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This study evaluated the influence of the milling process on solid state of rice flours according to water activity using ATR-FTIR. A band at 1740 cm−1 attributed to the C=O stretching of lipids was detected for crystalline samples, and it disappeared at a high aw range. The CH band at 2930 cm−1 of crystalline samples gradually shifted to a higher wavenumber with aw. This band of the α-formed and wet-milled samples shifted to higher wavenumbers above 0.8aw. A band due to OH stretching mode in the 3500-3000 cm−1 region did not shift with aw. The result obtained from IR spectra suggests that the parameter K calculated by Guggenheim–Anderson–de Boar model reflected not only the interaction between water molecules but also the changes of state in solids. Consequently, the results from this study provide insights about the adsorption properties of nonideal solids such as rice flour.

In this study, the bubbles in rice flour batter were investigated under a constant temperature, because the bubble size distribution is important for the control of food texture. We obtained experimental data using a hand mixer and compared the properties of doughs prepared using six rice flours; each flour was prepared through a different milling process. We also added the size effect of the rice flour particles as the Bond number. Furthermore, we performed a dynamic wettability test to estimate the wettability of the rice flour surface. The results of this test were described well by the Washburn equation, and dccosθ/dp was calculated as a wettability parameter (where, dc = effective diameter of a capillary in a powder bed, cosθ = the contact angle, dp = mean particle diameter of rice flour). If bubble sizes depend mainly on the inertial force, viscous force, surface tension, and gravity, then the normalized mean bubble diameter should be a function of the Reynolds number, Weber number, and Froude number. The mean bubble diameter (dbm) generated by whipping was expected to be affected by the thickness (d) of the rod of the mixer, its movement speed, and physical properties of the material. Therefore, dimensionless mean diameter (dbm/d) was expressed based on a dimensionless equation. In the three‐phase dispersion, different empirical equations were obtained depending on the amount of rice flour added, and the bubble diameter could be predicted using dimensionless parameters. In addition, the equations were generally applicable to the various materials selected for this study. Practical Application The powder properties of rice flour were investigated, and dimensionless parameters were analyzed to construct an appropriate process control system for rice flour‐based food products. Although the process method optimized for flour products is also used for rice flour products in practical situations, the comprehensive evaluation based on dimensionless parameters leads to optimization of the process for rice‐flour based products. Moreover, this optimization might strongly support the creation of a new texture, and thus, the potential for market expansion of rice‐flour based products is considerable.

The purpose of this study was to understand the ordered structure of starch in rice flour based on a physical modification with non-heating, milling, and water sorption through the structural evaluation of rice flour using small-angle X-ray scattering (SAXS) and infrared spectroscopy within the 4000–100 cm−1 region. The SAXS pattern of the samples with low moisture contents subjected to milling yield a band within the 0.4–0.9 nm−1 of the q range owing to a lamellar repeat of starch with an ordered structure in rice flour. We proposed an order parameter using the intensity of the SAXS band to quantify the order structure of starch in rice flour, and the true density was negatively correlated with the order parameter. Infrared band at 990 cm−1 in COH bending mode applied to the hydroxyl group of C6 shifted to a low wavenumber corresponding to the order parameter. A linear correlation was found between the order parameter and the 990 cm−1 and band at 861 cm−1 owing to COC symmetrical stretching of glycoside bond and CH2 deformation of the glucose unit of starch, 572, 472, and 436 cm−1, owing to the pyranose ring in the glucose unit of starch. The identified infrared bands are effective for quantifying the ordered structure of starch at the lamellar level. When subjected to water sorption, the band position at 990 cm−1 shifted to a higher wavenumber above a water activity of 0.7. This result revealed that the water-induced transition of glass to rubber of starch in rice flour can be clearly evaluated through infrared spectroscopy using the band at 990 cm−1. In addition, the band at 861 cm−1 also shifted to a higher wavenumber, whereas those at 572 and 436 cm−1 did not show a significant shift. These results indicate that water sorption slightly affects the internal structure and may mainly affect the surface of starch.

