Abstract

Measuring the reflectance and transmittance of narrow samples can be difficult, as the width of the illuminating beam may be greater than the width of the sample. The small sample area can also compound the already time-consuming process of reconfiguring the instrument between reflectance and transmittance measurements by introducing additional alignment problems. A method of measuring the reflectance and transmittance properties of narrow-leaf samples using reflectance configurations only is developed and tested. The method uses a mask and mask correction and relationships between reflectance measurements against contrasting backgrounds to determine sample reflectance and transmittance. The design of the accompanying sample-holding apparatus is also described. In testing, the mean error was less than 1% reflectance∕transmittance, and standard deviation of the error was approximately 1% reflectance and 2% transmittance as compared to samples measured using conventional measurement configurations.

© 2007 Optical Society of America

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References

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  1. S. D. Noble, "Crop and weed leaf reflectance and classification," M.S. thesis (University of Saskatchewan, Saskatoon, SK, 2002).
  2. G. Schaepman-Strub, M. E. Schaepman, and T. H. Painter, "Reflectance quantities in optical remote sensing-definitions and case studies," Remote Sen. Environ. 103, 27 (2006).
    [CrossRef]
  3. C. S. T. Daughtry, L. L. Biehl, and K. J. Ranson, "A new technique to measure the spectral properties of conifer needles," Remote Sens. Environ. 27, 81 (1989).
    [CrossRef]
  4. M. A. Mesarch, E. A. Walter-Shea, and G. P. Asner, "A revised measurement methodology for conifer needles spectral optical properties: evaluating the influence of gaps between elements," Remote Sens. Environ. 68, 177 (1999).
    [CrossRef]
  5. J. W. Harron and J. R. Miller, "An alternative methodology for reflectance and transmittance measurements on conifer needles," presents at the Seventeenth Canadian Symposium on Remote Sensing, Saskatoon, SK, Canada, 16-17 June 1995.
  6. J. R. Miller, Department of Earth and Space Science and Engineering, York University, 4700 Keele Street, Toronto, ON Canada, M3J IP3 (personal communication, 2007).
  7. LI-COR, Inc., 1800-12 Integrating Sphere Instruction Manual (LI-COR, Lincoln, NE, USA), 1988).
  8. D. J. Major, S. M. McGinn, and T. J. Gillespie, "A technique for determination of single leaf reflectance and transmittance in field studies," Remote Sens. Environ. 43, 209 (1993).
    [CrossRef]
  9. O. Lillesaeter, "Spectral reflectance of partly transmitting leaves:laboratory measurements and mathematical modeling," Remote Sens. Environ. 12, 247 (1982).
    [CrossRef]

2007 (1)

J. R. Miller, Department of Earth and Space Science and Engineering, York University, 4700 Keele Street, Toronto, ON Canada, M3J IP3 (personal communication, 2007).

2006 (1)

G. Schaepman-Strub, M. E. Schaepman, and T. H. Painter, "Reflectance quantities in optical remote sensing-definitions and case studies," Remote Sen. Environ. 103, 27 (2006).
[CrossRef]

2002 (1)

S. D. Noble, "Crop and weed leaf reflectance and classification," M.S. thesis (University of Saskatchewan, Saskatoon, SK, 2002).

1999 (1)

M. A. Mesarch, E. A. Walter-Shea, and G. P. Asner, "A revised measurement methodology for conifer needles spectral optical properties: evaluating the influence of gaps between elements," Remote Sens. Environ. 68, 177 (1999).
[CrossRef]

1995 (1)

J. W. Harron and J. R. Miller, "An alternative methodology for reflectance and transmittance measurements on conifer needles," presents at the Seventeenth Canadian Symposium on Remote Sensing, Saskatoon, SK, Canada, 16-17 June 1995.

1993 (1)

D. J. Major, S. M. McGinn, and T. J. Gillespie, "A technique for determination of single leaf reflectance and transmittance in field studies," Remote Sens. Environ. 43, 209 (1993).
[CrossRef]

1989 (1)

C. S. T. Daughtry, L. L. Biehl, and K. J. Ranson, "A new technique to measure the spectral properties of conifer needles," Remote Sens. Environ. 27, 81 (1989).
[CrossRef]

1988 (1)

LI-COR, Inc., 1800-12 Integrating Sphere Instruction Manual (LI-COR, Lincoln, NE, USA), 1988).

