Expand this Topic clickable element to expand a topic
Skip to content
Optica Publishing Group

Method for high-accuracy reflectance measurements in the 2.5-μm region

Not Accessible

Your library or personal account may give you access

Abstract

Reflectance measurements with spectroradiometers in the solar wavelength region (0.4–2.5 μm) are frequently conducted in the laboratory or in the field to characterize surface materials of artificial and natural targets. The spectral surface reflectance is calculated as the ratio of the signals obtained over the target surface and a reference panel, yielding a relative reflectance value. If the reflectance of the reference panel is known, the absolute target reflectance can be computed. This standard measurement technique assumes that the signal at the radiometer is due completely to reflected target and reference radiation. However, for field measurements in the 2.4–2.5-μm region with the Sun as the illumination source, the emitted thermal radiation is not a negligible part of the signal even at ambient temperatures, because the atmospheric transmittance, and thus the solar illumination level, is small in the atmospheric absorption regions. A new method is proposed that calculates reflectance values in the 2.4–2.5-μm region while it accounts for the reference panel reflectance and the emitted radiation. This technique needs instruments with noise-equivalent radiances of 2 orders of magnitude below currently commercially available instruments and requires measurement of the surface temperatures of target and reference. If the reference panel reflectance and temperature effects are neglected, the standard method yields reflectance errors up to 0.08 and 0.15 units for 7- and 2-nm bandwidth instruments, respectively. For the new method the corresponding errors can be reduced to approximately 0.01 units for the surface temperature range of 20–35 °C.

© 2003 Optical Society of America

Full Article  |  PDF Article
More Like This
Accuracy of lowtran 7 and modtran in the 2.0–5.5-μm region

Jonathan C. Wright
Appl. Opt. 33(9) 1755-1759 (1994)

Reflectance-based calibration of SeaWiFS. I. Calibration coefficients

Robert A. Barnes and Edward F. Zalewski
Appl. Opt. 42(9) 1629-1647 (2003)

Reflectance-based calibration of SeaWiFS. II. Conversion to radiance

Robert A. Barnes and Edward F. Zalewski
Appl. Opt. 42(9) 1648-1660 (2003)

Cited By

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access Optica Member Subscription

Figures (11)

You do not have subscription access to this journal. Figure files are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access Optica Member Subscription

Equations (13)

You do not have subscription access to this journal. Equations are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access Optica Member Subscription

Select as filters


Select Topics Cancel
© Copyright 2024 | Optica Publishing Group. All Rights Reserved