Double-sided mirror

Fig. 2. Diagram of the optical path of the bilateral laser scanning confocal microscope (InSIGHT). Real-time confocal imaging is obtained through the use of a double-sided mirror which simultaneously scans the sample and the oculars or detector at video rates. BSO, beam shaping optics LM, laser mirror D, dichroic M4, mirrors SM, scanning mirror G, galvonometer L1-L3 lenses S, variable slit.

Figure 4.26. Schematic layout of Perkin-Elmer PEDR accessory Mi — double-sided mirror M2, Ms, Ms, Me — plane mirrors M4 — ellipsoidal mirror. Courtesy of Perkin-Elmer, Inc.

The concept of reflection planes refers to symmetry assessed using the mirror-image approach an imaginary double-sided mirror is used to bisect the molecule along various planes, and the reflection from each side of the mirror is used to reconstruct the other side of the molecule. Thus, once this mental reconstruction or visualization of the molecule is completed, a symmetrical molecule will be indistinguishable from the original when using this method. 

Figure 5.15. Construction of an interferometer manufactured by On-Line Technologies. Radiation hits the beamsplitter (A) and is reflected to a cube-comer retroreflector (D) onto one side of a moving doubie-sided mirror (C). The beam that is transmitted through the beamspiitter is reflected from a fixed mirror (B) to the other side of the moving double-sided mirror (C). (Reprodueed from [5], by permission of John Wiley Sons, Ltd. copyright 2002.)...

The position of ZPD (Zero Path Difference) is critical to the Fourier Transform calculation, since the algorithm assumes that the central burst in the interferogram is in fact the ZPD. However, due to the refractive index properties of the beamsplitter material, the ZPD is not at the same position for every wavelength measured. There are several ways to overcome these phase differences. The most common method is to use a correction factor, which is known as phase correction. This correction factor is calculated for every wavelength, based on a double sided interferogram, since this tends to minimize the effects of phase difference. In practice, most infrared spectrometers collect single sided interferograms, since this halves the mirror movement, and consequently the number of datapoints to be Fourier transformed. 

Figure 1.38. A double-sided video disk. Abbreviations are as follows S is the transparent substrate, A is the adhesion layer, L is the polymeric information layer with picture and sound information in the form of pits, M is the mirror coating, PR is the protective layer, and G is the adhesive layer holding both sides together. Reproduced with permission from reference 55. Copyright 1982 Philips Research Laboratories.)...

One can also derive a similar equation to Equation 9.1 for emission through the mirror Mj if it also permits optical transmission (e.g., in transparent OLEDs and double-side-emitting OLEDs). 

The third type of symmetry element that we will consider is the mirror plane, usually designated a. A mirror plane can be considered to be equivalent to an infinitely thin, double-sided planar mirror within the molecule or object. The simplest example of a mirror plane is the molecular plane for any planar molecule. Reflection of the atoms in the molecular plane... 

ELID double-side grinding can be employed to produce mirror-like surface finish. 

Figure 18.15 shows the schematic of the fabrication process. After oxidation of the double-side polished silicon substrate wafer, a first lower poly-Si layer with a thickness of 45 pm is deposited by means of an epi-poly process. In order to remove spikes and obtain a smooth surface, 5 pm of poly-Si has to be removed by poly-Si CMP. This polishing is a two-step process, consisting of a 5 pm bulk removal by means of a fiimed-silica slurry and a subsequent final polish of several 10 nm with a haze-firee slurry. After deposition and stmcturing of some intermediate layers, a second upper poly-Si layer, again with a thickness of 45 pm, is deposited and subsequendy polished with the same two-step poly-Si CMP process. As this will be the surface of the evaporated silver mirror, a smooth as well as flat surface has to be achieved. After a backside silicon etch and the removal of the sacrificial layer, the scanning mirror device is released, see Figure 18.16(a) and (b). 

The beginning of the density revolution occurred when designers began implementing double-sided technologies to allow for the placement of surface-mount components on both sides of a PWB. The continued push toward device density has resulted in placement of BGA components in mirror and quasi-mirror configurations, shown in Figs. 58.7 and 58.8. 

FIGURE 58.7 Double-sided BGA in mirror configuration. Note that the PCA is an exact mirror about the center line of the PWB. In some instances the top- and bottom-side packages share common vias. 

FIGURE 58.8 Double-sided BGA in quasi-mirror configuration. Note that although the packages are not right over each other, there is some overlap when looking from the top down or from the bottom up. 

Semiconductor laser diodes are widely used in CD players, DVDs, printers, telecommunication or laser pointers. In the structure, they are similar to LEDs but they have a resonant cavity where laser amplification takes place. A Fabry-Perot cavity is established by polishing the end facets of the junction diode (so that they act as mirrors) and also by roughening the side edges to prevent leakage of light from the sides of the device. This structure is known as a homojunction laser and is a very basic one. Contemporary laser diodes are manufactured as double heterojunction structures. 

Diastereoisomers are stereoisomers which do NOT have a mirror image of one another. Figure 11.20 shows the diastereoisomers of 2-butene (alkenes such as this are sometimes called geometric isomers and are a consequence of the prohibition of rotation about double bonds). If a vertical mirror was placed between the two structures in Fig. 11.20 they would not reflect onto one another. If the functionality is on the same side then the isomer is the cis-form, if on the opposite side then it is the trans- form. The chemical properties are very similar because the functional groups are identical. However, as they have different shapes their physical properties are different. Interconversion requires breaking and remaking bonds so these isomers are also stable under normal conditions. 

Prochirality Planar molecules possessing a double bond such as alkenes, imines, and ketones, which do not contain a chiral carbon in one of the side chains, are not chiral. When these molecules coordinate to a metal a chiral complex is formed, unless the alkene etc. has C2V symmetry. In other words, even a simple alkene such as propene will form a chiral complex with a transition metal. So will trans-2-butene, but cis-2-butene won t. If a bare metal atom coordinates to cis-2-butene the complex has a mirror plane, and hence the complex is not chiral. It is useful to give some thought to this and find out whether or not alkenes and hetero-alkenes form chiral complexes. One can also formulate it as follows complexation of a metal to the one face of the alkene gives rise to a certain enantiomer, and complexation to the other face gives rise to the other enantiomer. 

---