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Characterization methods of optical components: spectrophotometry and microscopy

Once the design and realization of optical components, it is important to be able to characterize them in terms of optical response and geometrical properties. In this context, the RCMO team has different spectrophotometry or microscopy instruments.

1- Spectrophotometric characterisation

Reflection / Transmission / Absorption measurements of optical filters are done with spectrophotometers developed by the company Perkin Elmer. We have two spectrophotometer Lambda 1050+, and four independent modules of measurement.

The first measurement module is classical, and allows the flow transmission measurement. It uses 3 detectors PMT, InGaAs, PbS, allowing to cover the spectral range 185-3300nm, with a dynamic range higher than 10^6. The accuracy is of the order of 0.1% in absolute value, the achievable resolutions are of the order of 0.1nm in the UV/vis and 0.2nm in the NIR.

The second module (TAMS) was developed by OMT solution and allows an automated measurement in reflection and transmission of a sample placed on a motorized plate allowing a 360 degrees rotation. The detectors, either Si or InGaAs detectors, are also mobile around the axis of the sample support. The spectral range covered is between 250 and 2500nm, and the polarization and incidence are also tunable.

The third module is a URA accessory, with an absolute measurement in reflection in the range 250-2500nm.

Finally, unique in France, we have an 8RT module allowing the measurement under strictly identical conditions of illumination and detection, in reflection and transmission, with an integration sphere, but for a fixed incidence of 8 degrees.

View of the Lambda 1050+ system and the associated motorized module

Fundings: PACA Region

Contacts: Fabien Lemarchand/Julien Lumeau

2- Scanning Near field Optical Microscopy (s-SNOM)

SNOM has become an essential tool for optical characterization at the nanoscale for researchers in nanophotonics. This sub-wavelength microscope can exceed the diffraction limit and reach a spatial resolution of 10 nm. When properly coupled with appropriate illumination and detection, it can be used in many applications. Based on the AFM technique, the s-SNOM offers great flexibility and imaging and spectroscopy capabilities over a wide range of wavelengths, with the optical near field extracted from the scattered light resulting from the sample-tip interaction.

Our s-SNOM configuration is a reflection configuration allowing to perform imaging in the visible range. The light detection uses an interferometric system to record both the amplitude and the phase of the optical signal as well as the topography and the mechanical phase. Furthermore, in collaboration with Neaspec Gmbh Attocube, we performed IR local spectroscopy (nano-FTIR) study on plant cell walls.

Multi-modal s-SNOM for local imaging of structure and associated physical properties

Collaborators: Neaspec Gmbh Attocube

Fundings: PACA Region

Contact: Aude Lereu