The fractional Fourier transformation is used to transform the rectangular Gabor lattice into a quin-cunx lattice. By using the isometric property of the unitary fractional Fourier transformation, the biorthog-onality relation for the rectangular lattice is transformed into a relation which holds for the quincunx lattice. Since a Gaussian function, which plays an important role as a window func...

We have observed the spectrum of neutral neon (Ne I) emitted by a microwave-excited electrodeless discharge lamp with the National Institute of Standards and Technology 2 m Fourier transform spectrometer. The spectra cover the regions 6929 Å to 11 000 Å with a resolution of 0.01 cm(-1) and 11 000 Å to 47 589 Å with a resolution of 0.007 cm(-1). We present a line list that includes more than 650...

We present an analysis of Fourier-transform arrayed waveguide gratings in the Fresnel diffraction regime. We report a distinct spatial modulation of the interference pattern referred to as the Moiré-Talbot effect. The effect and its influence in a FT AWG device is explained by deriving an original analytical expression for the modulated field, and is also confirmed by numerical simulations usin...

A new design of laser warning system is proposed. This novel system is composed of an optical antenna based on fiber bundle and a spatially modulated stationary Michelson interferometer as Fourier transform device. The interferometer has no moving parts, which can distinguish laser from background noise and from other non-coherent radiation such as flares, sunlight, and lighting. Based on Fouri...

The Smithsonian far-infrared spectrometer is a remote sensing Fourier transform spectrometer that measures the midand far-infrared thermal emission spectrum of the stratosphere from balloon and aircraft platforms. The spectrometer has had nine successful balloon flights from 1987 to 1994, flying at float altitudes of 36–39 km and collecting 131 hours of midlatitude stratospheric limb spectra. T...

Direct sunlight absorption by trace gases can be used to quantify them and investigate atmospheric chemistry. In such experiments, the main optical apparatus is often a grating or a Fourier transform spectrometer. A solar tracker based on motorized rotating mirrors is commonly used to direct the light along the spectrometer axis, correcting for the apparent rotation of the Sun. Calculating the ...

Design and performance of a novel hybrid mass spectrometer is described. It couples a linear ion trap mass spectrometer to an orbitrap mass analyzer via an rf-only trapping quadrupole with a curved axis. The latter injects pulsed ion beams into a rapidly changing electric field in the orbitrap wherein they are trapped at high kinetic energies around an inner electrode. Image current detection i...

We employ three highly sensitive spectrometers: a photoacoustic spectrometer, a photothermal common-path interferometer and a whispering-gallery-resonator-based absorption spectrometer, for a comparative study of measuring the absorption coefficient of nominally transparent undoped, congruently grown lithium niobate for ordinarily and extraordinarily polarized light in the wavelength range from...

We report on the application of a silicon micromachined lamellar grating interferometer in a Fourier Transform Infrared (FTIR) spectrometer for the detection of gases in the mid-infrared (MIR) region. The FTIR spectrometer was equipped with MIR optical fibers for light coupling. Gas measurements in the MIR region were focused on specific gases (CO2, CH4) in order to determine the limit of detec...