High spatial resolution ellipsometer for characterization of epitaxial graphene.

An ellipsometer with 3μm×5μm spot size constructed with a single focusing and imaging element is used to measure the layer number of exfoliated graphene on glass and expitaxial graphene on SiC. Ellipsometric sensitivity to graphene layer number increases with decreasing layer number and decreasing substrate refractive index. Single-atomic-layer sensitivity has been achieved.

An open-source, extensible system for laboratory timing and control.

We describe a simple system for timing and control, which provides control of analog, digital, and radio-frequency signals. Our system differs from most common laboratory setups in that it is open source, built from off-the-shelf components, synchronized to a common and accurate clock, and connected over an Ethernet network. A simple bus architecture facilitates creating new and specialized devices with only moderate experience in circuit design.