Far-infrared (FIR) and low-frequency Raman bands in the 90–400 cm–1 region of crystalline nylon 6 in α form were assigned based on comparisons of experimental spectra and quantum mechanical calcula...

In this study, the bubbles in rice flour dough were investigated under a constant temperature. The bubble size distribution is important for the control of food texture. If bubble sizes depend mainly on the inertial force, viscous force, and surface tension, then the normalized mean bubble diameter should be a function of the Reynolds number and Weber number. We obtained experimental data using a hand mixer, and compared the properties of doughs prepared using six rice flours; each flour was prepared through a different milling process. We also added the size effect of the rice flour particles as the Bond number. Furthermore, we performed a dynamic wettability test to estimate the wettability of the rice flour surface. The results of this test were described well by the Washburn equation, and dccosθ was calculated as a wettability parameter (where, dc: effective diameter of a capillary in a powder bed, cosθ: the contact angle). The mean bubble diameter (dbm) generated by whipping was expected to be affected by the thickness (d) of the rod of the mixer, its movement speed, physical properties of the material, and gravitational acceleration. Therefore, dimensionless mean diameter (dbm/d) was expressed by a dimensionless equation. The empirical equation obtained was generally applicable to the variety of materials selected for this study.

We present a rapid switching system between a newly developed near-infrared (NIR) spectrometer and its imaging system to select the spot size of a diffuse reflectance (DR) probe. In a previous study, we developed a portable NIR imaging system, known as D-NIRs, which has significant advantages over other systems. Its high speed, high spectral resolution, and portability are particularly useful in the process of monitoring pharmaceutical tablets. However, the spectral accuracies relating to the changes in the formulation of the pharmaceutical tablets have not been fully discussed. Therefore, we improved the rapid optical switching system and present a new model of D-NIRs (ND-NIRs) here. This system can automatically switch the optical paths of the DR and NIR imaging probes, greatly contributing to the simultaneous measurement of both the imaging and spot. The NIR spectra of the model tablets, including 0–10% ascorbic acid, were measured and simultaneous NIR images of the tablets were obtained. The predicted results using spot sizes for the DR probe of 1 and 5 mm diameter, resulted in concentrations of R2 = 0.79 and 0.94, with root mean square errors (RMSE) of 1.78 and 0.89, respectively. For tablets with a high concentration of ascorbic acid, the NIR imaging results showed inhomogeneity in concentration. However, the predicted values for the low concentration samples appeared higher than the known concentration of the tablets, although the homogeneity of the concentration was confirmed. In addition, the optimal spot size using NIR imaging data was estimated to be 5–7 mm. The results obtained in this study show that the spot size of the fiber probe, attached to a spectrometer, is important in developing a highly reliable model to determine the component concentration of a tablet.

The present study aims to suggest a method to identify defective tablets by near infrared (NIR) imaging. A newly developed portable imaging system (D-NIRs) was used in this study, in which the spectrometer is equipped with a high- density photodiode array detector to record high-quality spectra with 1.25 nm spectral resolution. This system is highly portable and allows an image of a target tablet to be developed in approximately 10 s. Normal tablets containing 0.1–20 % magnesium stearate, ascorbic acid, corn starch and talc were prepared. NIR spectra in the 950–1700 nm region of each pixel in a tablet were measured, and NIR images were generated from the second derivative of the spectra at 1213 nm. It was confirmed that the spectral distribution in a tablet passed as a normal distribution by the goodness-of-fit test (p ≤ 0.05). Consequently, the average of the spectra obtained from each pixel of the whole tablet was used to predict the concentration of magnesium stearate. The quantitative accuracy of the prediction model by the second derivative spectra achieved R2 = 0.931 and RMSE = 1.90 %. Defective tablets were prepared with localised magnesium stearate. The skewness of the second derivative in the defective tablet was larger than that of the standard distribution. Specifically, the distribution of defective tablets was biased to the right as compared to the standard distribution. The results of the presented study suggest that spectral imaging combined with distribution analysis is an effective method to identify defective tablets.

