DESC:FIELD OF THE INVENTION
[001] The present subject matter described herein, relates to field of Near Infrared Spectroscopy (NIRS) with improved illumination module. More particularly, it relates to an apparatus and method for performing multipoint and standoff distance measurement of heterogeneous samples in stand-alone and in-line mode.

BACKGROUND OF THE INVENTION
[002] Near Infrared Spectrometer (NIRS) is a secondary method that characterizes a material based on its absorption in the region of 780 – 2500nm, corresponding to vibrational overtones and combination modes. The main advantage of NIRS is that it is a non-destructive method which allows intact sample analysis without any pre-treatment. To extract spectral information in near infrared region, typically employed a spectrometer and an illumination module based on selected measurement mode. A spectrometer comprises an entrance, reflection/refraction optics for collection and focus the light, a dispersion element such as a refraction/reflection grating for dispersing the light and single/linear array detector placed at focal plane for detecting spectral components of the light and convert them into an electrical signal. Illumination module employed lamp source to illuminate sample and an appropriate optics for collect reflection/transmission light from irradiated sample and couple to the spectrometer.
[003] To enable non-invasive radiation interaction with the material, the NIRS employed few standard measurement modes such are transmittance, transflectance, and diffuse reflectance. The selection of measurement mode depends mainly on sample type or sample location and sensing wavelength region. The improvement the illumination module geometries for employing a measurement mode is a key parameter for highly performing NIRS.
[004] Multipoint analysis, instead of single-point analysis, is required to analyse the heterogeneous samples and to overcome the major interference caused by water and physical attributes e.g. sample size, shape, and hardness. Therefore, the existing methods accommodate multiple fiber probes with combination of NIR spectrometers and a compact Fabry–Perot interferometer to performs simultaneous multipoint analysis in real-time, all the above explained methods are expensive and complex.
[005] Further, to evolve from laboratory equipment into portable for lab, and remote area applications and to create an opportunity for large to small-scale industries and retailers to use the technology, it demands fast, reliable, accurate, portability and cost-effective solutions. Therefore, most existing NIR instruments equipped with a traditional grating spectrometer either consists of fixed grating with a linear array detector (InGaAs) or scanning grating with a single-element detector (InGaAs). The traditional spectrometer based on grating with linear image sensors are very expensive, low resolution, sometimes requires a single or multi-stage thermoelectric cooler (TEC). Simultaneously, scanning spectrometer grating with a single element detector is complicated in the mechanical structure, especially in the-case-of portability.
[006] DMD based NIRnano Scan EVM spectrometer has a high signal-noise ratio (SNR), wavelength selection ability, speed, mechanical stability, and affordable price which make it an alternative for traditional grating-based NIRS and FT-NIRS. Though the NIRnano Scan EVM is a potential and popular choice of analytical tool for NIRS, it performs single point analysis in real time. Other limitations like depth of illumination and size of sample window are identified with the same instrument. Addressing those challenges, the performance of NIRS can be greatly improved.
[007] Representatives of the art can be categorized in accordance of their construction features associated with NIR spectrometers: Scan grating spectrometers, fixed grating spectrometers, DMD spectrometers, compact spectrometers, and multipoint spectrometers.
[008] Representative of the art for scanning grating spectrometer is U.S. Pat. No. 4,027,975 (June7, 1977) to David Turner et al., which discloses a monochromator of classical configuration comprising a concave reflecting grating to collect a light from source through a slit followed by dispersion and focus at exit slit plane. U.S. Pat. No. 5,274,435 (Dec. 28, 1993) to Michael C.Hettrick et al., which employs a diffraction grating which scans the wavelength diffracted to a fixed location by rotating the grating about its surface normal. It provides a wide scanning range without changing any geometrical positions.
[009] Representative of the art for Fixed grating spectrometer is U.S. Pat. No. 5,139,335 (Aug. 18, 1992) to David Turner et al., which discloses a spectrometer configuration comprising a concave holographic grating and an array detector. It permits monitoring a plurality of wavelengths simultaneously without mechanical scanning. U.S. Pat. No. 5,880,834 0(Mar. 9, 1999) to Michael P. Chrisp et al., Which employs imaging spectrometer based on a convex diffraction grating and off-axis concave spherical mirrors. It permits high spectral and spatial resolution when interfacing with a detector array.
