ARCoptix fiber coupler FT-IR

The ARCoptix FT-IR spectrometer is an all-fibered alternative to our "Rocket" configurations. It features the same components as the FT-NIR or FT-MIR Rocket instruments, with the addition of an internally mounted optical source that enables to modulate light before coupling it to the output port of the device. This architecture is thus more robust to external perturbations such as background thermal emission, as such parasitic light would not go through the interferometer before reaching the detector. Our FTIR-FC is ideal for fibered applications such as reflection probes used for diffuse reflection measurements.

4-TE or Liquid-Nitrogen cooled MCT detectors available
The Arcoptix FTIR-FC can be equipped with both 4-stage thermo-electrically (TE) cooled or liquid-nitrogen cooled MCT detectors. The TE-cooled detectors in the FTIR-FC are the most sensitive TE-cooled detectors availabe on the market and offer a reliable and maintenance-free operation. For ultimate sensitivity levels, the FTIR-FC can also be equipped with a liquid-nitrogen cooled detector. In the NIR, the FTIR-FC can also feature an extended InGaAs detector.


  • Ideal for operation with fibered probes
  • All-in-one solution: source, interferometer, detector and fiber-couplers
  • Most compact fiber-coupled FT-IR on the market
  • Available with TE-cooled or liquid-nitrogen cooled MCT detectors
How does it work?
Permanently aligned interferometer

The heart of the FT-Rocket is dual corner-cube (retro-reflector) interferometer. The two corner-cubes are fixed to a common swinging arm, which rotates to create an optical path difference (with respect to the beam splitter) in the two arms of the interferometer.
This type of design is called a permanently aligned interferometer. This particular arrangement of the interfeormeter is known to be the most robust against vibrations and temperature drifts. It never has to be realigned.
The swinging arm of the interferometer rotates on wear-free flexure system, making this mechanical system extremely robust and durable.

Solid-state reference laser

For measuring the movement of the mirrors, a solid-state reference laser is coupled into the interferometer. Compared to classic HeNe lasers, the solid-state lasers that we use are more compact and have a much longer life-time. They have a very low temperature-induced wavelegnth drift and, when kept at constant temperature with a Peltier element, their wavelength can be stabilized to a few PPM, thus providing a very accurate and reproducible wavelength scale. This is crucial for ensuring a day-to-day and unit-to-unit consistency.

Model-dependent specifications

Product code FTNIR-FC-025-2TE
Beam-spliter material CaF2 ZnSe
Spectral Range [cm-1] 11'000 - 4'000 5'000 - 1'660 5'000 - 830 5000 - 650
Spectral Range [μm] 0.9-2.5 2.0-6.0 2.0-12.0 2.0-16.0
Detector Type InGaAs (2-TE cooled) MCT (4-TE cooled) MCT (LN2 cooled)
D* [cm Hz1/2W-1] >2x10E11 >1x10E11 >4x10E9 >5x10E10
Signal-to-Noise (4cm-1 resolution, 1 min scan time) > 100'000:1 > 40'000:1 > 70'000:1
Recommended fiber Low-OH, multimode silica fiber CIR or PIR depending of the application PIR (polycrystalline) fiber
Internal reference laser Temperature-stabilized, @795nm Temperature-stabilized, @850nm
Built-in light source 20W QTH bulb (2850K) 20 SiC globar (1550K)
Power requirement 40W @12VDC 30W @12VDC


Common specifications

Interferometer type

Permanently aligned, double retro-reflector design

Resolution [cm-1 ]


Wavenumber repetability

Scan frequency

>4 Hz @ 4cm-1

Control laser

solid-state laser @850nm

A/D Converter 24 bit
Operating temperature 10°C-40°C
Free-space input Aperture Ø: 12.7mm
Acceptance full angle: 3.2°
Removable fiber-couplers Connector: SMA 905
Fiber core Ø: up to 1mm
NA=0.25 (lensed coupler) or NA=0.3 (reflective coupler)
Communication Interface USB 2.0
Software Interface

Windows 7/10/11
API for controlling the instrument via our DLL

Dimensions 180mm x 160mm x 80mm (excluding LN2 dewar)
Weight 2200 g (excluding LN2 dewar)


Frequently Asked Questions
What is the equivalent wavelength resolution of my FT-IR?