This paper presents a nondestructive method for evaluating changes in the moisture content and in the interaction between contents such as protein and water molecule in beef cut by using visible and near infrared spectroscopies. Spectral variations in the 450–1100 nm region were measured for a beef cut using two types of spectrometers. Bands were observed in the 540–570, 600–660 and 920–980 nm regions according to the change in moisture contents. The PLS regression of moisture contents by using the second derivative in the 920–980 nm region provided a very good predictive model with R 2 = 0.96 and RMSE = 0.04. Moreover a band in the 600–660 nm shifted to longer wavelength in the 0.9–1.0 of water activity range and then this band slightly shifted to shorter wavelength in the lower water activity range. This spectral behavior may reflect the appearance and oxidation of myoglobin due to dry in/on beef. Simultaneously, it is very likely that the behavior of each water state; free and bonded can describe well by that band shift. These results obtained therefore provide a fundamental chemical understanding of band behavior in the 600–660 nm region and suggested that one can evaluate the quality degradation in beef cut by using visible and NIR spectral region.

An alternative baseline correction method for diffuse reflection near-infrared (NIR) spectra, searching region standard normal variate (SRSNV), was proposed. Standard normal variate (SNV) is an effective pretreatment method for baseline correction of diffuse reflection NIR spectra of powder and granular samples; however, its baseline correction performance depends on the NIR region used for SNV calculation. To search for an optimal NIR region for baseline correction using SNV, SRSNV employs moving window partial least squares regression (MWPLSR), and an optimal NIR region is identified based on the root mean square error (RMSE) of cross-validation of the partial least squares regression (PLSR) models with the first latent variable (LV). The performance of SRSNV was evaluated using diffuse reflection NIR spectra of mixture samples consisting of wheat flour and granular glucose (0–100% glucose at 5% intervals). From the obtained NIR spectra of the mixture in the 10 000–4000 cm−1 region at 4 cm intervals (1501 spectral channels), a series of spectral windows consisting of 80 spectral channels was constructed, and then SNV spectra were calculated for each spectral window. Using these SNV spectra, a series of PLSR models with the first LV for glucose concentration was built. A plot of RMSE versus the spectral window position obtained using the PLSR models revealed that the 8680–8364 cm−1 region was optimal for baseline correction using SNV. In the SNV spectra calculated using the 8680–8364 cm−1 region (SRSNV spectra), a remarkable relative intensity change between a band due to wheat flour at 8500 cm−1 and that due to glucose at 8364 cm−1 was observed owing to successful baseline correction using SNV. A PLSR model with the first LV based on the SRSNV spectra yielded a determination coefficient (R2) of 0.999 and an RMSE of 0.70%, while a PLSR model with three LVs based on SNV spectra calculated in the full spectral region gave an R2 of 0.995 and an RMSE of 2.29%. Additional evaluation of SRSNV was carried out using diffuse reflection NIR spectra of marzipan and corn samples, and PLSR models based on SRSNV spectra showed good prediction results. These evaluation results indicate that SRSNV is effective in baseline correction of diffuse reflection NIR spectra and provides regression models with good prediction accuracy.