[0010] Representative of the art for compact spectrometer is U.S. Pat. No. 7,041,979 B2 (May. 9, 2006) to Michael P.Chrisp, which discloses an imaging spectrometer configuration comprising an entrance slit, two mirrors, an immersive diffraction grating, and array detector. It can be utilized for remote applications where size and weight are of primary importance. U.S. Pat. No. 4,568,187 (1986) to Kita et al., which discloses a compact spectrometer comprising a single concave grating for optimum performance, and functions for both dispersing and imaging, leading to a simplest structure form. U.S. Pat. No. 5,424,826 (1995) to kinney et al., which discloses an optical micro-spectrometer system as infrared spectrometric sensor for specific applications.
[0011] Representative of the art for DMD based spectrometer is U.S. Pat. No. 7,852,475, B2 (Dec. 14, 2010) to Douglas E. Crafts et al., which discloses a scanning optical spectrometer with DMD and detector array to enable multi-wavelength simultaneous monitoring. U.S. Pat. No. 10,309,829 B2 (Jun. 4, 2019) to Jerome J. Workman et al., which discloses a micro mirror spectrometer assembly includes a diffraction grating to disperse broadband light over a range of wavelengths, a detector, a digital micro mirror device (DMD) configured to scan through and reflect at least a portion of the range of wavelengths toward the detector. U.S. Pat. No. 0174777 A1 (Jul. 24, 2008) to Keith Carron et al., which discloses Echelle gratings and microelectromechanical system(MEMS) digital micro-mirror device(DMD) detectors are used to provide rapid, small, and highly sensitive spectrometers.
[0012] Representative of the art for Multipoint analysis is U.S. Pat. No. 8,094,294 B2 (Jan. 10, 2012) to Patrick J Treado et al., which discloses apparatus and methods for assessing occurrence of a hazardous agent in a sample by performing multipoint analysis of the sample.
[0013] The present invention, overcome the challenges of the NIR nano Scan EVM. This module has limitation on its illumination module that does not allow the collection of quality spectral information from the heterogeneous samples at a standoff distance. It allows placing the sample <0.75mm against a sapphire window for accurate measurements and supports single-point analysis. To be adapted for the sample rotating mechanism and standard sample holders, it requires a space of more than 0.75mm between the sapphire window and sample. Therefore, the existing illumination module is not suitable for the multipoint and standoff distant sample analysis.
[0014] To overcome this drawback, we are proposing here a modified optical design of the illumination module to the targeted standoff distance. To optimize the illumination module and its instrumental features, the parameters like active area, illumination depth, and collection of diffuse reflected light from the target samples placed at standoff distances are studied thoroughly.
[0015] With this background, an improved portable NIR Spectrometer is proposed to use for evaluating multipoint sample analysis.

OBJECT OF THE INVENTION
[0016] In an embodiment, the present invention discloses an apparatus for extracting and measuring the spectral characteristics of a heterogeneous sample at a standoff distance and multipoint analysis.
[0017] The object of the invention is to disclose an NIRS with improved illumination module and modified geometry.
[0018] It is another object of the invention to provide an improved illumination module for diffuse reflection measurement mode which enhances the depth of illumination, size of sample window (illuminated active area at sample plane) and for a standoff distance measurement.
[0019] It is another object of the invention to provide an improved illumination module which employs a miniature double filament lens end lamp source for enhanced illumination power.
[0020] It is another object of the invention to provide an improved illumination module with an appropriate collection optics for the collection of diffused reflection light.
[0021] It is another object of the invention to provide an improved illumination module with an appropriate collection lens which enhances the throughput & SNR of the spectrometer.
[0022] It is another object of the invention to provide a newly designed portable NIR spectrometer with improved illumination module which enables it for used in Lab and Remote applications.
[0023] It is another object of the invention to provide a newly designed portable NIR spectrometer with improved illumination module that provides multipoint analysis at less complexity and low cost in comparison to the existing spectrometers.

SUMMARY OF THE INVENTION
[0024] In an embodiment, an apparatus for perform the scan analysis of standoff distant heterogeneous samples is provided.
[0025] The apparatus comprises of Double-filament lens end lamps positioned for controlled the divergence of light emitted by said lamps and illuminate the said sample. The position and angle geometry of the two lamps defined the standoff distance of the said sample, active region for illuminate the said sample, and illumination depth. The said sample is illuminated by said diverging light signals from said lamps and provides diffused reflection, wherein said sample is positioned in said standoff distance & active region and also aligned in said illumination depth such that the more diffused reflection will be achieved from the said sample.
