It has been one of the most discussed and intriguing topics -the quest to control neural circuitry as a precursor to
decoding the operations of the human brain and manipulating its diseased state. Electrophysiology has created a gateway
to control this circuitry with high precision. However, it is not practical to apply these techniques to living systems
because these techniques are invasive and lack the spatial resolution necessary to properly address various neural cell
components, cell assemblies or even tissues. Here we describe a new instrument that has the potential to replace the
conventional patch clamping technique, the workhorse of neural physiology. A Digital Light Processing system from
Texas Instruments and an Olympus IX71 inverted microscope were combined to achieve neuronal control at a subcellular
spatial resolution. Accompanying these two technologies can be almost any light source, and for these
experiments a pair of pulsed light sources that produced two pulse trains at different wavelengths tuned to activate or
inactivate selectively the ChR2 and NpHR channels that were cloned to express light sensitive versions in neurons. Fura-
2 ratiometric fluorescent dye would be used to read-out calcium activity. The Pulsed light sources and a filter wheel are
under computer control using a National Instruments digital control board and a CCD camera used to acquire real time
cellular responses to the spatially controlled pulsed light channel activation would be controlled and synchronized using
NI LabVIEW software. This will provide for a millisecond precision temporal control of neural circuitry. Thus this
technology could provide researchers with an optical tool to control the neural circuitry both spatially and temporally
with high precision.
By combining unique light sources, a Texas Instruments DLP system and a microscope, a submicron
dynamic patterning system has been created. This system has a resolution of 0.5 microns, and can
illuminate with rapidly changing patterns of visible, UV or pulsed laser light. This system has been used
to create digital masks for the production of micron scale electronic test circuits and has been used in
biological applications. Specifically we have directed light on a sub-organelle scale to cells to control
their morphology and motility with applications to tissue engineering, cell biology, drug discovery and
By taking advantage of the continuous spectrum collected for each image pixel by the Hyperspectral Microscopy
Imaging (HMI) system, the data spectra can be de-convolved into a set of standard spectra coefficients for each pixel.
The coefficients are calculated by the analysis program and indicate the relative amounts of each standard necessary to
reproduce the data spectra for each image pixel. Images of a single color or composite images of two or more colors can
be produced for visual analysis. The HMI system is composed of an Olympus inverted microscope, imaging
spectrograph, CCD camera, motorized X-Y stage and illumination sources. This system has been used to scan and
analyze pathology tissue samples which have been stained with 4 standard fluorochromes (not including the dynamic
background spectrum) attached to specific antibodies. The typical wavelength range is 420nm to 785nm with the
longest wavelength markers emitting in the spectral region where the human eye is not sensitive. Quantitative values are
recorded and can be compared to the visual interpretations.
We have established that the digital micromirror device (DMD), a component of the Texas Instrument Digital Light Processing system, can be used as a holographic medium by calculating a computer-generated hologram (CGH) and projecting multiple objects at various distances with a single hologram. Like other spatial light modulators (SLM), the DMD has the dynamic capability to display holograms at video rates. Unlike other SLMs, the high reflectivity of the DMD provides the intensity necessary to project a holographic 3D scene. We have characterized many of the properties for utilizing the DMD for holography, including the grating effect of the mirror arrays, resolution, viewing angle, field of view and the number of gray levels that can be displayed by the DMD. Several techniques and algorithms that were investigated to calculate the CGH for vivid display with a DMD are discussed. Prototypes of a holographic real image projection system and a virtual image viewer are being pursued. Since a good, low cost medium for displaying holographic projections does not yet exist, we are developing a volumetric display system consisting of a series of liquid-crystal layers with sequencing electronics. Analysis of image definition, inverted image overlap, and depth of field associated with the current projection system design are also presented. Potential uses of holographic viewing systems are reviewed along with methods for overcoming the challenges of using the DMD for the next generation holographic projection system.