That depends on what the composition of your coating is. You could try ellipsometry, provided you could fit a suitable model. For this, ideally your substrate should be an Si wafer. If you have a film edge, i.e. from a masked region or the dip coated film edge, you could use a technique such as stylus or optical profilometry or AFM. The most suitable technique also depends on whether your film is um or nm thick.

Yes. Measure

I think you will find most of your answers in the following link which will guide you to measure it.

https://www.unm.edu/~solgel/PublicationsPDF/1991/BrinkerFundamentals1991.pdf

Dear researchers

Thank you for your answers

I mean how to measure them by the method of interference fringes

You measure using destructive or non destructive tests as it depends on the type of coating and you use these tests for optimizing.

PLZZ TILE ME ABOUT THIS TOPIC

Dear Abdelkader Hafdallah,

1. ION BEAM ANALYSIS TECHNIQUES: One of the Best Method is Ion Beam Analysis Techniques.

[1] Rutherford backscattering spectrometry (RBS)

[2] Particle induced x-ray emission (PIXE)

[3] Elastic recoil detection analysis (ERDA)

[4] Resonant scattering and Nuclear reaction analysis (NRA)

[5] Ion channeling spectrometry

No sample preparation required, analysis will be done very fast and

direct. Wide range of elemental coverage and can be applied to

crystalline or amorphous materials.

[1] RBS: The energy of the backscattered He ions are dictated by

conservation of energy and momentum between the incident ion and

the scattering atom and can be related to the depth and mass of the target. The amount of backscattered ions from any given element is proportional to its concentration. Therefore RBS can be used as a tool to investigate the depth profile of individual elements in a solid.

[2] PIXE: relies on the spectrometry of characteristic x-rays emitted by the target elements due to the irradiation of a high energy ion beam (typically 1-2 MeV of H or He). It can identify various constituents in a compound target. Has, a detection limit ~1 ppm for thin foils & ~10 ppm for thick samples.

[3] ERDA: When a MeV He ion beam incident on a sample with H and D, the H and D in the sample will be scattered in the forward direction. Spectrometry of these forward recoiled atoms gives rise to the quantitative depth profiling of these species in the sample. Due to relatively small energy loss of H in solid, the depth resolution of this method is typically ~300-600Å. It is also called forward recoil spectrometry (FRS).

[4] NRA: Here energetic particle hits a nucleus in a target, depending on the mass of the particle and target and the energy of the particle, a variety of final products may form. It is useful tool for the detection and profiling of light elements in heavy matrix. It is also known as particle-induced gamma emission (PIGE) when it is the resulting γ-rays that are detected.

[5] Ion Channeling: When an ion beam is well aligned with a low index crystallographic direction of a single crystal, e.g of Si, there is a >95% reduction in the yield of small impact parameter interactions processes, namely RBS, PIXE and NRA.

2. TEM: converging, electron wavefront is produced by concentrating the electron beam into a fine probe at the sample surface, the interaction of the convergent beam can provide information beyond structural data such as sample thickness. Samples cannot be viewed at a full 180° rotation. Sample preparation can be a complex procedure so more time is required. The samples should be less than 100 nm thick.

3. Ellipsometry: Is an optical technique for investigating the dielectric properties of thin films. It can be used to characterize composition, roughness, thickness(depth), crystalline nature, doping concentration, electrical conductivity and other material properties. It is used to characterize film thickness for single layers or complex multilayer stacks ranging from a few angstroms or tenths of a nm to several mmwith an excellent accuracy. Here, the interpretation is not easy.

Few other Standard methods for elemental depth profiling of thin films are mentioned below:

4. Secondary ion mass spectrometry (SIMS).

5. Cross-sectional transmission electron microscopy (XTEM).

6. Scanning Auger microscopy (SAM).

7. Glow discharge optical emission spectroscopy (GD-OES).

8. X-ray photoelectron spectrometry (XPS).

9. Laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS).

10. X-ray fluorescence (XRF).

11. Scanning electron microscope (SEM): SEM analysis can be performed as part of a film layer analysis to determine the thickness of a film.

12. Electron-induced XRF using a scanning electron microscope (SEM), either withenergy-dispersive X-ray spectrometry (SEM-EDX) or with electron-probe microanalysis (EPMA) which uses wavelength dispersive X-ray spectrometry (WDX).

13. Auger electron spectra (AES).

14. Low-energy ion scattering spectroscopy (LEIS), or Ion scattering spectroscopy (ISS).

15. Atomic force microscopy (AFM) or Scanning force microscopy (SFM) is a very-high-resolution type of scanning probe microscopy(SPM).

16. UV-Vis spectroscopy: used to measure the thickness and optical properties of thin films on a wafer.

17. Stylus profilometer: Measures thin film thickness, stress, & surface roughness.

The best method depends on the characteristics of the film material. Also factors like, destructive or non-destructive testing, thin film or thick film, amount of roughness in your film, etc.

I hope the information will help you.

With Best Wishes,

Samir G. Pandya