Near infrared (NIR) technology has several attractive features, such as suitability for non-destructive and in situ analysis, suitability for collection of transmission measurements, availability of optical fibres, high-speed monitoring and stability; it is therefore widely used in the analysis of pharmaceuticals, polymers, biological materials, biomedical samples, agricultural products etc. 1–3 Moreover, recently, NIR imaging technology has considerably enhanced the potential of NIR spectroscopy used in practical situations, because it can provide insightful evaluations regarding surface homogeneity, morphology and component distribution in a sample. Consequently, a number of NIR imaging devices have been developed by commercial companies and researchers in the past decade. Generally, imaging devices involving microscopy have been employed to facilitate detailed analysis of the target material. Moreover, portability and the capability to make wide-area measurements at high speed are integral parts of the development of new NIR imaging devices for diverse practical situations such as on-line process monitoring. However, NIR imaging devices which have the above advantages are still under development and elucidation of the optimum evaluation method(s) to predict component distributions in a target based on NIR imaging has not yet been fully realised for most applications. Our research group has collaborated with a number of companies and has recently developed two NIR imaging devices. 4–7

The technique of moving-window two-dimensional heterospectral (MW2DHetero) correlation spectroscopy is proposed. This computational method is based on the ideas of perturbation-correlation moving-window two-dimensional (PCMW2D) correlation spectroscopy and two-dimensional heterospectral correlation analysis. Not only small spectral variations, but also detailed bands assignments were captured using the analysis. This method was applied to near-infrared (NIR) spectra in the 10 000–4000 cm−1 region and mid-infrared (mid-IR) spectra in the 5000–1200 cm−1 region, which were simultaneously detected using a dual-region spectrometer. Near-infrared and mid-IR spectra collected during an alcoholic fermentation process using a solution containing glucose and fructose were reported. Slight time differences for the consumption of sugars compared with the production of ethanol were found between 50 and 150 min. It was concluded that these slight time differences are evidence for different consumption times between glucose and fructose during the fermentation process. The result proved a possibility of the selective monitoring of the simultaneous reaction processes between productive and consumptive components.

In the present study we have developed a new version (ND-NIRs) of a polychromator-type near-infrared (NIR) spectrometer with a high-resolution photo diode array detector, which we built before (D-NIRs). The new version has four 5 W halogen lamps compared with the three lamps for the older version. The new version also has a condenser lens with a shorter focal point length. The increase in the number of the lamps and the shortening of the focal point of the condenser lens realize high signal-to-noise ratio and high-speed NIR imaging measurement. By using the ND-NIRs we carried out the in-line monitoring of pharmaceutical blending and determined an end point of the blending process. Moreover, to determinate a more accurate end point, a NIR image of the blending sample was acquired by means of a portable NIR imaging device based on ND-NIRs. The imaging result has demonstrated that the mixing time of 8 min is enough for homogeneous mixing. In this way the present study has demonstrated that ND-NIRs and the imaging system based on a ND-NIRs hold considerable promise for process analysis.

We aimed to achieve wide area rapid monitoring of the crystallinity change in poly(lactic acid) (PLA) during photodegradation caused by ultraviolet (UV) light by using a newly developed near-infrared (NIR) camera (Compovison). Several kinds of PLA samples with different crystallinities and their blends with poly[(3)-(R)-hydroxybutyrate] were prepared. Their two-dimensional NIR spectra in the 1,000-2,350-nm region were measured by Compovision at a 5-min interval during photolysis. An intensity decrease of the band in the 1,900-1,925-nm region due to the second overtone of the C = O stretching vibration of PLA was observed during photolysis. This suggests that an anhydride carbonyl is produced during photolysis. The NIR image of the crystallinity change monitored by the band at 1,917 nm in the standard normal variate spectra clearly shows the inhomogeneity of crystal evolution. A logarithmic increase was observed for all identified areas in the PLA film; however, the time to reach the maximum crystallinity was slightly different according to the initial crystallinity of the sample. It is likely that the initial crystallinity of the sample influences the degradation speed more than the degradation amount. These imaging results have provided fundamental chemical insights into the photolytic process for PLA, and at the same time they have demonstrated that the two-dimensional spectral data obtained by Compovision are useful for process monitoring of polymers.