1982 (1)

O. Lillesaeter, "Spectral reflectance of partly transmitting leaves:laboratory measurements and mathematical modeling," Remote Sens. Environ. 12, 247 (1982).
[CrossRef]

Asner, G. P.

M. A. Mesarch, E. A. Walter-Shea, and G. P. Asner, "A revised measurement methodology for conifer needles spectral optical properties: evaluating the influence of gaps between elements," Remote Sens. Environ. 68, 177 (1999).
[CrossRef]

Biehl, L. L.

C. S. T. Daughtry, L. L. Biehl, and K. J. Ranson, "A new technique to measure the spectral properties of conifer needles," Remote Sens. Environ. 27, 81 (1989).
[CrossRef]

Daughtry, C. S. T.

C. S. T. Daughtry, L. L. Biehl, and K. J. Ranson, "A new technique to measure the spectral properties of conifer needles," Remote Sens. Environ. 27, 81 (1989).
[CrossRef]

Gillespie, T. J.

D. J. Major, S. M. McGinn, and T. J. Gillespie, "A technique for determination of single leaf reflectance and transmittance in field studies," Remote Sens. Environ. 43, 209 (1993).
[CrossRef]

Harron, J. W.

J. W. Harron and J. R. Miller, "An alternative methodology for reflectance and transmittance measurements on conifer needles," presents at the Seventeenth Canadian Symposium on Remote Sensing, Saskatoon, SK, Canada, 16-17 June 1995.

Lillesaeter, O.

O. Lillesaeter, "Spectral reflectance of partly transmitting leaves:laboratory measurements and mathematical modeling," Remote Sens. Environ. 12, 247 (1982).
[CrossRef]

Major, D. J.

D. J. Major, S. M. McGinn, and T. J. Gillespie, "A technique for determination of single leaf reflectance and transmittance in field studies," Remote Sens. Environ. 43, 209 (1993).
[CrossRef]

McGinn, S. M.

D. J. Major, S. M. McGinn, and T. J. Gillespie, "A technique for determination of single leaf reflectance and transmittance in field studies," Remote Sens. Environ. 43, 209 (1993).
[CrossRef]

Mesarch, M. A.

M. A. Mesarch, E. A. Walter-Shea, and G. P. Asner, "A revised measurement methodology for conifer needles spectral optical properties: evaluating the influence of gaps between elements," Remote Sens. Environ. 68, 177 (1999).
[CrossRef]

Miller, J. R.

J. R. Miller, Department of Earth and Space Science and Engineering, York University, 4700 Keele Street, Toronto, ON Canada, M3J IP3 (personal communication, 2007).

J. W. Harron and J. R. Miller, "An alternative methodology for reflectance and transmittance measurements on conifer needles," presents at the Seventeenth Canadian Symposium on Remote Sensing, Saskatoon, SK, Canada, 16-17 June 1995.

Noble, S. D.

S. D. Noble, "Crop and weed leaf reflectance and classification," M.S. thesis (University of Saskatchewan, Saskatoon, SK, 2002).

Painter, T. H.

G. Schaepman-Strub, M. E. Schaepman, and T. H. Painter, "Reflectance quantities in optical remote sensing-definitions and case studies," Remote Sen. Environ. 103, 27 (2006).
[CrossRef]

Ranson, K. J.

C. S. T. Daughtry, L. L. Biehl, and K. J. Ranson, "A new technique to measure the spectral properties of conifer needles," Remote Sens. Environ. 27, 81 (1989).
[CrossRef]

Schaepman, M. E.

G. Schaepman-Strub, M. E. Schaepman, and T. H. Painter, "Reflectance quantities in optical remote sensing-definitions and case studies," Remote Sen. Environ. 103, 27 (2006).
[CrossRef]

Schaepman-Strub, G.

