Set-up

Our experimental set-up for magneto-optical (MO) analysis is depicted in the figure on the left.
The microscope is a custom-modified Optiphot^® by Nikon^™, equipped with a Glan-Thompson polariser and a rotating polarisation analyser (Nikon^™). The light beam, from the Hg lamp, is collimated by a bi-convex lens before passing through a polariser. After the exciting filter (in the wavelength range centred at 530 nm, in order to obtain the maximum Faraday rotation from the indicator film), the light hits a beam-splitter and is focused by the objective lens onto the indicator surface. The indicator film is put over the superconducting sample inside the cryostat.

Generally, an external magnet, cooled with water, generates a uniform magnetic field in the direction perpendicular to the indicator plane. The refracted light passes through the lens, the beam-splitter and the rotating analyser, before being focalised by the camera lens and captured in the CCD matrix of the video-camera.

The cryostat (on the left) is a custom design by Oxford^™, with continuous flow of refrigerator liquid; an heater and a temperature controller allow working in the temperature range from 3.5K to 350K.

On the right there is a zoom view of the cold finger. On the bottom, the optical picture shows the MO set-up at work.

The MO setup has been improved for magneto-optical and dc electrical transport joined measurements.

è DC current generator Keithley Mod. 224
è 2 channel digital voltmeter Keithley Mod. 2182

A further improvement is in progress: the setup will be integrated with an electric transport measurement setup for fast signal detection.

The main component for the new experimental set up is the ACQIRIS Mod. DP240 8-bit Digitizer board, dual-channel (2GSampling/s).

The 8MB total memory, together with the high frequency bandwidth will allow fast sampling rate and therefore good timing resolution. The fast sampling rate ensures that all high-frequency signal components, up to the full bandwidth of the digitizer, are accurately recorded.

The system will be completed by high quality electronic components for noise reduction.

Data acquisition will be controlled by means of Labview custom-developed software, using the original Acqiris drivers, for full integration and compatibility with the pre-existing magneto-optical measurements software.

è Oxford cryostat (custom-design) Temperature operative range: 4 – 350 K
è Oxford electromagnet (custom-design) Magnetic field up to 0.18 T
è Optiphot Nikon Microscope with a Glan-Taylor polarizer, rotating analyzer and excitation filter in the wavelength range 525-540 nm
è Keithley Mod. 224 current generator
è Keithley Mod. 2182 nanovoltmeter for dc measurements

	Our experimental set-up for magneto-optical (MO) analysis is depicted in the figure on the left. The microscope is a custom-modified Optiphot^® by Nikon^™, equipped with a Glan-Thompson polariser and a rotating polarisation analyser (Nikon^™). The light beam, from the Hg lamp, is collimated by a bi-convex lens before passing through a polariser. After the exciting filter (in the wavelength range centred at 530 nm, in order to obtain the maximum Faraday rotation from the indicator film), the light hits a beam-splitter and is focused by the objective lens onto the indicator surface. The indicator film is put over the superconducting sample inside the cryostat.
Generally, an external magnet, cooled with water, generates a uniform magnetic field in the direction perpendicular to the indicator plane. The refracted light passes through the lens, the beam-splitter and the rotating analyser, before being focalised by the camera lens and captured in the CCD matrix of the video-camera.
	The cryostat (on the left) is a custom design by Oxford^™, with continuous flow of refrigerator liquid; an heater and a temperature controller allow working in the temperature range from 3.5K to 350K.
On the right there is a zoom view of the cold finger. On the bottom, the optical picture shows the MO set-up at work.