The purpose of this review article is to outline the recent progress in near-infrared (NIR) imaging technology with particular emphasis on new instrumentation. Superior features of NIR imaging such as suitability for nondestructive and in-situ analysis, transmission ability, availability of optical fibers, high-speed monitoring and stability are very attractive not only for laboratory-based studies but also for diverse practical applications. In this review, introduction to chemical imaging is described, and then, a comparison among NIR, infrared (IR) and Raman imaging are made. Furthermore, the features of new NIR imaging instruments developed by our research group in collaboration with Yokogawa Electric Corporation and Sumitomo Electric Industries, Ltd. are discussed. Finally, some examples of applications of NIR imaging are introduced. Particularly, the performance and usefulness of the newly-developed imaging devices are demonstrated through their applications to pharmaceutical tablets and polymers.

The feasibility of real-time release testing of bilayer tablets was investigated using near infrared (NIR) spectroscopy. The newly developed polychromator-type NIR spectrometer was used to compare the diffuse reflectance (DR) and transmittance (Tr) NIR spectroscopic techniques. This spectrometer not only performs highly sensitive NIR measurements but also yields the NIR spectra of an intact tablet on a millisecond (ms) timescale; i.e. 500 ms for the DR-NIR measurements and 400 ms for the Tr-NIR measurements. The bilayer tablets were prepared with the first layer comprising 0–10% ascorbic acid (AsA), 20% corn starch, 5% talc, 30% microcrystalline cellulose and 45–35% lactose, and the second layer comprising 20% corn starch, 5% talc, 30% microcrystalline cellulose and 45% lactose; their DR-and Tr-NIR spectra were acquired from both sides of the tablet. With these spectra, the feasibility of DR- and Tr-NIR spectroscopy for the quantitative analysis of AsA in the bilayer tablets was compared. The DR- and Tr-NIR spectra of the bilayer tablets and their second-derivative spectra were studied. The AsA bands were not identified in the DR- and Tr-NIR spectra. However, the AsA bands at 995 nm and 1458 nm were observed in the second-derivative spectra. All the developed regression models predicted the AsA concentration, and regression vectors indicated that the prediction was based on the AsA bands. In addition, the model using the Tr-NIR spectra was able to predict the AsA concentration, even when the bilayer tablet was flipped.

The aim of this study was to clarify the change in the powder properties of rice flour depending on the milling process. Rice flour samples, which have gradual mechanical shock properties, were prepared using different milling methods. Furthermore, the correlation between the starch damage, owing to mechanical shock, and powder properties of rice flour was investigated. The particle size was changed gradually through each milling process; however, the change did not clearly correlate with starch damage. The results of the X-ray diffraction (XRD) pattern of nongelatinized samples showed the typical A-type structure of starch. The crystal structure of starch in rice flour may change to a disorder state with the progress of milling; thus, in this study, instead of crystallinity, we considered the disorder index (DI) calculated from the XRD intensity of samples. Relationship between DI and starch damage was confirmed with R 2 = 0.923. Therefore, the mechanical shock caused by the milling process contributes to the crystal state of starch. The parameter q m calculated from the Guggenheim-Anderson-de Boer (GAB) equation of each sample corresponded to the DI. This result suggested that the sorption site of rice flour decreased, and a positive correlation was observed between the parameter K and DI. Thus, the interaction between the rice flour and water molecules weakened because of the mechanical shock. In addition, the use of a SEM image supports the insight that the change in parameter K may reflect the structural change in the solid phase. These results demonstrated that the change in powder properties of rice flour caused by mechanical shock of the milling could evaluate quantitatively.

