More scattering means more light is absorbed in transmission mode and less light absorbed in reflectance mode.

"A fungal–infected kernel would
also scatter more light than a sound, vitreous kernel because
the invasion of the fungus causes the kernel endosperm to
become powdery (Hesseltine and Shotwell, 1973; Lillehoj et
al., 1976). This scattering would cause more NIR (>750 nm)
radiation to be absorbed in transmission mode, and less NIR
radiation to be absorbed in reflectance mode. Powdery
substances with refractive indices different than air, such as
in the air–endosperm interface of infected kernels, cause
more light to be reflected (Birth and Hecht, 1987), as opposed
to the more crystal–like property of normal kernels."

(Page 1250 in
Pearson, T.C., Wicklow, D.T., Maghirang, E.B., Xie, F., Dowell, F.E. (2001) DETECTING FLATOXIN IN SINGLE CORN KERNELS BY TRANSMITTANCE AND REFLECTANCE SPECTROSCOPY, Transactions of the ASAE, Vol 44(5), 1247 - 1254.)

No deep cooling necessary for InGaAs detector in a range of 900 to 1700 nm

1. "Thermal noise in InGaAs photodetectors is a big issue, so we pay thousands of ... I need 30 – 35 seconds for each sample, will FT-NIR suit? ... with upper limit of 1900 nm, you see that they do not need cooling system and as ... The 2200nm cut off detectors are 10x more noisy than the 1700nmtype, and the ..."

NIR Discussion Forum: Detectors - IM Publications

www.impublications.com › ... › Bruce Campbell's List › Calibration transfer

Feb 17, 2011 - 42 posts

2. "While other sensor technologies are equally capable of covering all or parts of the NIR spectrum covered by standard InGaAs FPAs (900 to 1700 nm), most other technologies have some drawback that make then less attractive. InSb can be used to cover the same range with a high performance sensor but requires cryogenic cooling, resulting in a higher cost, and lower reliability camera due to the sterling cooler. Short wavelength HgCdTe, like InGaAs does not require cryogenic cooling, but is relatively more expensive due to limited commercial availability of he detector material."

From Extended short wavelength spectral response

from InGaAs focal plane arrays

Theodore R. Hoelter, Jeffrey B. Barton

Indigo Systems Corporation, 50 Castilian Drive, Goleta, CA USA 93117

Infrared Technology and Applications XXIX, Bjørn F. Andresen, Gabor F. Fulop, Editors,

Proceedings of SPIE Vol. 5074 (2003) © 2003 SPIE · 0277-786X/03/$15.00

3. "The IK1112 camera is a highly sensitive infrared camera (SWIR, NIR) with 320x256 pixel and a framrate of 110fps. The sensitivity interval reaches from 900nm to 1700nm. The sensor doesn't need active cooling and thus powered by USB bus (no external power supply needed)."

http://www.ehd.de/products/InGaAscameras/InGaAs_SWIR_Infrared_Cameras.html

4. "Unlike other IR detectors, InGaAs detectors do not require deep cooling. However, moderate thermoelectric cooling reduces the detector noise and improves the image quality"

http://83.169.23.21/files/downloads/xenics/eu/NIR_SWIR_FPA_Cameras_eu.pdf

Aluminum presents a constant absorbance throughout the NIR range.

"Aluminum was the chosen material because it presents a constant absorbance throughout the NIR range, i.e. it is optically neutral. This property allows the spectra of the samples to be measured without any interference from the platform." From P. Mishra et al. J. Near Intrared Spectrosc. 23, 15-22 (2015)