G. Schaepman-Strub, M. E. Schaepman, and T. H. Painter, "Reflectance quantities in optical remote sensing-definitions and case studies," Remote Sen. Environ. 103, 27 (2006).
[CrossRef]

Walter-Shea, E. A.

M. A. Mesarch, E. A. Walter-Shea, and G. P. Asner, "A revised measurement methodology for conifer needles spectral optical properties: evaluating the influence of gaps between elements," Remote Sens. Environ. 68, 177 (1999).
[CrossRef]

Remote Sen. Environ. (1)

G. Schaepman-Strub, M. E. Schaepman, and T. H. Painter, "Reflectance quantities in optical remote sensing-definitions and case studies," Remote Sen. Environ. 103, 27 (2006).
[CrossRef]

Remote Sens. Environ. (4)

C. S. T. Daughtry, L. L. Biehl, and K. J. Ranson, "A new technique to measure the spectral properties of conifer needles," Remote Sens. Environ. 27, 81 (1989).
[CrossRef]

M. A. Mesarch, E. A. Walter-Shea, and G. P. Asner, "A revised measurement methodology for conifer needles spectral optical properties: evaluating the influence of gaps between elements," Remote Sens. Environ. 68, 177 (1999).
[CrossRef]

D. J. Major, S. M. McGinn, and T. J. Gillespie, "A technique for determination of single leaf reflectance and transmittance in field studies," Remote Sens. Environ. 43, 209 (1993).
[CrossRef]

O. Lillesaeter, "Spectral reflectance of partly transmitting leaves:laboratory measurements and mathematical modeling," Remote Sens. Environ. 12, 247 (1982).
[CrossRef]

Other (4)

S. D. Noble, "Crop and weed leaf reflectance and classification," M.S. thesis (University of Saskatchewan, Saskatoon, SK, 2002).

J. W. Harron and J. R. Miller, "An alternative methodology for reflectance and transmittance measurements on conifer needles," presents at the Seventeenth Canadian Symposium on Remote Sensing, Saskatoon, SK, Canada, 16-17 June 1995.

J. R. Miller, Department of Earth and Space Science and Engineering, York University, 4700 Keele Street, Toronto, ON Canada, M3J IP3 (personal communication, 2007).

LI-COR, Inc., 1800-12 Integrating Sphere Instruction Manual (LI-COR, Lincoln, NE, USA), 1988).

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Figures (10)

Fig. 1
Fig. 1

Sample holder with leaf and clamp section in place.

Fig. 2
Fig. 2

End view of the background modules: (left) black, and (right) white.

Fig. 3
Fig. 3

Cross-sectional overhead view of the integrating sphere faceplate, indicating the threaded mounting hole, and the offset and angle of the sample port.

Fig. 4
Fig. 4

Integrating sphere face and adapters:(A) faceplate adapter ring; (B) large sample holder adapter; (C) integrating sphere face and sample port.

Fig. 5
Fig. 5

Rendered assembly view of sample holder adapters and major components.

Fig. 6
Fig. 6

Sample holder in position, ready for scanning with the black background module.

Fig. 7
Fig. 7

Masked sample holder view port at the bottom of the base module of the sample holder. A section of the white background is visible.

Fig. 8
Fig. 8

Comparison of mask-corrected and uncorrected reflectance of white background to unmasked Spectralon. Mask-corrected and unmasked samples are almost indistinguishable at this scale.

Fig. 9
Fig. 9

Comparison of mean error between calculation of reflectance using Eq. (19) (method A) and Eq. (22) (method B), which accounts for multiple reflections between the sample and background, in four wavebands. Error bars indicate ± 1 standard deviation. Error is relative to the full-beam measurement of the respective samples.

Fig. 10
Fig. 10

Comparison of mean error between calculation of transmittance using the square root of Eq. (17) (method A) and Eq. (23) (method B), which accounts for multiple reflections between the sample and background, in four wavebands. Error bars indicate ± 1 standard deviation. Errors are relative to the full-beam measurements of the respective samples.