[0026] An optical lens positioned for collect and receiving said diffused reflection light from said sample and for converging said light to NIR spectrometer; and NIR spectrometer includes, a slit for receiving converging diffused light from said optical lens and for diverging said light, a collimated optical system for receiving said diverging light signals from said slit and for collimate said light, a dispersion element for receiving said collimated light from said collimated optical system and dispersing different wavelengths to form separately focused through a focusing optical system onto a digital micro-mirror device (DMD) plane, a condensed optical system for receiving light signal of a selected wavelength by the said DMD and for converge said light, and a detector for detecting each of said selected wavelength signal, wherein said detector detects each of said focused signal and generates a corresponding output signal correlative to the spectral characteristics of the said sample.
[0027] In another embodiment, two-lamp geometry for perform the scan analysis of standoff distant heterogeneous samples is provided. The two double-filament lens end lamps positioned for controlled the divergence of light emitted by said lamps and illuminate the sample. The position and angle geometry of the two lamps defined the standoff distance of the said sample, active region means overlap of illumination area of said two lamps for illuminate the said sample, and illumination depth. The said sample is illuminated by said diverging light signals from said lamps and provides diffused reflection, wherein said sample is positioned in said standoff distance & active region and also aligned in said illumination depth such that the more diffused reflection will be achieved from the said sample.
[0028] An optical lens positioned for collect and receiving said diffused reflection light from said sample and for converging said light to said NIR spectrometer, wherein NIR spectrometer detects and analyze each of said focused signal and predicts content of the said sample.
[0029] In another embodiment, four-lamp geometry for perform the scan analysis of standoff distant heterogeneous samples is provided. Four double-filament lens end lamps positioned for controlled the divergence of light emitted by said lamps and illuminate the sample. The position and angle geometry of the two lamps defined the standoff distance of the said sample, active region means overlap of illumination area of said two lamps for illuminate the said sample, and illumination depth. The said sample is illuminated by said diverging light signals from said lamps and provides diffused reflection, wherein said sample is positioned in said standoff distance & active region and also aligned in said illumination depth such that the more diffused reflection will be achieved from the said sample.
[0030] An optical lens positioned for collect and receiving said diffused reflection light from said sample and for converging said light to said NIR spectrometer, wherein NIR spectrometer detects and analyse each of said focused signal and predicts content of the said sample.
[0031] In another embodiment, an apparatus for perform the multipoint scan analysis of standoff distant heterogeneous samples is provided. Two or Four double-filament lens end lamps positioned for controlled the divergence of light emitted by said lamps and illuminate the sample. The position and angle geometry of the two or four lamps defined the standoff distance of the said sample, active region means overlap of illumination area of said lamps for illuminate the said sample, and illumination depth. Said standoff distance allows a standard sample cups for hold the said sample and scan rotating mechanism, wherein said scan rotating mechanism consists a microcontroller to rotate the motor where the sample holder is rotating and makes several measurements as homogeneous as possible of said sample while the sample holder rotates. The said sample is illuminated by said diverging light signals from said lamps and provides diffused reflection, wherein said sample is positioned in said standoff distance & active region and also aligned in said illumination depth such that the more diffused reflection will be achieved from the said sample.
[0032] An optical lens positioned for collect and receiving said diffused reflection light from said sample and for converging said light to said NIR spectrometer, wherein NIR spectrometer detects and analyze each of said focused signal and predicts content of the said sample.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0033] The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:
[0034] Figure 1 illustrates Sample Detection and Data Processing & Analysis Flow Diagram in accordance with the present invention;
[0035] Figure 2 illustrates Optical Ray Diagram of Illumination Module in accordance with the present invention;
[0036] Figure-3 illustrates Geometry of Illumination Module in accordance with the present invention;
[0037] Figure-4 illustrates Multiview Isometric Drawings of Two & Four-Lamps Illumination Module in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION
[0038] In the present invention, a low cost and newly designed NIR Spectrometer is disclosed with a modified illumination module. Further, the invention achieves illumination depth of 3.5 mm against the existing 0.75 mm and the illumination depth upto 2 mm.
[0039] The present invention discloses an improved NIRS with improved geometry and changes like angle and position of the two/four lens-end double filament lamps and a 3.5mm standoff distance targeted against the sensor window to scan the sample.