This article aims at outlining recent progress in near-infrared (NIR) imaging particularly for polymer science and engineering. NIR imaging is useful in nondestructive and in situ analysis of various kinds of polymers, even thick films and bulk materials. NIR imaging provides novel information about the spatial distribution of sample components, the distribution of different morphologies or physical properties, and dynamic process such as polymer dissolution. In this article, the characteristics and advantages of NIR imaging are described first and then two newly developed NIR imaging instruments are introduced. Finally, several examples of applications of NIR imaging to polymer science and engineering are discussed. Keywords: near-infrared imaging; polymer

This study investigated the heterotrophic growth behavior of mung beans cultivated in an individual bed under water supply. The fresh weight of mung beans in the bed was estimated, and changes in temperature, and oxygen and carbon dioxide concentrations were recorded during the cultivation period. The specific growth rate, oxygen uptake rate, and carbon dioxide evolution rate, based on the fresh weight in the bed, were calculated. Growth under heterotrophic cultivation can be classified into the following three stages. Reductions in specific oxygen uptake rate, specific carbon dioxide evolution rate, and specific energy production rate corresponded to that of specific growth rate. Indicators of biological activity related to oxygen and carbon dioxide were evaluated quantitatively for beds under high-density heterotrophic cultivation. Moreover, the results obtained from this study successfully demonstrate that there is a relationship between the growth of mung beans and indicators of biological activity.

In this work, the growth of fertilized Japanese medaka (Oryzias latipes) eggs was monitored in vivo at the molecular level using near-infrared (NIR) spectroscopy and NIR imaging. NIR spectra were recorded noninvasively for three major parts of a fertilized medaka egg, the embryonic body, the oil droplets and the yolk, from the first day after fertilization to the day before hatching. Principal component analysis (PCA) revealed that water, protein and lipid contents in the egg yolk and oil droplets changed significantly just before hatching. The ratio of the characteristic peaks due to proteins and lipids in the second derivative spectra suggested that the relative concentration of proteins to lipids was constant in the egg yolk, while it dramatically increased just before hatching in the oil droplets. Furthermore, linear discriminant analysis (LDA) predicted the hatching possibility on the next day with 100% and 99.3% accuracy for yolk and oil droplets data, respectively. Two types of NIR images were developed in situ using the band intensities of the lipids and proteins in the second derivative spectra. The egg’s protein and lipid content was successfully visualized noninvasively. This technique should enable noninvasive quality testing of fertilized eggs in the future.

Remote sensing has been studied for evaluation and/or estimation of growth and yields of many types of crops. Most of these were reported on the crops with leaves distribution vertically. On the other hand, for the crops with leaves of horizontal distribution, few remote sensing studies have been reported. Especially, for sweet potato (Ipomoea batatas Lam. cv. kogane-sengan), development of the monitoring technique during cultivating period has been expected.This study was conducted to clarify the relationships between a tuberous root fresh weight per plant and leaf area, experimentally. The spectral characteristics from the leaves of sweet potato were measured by a handheld spectroradiometer during cultivating period. And the relationships among the tuberous root fresh weight, leaf area (LA) and the spectral characteristics were analyzed.The growth estimation index (ND710, 510) was defined as following formula used spectral reflectance of 710 nm and 510 nm; ND710, 510=(R710-R510)/(R710+R510). It was confirmed that there was a negative correlation between LA and the growth index with negative correlation coefficient. It is thought that this originates in the change of the spectral reflectance immediately after planting. Moreover nitrogen content in leaves per plant in growing period was estimated NDVI, RVI and leaf contents indices shown by the following expressions; ND770, 660=(R770-R660)/(R770+R660), ND530, 510=(R530-R510)/(R530+R510).These results showed the possibility of estimating the mass tuberous root during growth with non-destructive technique using spectral reflectance of sweet potato leaves.