Owing to its operating principle, a FT-IR delivers a spectrum uniformly sampled over a given spectral range in wavenumbers (ν), with units of cm-1. The wavenumber is simply defined as the inverse of the wavelength (λ). The resolution of an FT-IR is constant in wavenumber (Δν), but varies with wavelength (Δλ) due to the inverse relationship between these two units. The conversion betwen wavenumber resolution and wavelength resolution is Δλ=λ2 · Δν and is shown in the graph below:

How to choose the best detector for my application ?

The choice of a detector is a most sensitive one as it contributes to a large extent to the overall quality of your measurement. ARCoptix offers several types and models of detectors, namely extended InGaAs detectors (2 stage thermo-electric cooling), HgCdTe (MCT) detectors with either thermoelectric cooling (4 stages) or liquid nitrogen cooling as well as pyroelectric (DLATGS) detectors. Selection of a given detector is application driven, and depends on the spectral signatures that you are willing to analyze. In order to deliver a faire comparison between various types of photodetectors (or thermal detectors), the most widespread metric is the specific detectivity (labelled D*), which is given in the figure below for all of our available detectors.

ARCoptix Digital Acquisition Acquisition system: AoDAQ

The AoDAQ is a multi-threading, cross-platform and versatile software that simultaneously takes care of:

  • (1) Handling communication with the FT-IR via USB
  • (2) Processing raw signals to deliver the spectrum
  • (3) Running a TCP ethernet server

The AoDAQ can be installed on all sorts of computers, from desktop machines to embedded, low-power single board computers. Thanks to the hosting of a TCP server, the instrument data and parameters can be accessed locally and/or remotely. All communication with the instrument eventually reduces to a set of TCP/IP commands that allow to quickly acquire data, adjust parameters, monitor the instrument status etc. using the programming environment of your choice.

Free GUI basic software

The FTIR Rocket is delivered with a free Windows 7 & Windows 10 compatible graphical user interface (GUI) program.

The free basic software package allows the user to:

  • Configure hardware measurement parameters (amplifier gain, averaging, ...).
  • Display real-time spectral measurement results.
  • Set reference spectra (white, dark) and choose among raw spectra, transmission or reflection mode.
  • Usual features such as save, open, zoom, rescale...
  • Some specific features related to Fourier transform spectrometry: choose among spectrum or interferogram averaging, apodization, look and save the interferograms, etc.
Free API & Examples

The FTIR Rocket is also delivered with a free API that allows you to control the spectrometer with custom code via our DLLs. Examples are available for the following languages:

  • C++
  • C#
  • Labview
  • Matlab
Advanced data processing & analysis software
In collaboration with Labcognition GmbH in Germany we also offer additional Panorama software packages:
Math Add-on module

contains a set of standard manipulation operations used in spectroscopy, like normalization, derivative, baseline correction, peak picking and more. In addition some special operations are available, like multiplicative scatter correction, thickness correction or standard normal variate correction and others.

Quantity Add-on module
is an expert in multivariate data analysis with quantitative methods like PLS and MLR. A convenient and intuitive wizard guides you through all steps of calibration model development. Complex statistical methods become very easy to use even for non-experienced users.
Search Add-on module
is an ideal add-on to archive your spectroscopic data and related information. It includes spectrum and full text search functionality on spectral libraries of various different library formats or directly on data in the file system.
IRAnalyze software package

is a highly sophisticated IR spectrum interpretation tool. Based on an IR spectrum, it provides you with automatic results for IR bands to functional group correlations and their characteristic frequencies. Furthermore, it is a comprehensive electronic dictionary to browse frequiencies for correlated IR bands.



Fibered reflection probes

ARCoptix offers three types of optical fiber reflection probes for the near infrared and mid-infrared:

  • Near-infrared (NIR) reflection probes are made of low-OH fused silica and transmit efficiently between 400 and 2500 nm. (25'000-4'000cm-1). The bundle consists in 6x 600µm core diameter fibers with one central reading fiber, also with a core diameter of 600µm, held in a ⅛" ferrule.
  • Chalcogenide-IR (CIR) reflection probes transmit IR-radiation in the spectral range of 1-6μm (10000 - 6500cm-1). The bundle consists in 6x 500µm core CIR fibers and a single 500µm core CIR fiber for readout that are held in a ¼" ferrule. These probes ideally match the range of our spectrometers using 2-6 µm MCT detectors.
  • polycrystalline infrared (PIR) reflection probes transmit IR-radiation in the spectral range of 4-18μm.The bundle consists in 6x 400µm core CIR fibers and a single 900µm core CIR fiber for readout that are held in a ¼" ferrule. These fibers ideally match the range of our spectrometers using 2-12 µm MCT detectors.

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