[0040] In the present invention Lamps formed an active overlap area of 4.0 mm and were considered the field angle for the design of the collection optics. The Optical throughput was maximized by selecting the appropriate, effective focal length and clear aperture for the collection optics. These are generated by considering both the field angle from the sample active area on the object side and the f / number of the NIR spectrometer as well as slit size on the image side.
[0041] The present invention prevents stray light from entering the spectrometer and minimizes its impact on accurate measurements. A maximum depth of illumination of 2 mm is achieved with present NIR geometry to access the sample location without drastically altering the measurements' accuracy.
[0042] With this the throughput has improved over the entire wavelength range by 40 to 100%, the instrument baseline has improved from <± 0.005Abs to <± 0.001Abs, and improved SNR. The modified illumination module of the NIR spectrophotometer opens up new possibilities for multipoint analysis and combined with chemometrics, has great potential as a stand-alone or inline monitoring tool for food applications.
[0043] In an embodiment, an apparatus for perform the scan analysis of standoff distant heterogeneous samples is provided. The apparatus comprises: Double-filament lens end lamps positioned for controlled the divergence of light emitted by said lamps and illuminate the said sample. The position and angle geometry of the two lamps defined the standoff distance of the said sample, active region for illuminate the said sample, and illumination depth. The said sample is illuminated by said diverging light signals from said lamps and provides diffused reflection, wherein said sample is positioned in said standoff distance & active region and also aligned in said illumination depth such that the more diffused reflection will be achieved from the said sample. An optical lens positioned for collecting and receiving said diffused reflection light from said sample and for converging said light to NIR spectrometer.
[0044] In another embodiment, two-lamp geometry for perform the scan analysis of standoff distant heterogeneous samples is provided. Two double-filament lens end lamps positioned for controlled the divergence of light emitted by said lamps and illuminate the sample. The position and angle geometry of the two lamps defined the standoff distance of the said sample, active region means overlap of illumination area of said two lamps for illuminate the said sample, and illumination depth. The said sample is illuminated by said diverging light signals from said lamps and provides diffused reflection, wherein said sample is positioned in said standoff distance & active region and also aligned in said illumination depth such that the more diffused reflection will be achieved from the said sample. An optical lens positioned for collect and receiving said diffused reflection light from said sample and for converging said light to said NIR spectrometer, wherein NIR spectrometer detects and analyse each of said focused signal and predicts content of the said sample.
[0045] In another embodiment, four-lamp geometry for perform the scan analysis of standoff distant heterogeneous samples is provided. Four double-filament lens end lamps positioned for controlled the divergence of light emitted by said lamps and illuminate the sample. The position and angle geometry of the two lamps defined the standoff distance of the said sample, active region means overlap of illumination area of said two lamps for illuminate the said sample, and illumination depth. The said sample is illuminated by said diverging light signals from said lamps and provides diffused reflection, wherein said sample is positioned in said standoff distance & active region and also aligned in said illumination depth such that the more diffused reflection will be achieved from the said sample. An optical lens positioned for collect and receiving said diffused reflection light from said sample and for converging said light to said NIR spectrometer, wherein NIR spectrometer detects and analyse each of said focused signal and predicts content of the said sample.
[0046] In another embodiment, an apparatus for perform the multipoint scan analysis of standoff distant heterogeneous samples is provided. Two or Four double-filament lens end lamps positioned for controlled the divergence of light emitted by said lamps and illuminate the sample. The position and angle geometry of the two or four lamps defined the standoff distance of the said sample, active region means overlap of illumination area of said lamps for illuminate the said sample, and illumination depth. Said standoff distance allows a standard sample cups for hold the said sample and scan rotating mechanism, wherein said scan rotating mechanism consists a microcontroller to rotate the motor where the sample holder is rotating and makes several measurements as homogeneous as possible of said sample while the sample holder rotates. The said sample is illuminated by said diverging light signals from said lamps and provides diffused reflection, wherein said sample is positioned in said standoff distance & active region and also aligned in said illumination depth such that the more diffused reflection will be achieved from the said sample. An optical lens positioned for collect and receiving said diffused reflection light from said sample and for converging said light to said NIR spectrometer, wherein NIR spectrometer detects and analyse each of said focused signal and predicts content of the said sample.
