Interferometer construction

These interferometers have been demonstrated for refractive index sensing. The sensitivity was around 33 nm spectral shift per RIU change when they were used for refractive index measurement. The maximum fringe visibility of these interferometers was around 9 dB, which was relatively small compared with the interferometers constructed by other methods. 

The instrument, Figure 1, involves a two-arm Mach-Zehnder interferometer constructed from mono-mode fiber optic waveguides. One arm of the interferometer is coated with an immobilized enzyme, while the other is used as a reference. Both arms of the interferometer are firmly held in the middle of a conduit that is incorporated into a flow injection analysis (FIA) system, serving as a substitute for the normal absorbance, fluorescence, pH, or electrochemical detectors. A common source of phase coherent light is launched down both arms of the interferometer. 

There are still many other designs of interferometer construction, intended for various physical measurements. In particular, using a specially designed interferometer, Michelson and Morley in 1881 established the independence of light speed from the speed of its source (refer to Section 1.6). Einstein took this fact as a principle of his Special Theory of Relativity. 

The operating principles of the reviewed interferometers are well studied. However, by no means these devices are matured. For example, a mode-selective, wavelength-independent and environmental-resistant 3-dB core-cladding mode coupler is yet to be found to construct an ideal CCMI. As technology advances and research continues, we expect that more device structures will be explored and new methods will be investigated to fabricate these devices. Although the applications of these two types of sensors are yet to be explored, it is almost certain that they will find their way into real-world applications in the future. 

An interferometer is a device that utilizes a moveable and a fixed mirror to manipulate the wave patterns of a split light beam to create constructive and destructive interference in this beam. 

Fresnel, Augustin Jean (1788—1827). A French physicist noted for his work on optics, such as aberration of light, interference, wave theory of light, etc. He constructed the first practical "interferometer", which is used at present in modified form in Ordnance, such as "interferometric analysis of air flow about projectiles In free flight"... 

FT-IR utilizes the Michelson interferometer rather than the grating or prism of the dispersive system. The Michelson interferometer has two mutually perpendicular arms. One arm of the interferometer contains a stationary, plane mirror the other arm contains a moveable mirror. Bisecting the two arms is a beamsplitter which splits the source beam into two equal beams. These two light beams travel their respective paths in the arms of the interferometer and are reflected back to the beam splitter and on to the detector. The two reunited beams will interfere constructively or destructively, depending on their path differences and the wavelengths of the light. When the path lengths in the two arms are the same, all of the frequencies... 

The signal seen at the detector for a given value of the optical path difference (OPD), given by the symbol 6, is dependent upon the wavelengths, amplitudes, and phases of the components of the radiation. Constructive interference for all components occurs only at S = 0, where the maximum signal is observed (often referred to as the centerburst or central maximum). The signal that is seen at the detector as a function of S, 1(5) for an ideal interferometer, is given by... 

In Fourier transform spectrometry, the wavelength components of light are not physically separated. Instead, the light is analyzed in the time frame of reference (the time domain) by passing it through a Michelson interferometer. The Michelson interferometer is so constructed that light is separated into two beams by a beamsplitter. One beam strikes a stationary mirror and is reflected back to the beamsplitter. 

It is possible to construct a rugged interferometer suitable for use in a factory or production environment with careful attention to design details. Manufacturers specializing... 

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