The ISI (Infrared Spatial Interferometer) involves three movable telescopes of Pfund design, each in trailers, each with a radiation collecting mirror 65 inches in diameter. The telescopes can be moved, and then set down on concrete pads for stability. They are located on Mt. Wilson, where pads have been arranged to give baselines varying from 4 to approximately 75 meters and oriented in variou...

A method for detection of thermal infrared radiation from astronomical sources is discussed from an instrumentation point of view. This method utilizes heterodyne detection, whereby light collected by a telescope is spatially mixed with single-mode radiation from an infrared laser local oscillator onto a HgCdTe photodiode. The operating wavelength range of the receiver is adjustable from approx...

We describe the design, fabrication and laboratory tests of a Doppler Asymmetric Spatial Heterodyne (DASH) interferometer for upper atmospheric wind and temperature observations of the O[1D] 630 nm emission. The monolithic interferometer has no moving parts, a large étendue, relaxed fabrication and alignment tolerances and can measure multiple emission lines simultaneously. Laboratory measureme...

A simple grating lateral shear interferometer is described that can be made to give simultaneously two interferograms having shear in two orthogonal directions. The shear for the two orthogonal directions is produced in one plane by one double frequency crossed diffraction grating that can easily be produced holographically. Translating the grating sideways causes the irradiance of the interfer...

The precision stage is an essential device for optic fiber assembly systems, micro machines and semiconductor equipments. A new piezoelectric inchworm type actuator is proposed to implement an actuator-integrated long-stroke linear stage. An in-and-quadrature phase (I/Q) heterodyne interferometer is developed as a feedback sensor of a servo system, and a synchronized counting method is proposed...

We perform double sideband and single sideband suppressed-carrier modulators using a MachZehnder interferometer in free space. Two bulk LiNbO3 crystals are used to modulate the optical beam at 1319 nm in both branches of the interferometer. We present experimental results of the optical spectrum using heterodyne measurement technique. These results show maximum carrier and sideband suppression ...

We describe a novel heterodyne interferometer currently under construction at Oxford. The instrument employs new techniques in heterodyne interferometry, with the aim of achieving very high brightness sensitivity in the millimetre band. It is a single-baseline tracking interferometer for operation in the frequency range 185-275 GHz with two 0.4m offset parabolic antennas separated by a 0.5 m ba...