Affective state control for neuroprostheses.

The control and communication in man and the machine has been an active area of research since the early 1940's and since then the usage of the computing machine for the enhancement, augmentation, and rehabilitation of mankind has been broadly investigated. One active area of such research is the interface of the human brain to the computer; brain-computer-interfacing (BCI) or neuroprostheses. Current examples of functional BCI typically control the computer screen cursor movement, but require extensive subject training and significant, if not full, cognitive focus.

The digital hearing aid, wearable computing, and electrophysiological response.

Presbycusis is the most common form of hearing loss caused by aging and long-term exposure to sound energy. This type of ailment decreases the ear's ability to perceive high frequencies and localize sound, thus making comprehension more difficult. To compensate for this loss, the choice of a digital hearing aid has become more common.

Multiple line and polarization control in a far infrared laser with a compound grating resonator.

Operating principles and the efficacy of two types of coupled laser resonator are described and their experimental verification presented: a compound mirror-grating-mirror resonator (MGM), and a mirror-grating-grating resonator (MGG). The coupling for both resonators is through the zero-order diffraction of the resonator's primary grating. The coupling mechanism makes it possible to obtain a particular wavelength and polarization from the resonators.

Carbon dioxide absorption of He-Ne laser radiation at 4.2 microm: characteristics of self and nitrogen broadened cases.

A laser resonance absorption spectrometer is used to investigate the characteristics of both self and nitrogen collision broadened carbon dioxide in resonance with He-Ne laser radiation at 4.2 microm. The absorption coefficient in these broadening conditions has contributions from the R(28) to R(34) absorption lines of the nu(3) CO(2) spectrum.

Pulsed and cw operation of helium-water vapor laser at 28 microm.

The operating characteristics of a water vapor-helium laser working at 28 microm are presented. Comparison is made of power output in continuous and pulsed operation for various gas mixtures and discharge currents for the same laser cavity.

Absorption line parameter measurements using laser spectroscopy.

An analytical method is described for obtaining the precise location of an absorption line and the pressure broadening coefficients due to self-broadening or foreign gas broadening from experimental measurements using a laser operating on a single line near the absorption line. These absorption line characteristics are obtained from the pressure dependence of the transmittance of the laser radiation for the gas of interest, the analysis involving a least squares fit to a family of Lorentz curves. The method includes a computer search for the region of best fit to the Lorentz profile and provides both the values of and errors in the above coefficients.

Excitation processes and relaxation rates in the pulsed water vapor laser.

This paper presents an experimental study of time-resolved gain in H(2)O, H(2)O-He, and H(2)O-H(2) mixtures as a function of gas composition and excitation current. Utilizing the fast rising (~70 nsec) pulse from H(2)O-He laser as a probe, the amplifier gain was measured with a time resolution of about 100 nsec. The gain was observed to follow the excitation current pulse rather closely indicating that population inversion was established in times less than 100 nsec.

Analysis of gain measurements of a pulsed two-level laser system.

A fast and convenient method for the extraction of basic constants from time resolved laser amplifier gain measurements is described. The method is based on the assumption of a two-level laser system having direct electron excitation of the levels involved. The experimentally measured pulsed discharge current waveforms and time resolved gain curves are analyzed by a digital computer and fitted to the above model.