Plane-mirror Michelson interferometer

Figure 5.11. Principle of a comer retroreflector (a) both retroreflectors are in good alignment, so there is no essential difference from the case of a plane-mirror Michelson interferometer (b) one of the retro-relectors is tilted, but the output beams from each retroreflector are still parallel, unlike the case for a plane-mirror Michelson interferometer. The concept of the roof retroreflector shown here can be extended into three dimensions through the use of cube comers.

This interferometric dilatometer consists of a rather simple and small Michelson interferometer, in which the two arms are parallel, and of a 4He cryostat, in which the sample to be measured is hold. The sample is cooled to 4 K, and data are taken during the warm up of the cryostat. The optical path difference between the two arms depends on the sample length hence a variation of the sample length determines an interference signal. The Michelson interferometer consists of a He-Ne stabilized laser (A = 0.6328 xm), two cube corner prisms, a beam splitter, three mirrors and a silicon photodiode detector placed in the focal plane of a 25 mm focal length biconvex lens (see Fig. 13.1). 

A diagram of a typical interferometer (Michelson type) is shown in Figure 7.8. It consists of fixed and moving front-surface plane mirrors (A and B) and a beamsplitter. Collimated infrared radiation from the source incident on the beamsplitter is divided into two beams of equal intensity that pass to the fixed and moving mirrors respectively. Each is reflected back on itself, recombining at the beamsplitter from where they are directed through the sample compartment and onto the detector. Small... 

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 Michelson interferometer consists simply of two mutually perpendicular plane mirrors one of which is fixed and the other able to move at 90° to its plane. A semi-reflecting film or beamsplitter ... 

The Michelson interferometer is shown schematically in Figure 1. It consists of two mutually perpendicular plane mirrors, one of which can move at a constant rate along the axis and one of which is stationary. Between the fixed mirror and the movable mirror is a beam splitter where a beam of radiation from an external source can be partially... 

Now, the mathematical form of the interferogram / (s) is to be derived. The partial beams in the two arms of the Michelson interferometer (see Fig. 2) are described as plane waves. The amplitude or the electric field of the wave reflected at the fixed mirror is... 

The Michelson interferometer consists of two mutually perpendicular plane mirrors, one of which can move along the axis shown in Fig. 37(a) and... 

In the Michelson interferometer a collimated light beam is divided at a beam splitter into two coherent beams of equal amplitude that are incident normally on two plane mirrors. The reflected beams recombine coherently at the beam splitter to give circular interference fringes at infinity focused by a lens at the plane of the detector (see figure on GC-FTIR). 

The heart of the optical hardware in a FT spectrometer is the interferometer. Nowadays, the most common set-up used is the classic two-beam Michelson interferometer shown schematically in Fig. 5.1. It consists of two mutually perpendicular plane mirrors, a fixed mirror Ml and a movable one M2. A semi-reflecting mirror, the beam splitter, bisects the planes of these two mirrors. A beam emitted by a source S is split in two by the beam splitter. The reflected part of the beam travels to the fixed mirror Ml through the distance L, is reflected there and hits the beam splitter again after the total path length of 2L. The same happens to the transmitted radiation. However, as the mirror M2 is not fixed at the same position L but can be moved very precisely back and forth around L by a distance x, the total path length of the transmitted part is accord-... 

Figure2.1 shows the simplest form of a Michelson interferometer. It consists of two perpendicular plane mirrors, one fixed and one movable to introduce the required...

Fig. 2.1 The simplest Michelson interferometer, consisting of two mutually perpendicular plane mirrors, one of which can move along an axis that is perpendicular to its plane. A collimated light source red) reaches the beamsplitter, which splits the light in two paths reflected blue arrow) and transmitted green arrow). The fixed mirror reflects the light back to the beamsplitter, and the movable mirror reflects the transmitted light to the beamsplitter, where they interfere...

The interferometer was developed by Michelson in 1887 and used by him to measure the wavelength of light. Figure 3-13 shows the essential features of an interferometer. It consists of two plane mirrors and a beam splitter. The beam splitter transmits approximately half of all incident radiation to a movable mirror and reflects half to a stationary mirror. Each component reflected by the two mirrors returns to the beam splitter, where the waves are combined. 

They are superimposed in the plane of observation B after reflection from the mirrors Mi, M2. This arrangement is called a Michelson interferometer (Sect. 4.2). The two beams with wavelength A travel different optical path lengths SMiSB and SM2SB, and their path difference in the plane B is... 

The principle of a Michelson interferometer which is used in a Fourier transform infrared (FT-IR) spectrometer is illustrated in Fig. 2.4. As seen in Fig. 2.4(a) the device consists of two plane mirrors, one fixed and one moveable, and a beam splitter. One type of beam splitter is a thin layer of germanium on an IR-transmitting support. The radiation from the source is made parallel and as seen in Fig. 2.4(b), strikes the beam splitter at 45. The beam splitter has the characteristic that it transmits half of the radiation and reflects the other half. The transmitted and reflected beams from the beam splitter strike two mirrors oriented perpendicular to each beam, and are reflected back to the beam splitter. 

The quality of spectra measured on a Michelson interferometer depends both on the alignment of the fixed mirror relative to the moving mirror and on how accurately the plane of the moving mirror is maintained during the scan. These effects are discussed in this section and Section 2.8, respectively. 

---