FTIR FTIR

FTIR

FTIR (Fourier Transform Infrared Spectroscopy) is one method of infrared spectroscopy.
First, a sample (solid, liquid, or gas) is irradiated with infrared light, then transmitted light or reflected light is interfered using an interferometer, and spectral information is acquired by Fourier transforming the signal intensity. Analysis is then done on the qualitative, quantitative, and identifying features of substances based on that spectral information.
This method is used in various fields, including chemical analysis, medical treatment, environmental analysis, and material analysis, in the form of an FTIR analyzer or a Fourier transform infrared spectrophotometer.

Hamamatsu products for FTIR

Hamamatsu offers spectroscopic modules and infrared detectors suitable for FT-NIR and FT-IR.

For FT-NIR

FTIR engine (FT-NIR spectrometer)

The FTIR engine is a Fourier transform spectroscopic module that integrates an optical interferometer and a control circuit in a compact housing. It has high sensitivity in the near infrared region of wavelengths 1.1 to 2.5 μm. It fits the palm of your hand, and can be incorporated into an FTIR analyzer. This contributes to the miniaturization and portability of stationary FTIR analyzers, which were the mainstream until now.

Features of FTIR engine

Detection performance on par with stationary FTIR equipment

To eliminate the decrease in incident light level caused by miniaturization, we used Hamamatsu original MEMS technology to develop a movable mirror that composes the actuator inside the optical interferometer, then improved upon it so that the reflected light can be used efficiently. Furthermore, we integrated the movable mirror and the fixed mirror as a MEMS chip, thereby making it compact and reducing error in the relative angle between the mirrors to about 1/100. By optimizing the structure and drive method of the MEMS actuator and eliminating blurring when in operation, we have suppressed the spread of infrared light inside the optical interferometer and reduced loss. By doing so, we have realized detection performance comparable to conventional stationary type devices.

Realizes high wavelength reproducibility

Optical interference occurs when the light being measured (incident light) is split by a beam splitter, reflected by the movable mirror and fixed mirror, then combined again. Interference light intensity, which changes depending on the position of the movable mirror, is detected by a photodetector (InGaAs PIN photodiode), then the signal is subjected to arithmetic processing (Fourier transform) to obtain the optical spectrum. By measuring the position of the movable mirror inside the interferometer using a photodetector (Si PIN photodiode) and semiconductor laser (VCSEL), it is possible to obtain an optical spectrum with high wavelength reproducibility.

FTIR engine measurement example

Reflection measurement (absorbance comparison of sugar)

Comparing the reflection measurement results of sugar powder samples (glucose, sucrose) from the FTIR engine and from a stationary spectrometer, we found it was possible to accurately measure even minute peak patterns with the FTIR engine, similar to spectra obtained with the stationary spectrometer.

 Transmission measurement (Comparison of absorbance of alcoholic beverages and estimation of alcohol concentration)

In the near infrared region of wavelengths 1.1 to 2.5 μm, there is absorption by OH groups in water (1.45 μm band, 1.9 μm band) and absorption by CH groups of alcoholic beverages (2.1 to 2.5 μm). With transmission measurement results, we were able to obtain the characteristic spectrum in the absorption bands of water and alcoholic beverages. In addition, with the results of estimating the alcohol concentration from absorbance in the 2.3 µm band, we confirmed that the estimated values and numerical values of components contained in the beverage matched, and that high accuracy measurement is possible.

FTIR engine applications

We expect to find many applications for FTIR engines in a wide range of situations where it was difficult to make measurements in a timely manner, including pre-harvest inspection of agricultural products, soil analysis, and plastic screening.

Recommended product

Compact Fourier transform infrared spectroscopic module

Various measurement examples by FTIR engine

Various data measured by HAMAMATSU and external experts are available.

For FT-IR

Type Ⅱ superlattice infrared detector

This is an infrared detector for FTIR, given sensitivity up to the 14 μm band with the Hamamatsu original crystal growth technology and process technology. It does not contain mercury or cadmium, an RoHS regulated substance, so it can be used as a substitute for MCT photovoltaic detectors.

Type Ⅱ superlattice infrared detector features

High sensitivity up to the 14.5 μm band

With this, we realized a cutoff wavelength of 14.5 μm, which is longer than that of conventional MCT photovoltaic detectors. It also has excellent linearity that realizes a wide dynamic range, and this is expected to contribute to higher accuracy in FTIR analyzers.

Module type is also available.

We also offer the "Infrared detection module with preamplifier C15780-401”, which comes equipped with the Type Ⅱ superlattice Infrared Detector. Similar to the MCT detector, no power supply to the detector is necessary, so it can run with low current consumption.

Recommended products

Detectable wavelength: 1 to 14.5 μm

Detectable wavelength: 1 to 2.5 μm

Detectable wavelength: 1 to 3.8 μm

Detectable wavelength: 1 to 5.5 μm

Detectable wavelength: 1 to 11 μm

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