[0047] The illumination module as disclosed in the present invention is a one of key module of Near Infrared Spectrometer (NIRS) and is used to illuminate the targeted sample and collect more diffuse reflection of light from the sample then couple it into the spectrometer for determining the optical characteristics of a sample. The optical characteristics to be determined by analysing absorption spectra of a sample and are useful to assess the quality attributes of the sample such as moisture, protein, fat, etc. The enhanced optical geometry of the illumination module as disclosed in the present invention is allows to accommodate non-contact measurements, to perform single and multipoint analysis for the standoff distant heterogeneous sample measurement to overcome the major interference caused by water and physical attributes e.g. sample size, shape, and hardness. The near infrared spectrometer with improved illumination module is enabling to use as a stand-alone and in-line mode in various factories for quality control of inventory.
[0048] The present invention studies bulk samples such as solids and liquids in both stand-alone and in-line mode. For example, the sample may be poultry raw material such as soya, maize, de-oiled rice bran, rape seed meal that can be analysed in stand- alone mode to assess the quality attributes and in-line study of blending uniformity in final feed meal mixture at Poultry farms. In-line monitoring of blending of pharmaceutical powders to ensure there is a homogeneous mixtures of the all ingredients in pharmaceutical industries. Post harvesting moisture can be studied at various process stages of dry to storage in many raw food samples. Study the milk quality attributes and adulterants in milk such as fat, protein, water, no fat solids, urea, and etc. in dairy industries. The above are a few examples of the many applications in which the present invention may be employed.
[0049] Referring to Figure 1, a layout of a Near Infrared spectrometer in accordance with an embodiment of the invention is illustrated. The NIR Spectrometer is mainly consists of an illumination module, DMD based polychromator, data process & analysis, and display unit. The illumination module is integrated with DMD based polychromatic module and the whole instrument is positioned at a defined distance from an analyte. The lamps are positioned in illumination module at a defined geometry to illuminate the sample. The sample is placed at overlap region formed by two lamps and is irradiated. The beam of light falls on opaque samples then reflects in different directions that not only does light reflected from the material come from the surface (specular reflection) but some is reflected internally(diffuse reflection). The amount of light absorbed at each wavelength is dependent on the molecular orbital of the targeted material and remaining non-absorbed light is diffusely reflected from the sample. The geometry of the illumination module minimizes the collection of specular information which does not contain any chemical information. The Spectral characteristics raw date is to be captured through collecting more diffuse reflectance light from the sample and directed it to the DMD based polychromator module using an appropriate optics. DMD based polychromator is an ultra-portable post-dispersive spectrometer that can achieve miniaturization, low cost, and high performance, whereas with traditional spectrometer structure these limitation are difficult. DMD in conjuction with a single photo detector and fixed plane grating adds the functionality of programmable wavelength selection. The signal at the photodetector is amplified and converted to a digital raw data. The raw data is processed using pre-processing techniques and build partial least square regression models then predict the spectral contents at data process and analysis unit then display the results.
[0050] Referring to Figure 2, a ray tracing layout of an illumination module in accordance with an embodiment of the invention is illustrated. The illumination module is a removable diffuse reflectance illumination module and is mainly designed for non-contact sample measurements. It mainly consists of lamps to illuminate the sample under test at an defined angle, an optics to capture maximum diffused reflected collimated light from the sample and couple into the DMD based polychromator through a slit, and an optical window is a optically transparent flat window and protect & highly resistant to an outside environment. To increase the source illumination intensity strength at the sample, choose the tungsten halogen lamps having features of lens end bulb and dual filament types. The front end of the glass bulb is formed into a lens to direct more light from the filament to the sample test region and dual filament type lamps are increase the intensity of lamp at sample without increasing the lamp quantity, power or size of the lamps and helps in module downsizing. To increase the signal strength of the spectrometer input, the optics collection region at the sample plane is matched to the illumination overlap region created by the lamps. Sapphire windows are commonly employed as an optical window in a variety of optical products due to its excellent optical characteristics from UV to IR, high strength, chemical inertness, and scratch resistance. Sapphire windows with anti-reflection coating in the specified operating range are recommended for incidence angles of less than 40 degrees to improve optical throughput, but the product's cost will be increased slightly. In non-imaging optical systems, the interference fringes created by this optical window had little impact. Hence for non-imaging applications, optical window specifications such as 3.5 arc minutes parallelism and 2 arc minutes surface flatness are sufficient.
