrives at a constant value as high as 0.87 in the case of d ~ 1 mm. Reflectance at the air-to-liquid crystal interface and the absorption coefficient of the liquid crystal layer are found to be 0.130 and 7.24 × 10−3μm−1, respectively. The dependency of on d is interpretable on the basis of McMahon’s theory of radiant characteristics of semitransparent radiators.

© 1978 Optical Society of America

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References

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  1. For example, C. Tingwaldt, U. Schley, J. Verch, S. Takata, Optik 22, 48 (1965).
  2. S. Takata, J. Soc. Instrum. Control Eng. 4, 867 (1965) (in Japanese).
  3. H. O. McMahon, J. Opt. Soc. Am. 40, 376 (1950).
    [CrossRef]
  4. J. C. Richmond, W. M. Harrison, J. Res. Nat. Bur. Stand. Sect. C: 66, 261 (1962).

1965 (2)

For example, C. Tingwaldt, U. Schley, J. Verch, S. Takata, Optik 22, 48 (1965).

S. Takata, J. Soc. Instrum. Control Eng. 4, 867 (1965) (in Japanese).

1962 (1)

J. C. Richmond, W. M. Harrison, J. Res. Nat. Bur. Stand. Sect. C: 66, 261 (1962).

1950 (1)

Harrison, W. M.

J. C. Richmond, W. M. Harrison, J. Res. Nat. Bur. Stand. Sect. C: 66, 261 (1962).

McMahon, H. O.

Richmond, J. C.

J. C. Richmond, W. M. Harrison, J. Res. Nat. Bur. Stand. Sect. C: 66, 261 (1962).

Schley, U.

For example, C. Tingwaldt, U. Schley, J. Verch, S. Takata, Optik 22, 48 (1965).

Takata, S.

For example, C. Tingwaldt, U. Schley, J. Verch, S. Takata, Optik 22, 48 (1965).

S. Takata, J. Soc. Instrum. Control Eng. 4, 867 (1965) (in Japanese).

Tingwaldt, C.

For example, C. Tingwaldt, U. Schley, J. Verch, S. Takata, Optik 22, 48 (1965).

Verch, J.

For example, C. Tingwaldt, U. Schley, J. Verch, S. Takata, Optik 22, 48 (1965).

J. Opt. Soc. Am. (1)

J. Res. Nat. Bur. Stand. Sect. C (1)

J. C. Richmond, W. M. Harrison, J. Res. Nat. Bur. Stand. Sect. C: 66, 261 (1962).

J. Soc. Instrum. Control Eng. (1)

S. Takata, J. Soc. Instrum. Control Eng. 4, 867 (1965) (in Japanese).

Optik (1)

For example, C. Tingwaldt, U. Schley, J. Verch, S. Takata, Optik 22, 48 (1965).

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Figures (6)

Fig. 1
Fig. 1

Thermal radiation of liquid crystal film on Al evaporated surface.

Fig. 2
Fig. 2

Experimental equipment for the measurement of thermal emissivity.

Fig. 3
Fig. 3

Experimental setup for the film thickness measurement.

Fig. 4
Fig. 4

Relation between thermal emissivity and thickness d for thin samples.

Fig. 5
Fig. 5

Relation between lnz and 2d.

Fig. 6
Fig. 6

Relation between thermal emissivity and thickness d, including the thick sample.

Equations (5)

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= ( 1 R 12 ) ( 1 τ ) ( 1 + R 23 τ ) 1 R 12 R 23 τ 2 + ( 1 R 12 ) ( 1 R 23 ) τ 1 R 12 R 23 τ 2 = ( 1 R 12 ) ( 1 R 23 τ 2 ) / ( 1 R 12 R 23 τ 2 ) ,
( R 23 = 1 ) = ( 1 R 12 ) ( 1 τ 2 ) / ( 1 R 12 τ 2 ) .
= Δ L S ( T ) / Δ L B ( T ) ,
α = [ ( ln z ) / ( 2 d ) ] ,
z = ( 1 R 12 ) ( d ) R 23 ( 1 R 12 ) [ ( d ) ] R 12 R 23 .

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