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Mid-IR Spectrometer: upconverting Mid-Infrared Light to NIR Light to reach higher performance
The NLIR 2.0 – 5.0 µm Mid-IR Spectrometer is based on a novel measurement scheme that upconverts the MIR light to near-visible light. Using advanced silicon-based light detectors allows outperforming conventional MIR light detectors in sensitivity, speed, and noise, bringing these attractive features and their advantages to the MIR regime.
The NLIR Mid-IR Spectrometer models have sensitivities of -80 dBm/nm or better, with an unprecedented maximum full-spectrum readout rate of 130 kHz! As a result, the spectrometer enables the characterization of light sources and measuring spectral content from chemical processes with a time resolution of less than 10 µs.
The spectrometer is made in different models: S2050–400 is the most sensitive with a maximum 400 Hz full spectrum readout rate; S2050–1k is faster and has better resolution but lower sensitivity; S2050–130k has the best resolution and the highest readout rate. All versions come with an external trigger and a GUI interface for easy plug–and–play measurements in various applications; additionally, API interfaces for MATLAB, Python and C (DLLs) are available.
NLIR spectrometers are also available in convenient bundles that include a light source, optical fibers and probes to perform general transmission and reflection measurements, or measurements on well-defined small areas such as those required during the inspection of small silicon wafer production. Get in touch to discuss your application and request a quote for an instrument or a bundle that meet your needs!
To visit the manufacturer’s page NLIR, click here .
To discover our line of handheld spectrometers for Visible or NIR bands, click here .
Applications of Mid-IR spectrometers
Optical Coating Measurements
A 30 W globar was used as light source for these transmission measurement of coated optical windows: a Ge bandpass filter (BPF) for 3.7 – 4.5 µm and a YAG mirror coated with high reflection at 1064 nm and high-transmission at 2.1 – 4.5 µm. The S2050-400 spectrometer was set to 20 ms exposure time and capturing just single shots. No averaging or smoothing has been applied to the data subsequently. Such measurements are used for coating quality control or even production monitoring.
80 kHz Mid-Infrared Spectrometer
The drive current of a mid-infrared laser at 3329 nm is modulated in amplitude at 1 kHz and the ultra-fast 80 kHz edition of the NLIR 2.0 – 5.0 µm mid-IR spectrometer measures the laser spectrum with a temporal resolution of 12.5 µs. When the drive current is modulated, the amplitude and center frequency of the laser changes, and these characteristics are clearly visible in the data shown in the figure. Measurement done by Marc-Simon Bahr at HAW Hamburg, Department of Information and Electrical Engineering.
kHz-Rate Optical Coherence Tomography
Optical coherence tomography is a well-known in-depth imaging technique in the near infrared that, however, has numerous advantages in the mid-infrared region. The NLIR upconversion technology is used to realize kHz line-rate spectroscopy that enables live mid-infrared OCT monitoring.
40 kHz Single Pulse Measurement
Single pulses from a super-continuum light source with a bandwidth of approx. 3.5 µm – 4.2 µm and a repetition rate of 40 kHz of 2 ns pulses were measured with 80 kHz full-spectrum readout rate. In the figure, (a) shows raw data of 12 ms data acquisition, (b) shows a zoom where every other readout is empty as expected from 40 kHz rep-rate and 80 kHz sampling, (c) shows 10 raw consecutive spectra. The fluctuations in the spectra is by far dominated by noise from the light source.
Based on this measurement, the S2050-130k mid-IR spectrometer is capable of characterizing fast modulations of infrared lasers and other dynamic events.
Plastic Transmission
Computer algorithms can certainly tolerate a much shorter exposure time, and thus a faster acquisition, in the context of plastic recognition or thickness analysis.
Fiber Reflection Probe
A fiber reflection probe is a single-bounce attenuated total reflection (ATR) crystal that has fiber-coupled input and output. In this measurement, light from a 30W globar was coupled to the input fiber, and the output fiber was connected to the S2050-400 spectrometer. By first taking a reference with the ATR probe in air, the probe was subsequently inserted into water, propane-2-ol, and sunflower oil, respectively, producing these absorption plots. The measurements were single-shot at an exposure time of 100 ms, and a 4-pixel wide Gauss filter was scanned through the data for smoothing.
