The ARCspectro Thin Film Thickness Measurement System
Non-Contact characterization of thin films with a high performant FT-NIR spectrometer

The combination of our high resolution NIR spectrometer and our dedicated Arcspectro Thin-Film software permits us to characterize film thicknesses and refractive indices of materials within minutes.
Thanks to our high performant FT-NIR spectrometer we can measure thick layers from 2 to 800 micrometers with no sample preparation or complex measurement procedure. The Arcspectro Thin-film software (mainly based on FT algorithms) is also capable to handle more complex multi-layer samples. Compared to competitor's products, which are mainly based on grating spectrometers, our system based on a NIR Fourier transform spectrometer (very different from grating spectrometers) has higher performances in SNR and resolution. The Arcspectro thin film is a versatile device that can also be used as a standard high-performance fibered NIR spectrometer for any other application in your lab!
Depending on your application spot size, probe or wavelength range must be adapted. We have almost for every situation a solution. Thanks to our variety of spectrometers (MIR, NIR or even a combination of VIS-NIR) and probes (fibered or direct illumination), we have an impressive toolbox to solve almost any problem.

PRICE of standard NIR system is only 18'900 EUR! (software and standard probe included)
  • Large spectral range (900nm to 2500nm) providing enhanced reliability.
  • Possibility to use MIR spectral range if requested.
  • Very high SNR (measure layers with small refractive index difference)
  • Fast measurements (about 10 seconds)
  • Versatile (NIR spectrometer can be used for other applications)
  • High resolution (permits to measure accurately thick layers up to 0.8mm)
  • Easy maintenance
  • Easy to use. No sample preparation. Simple procedure.
  • Customization of hardware and software on demand
  • Cost effective NIR range system.

Ellipsometry and spectral reflectance, on the other hand, are both non-contact optical techniques that permit to determinate precisely layer thicknesses. The Arcspectro THINFILM NIR spectrometer uses the spectral reflectance of the sample to determine the thickness of the different layers that compose the sample.
Due to the wave-like behavior of the light, the phenomenon of light interferences appears into a layer thinner than the half coherence length of the light. The light reflected at the first interface can interfere with the light reflected at the second interface and their interaction is dependant on the wavelength of the light and the refractive index of the layer. This effect leads to oscillations into the reflectance spectrum measured by this instrument. The frequency of this oscillation gives information about the thickness of the layer and its refractive index

As depicted in the schematic above, the first part of the incoming light is reflected at the interface n1/n2 (point A). The amount of light reflected depends on the incidence angle, n1 and n2. Some light pass through the first interface and is reflected at the second interface (n2/substrate at point B). The two “rays” of light that are reflected back by the sample have a phase difference linked to the optical path difference (OPD) given by ABC-AD.
If this difference is equal to a multiple of 2n, there is a constructive interference and it will lead to a maximum in the reflectance spectrum. If this difference worth 2n+1 , there is a destructive interference and it will result in a minimum in the reflectance spectrum. Finally, some wavelengths will lead to constructive interferences and some to destructive ones. Consequently, modulation with a certain contrast (depending on the phase step between the layers) of the measured spectrum is observed. By applying a frequency analysis (by FFT) of the measured spectrum (picture right) we can deduce the thickness of the layer present on the substrate.
The precision of the measurement will essentially be given by the performance of the spectrometer. The Arcspectro- NIR spectrometer has an excellent SNR and wavelength precision which cannot be achieved by usual grating spectrometers. Also, its high resolution permits to characterize relatively thick films (up to 800um) over a large spectral range.

Other parameters such as the precision of the refractive index of the material, the flatness and alignment of the sample, the divergence of the light will influence the absolute precision of the measurement.

General Specs table:
Features Arcspectro NIR THINFILM
Spectrometer type

Scanning FT-NIR spectrometer (900-2500nm)

Spectral range 900nm-2500nm
Spectral resolution 2cm-1 équivalent to 2 nm (optical, reporting interval: 1nm)
Measurement geometry Fiber illuminated and fiber collected light
Light source Arclight NIR halogen lamp 20W
Measurement time ~10s (depends of averaging)
SNR (Full dynamic range-signle
Thickness repetabiltiy measurement 10 nm
Measurable thickness range 2um to 800um (lower if used with VIS-NIR spectrometer on demand)
Minimal refractive index step < 0.01
Operating temperature 10°C-40°C
Operating power 12V / 15W (line power adaptor is included)
Communication Interface USB
Software interface Windows 7 / 10
Product dimensions 38mm x 25cm x 32cm
Product weight 2 kg
Measurement of thin plastic films

In a few clicks, you can verify the thickness of any plastic film. Ideal for quality control of plastic packing material. Indeed with the Arcspectro THINFILM you can measure films up to 800um which is sufficient for most packaging materials.

Coatings and membranes in Biomedial devices

The Arcspectro THINFILM spectrometer can also be used in the medical field to determine for example determine catheter and angioplasty Balloon wall thickness or on stends, small tubes, implants...Also drug packaging thickness can be determined easily.

Wafers and membranes

In combination with a x-y table the Arcspectro THINFILM can be used for thickness mapping of all sorts of wafers..

Refractive index characterization

Not only films thicknesses but also refractive indices can be determined. Indeed if the user knows exactely the the thickness of the layer (detrmined by other means) it can determine the refractive index of a material.

Materials that are only transparent in the IR

It happens that non-transparent materials must be characterized. Some materials are only transparent in the IR region of the spectrum. In this case, we can combine the Arcspectro THINFILM software in combination with our ARCspectro-MIR spectrometer and also an adequate transparent PIR or CIR fiber.

Contact Arcoptix to discuss your application.

The ARCspectro THINFILM is a Windows 7 & Windows 10 compatible program. The spectrometer is connected to a computer via the USB port and automatically recognized.

The Software is a very easy to use application that permits in a few clicks to measure thickness of layers. An integrated simulation algorithm permits to compare the actual measurement with theoretical measurement with the determined thicknesses and refractive indices, (see user manual in dowload section for more details)

Also standard Arcspectro NIR softwarw is povided with the device in order to be able to use the spectrometer for other measurement setups in your lab.

If you need application specific features or parameters, we can implement them on demand in the program within a few weeks. For any further information please contact us at

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DOWNLOADpdf Manual of ARCspectro THINFILM