High-speed spectral imager for imaging transient fluorescence phenomena.

We describe fluorescence spectral imaging results with the microscope computed-tomography imaging spectrometer (muCTIS). This imaging spectrometer is capable of recording spatial and spectral data simultaneously. Consequently, muCTIS can be used to image dynamic phenomena.

Convex grating types for concentric imaging spectrometers.

The properties of convex gratings fabricated by electron-beam lithography are investigated. Three grating types are shown. The first is a single-panel, true blazed grating in which the blaze angle stays constant relative to the local surface normal.

Steady-state vortex-screening solitons formed in biased photorefractive media.

We report the observation of steady-state photorefractive vortex-screening solitons. As a singly charged circular vortex nested on a broad beam propagates through a biased strontium barium niobate crystal, it self-traps in both transverse dimensions despite the inherent anisotropy of the photorefractive nonlinearity. When the vortex beam is a doughnut-shaped narrow beam, it breaks up into two elongated slices (with a self-defocusing nonlinearity) or into two focused filaments (with a self-focusing nonlinearity).

Demonstration of a high-speed nonscanning imaging spectrometer.

We report results from a field demonstration of a nonscanning high-speed imaging spectrometer [computed-tomography imaging spectrometer (CTIS)] capable of simultaneously recording spatial and spectral information about a rapidly changing scene. High-speed spectral imaging was demonstrated by collection of spectral and spatial snapshots of a missile in flight. This instrument is based on computed-tomography concepts and operates in the visible spectrum (430-710nm).

Demonstration of a computed-tomography imaging spectrometer using a computer-generated hologram disperser.

We have constructed a computed-tomography imaging spectrometer that uses a phase-only computer-generated hologram (CGH) array illuminator as the disperser. This imaging spectrometer collects multiplexed spatial and spectral data simultaneously and can be used for flash spectral imaging. The CGH disperser has been designed to maintain nearly equal spectral diffraction efficiency among a 5 x 5 array of diffraction orders and to minimize diffraction efficiency into higher orders.

High-Resolution Stark Spectroscopy in the nu(4) Band of NH(3) Using a Thin-Film Diode Laser.

Thin-film PbTe diode lasers are used for Doppler-limited Stark spectroscopy on the nu(4) vibration-rotation band of NH(3) in the 1545-1595-cm(-1) region. The lasers operate cw below 20 K and are frequency tuned by varying the diode current. The nu(4) excited state dipole moment of NH(3) is found to be about 1% less than the ground state value.