This study focused on how to identify a disaster stricken area hit by localized heavy rains using the remote sensing data from trees grown there. It has been known that the condition of a plant reflects the soil water-content. There is a good possibility, therefore, that trees in the areas caught in a heavy downpour should show some observable change in the remote sensing data.The spectral responses of broad-leaf trees, Sudaji (Castanopsis cuspidate (Thunb) Schottky, var. sieboldii Nakai, sp. sudaji), were measured by a handheld spectroradiometer (400 nm to 1,000 nm at 3 nm intervals, IFOV with 3 degrees) at various water-stress levels. From this fundamental experiment, a couple of indices were found to be candidates; normalized differential vegetation index, NDVI and the ratio of reflectances in green and red regions, RIGR, which could represent the water-content. These results were confirmed using aerial photographs as well as video camera images. Images of a video camera with several band pass filters were analyzed of which two band pass filters, namely 660 nm and 750 nm, were usable. Indices were subsequently derived using the following equations, ND750, 660 = (R750 - R660)/(R750 + R660).The concept of water-content fluctuation, WCF, representing the changes of water-content was introduced. WCF was derived by the following equation: WCF = [NDA - NDB]/NDB, where NDA and NDB represent the indices of the water-content of leaves. As the areas with lower WBF values collapsed after several weeks, it was confirmed this concept would be effective in estimating collapsed areas.

This study was conducted to develop a method to evaluate, growth and quality of tea leaves at each growing stage by spectral reflectance analysis. The spectral characteristics of tea canopies were measured using a handheld spectroradiometer during the growth season of new leaves. At the same time, the canopies were recorded with a video camera using several band pass filters. The newly picked leaves were also analyzed using an NIR analyzer to determine their chemical contents. The spectral reflectance curves were differentiated with respect to wavelength on the first and second orders. As a result, several characteristic peaks were identified. Characteristic waveband, CW was defined as the waveband of the characteristic peak ranging within 10 nm. Several indices consisting of these CW were proposed and compared with ground truth data. It was demonstrated that the normalized index, ND770, 660 = (R770-R660)/(R770+R660), strongly coincided with the results of the biomass of new leaves. Moreover, it was shown that the ND770, 540, ND770, 520, and ND540, 520 were in agreed with the quality components of the new tealeaves observed by the NIR products analyzer. Principal component analysis demonstrated that the first component changed according to a quadratic function based on time dependency. Calculating the peak value for this function, it shows that the suitable picked day is determined based on the quality of the tea leaves. AF value calculated by the ratio of amino acid and fiber content has been used as the index of the quality of tealeaves commercially. The ND710, 520 index highly correlated with the AF value. These results suggest that the spectral reflectance measured non-destructively is effective in estimating the leaf quality during the cultivating season.

This study has investigated hydrophilicity changes and their inhomogeneity of TiO2 films on Pyrex glasses by near-infrared (NIR) spectral imaging. Near-infrared spectra of TiO2 films in the 9000–4000 cm−1 region were measured using a newly developed NIR camera named Compovision. A band in the 5400–4800 cm−1 region, which is assigned to a combination ( v2 + v3) mode of bending ( v2) and antisymmetric stretching ( v3) modes of the H2O molecule, was clearly identified and its intensity increased with time in the air. It is interesting that the increased rate rose with ultraviolet (UV) light irradiation (300–400 nm, 1 mW cm−2) compared to without UV light irradiation. This result suggested that the hydrophilicity of TiO2 was enhanced about twice upon the UV light irradiation. Moreover, the NIR images clarified spatial distributions of the hydrophilicity on the TiO2 surface with a significantly wide area (20 × 40 mm) and a high speed (within 5 s for one image). This rapid imaging system enabled us to detect the hydrophilicity change during only 1 min. The potential of this camera is quite superior, not only for basic research, but also for diverse industrial applications.

This review paper reports near-infrared (NIR) imaging studies using a newly-developed NIR camera, Compovision. Compovision can measure a significantly wide area of 150 mmX 250 mm at high speed of between 2 and 5 s. It enables a wide spectral region measurement in the 1,000-2,350 nm range at 6 nm intervals. We investigated the potential of Compovision in the applications to industrial problems such as the evaluation of pharmaceutical tablets and polymers. Our studies have demonstrated that NIR imaging based on Compovision can solve several issues such as long acquisition times and relatively low sensitivity of detection. NIR imaging with Compovision is strongly expected to be applied not only to pharmaceutical tablet monitoring and polymer characterization but also to various applications such as those to food products, biomedical substances and organic and inorganic materials.