Abstract: FM laser spectroscopy apparatus includes a single modulator for modulating a laser beam with first and second modulation signals (.omega..sub.1, .omega..sub.2). The two modulation signals are generated by mixing a signal from a first oscillator (.omega..sub.1 +.omega..sub.2)/2 and a signal from a second oscillator (.omega..sub.1 -.omega..sub.2)/2 and producing the two modulation signals (.omega..sub.1, .omega..sub.2). The modulator produces three groups of sidebands on the laser beam at the laser frequency plus and minus the two modulation frequencies and at plus and minus the difference between the two modulation signal frequencies. The apparatus provides practical high frequency FM spectroscopy as required for the observation of pressure broadened spectral features.

Abstract: A phase-matched resonant waveguide modulator suitable for very high frequency modulation and applications such as FM laser spectroscopy is described. The width of a crystal modulator section of the waveguide is chosen so that the operating frequency is just above cut-off to achieve optical and RF phase velocity matching at high frequencies such as 10 GHz by virtue of the dispersion of the waveguide near cut-off. The waveguide contains air in opposite end sections so that those sections are below cut-off and the microwave is evanescent, with the result that the end sections preferably are open for ease of optical coupling to the waveguide.

Abstract: A spectroscopic technique in which the sample under investigation is probed with a generally monochromatic beam of light which has been modulated at two distinct modulation frequencies. The double modulation produces a plurality of sidebands, and the two modulation frequencies are related to one another such that a selection of sidebands falls into two groups of closely spaced component sidebands. A first group is disposed in frequency at the spectral feature of interest and serves to probe the spectral feature. The other group is disposed in frequency remote from the feature and serves as a reference group. Within each group the component sidebands are offset from one another by a characteristic offset frequency, which can be considerably less than the width of the spectral feature under investigation.

Abstract: Organic transfer laser method and means are disclosed employing a gas mixture which includes an acceptor gas comprising an organic molecular vapor, and a donor gas comprising a noble gas or a group II B transition metal, such as mercury, in the vapor state. The donor gas atoms are excited to high energy metastable and/or excimer states by electron beam excitation or electron beam initiated-sustainer discharge type exciting means. Collisional transfer of electronic excitation from the excited donor gas to the lasing organic molecules takes place for excitation of organic molecules to excited singlet states in sufficient number to establish a population inversion in the electronic energy levels thereof for lasing. Depending upon the mixture employed, the laser is tunable over the visible and ultraviolet regions of the electromagnetic spectrum. Operation at high peak power levels with high efficiency is possible.

Abstract: Isotope separation method and means are shown wherein an atomic beam containing two or more isotopes is exposed to radiation at a predetermined first wavelength to excite atoms of only one said isotope to a first intermediate excited state without substantially exciting atoms of other isotopes. These excited atoms are excited by a second radiation source at a second predetermined wavelength to a state of high principal quantum number, a Rydberg state, beneath the ionization continuum, again substantially without exciting atoms of said other isotopes to such high energy levels since substantially none of the other isotopes are in the intermediate excited state. From this bound atomic level only slightly below the ionization limit, the highly excited atoms are field ionized by electron tunneling and thence removed from the nonionized atoms by use of a moderate electric field.

Abstract: Highly sensitive method and apparatus for photon detection in the microwave and infrared regions of the electromagnetic energy spectrum are shown in which atoms of a material in the vapor state are excited to a first Rydberg energy level by use of radiation from one or more laser beams. The Rydberg excited material is subjected to the low energy radiation to be detected to induce therein an allowed electric dipole transition from said first to a second Rydberg energy level of the same or quite similar principal quantum number. Spontaneous high energy emission as a result of a distinctive radiative transition from said second Rydberg energy level is detected independently of other radiative transitions by conventional photodetector means such as a photomultiplier operable within the optical spectrum. The photomultiplier output provides a measure of said radiation to be detected.