Multimodal microscopy

P. Montgomery, M. Flury, F. Anstotz, S. Lecler, V. Maioli, D. Montaner, A. Nahas, F. Salzenstein.

What is multimodal nanoscopy?

The IPP team has been at the forefront of research in the field of interference microscopy for many years. The aims are several. More recently, they concern improving the lateral resolution to beyond the diffraction limit without using markers. The addition of different imaging modalities allows using the same imaging system to access different types of information such as the microscopic surface topography (static and moving), the high-resolution structure of transparent layers and the local spectroscopic response. The use of dedicated environmental chambers allows the study of specific parameters of samples in a controlled environment. The study of specific algorithms allows optimisation of fringe processing and the extraction of the required information.

The team is also extending its field of investigation of samples from the historical application areas of materials and micro- nanotechnologies to those of the biological field. It does this through strong links with local actors in the field (ICS, IPCMS, IGBMC, IPHC, etc.), starting from the fundamental understanding of the basic principles involved, through the development of prototype instrumentation, right through to the technology transfer of the techniques developed.

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  3D profile of a Fresnel micro-lens

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  3D profile of a Hall micro-sensor

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  3D profile of a MOEMS spectrometer

Scanning interference microscopy is a powerful technique based on far field optical reflection microscopy and interferometry that can be used for extracting information on micro- and nanostructures embedded in complex materials, devices and microsystems. While the technique is classically used for measuring static microscopic surface roughness and topography, we have developed other measurement modes and various techniques for improving the measurements.

• Principle

The following topics are covered:

Enhanced resolution: enhanced lateral resolution using glass microspheres to improve the resolving power in 2D reflection microscopy for high detail imaging and in interference microscopy for nanometrology. Studies are performed from both theoretical and experimental points of view. The theoretical study of the imaging properties of microspheres and resolution enhancement is carried out using rigorous 2D FEM simulation under COMSOL. Studies are also performed for developing a rigorous model for surface topography measurement using interference microscopy and in particular, using Phase Shifting Microscopy (PSM).

Local spectroscopy: local characterization of the optical properties of materials, layers and buried interfaces at a local scale of 3.5x3.5 µm and hyperspectral mapping over large areas.

Environmental chambers: measurement of specific material parameters using dedicated environmental chambers to control parameters such as temperature, pressure, humidity or the immersion medium.

4D microscopy (3D+time): 3D topographic measurement in real time of surfaces that evolve aperiodically, such as those found in soft materials, microsystems (MEMS and MOEMS) and chemical reactions.

• 4D Microscopy

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  Real-time aquisition of a 3D image

Tomography: high-resolution characterization of thick (>500 nm) transparent, semi-transparent or translucent layers of materials such as inorganic films, polymer films, colloidal layers or hydroxyapatite (biomaterials). These techniques are also useful for characterising nanostructured photonic devices developed in the theme Photonics Modeling and Simulation.

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  Tomography of 5 µm thick Milar polymer film with internal defects

• Complex layers

Fringe processing algorithms: adaptation of fringe processing techniques for specific imaging modalities. In particular, compact and robust Teager-Kaiser energy operators (TKEO) have been developed for tomography and 4D microscopy and Fourier Transform (FT) algorithms for local spectroscopy measurements together with the Frequency Domain Analysis (FDA) algorithm for the combined high-resolution topography measurements.

Optical nanoscopy: study of basic principles of optical nanoscopy techniques for imaging and characterizing microscopic structures with one or more dimensions at the nanometer scale either optically resolved using super-resolution or unresolved but detectable using nanodetection. Two classification schemes developed give a better perspective of the main techniques available.

• Nanoscopy

Other types of microscopy are also being developed, particularly for biomedical applications:

Full field OCT

Light sheet microscopy

Funding:

• PHC: Tassili
• ANR: LatexDry
• CNRS: NewMaps ("Time", collaboration with ICS)
• Grand Est region: MIRAGE (FRCR)
• University of Strasbourg: Idex conferences
• SPIE: SPIE Photonics Europe
• ICube internal projects: LocalSpec-PV

Past:

• Indonesian government: 2 Scholarships
• EU INTERREG III
• CNRS: PICS, Cooperation, ACO (collaboration with ESPCI, Paris), pRECISION ("Instrumentation at its limits challenge", collaboration with ICS)
• Grand Est Region: SuperMic (post-doc), MIRAGE (FRCR)
• SATT Conectus Alsace: CAM4D, Nano3D, SIBIC
• Industrial: Eotech SA, Michelin
• ICube internal projects: RTPPP, PiMeNtS, GLOBAL-INNOV