Films mirrors

Related to the plasmon resonance physics is the micromirror optical sensor for hydrogen (Butler, 1991). Like gold and silver, palladium is a free-electron gas metal in which charge groupings such as phonons or plasmons are likely to occur. As we have seen already, palladium has a natural selectivity due to its sorption of monoatomic hydrogen. In that sensor, the reflectivity of the thin Pd film mirror mounted at the end of cladded optical fiber (Fig. 9.19) is modulated by absorption of hydrogen. 

Commercially available are various types of aluminium front surface mirrors to suit different requirements. For the visible spectral range, there are standard mirrors such as Alflex A . If improved reflection is required, a multiple film mirror Alflex B can be used. Both types of mirrors are provided with a hard and resistant dielectric protection coating. Such mirrors were first made by Hass et al. [73, 74]. The aluminium film on the surface mirror Alflex is even protected by an interference film system, which also enhances the reflectance for the visible range. In the visible and infrared, the spectral curve of the reflectance is approximately the same for Alflex A as that of an unprotected aluminium surface. With a mirror type Alflex B. the increase in reflection in the visible, with a maximum at 550 nm, can be clearly seen in Fig. 12. If required, this maximum can also be shifted to other wavelengths in the visible spectrum. 

Thin films are integral parts of many micro-electro-mechanical systems designed to serve as sensors or actuators. For example, a piezoelectric or piezoresistive thin film deposited on a silicon membrane can be used to detect electronically a deflection of the membrane in response to a pressure applied on its surface or by an acceleration of its supports. Devices based on thin film technology are used as microphones in hearing aids, monitors of blood pressure during exercise, electronically positioned thin film mirrors on flexible supports in optical display systems, and probes for detecting the degree of ripeness of fruits. 

Antl-fogging film Mirror Si02-Zr02-colloidal SI02 film (Ogawa, 2003)... 

Lead sulfide is used in photoconductive cells, infrared detectors, transistors, humidity sensors in rockets, catalysts for removing mercaptans from petroleum distillates, mirror coatings to limit reflectivity, high temperature solid-film lubricants, and in blue lead pigments (82). 

Capstan imagesetters, the third common technology, slowly advance the film or paper across a flat surface. A single laser beam is scaimed across the width of the medium by a rotating polygon or resonant mirror. 

These lead-based materials (PZT, PLZT, PMN) form a class of ceramics with either important dielectric, relaxor, pie2oelectric, or electrooptic properties, and are thus used for appHcations ia actuator and sensor devices. Resistive properties of these materials ia film form mirror the conduction processes ia the bulk material. Common problems associated with their use are low dielectric breakdown, iacreased aging, and electrode iajection, decreasiag the resistivity and degrading the properties. 

Most electroless silver appHcations are for silvering glass or metallizing record masters. Mirror production is the principal usage for electroless silver. The glass support is cleaned, catalyzed using a two-step catalyst, and coated on one side with an opaque silver film (46). Silver-plated nylon cloth is used as a bacteriostatic wound dressing. A tiny current appHed to the cloth causes slow silver dissolution. The silver acts as a bactericide (47). 

Surface modifications and surfiice roughness Cu, Mo, and Be laser mirrors atomic oxygen modified (corroded) surfaces and films, and chemically etched surfaces. 

Conventionally RAIRS has been used for both qualitative and quantitative characterization of adsorbed molecules or films on mirror-like (metallic) substrates [4.265]. In the last decade the applicability of RAIRS to the quantitative analysis of adsorbates on non-metallic surfaces (e.g. semiconductors, glasses [4.267], and water [4.273]) has also been proven. The classical three-phase model for a thin isotropic adsorbate layer on a metallic surface was developed by Greenler [4.265, 4.272]. Calculations for the model have been extended to include description of anisotropic layers on dielectric substrates [4.274-4.276]. 

Molybdenum is used for high energy laser mirrors which require water cooling. Corrosive action of the circulating cooling water can be prevented by coating the waterways with a thin film of tungsten by chemical vapour deposition. US Pat Application 308976 (1982). 

Figure 10-12. Lcfi hand side Slruclure of a PPV microcavily. A thin film of ihe conjugated polymer is deposited on top of a highly reflective distributed Bragg refieclor (DBR). The second mirror is then fabricated by evaporation of a silver layer. Right hand side Emission spectra of the microcavily at excitation cnetgics or 0.0S pJ (dashed line) and l. l pJ (solid line), respectively. Laser pulses ol duration 200-300 ps and a wavelength of 355 nm were used for optical excitation (according to Ref. [39]).

The focusing of radiation within the instrument was formerly done by means of lenses, but these suffer from chromatic aberration and particularly in respect of the relationship between the visible and ultraviolet parts of the spectrum. Focusing is now usually carried out by means of suitably curved mirrors having a reflecting surface coated with aluminium which is protected by a silica film. 

Heat- and light-separation coatings (also known as hot and cold mirrors) are important applications that separate the hot (infrared) from the cold (visible) radiation. The principle is shown schematically inFig. 16.2. The transmittance of a cold mirror is shown in Fig. 16.3a. This mirror is coated with a dielectric film reflecting more than 90% of the... 

Hot- and cold-mirror CVD coatings are used in projectors to maintain the film gate at low temperature and avoid damaging the film. They are also used increasingly in tungsten-halogen lamps. 

Carver, G. E., and Seraphin, B., Chemical Vapor Deposition Molybdenum Thin Films for High-Power Laser Mirrors, mLaser Induced Damage in Optical Materials, Publ. of National Bureau of Standards (Oct 1979)... 

In the ideal case, reversible cyclic voltammograms of redoxactive films should show completely symmetrical and mirror-image cathodic and anodic waves with identical peak potentials and current levels 34-i37) pjg... 

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