[0051] In the present invention, diffuse reflection mode is selected for sample analysis, where the light source and detector are place on the same side of sample and illuminates the sample at an derived angle so that specular reflections are not collected while collect and directing to the slit. Two tungsten lamps with lens end focus the light beam at about 3mm away from the lamps and intersect past the sapphire window at targeted sample plane and create overlap spot size. The collection optics gathers diffused reflected light from the sample illuminated spot size. This configuration requires the sample be kept at defined distance in space above the sapphire window.
[0052] Referring to Figure 3, ray geometry of an illumination module in accordance with an embodiment of the invention is illustrated. In this invention we proposed modified illumination module geometry to the desired standoff distant sample analysis with improved optical parameters and instrument functionality. It can also overcome the challenges such as non-contact sample analysis, collecting high-quality spectral data from standoff distant sample analysis, multipoint analysis to average out spatial in homogeneities of the samples like bulk and heterogeneous samples, battery-powered operation, and an affordable compact module.
[0053] The optical parameters such as standoff distance(SD) of the sample, sample active illumination area(SAIA), and depth of illumination region(DOIR) is determined mainly by the lamp emission angle, the angle between the lamp axis and sample plane, and the distance between two lamps in the geometry. Multiple configurations were developed for the targeted standoff distance by using a set of equations referred to “1-to-5”. By comparing numerous designs, an optimum illumination module geometry was determined using a lamp emission angle (Ø) of about 14-21°, an angle between the lamp axis and perpendicular to the sample plane(?) of about 39.2-59°, and a distance between two lamps (d1+d2) of about 9-14 mm, as shown in Fig.3. In Fig. 3, S1 and S2 – are lamp emission point, ‘Ø’ is lamp emission angle, ‘L’ – is distance between lamps plane to sample plane, ‘SD’ – is standoff distance between sapphire window to sample plane, ‘?’ – is angle between lamp axis and perpendicular to the sample plane, ‘a’- is lamp half illumination area at 0° angle, and x1,x2,x3 – overlap and non-overlap areas created by two lamps, S1 and S2.
[0054] The resultant illumination module geometry is simulated using Zemax non-sequential simulation tool and studied the illumination power at various standoff distances (SD) against the sapphire window then calculated the corresponding optical parameters such as SAIA and DOIR. From the theoretical geometrical calculations and Zemax simulation results, the invented illumination module achieved SAIA of about 4 mm, DOIR of about 2 mm, and SD of about 3.5mm. The DOIR range of 2.5 to 4.5mm above the sapphire window is used to keep the sample for reliable analysis. Table-1 shows the geometry enhanced parameters of the illumination module.
Table-1: Specifications of ELICO NIR Spectrometer (For Two & Four - Lamp Illumination Modules)
Parameter ELICO NIR Prototype
Design Parameters:
Source Tungsten double filament lens end lamp
Illumination Module Geometry Two-Lamp Geometry and Four-lamp Geometry
Separation of Two Lamps 9-14mm
Lamp-Spectral Divergence Angle 14º-21º
Angle between Lamp axis and Sapphire window 39.2º - 59º
Optical Lens Obj. Space NA 0.15-0.3
Imag. Space NA 0.15-0.29
Geometry Enhanced Parameters:
SD: Standoff Distance 3.5mm
AR: Active Region 4.0mm
ID: Illumination Depth 2.0mm
Performance Enhanced Parameters: (Test Results of Two-Lamp based geometry)
Throughput (Intensity) @ 1350nm 7000 AU
Baseline < ± 0.001
SNR @ Peak Wavelength 15ms 1900 @ 2.34nm
30ms 2500 @ 2.34nm
60ms 10000 @ 23.4nm

[0055] The present invented illumination module modified the angle and orientation of the two lens-end dual filament lamps to achieve the desired 3.5mm standoff distance (SD) against the sapphire window for accurate scanning of the sample. Both lamps formed an SAIA of 4.0mm at the sample position, coinciding with the collection optics’ vision angle. To maximize optical throughput, the field angle from SAIA on the object side and the spectrometer’s “f/number’ (NIR Polychromator) and slit size on the image side are used to determine appropriate and effective focal length as well as clear aperture for designing collection optics. This configuration prevents stray light from entering the spectrometer and reduces its effect on accurate measurements. As the angle between the lamp axis and the vertical axis of the sample plane decreases, the DOIR increases. Fig. 4 shows Multiview Isometric Geometry of the present invented illumination module with two lamps and four lamps.

