NLIR S76120 Prototype Mid-Infrared Upconversion Spectrometer (7.6–12 µm)

Overview

The NLIR S76120 Prototype is a high-speed, upconversion-based mid-infrared (MIR) spectrometer engineered for operation across the 7.6–12 µm spectral band (1316–833 cm⁻¹). Unlike conventional thermal-detector-based MIR instruments—such as those employing mercury cadmium telluride (MCT) or thermopile arrays—the S76120 leverages patented nonlinear optical upconversion technology developed at DTU Fotonik. In this architecture, incident MIR photons are mixed with a fixed-wavelength pump laser in a periodically poled lithium niobate (PPLN) crystal, generating near-infrared (NIR) signal photons via sum-frequency generation (SFG). These upconverted photons are then detected by a high-quantum-efficiency, low-noise silicon CCD or CMOS sensor—enabling orders-of-magnitude faster acquisition and superior signal-to-noise ratio (SNR) at room temperature.

Key Features

• Real-time spectral acquisition at up to 50 full-spectrum frames per second, supporting dynamic process monitoring and transient event capture.
• High spectral resolution of 8–10 cm⁻¹ across the entire 7.6–12 µm range, suitable for resolving fundamental vibrational bands of organic molecules, gases (e.g., CH₄, CO₂, NO₂), and polymers.
• Free-space optical input with large acceptance aperture (2.1° FWHM full-angle FOV), facilitating straightforward alignment with ATR crystals, gas cells, fiber-coupled probes, and collimated broadband sources.
• Room-temperature operation without cryogenic cooling—eliminating vacuum dewars, liquid nitrogen logistics, and associated thermal drift.
• Polarization-sensitive design (optimized for vertically polarized input), enabling polarization-resolved measurements when integrated with external waveplates or polarizers.
• 14-bit digitization with calibrated dark noise floor of ≤7 counts RMS (100 ms integration), ensuring quantitative stability over extended measurement sessions.

Sample Compatibility & Compliance

The S76120 prototype supports diverse sample configurations including transmission through thin films or gas cells, specular and diffuse reflection from solids and powders, and evanescent-wave sampling via ATR accessories. Its wide spectral coverage overlaps key molecular fingerprint regions—particularly C–H stretch/bend, C=O, N–H, and O–H vibrations—making it applicable to pharmaceutical raw material ID (per USP , ), polymer composition analysis (ASTM D3418, ISO 4624), and environmental gas quantification (EPA Method 320). While the current prototype is not yet certified for GMP/GLP environments, its digital output architecture is compatible with audit-trail-ready software platforms that support 21 CFR Part 11-compliant data handling when deployed with validated acquisition systems.

Software & Data Management

The spectrometer interfaces via USB 3.0 to NLIR’s proprietary control and analysis suite, which provides real-time spectral visualization, wavelength calibration (using built-in reference lines), background subtraction, and export in HDF5, CSV, and JCAMP-DX formats. API support (C/C++, Python, MATLAB) enables integration into custom automation frameworks—for example, coupling with LabVIEW-based industrial PLCs or Python-driven machine learning pipelines for spectral classification. All acquired spectra include embedded metadata: timestamp, integration time, detector temperature, and user-defined experimental tags—ensuring traceability and reproducibility in multi-user lab environments.

Applications

• Real-time monitoring of chemical reactions and catalytic processes in flow reactors.
• In-line quality assurance of polymer extrusion, coating uniformity, and pharmaceutical tablet film integrity.
• Non-contact identification of hazardous substances in security screening or waste sorting systems.
• Characterization of optical coatings and metamaterials via reflectance/absorbance mapping.
• Time-resolved spectroscopy of ultrafast laser-induced phenomena (e.g., carrier dynamics in 2D materials).
• Calibration reference for FTIR systems requiring high-SNR validation in the long-wave MIR region.

FAQ

What is the primary advantage of upconversion detection over traditional MCT detectors?
Upconversion eliminates thermally induced dark current, enabling room-temperature operation with sub-pW/nm sensitivity and microsecond-level temporal resolution—unachievable with cooled MCT under comparable optical throughput.
Is spectral calibration traceable to NIST standards?
Yes—factory calibration uses certified gas absorption lines (e.g., N₂O, CO) and is documented with uncertainty budgets compliant with ISO/IEC 17025 guidelines; end-user recalibration tools are provided.
Can the S76120 be fiber-coupled?
The prototype features free-space input only; however, NLIR offers optional collimator modules for coupling to multimode ZrF₄ or chalcogenide fibers (6–12 µm transmission), subject to angular and NA constraints.
Does the system require laser safety certification?
The internal pump laser (1550 nm) is fully enclosed and Class 1 compliant per IEC 60825-1; no external interlocks or operator training beyond standard lab safety protocols are required.
How is input power nonlinearity corrected?
A two-point power calibration routine (low/high intensity reference) is implemented in firmware to linearize response across the full dynamic range (−67 to −30 dBm/nm).