Fluorescent nanodiamonds have proven useful as nontoxic probes for optical tracking of subcellular processes. Here, we demonstrate that a resonant magnetic field can be used to transfer spin polarization from intrinsic defects at nanodiamond surfaces into surrounding solution, enabling imaging of nanodiamond via MRI. In combination with fluorescence techniques, this new MRI modality promises to enable nanodiamond as a bioprobe for noninvasive imaging over subcellular to whole body lengthscales.
Ultrasound-modulated optical tomography uses a well focused ultrasound beam to modulate diffuse light inside soft
biological tissues. This modality combines the advantages of ultrasound resolution with optical contrast. However,
because of the low ultrasound modulation efficiency, the large background of un-modulated photons gives a low
signal-to-noise ratio. Here we report a technique for detection of ultrasound-modulated light using a phase conjugated signal
generated by four-wave mixing in a photorefractive polymer. The experimental results demonstrate the potential of this
method to detect ultrasound-modulated optical signals in a highly scattering media with an excellent signal-to-noise
We present a novel optical quantum sensor using spectral
hole-burning for detecting signals in ultrasound-modulated
optical tomography. In this technique, we utilize the capability of sub-MHz spectral filtering afforded by a spectral hole
burning crystal to select the desired spectral component from the ultrasound-modulated diffuse light. This technique is
capable of providing a large etendue, processing a large number of speckles in parallel, tolerating speckle decorrelation,
and imaging in real-time. Experimental results are presented.
Ultrasound-modulated optical tomography (UOT) is a new technique that combines laser light and ultrasound to provide images with good optical contrast and good ultrasound resolution in soft biological tissue. We improve the method proposed by Murray et al to obtain UOT images in thick biological tissues with the use of photorefractive crystal based interferometers. It is found that a long ultrasound burst (on the order of a millisecond) can improve the signal-to-noise ratio dramatically. Also with a long ultrasound burst, the response of the acoustic radiation force impulses can be clearly observed in the UOT signal, which will help to acquire images that record both the optical and mechanical properties of biological soft tissues.