Large differences between SEC and SEP indicate too many latent variables are introduced in the model and that data noises is also being modeled.

"Acceptable models should
have lower SEC and SEP, high correlation coefficients
and small differences between SEC and SEP. Large differences
indicate that too many latent variables are introduced
in the model and that data noises is also being
modeled."
page 674 in

Visible/near infrared spectrometric technique for
nondestructive assessment of tomato ‘Heatwave’ (Lycopersicum
esculentum) quality characteristics
by Yongni Shao, Yong He , Antihus H. Go´mez , Annia G. Pereir , Zhengjun Qiu ,
Yun Zhang

Journal of Food Engineering 81 (2007) 672–678

Sugar concentrations relied strongly on the 910 nm sugar CH related bands.

Appl Spectrosc. 2003 Feb;57(2):139-45.

Short-wavelength near-infrared spectra of sucrose, glucose, and fructose with respect to sugar concentration and temperature.

Golic M1, Walsh K, Lawson P.

Author information

Abstract

Short-wavelength near-infrared (SW-NIR) (700-1100 nm) spectra of aqueous solutions of sucrose, D-glucose, and D-fructose were monitored with respect to change in temperature and sugar concentration. Sugar OH and CH related vibrations were identified by analysis of the spectra of sugar solutions in deuterium oxide (D2O), and of sucrose-d8 solutions in D2O. Absorption spectra were explained in terms of the second and third overtones of OH stretching vibrations and the third overtone of CH2 and CH stretchings. In deuterated solutions, CH and CH2 higher overtone vibration bands became apparent. The major spectral effect of decreased temperature or increased sugar concentration was a decrease in absorbance at 960 nm and an increase in absorbance at 984 nm, interpreted as an increase in the degree of H bonding. Partial least-squares (PLS) calibrations on sugar concentrations (with spectra collected at several sample temperatures) relied strongly on the 910 nm sugar CH related bands, whereas calibrations on temperature depended equally on all OH associated vibrations (750, 840, 960, and 985 nm).

PMID:

 

14610949

 

DOI:

 

10.1366/000370203321535033

[PubMed - indexed for MEDLINE]

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)

1100 to 1800 nm winds up being the critical range for many analysis.

Extracted from
http://www.impublications.com/discus/messages/5/213.html?1060210133

"Then there is the detector selection. If we take the visible/NIR cutoff as where the optimum detector choice changes, it is about at 1100 nm. In the wavelength range below 1100, there is limited vibrational information available, so many scanning instruments have that as the lower end of the wavelength range. If you scan only below 1100, many of us would say you are not really doing NIR Spectroscopy, but rather visible. 
For data collected in the reflection mode, the data above 1800 nm or so is of limited utility because absorptions tend to be so strong as to make quantitation in the presence of surface reflection less reliable. 
So, in my experience, 1100 to 1800 nm winds up being the critical range for many analysis, and I recommend to my clients that they make sure that the instrument they buy operates reliably in this range. However, the adjoining wavelengths can add versatility that at times can be very important for specific applications. 

By DJ Dahm "

"Generally, 700 -1800 nm covers almost all applications. If you are considering 700 – 1100 nm then more caution would be advised There will be some calibrations which cannot be replaced with Herschel wavelengths.

By Tony Davies (Td)"

Correlation is not the most important statistic in regression analysis.

Extracted from
http://www.impublications.com/discus/messages/5/6974.html?1280931124


"Correlation is not the most important statistic in regression analysis. The standard error of prediction (SEP) which is the error in predicting the independent validation samples is the first test of any NIR method. You can compare this to the SER for your reference analysis. 

Hope this helps, 

Best wishes, 

Tony"

"The correlation coefficient is influenced by the range. The most important information is given to us by the SEP which answers the question "How variable are the answers from this model"? If the SEP is less than that required for the analysis then you have a method. R and r^2 are important but not the most important or useful statistics. 

Best wishes, 

Tony"

(Tony Davies (td) )