LIGHT AND ELECTRON MICROSCOPY

Optical and electronic microscopes are essential analytical tools in the field of conservation and restoration sciences of cultural heritage. Aim of the course is to give, as far as possible, a unitary approach of Optics, introducing step-by-step the differences between optical and electronic instruments, which are due to the different kind of interactions of the two "probes" with matter. The goal is to allow the student to use microscopes with awareness.

The student will be able to align an optical microscope and correctly set-up the aperture in order to work under optimised conditions. He/she will have awareness of the different techniques to be used in relation to the samples to be examined. The student will be able to understand the features of the different signals used in scanning (SEM) and transmission (TEM) electron microscopy and the influence that the different operational parameters may have on the images.

Only basic knowledge of the physics of waves and of electromagnetism are requested.

Visible light and electron features: a comparison.
Geometrical optics.
Inter-relationships between diffraction limit, aberrations, resolution and depth of field.
Abbe’s theory.
Conjugated planes and apertures’ functions.
Light and electron microscopes (transmission, reflection, scanning).
Aberrations.
Light-matter vs electron-matter interaction and contrast mechanisms.
Spectroscopy in the electron microscope (EDS, EELS).

- M. Abramowitz, "Microscope: Basics and Beyond" & W. Davidson, M. Abramowitz, "Optical Microscopy", both may be downloaded from: www.microscopy.fsu.edu (where a great deal of other useful materials may be found)

- A. Armigliato, U. Valdrè, "Microscopia elettronica a scansione e microanalisi", Parte I

- Power point slides and teaching notes

The progress in learning will be checked through the discussion of specific topics pertaining to the theory developed during the classes.

The theory is described in the class with the aid of a Power Point presentation which is given to the students at the end of the course.
The last hours of the course are dedicated to practical demonstration divided in two parts:
1) light microscope: alignment and correct use of field diaphragm and aperture diaphragm (imaging of the back focal plane of the objective lens, also using a diffraction grating); demonstration of birefringence of a calcite crystal and polarisation contrast.
2) TEM: demonstration of bright field on nanoparticles and effect of the objective aperture on the image; high resolution (HRTEM); Fourier Transform of a HRTEM image and use of a mask for the anti-transform, as an aid to understand the Abbe theory of image formation: electron diffraction; EDX microanalysis.
Usually SEM is not demonstrated because already shown in the course Anaytical Chemistry and Archeometry during the first semester.

Italian

Accessibility, Disability and Inclusion

Accommodation and support services for students with disabilities and students with specific learning impairments:
Ca’ Foscari abides by Italian Law (Law 17/1999; Law 170/2010) regarding supportservices and accommodation available to students with disabilities. This includes students with mobility, visual, hearing and other disabilities (Law 17/1999), and specific learning impairments (Law 170/2010). In the case of disability or impairment that requires accommodations (i.e., alternate testing, readers, note takers or interpreters) please contact the Disability and Accessibility Offices in Student Services: disabilita@unive.it.

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