This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). A rapidly expanding field of research concerns the development of new techniques for optical imaging of nanometer to micron scale structures, such as biological molecules with integrated functional elements, semiconductor optoelectronic devices and cells. The investigator team proposes to develop an unconventional optical instrument capable of resolving structures on the scale of a few tens of nanometers, by using special correlated states of light (such as entangled two-photon states) in combination with an ultra stable optical platform with nanometer resolution scanning capabilities and recently-developed signal processing algorithms. In order to probe the special light-matter interactions that occur when phonon-induced dephasing is minimal, the system is designed to operate at cryogenic as well as ambient temperatures. The wide wavelength range of this nano-photonics imaging system would enable investigation of structures ranging from semiconductor nanodevices to DNA scaffolds to living cells. The research team consists of experts in the key technological aspects: quantum optics, high resolution optical imaging and high speed image processing, ultra-low vibration and low-temperature operation, and biological system design.
LAYMAN ABSTRACT: This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
Finding ways to use light to probe smaller and smaller structures, down to the tens of nanometer (nm) sizes of emerging synthetic DNA structures and the molecular machines within cells, is of enormous importance for current and future developments in science, technology, and medicine. Because traditional light microscopes can't see structures smaller than a few hundreds of nm, most of today's sub-micron imaging is done using non-optical, atomic force and electron microscopes, which can damage or obscure delicate structures within cells and nanodevices. To achieve high resolution together with the gentle, non-invasive imaging provided by light, the scientific team proposes to build a new type of optical instrument. The features that offer greatly improved resolution, of just a few tens of nm, are use of very special quantum-correlated states of light combined with high stability scanning methods and advanced data processing algorithms. To enable imaging of a wide range of nanoscale systems, the instrument will operate over a large range of light wavelengths, both at room temperature and at the much colder temperatures needed to prevent thermal agitation from degrading special quantum effects of the light on the tiniest, molecular-scale structures. The research team has the appropriate expertise in spectroscopic techniques, quantum optics and cryogenics techniques to be successful in developing this advanced nano-photonic, variable-temperature imaging instrument.
Intellectual merits: We designed, fabricated, and installed a nano-photonics imaging system that is capable of high-resolution optical imaging of optically active samples at temperatures ranging from 6 Kelvin to 300 Kelvin. The system is designed for multiple users and has an 8 Inch diameter "mini optical table" that is also cooled to the same temperature as the sample holder. This provides long-term stability and allows for averaging and scanning in order to enhance the optical resolution of the system. The sample is mounted on a three-dimensional translation system that is based on special piezo knobs that also operate at the same temperature as the sample (6-300 Kelvin). The resolution of the piezo knobs at low temperature is about 1-2 nm per step. Figure 1 shows the translations system with the special piezo knobs, designed in collaboration with Jansen Precision Engineering (JPE). Figure 2 shows the top of this translation system after gold coating (to prevent radiation heating form the 70 Kelvin heat shield) and after installation in the low-temperature chamber. The microscope objective is also inside the low temperature chamber and is mounted onto the radiation shield operating at a temperature of 70 Kelvin. This provides high thermal stability and allows for a small working distance of the objective, of the order 200 micrometers, without causing significant radiation heating of the sample. The system is designed to operate with a pulse-tube cooler. This required a significant effort to decouple the vibrations from the actual setup. The design of the system is such that the actual setup is rigidly connected to a large and massive optical table via thin walled steel rods that provide high stability and low thermal conductance. Figure 3 shows the completed system with at the back of the vacuum system the pulse tube cooler and in front the chamber with the optical imaging system. There are multiple optical windows to provide amply optical excess. The system has been complemented with a dye laser system (Matisse Spectra Physics) that covers the frequency range from 550nm to 590nm (visible behind the vacuum system in figure 3). This allows for the study of few-atoms silver clusters hosted by DNA which, for certain species, have an optical excitation in this frequency range. Broader Impacts: The system requirements are such that various different research topics can be addressed. The topics of primary interest that are related to the research of the PIs, are 1) investigating individual self-assembled silver nanoclusters in DNA, 2) enabling single electron-spin control in semiconductor quantum dots, 3) investigate quantum entangled two-photon microscopy, 4) optical microscopy of life-frozen-life cycles of biological organisms, and 5) optical-cooled atomic-force microscopy. The system is currently being extended and optimized for the study of Ag:DNA samples which have become a topic of great interests for biological imaging applications and led to various publications associated to this NSF Major Research Instrumentation Development project.
