Transmittance NIR Spectral Module

1. Key Features

• Integrated transmission optical path: built-in light source, collimating optics, cuvette holder and DLP near-infrared spectral module; insert a cuvette to start measuring.
• 1350-2150nm wavelength coverage: suited to NIR absorption analysis of hydrogen-containing groups such as O-H, C-H and N-H in liquid samples.
• Standard cuvette holder: supports the standard 10mm cuvette format, convenient for laboratory samples and compact instrument integration.
• Flexible communication interfaces: supports USB, UART and optional Bluetooth, connecting to PCs, embedded controllers or portable devices.
• Ideal for liquid detection instrument development: suitable for qualitative or quantitative analysis of beverages, medicinal liquids, fermentation broths, organic solvents and process liquids.

2. Specifications

2.1 Technical Parameters

2.2 Structure and Dimensions

Rear view

Top view

Right view

Isometric view

3. Applications

The NIR-M-T11 is primarily intended for liquid transmission NIR detection. Typical applications include moisture or solvent-ratio analysis, alcohol and organic-solvent concentration measurement, beverage sugar-content and formulation-consistency checks, process monitoring of medicinal or reaction liquids, and fermentation-broth state tracking.

For aqueous samples, the strong NIR absorption region tends to saturate at long path lengths. The product structure supports a standard cuvette holder, but for spectrum display and method development you should choose a short-path cuvette, dilute the sample or reduce the effective path length according to the sample's absorption strength. Illustrative spectra of aqueous samples are uniformly drawn with a short path length of no more than 2mm.

4. Typical Spectra

4.1 Typical Optical Path

The NIR-M-T11 uses an integrated cuvette transmission optical path: continuous near-infrared light from the built-in tungsten lamp is collimated and passes through a standard 10mm cuvette, where the sample selectively absorbs different wavelengths; the transmitted light then enters the DLP near-infrared spectral module for dispersion and detection. Users do not need external fibers, a separate light source or a cuvette holder — simply measure the blank reference and the sample in sequence to obtain a transmittance or absorbance spectrum.

A typical measurement workflow:

1. Insert a cuvette filled with blank solvent or blank matrix and acquire the Reference as the 100% transmission reference.
2. Insert a cuvette filled with the liquid under test and acquire the Sample.
3. In routine calculations no separate baseline is acquired; transmittance is computed directly from Sample and Reference, then converted to absorbance.

4.2 Typical Spectra

Transmission near-infrared measurements typically use absorbance spectra as modeling input. For liquid samples, the 1350-2150nm band lies in the long-wave NIR region and reveals overtone and combination absorption of hydrogen-containing groups such as O-H, C-H and N-H. This band covers key absorptions including the second overtone of the water O-H bond (around 1440nm) and the first overtones of C-H and N-H bonds, and is widely used for concentration analysis of moisture, alcohols, sugars and some organics. When building models, it is recommended to preprocess the absorbance spectra with smoothing, normalization, SNV, and first or second derivatives to reduce the influence of source fluctuation, cuvette variation and temperature drift on the model.

Because the NIR-M-T11 uses a fixed, integrated transmission optical path, typical spectra should be based on spectra actually acquired from real samples and blank references. For product demonstrations, use measured absorbance curves of liquid samples such as aqueous ethanol, sugar water, beverages or medicinal liquids; do not substitute spectra from reflectance samples or external optical-path samples.

The images below are illustrative spectra drawn from typical absorption features and do not represent actual measured data for this model. When preparing display spectra of aqueous samples, keep the path length within 2mm to avoid saturation from the strong water absorption above 1400nm at a 10mm path length; non-aqueous samples are labeled with their actual experimental path length.

Water transmittance-absorbance illustrative spectrum

Aqueous ethanol transmittance-absorbance illustrative spectrum

Glucose solution transmittance-absorbance illustrative spectrum

Dairy sample transmittance-absorbance illustrative spectrum

Organic solvent transmittance-absorbance illustrative spectrum

Fermentation broth transmittance-absorbance illustrative spectrum

5. Ordering Information

5.1 Bare-Board Module Selection

The NIR-M-T11 is a transmission near-infrared spectral module that integrates the light source, collimating optics and a standard cuvette holder. Routine liquid transmission measurements do not require a standard reflectance white reference; prepare blank solvent, quartz cuvettes and filtration or centrifugation consumables according to your sample system. If the sample absorbs too strongly or is turbid, first reduce saturation and scattering errors through a shorter path length, dilution or sample pretreatment.