Tables (2)

Tables Icon

Table 1 Symbols and Notation Used, Modeled After Schaepman-Strub et al. [2]

Tables Icon

Table 2 Standard Deviation from the Mean of Full-Beam Reference Sample Measurements

Equations (23)

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ρ a abs = ρ s i n s t ρ b 1 i n s t × ρ b 1 i n s t ρ b 2 i n s t × ρ b 2 i n s t ρ b 3 i n s t × × ρ b ( n 1 ) i n s t ρ b n i n s t × ρ n i n s t ρ s t d i n s t × ρ s t d a b s ,
ρ b 1 b 2  …  b n = k = 1 n ρ b k α b k ,
ρ s b 1 = ρ s inst ρ b 1 inst .
ρ s m b 1 = ρ s m inst ρ b 1 inst .
ρ s m b 1 = ρ s inst ( 1 α ) + ρ m inst ( α ) ρ b 1 inst ,
ρ s m b 1 ρ b 2 m b 1 = ρ s inst ( 1 α ) + ρ m inst ( α ) [ ρ b 2 inst ( 1 α ) + ρ m inst ( α ) ] ρ b 1 inst .
ρ s m b 1 ρ b 2 m b 1 = ( 1 α ) ( ρ s inst ρ b 2 inst ) ρ b 1 inst .
ρ s m ( b 1 m b 2 m ) ρ b 2 m ( b 1 m b 2 m ) = ρ s inst ( 1 α ) + ρ m inst ( α ) [ ρ b 2 inst ( 1 α ) + ρ m inst ( α ) ] ρ b 1 inst ( 1 α ) + ρ m inst ( α ) [ ρ b 2 inst ( 1 α ) + ρ m inst ( α ) ] = ( 1 α ) ( ρ s inst ρ b 2 inst ) ( 1 α ) ( ρ b 1 inst ρ b 2 inst ) = ( ρ s inst ρ b 2 inst ) ( ρ b 1 inst ρ b 2 inst ) .
ρ s m ( b 1 m b 2 m ) ρ b 2 m ( b 1 m b 2 m ) = ρ s ( b 1 b 2 ) ρ b 2 ( b 1 b 2 ) = [ A ] ,
( ρ s m inst ρ b 2 m inst ) ( ρ b 1 m inst ρ b 2 m inst ) = ( ρ s inst ρ b 2 inst ) ( ρ b 1 inst ρ b 2 inst ) = [ A ] .
ρ s ( b 1 b 2 ) = [ A ] + ρ b 2 ( b 1 b 2 ) ,
ρ s ( b 1 b 2 ) = [ A ] + ρ b 2 inst ( ρ b 1 inst ρ b 2 inst ) .
ρ s abs = [ [ A ] + ρ b 2 inst ( ρ b 1 inst ρ b 2 inst ) ] × ρ b 1 inst ρ b 2 inst ρ b 1 inst × ρ b 1 abs ,
ρ s abs = [ [ A ] ρ b 1 inst ρ b 2 inst ρ b 1 inst + ρ b 2 inst ρ b 1 inst ] × ρ b 1 abs .
ρ s abs = { [ ( ρ s m inst ρ b 2 m inst ) ( ρ b 1 m inst ρ b 2 m inst ) ] ρ b 1 inst ρ b 2 inst ρ b 1 inst + ρ b 2 inst ρ b 1 inst } × ρ b 1 abs .
ρ s / x = ρ s + ρ x τ s 2 .
τ s 2 = ρ s / L ρ s / D ρ L ρ D ,
ρ s = ρ s / D ρ D τ s 2 .
ρ s = ρ s / D ρ L ρ s / L ρ D ρ L ρ D .
ρ s / x = ρ s + ρ x τ s 2 + ρ s τ s 2 ρ s ρ x + ρ x τ s 2 ( ρ s ρ x ) 2 + + ρ x τ s 2 ( ρ s ρ x ) ,
ρ s / x = ρ s + ρ x τ s 2 ( 1 1 ρ s ρ x ) .
ρ s = ρ s / L ρ L ρ s / D ρ D ρ s / L ρ D ρ L + ρ L ρ s / D ρ D ρ L ρ D ,
τ s 2 = ρ s / L ρ s / L ρ L ρ s ρ s + ρ L ρ s 2 ρ L .

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