[0056] A larger standoff distance model requires a larger sample window, larger module size, and high- powered lamps. High-powered lamps consume a lot of power, making the development of battery-powered devices a challenge. Increasing the sample window and device size allows for more stray light and increases the price. Factoring all these challenges in this analysis, we propose an optimized geometry to meet current needs without sacrificing efficiency.

[0057] To examine the impact of invented geometrical illumination module on functionality of the NIR spectrometer, determine its functional parameters such as throughput, baseline, and SNR. The throughput of the NIR instrument was measured by capturing the NIR spectrum from a known standard diffuse reflectance standard. The present invented prototype geometry increases the intensity of the output by a factor of 2-3, and shown the result in Table-1. The initial baseline of the instrument is established by considering the effects of the environment and background noise. To get an accurate absorption profile, subtract the resultant baseline from the sample raw data. Next, a baseline test scan is performed at various gain settings across the entire wavelength range. Finally the corrected signal for the peak-to-peak fluctuations is determined and achieved < ± 0.003 Abs at gain-1 and <±0.001 Abs at gain-16 & 64, and the results are shown in Table-1. Signal-to-noise ratio (SNR or S/N) is a measure that compares the level of the desired signal to the level of background noise. NIR spectrometer requires large SNR and is achieved by the collection of maximum light intensity. Large SNR allows detecting small changes on a large signal and provides more precise measurements. On herein disclosed NIRS, SNR is measured by recording 100 scans at 15 ms, 30 ms, and 60 ms integration times and is determined using the formula below,

[0058] The present invention of NIRS illumination module using the NIR polychromator to perform multipoint scan analysis of standoff distant samples. The proposed module’s geometry improved optical characteristics in terms of SD, SAIA, and DOIR. The standoff distance (SD) achieved is about 3.5mm, allowing standard sample holders to retain the sample for a single point scan and a sample rotation mechanism for multi-point scan analysis. The model achieves an SAIA with a maximum intensity of 4.0 mm at a standoff distance of 3.5 mm from the sapphire window by improving optical geometry. It improves detectivity by a factor of 2-3 by collecting maximum diffused reflection light from the sample by proper collection optics. The DOIR increased to 2 mm, allowing the sample’s position without compromising the accuracy of the analysis. The evaluation results show a noticeable improvements in instrument baseline of around < ±0.001 Abs. The study’s findings revealed a low-cost portable instrument with improved signal to noise ratio and ability to conduct multi-point analysis on bulk, inhomogeneous, and heterogeneous samples. Therefore, it can be concluded that the NIRS is sensitive and is ready to use to build the prediction models to check quality of the samples in many food sectors.

[0059] The present invention has been shown and described with reference to particular embodiments and applications thereof, it has been presented for purposes of illustration by way of examples and description and is not intended to be exhaustive or to limit the invention to the particular embodiments and applications disclosed. The particular embodiments and applications were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such changes, modifications, variations, and alterations should therefore be seen as being within the scope of the present invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.
,CLAIMS:CLAIMS
We claim:
1. An apparatus for multi-point analysis of standoff distant analyte sample using near infrared spectrometer (NIRS), comprising of:
a. an illumination module;
b. an optical lens configured for collecting and receiving diffused reflection light from said sample and for converging said light to said NIR spectrometer;
c. a digital micro-mirror device (DMD) based polychromator;
d. a data process & analysis module; and
e. a display unit;
f. wherein the said illumination module includes a plurality of lamps, optics integrated with DMD based polychromatic module and positioned at a defined distance from analyte sample;
g. wherein the said lamps are positioned in illumination module at a defined geometry to illuminate the sample which is placed at overlap region formed by at least two lamps and is irradiated;
h. wherein said beam of light falls on opaque samples then reflects in different directions that not only does light reflected from the material come from the surface (specular reflection) but some is reflected internally (diffuse reflection) and the amount of light absorbed at each wavelength is dependent on the molecular orbital of the targeted material and remaining non-absorbed light is diffusely reflected from the said sample enabling the prediction for content of the said sample.