5.2 Standard Configuration and Optional Accessories

5.3 Enclosed Instrument Selection

For users who are not integrating the module or only need it for experiments, the enclosed transmission instrument NIR-T310 is recommended. The enclosed version adds a protective housing and USB Type-C adapter on top of the bare-board module, making it better suited to field testing, teaching experiments and mobile application validation.

6. Technical Principle

6.1 Chemical Principle

Near-infrared spectroscopy is a form of molecular vibrational spectroscopy. Molecular fundamental vibrations are located mainly in the mid-infrared region, while overtone and combination transitions fall into the 700-2500nm near-infrared region. This product covers the 1350-2150nm band and captures the characteristic absorption of hydrogen-containing groups such as O-H, C-H and N-H, making it suitable for qualitative identification, content prediction and process monitoring when combined with chemometric models.

Near-infrared spectra usually do not rely on a single peak but are modeled using the absorption features of multiple bands. Real projects typically combine preprocessing and modeling methods such as smoothing, normalization, SNV, first and second derivatives, MSC or PLS to reduce the influence of sample form, optical-path differences, scattering and temperature drift.

6.2 Optical Principle

The NIR-M-T11 optical system consists of the built-in tungsten lamp, collimating optics, fixed 10mm cuvette holder and DLP near-infrared spectral module. Continuous near-infrared radiation from the source is collimated and passes through the cuvette sample cell, where the sample selectively absorbs different wavelengths; the transmitted light then enters the spectral module for dispersion and detection. This optical path structurally fixes the relative positions of the source, sample cell and entrance slit, reducing the repeatability errors introduced by external optical-path assembly, fiber coupling and holder alignment.

The spectral module is based on a DLP grating dispersion architecture. Light passes through the slit, is collimated and illuminates the grating (diffraction); after dispersion by the grating, light of different wavelengths lands side by side on the digital micromirror array (DLP). By programming each micromirror, the light of the corresponding wavelength is reflected in sequence onto a single-point InGaAs detector, then converted to a digital signal by the ADC and resolved into a spectral curve. The principle diagram is as follows:

This structure replaces the traditional linear-array detector with a single-point InGaAs detector, reducing system cost while preserving near-infrared spectral acquisition capability, and is suited to miniaturized, high-volume and embedded integration.

6.3 Measurement Principle

Transmission measurement usually acquires the blank reference first, then the sample spectrum. Transmittance can be calculated as T = Sample / Reference, and absorbance as A = -log10(T). For aqueous systems, pay particular attention to the risk of saturation in the strong-absorption region, and use a short path length of no more than 2mm where necessary.

7. Usage Guide

7.1 Software Usage

• First insert a blank cuvette or blank solvent and acquire the Reference.
• Then insert the sample cuvette and acquire the Sample, converting it to transmittance or absorbance.
• Keep the cuvette type, fill height, orientation, temperature and integration time consistent across samples in the same batch.

7.2 Precautions

• Aqueous samples absorb strongly above 1400nm and may saturate at long path lengths.
• Wipe the cuvette outer wall clean to avoid water droplets, fingerprints and bubbles affecting the spectrum.
• Turbid samples can be filtered, centrifuged or diluted to reduce scattering.

7.3 FAQ

Q1: Can the NIR-M-T11 measure aqueous solutions directly with a 10mm cuvette?

A: It can be placed in the standard cuvette holder, but aqueous solutions tend to saturate in the strong NIR absorption region. For formal modeling, choose a short-path cuvette or dilute the sample according to the band and concentration.

Q2: Can the illustrative spectra be used as modeling data?

A: No. The illustrative spectra only show typical absorption regions; actual modeling must use data acquired from the customer's own samples, blank references and fixed experimental conditions.