Photo of the Month
The November issue of Popular Science features an article about Matt Rosen and the Low Field Imager (LFI). Since being relocated to the Martinos Center in Charlestown MA, the low-field laboratory has been able to make rapid progress in the group's long-running low-field MRI program. The LFI lab houses several new and novel imaging activities and its location in the Center facilitates collaboration with a wide range of biological imaging research groups. The full article, "The DIY MRI", is available here.
Exterior view of the Northwest Building on the main Harvard campus, which houses a variety of researchers in multiple disciplines including neuroscience, systems biology, bio-engineering, and physics. Part of the Walsworth group has recently moved into a new lab here, facilitating ongoing collaborations related to efforts to develop novel techniques for biological imaging.
Ron Walsworth at the nano-MRI conference in France talking with Dan Rugar and John Mamin of IBM.
In recent months, the open-access, low-field MRI system - built for posture-dependent lung imaging in the Walsworth Group laboratory - has been redesigned and upgraded signficantly. The imager previously seen here, has been relocated to the Martinos Center for Biomedical Imaging at Massachusetts General Hospital. Shown above is a glass head "phantom", which we use to optimize and practice the high-speed imaging sequences used for hyperpolarized gas imaging in the human lung. Take a video tour of the imaging laboratory here.
Pictured above is a confocal microscope we have constructed for the imaging single NV centers, with the goal of comparing their individual coherence properties to the ensemble characteristics measured in the first apparatus. This comparison can be carried out for a range of diamond samples with varying NV densities and implantation geometries, in order to gain information about the optimal material properties for magnetometry in a variety of applications. We are also in the process of developing the confocal apparatus to be able to perform stimulated emission depletion (STED) microscopy. This technique allows for subwavelength imaging by using a ring-shaped mode of red light to suppress spontaneous fluorescence from all emitters except for those in the dark spot at the center of the excitation beam, which can be just a few tens of nanometers in diameter. We plan to apply STED both to NV centers in diamond and to ion-selective optode molecules for applications in bioimaging. More details on this interdisciplinary project can be found here.
Pictured above is part of an apparatus being used to study nitrogen-vacancy (NV) defect centers in diamond. Shining green laser light on the NV centers causes them to emit red light, and an image of that red light is formed using a microscope. We can determine the magnetic field at the location of each NV center by manipulating its quantum state using short pulses of microwaves and green light, and measuring the amount of red light emitted in response. By simultaneously observing many NV centers in a diamond, we plan to demonstrate the capabilities of this technology to form images of magnetic field patterns with high sensitivity and spatial resolution. In the picture above, coils of wire are used to produce magnetic fields while a diamond is illuminated with green light. More details on this long-running project can be found here.