2. The apparatus for multi-point analysis as claimed in claim 1, wherein said NIR spectrometer includes:
a. a slit for receiving converging diffused light from said optical lens and for diverging said light;
b. a collimated optical system for receiving said diverging light signals from said slit and for collimate said light;
c. a dispersion element for receiving said collimated light from said collimated optical system and dispersing different wavelengths to form separately focused through a focusing optical system onto a digital micro-mirror device (DMD) plane;
d. a condensed optical system for receiving light signal of a selected wavelength by the said DMD and for converge said light, and a detector for detecting each of said selected wavelength signal, wherein said detector detects each of said focused signal and generates a corresponding output signal correlative to the spectral characteristics of the said sample.
3. The apparatus for multi-point analysis as claimed in claim 1, wherein the geometry of the said illumination module minimizes the collection of specular information that does not contain any chemical information.
4. The apparatus for multi-point analysis as claimed in claim 1, wherein the spectral characteristics date is captured through collecting more diffuse reflectance light from the sample and directed it to the DMD based polychromator module using optics.
5. The apparatus for multi-point analysis as claimed in claim 1, wherein the said DMD in conjunction with a single photo detector and fixed plane grating adds the functionality of wavelength selection and the signal at the photodetector is amplified and converted to a digital data.
6. The apparatus for multi-point analysis as claimed in claim 1, wherein said digital data is processed using pre-processing techniques and build partial least square regression models configured to predict the spectral contents at data process and analysis unit then display the results.
7. The apparatus for multi-point analysis as claimed in claim 1, wherein the said illumination module is a removable diffuse reflectance illumination module and is mainly designed for non-contact sample measurements.
8. The apparatus for multi-point analysis as claimed in claim 1, wherein said lamps are tungsten halogen lamps having features of lens end bulb and dual filament types; and
wherein the front end of the glass bulb is formed into a lens to direct more light from the filament to the sample test region and dual filament type lamps are increase the intensity of lamp at sample without increasing the lamp quantity, power or size of the lamps.
9. The apparatus for multi-point analysis as claimed in claim 1, wherein under non-imaging applications, the optical window specifications are preferably 3.5 arc minutes parallelism and 2 arc minutes surface flatness.
10. The apparatus for multi-point analysis as claimed in claim 1, wherein in order to increase the signal strength of the spectrometer input, the optics collection region at the sample plane is matched to the illumination overlap region created by the lamps.
11. The apparatus for multi-point analysis as claimed in claim 1, wherein in order to increase the signal strength of the spectrometer input, two lamps or four lamps geometry is provided.
12. The apparatus for multi-point analysis as claimed in claim 1, wherein said standoff distance allows a standard sample cup for hold the said sample and scan rotating mechanism, wherein said scan rotating mechanism consists a microcontroller to rotate the motor where the sample holder is rotating and makes several measurements as homogeneous as possible of said sample while the sample holder rotates.
13. The apparatus for multi-point analysis as claimed in claim 1, wherein the separation of Two Lamps is preferably at 9 -14mm, the lamp-Spectral Divergence Angle is preferably at 14º - 21º; and the angle between Lamp axis and Sapphire window is preferred at 39.2º - 59º respectively.
14. An apparatus for multi-point analysis of standoff distant analyte sample using near infrared spectrometer (NIRS) comprising of :
a. an illumination module;
b. an optical lens configured for collecting and receiving diffused reflection light from said sample and for converging said light to said NIR spectrometer;
c. a digital micro-mirror device (DMD) based polychromator;
d. a data process & analysis module; and
e. a display unit;
f. wherein the said illumination module includes a plurality of lamps integrated with DMD based polychromatic module and positioned at a defined distance from analyte sample;
g. wherein the said lamps are positioned in illumination module at a defined geometry to illuminate the sample through sapphire window with anti-reflection coating which is placed at overlap region formed by at least four lamps and is irradiated;
h. wherein said beam of light falls on opaque samples then reflects in different directions that not only does light reflected from the material come from the surface (specular reflection) but some is reflected internally(diffuse reflection) and the amount of light absorbed at each wavelength is dependent on the molecular orbital of the targeted material and remaining non-absorbed light is diffusely reflected from the said sample enabling the prediction for content of the said sample; and
i. wherein the separation between Two Lamps is preferably at 9 - 14mm, the lamp -spectral Divergence Angle is preferably at 14º - 21º; and the angle between Lamp axis and said Sapphire window is preferred at 39.2º - 59º respectively.