Other Optical Components

A remarkable application of a simple optical waveguide is its use as a chemical vapvi microsensor 

The waveguide is made by laser irradiation of a thin liquid layer, enclosed between two glass plates. The liquid is a divinyl oligomer containing uranyl perchlorate as a photoinitiator. After removal of the cover glass and the unexposed material, the 

The performance of UV-curable adhesives for the assembly of lenses, prisms, etc. has been compared with traditionally used two- or three-component epoxy adhesives by Seo Important advantages claimed are suitable for mass production while maintaining hi performance, rapid curmg and elimination of mixing and storage problems. 

A recent application of photopolymerization is the protection of the surface of optical components made of polycarbonate or acrylic resins. The surfaces of these parts are vulnerable to scratches and attack by chemicals. Coating of the surface with a thin layer (2-4 pm) of a UV-curable acrylic coating may increase the abrasion resistance and the chemical inertness considerably. 

An additional advantage is that these coatings may be used on materials with low heat-distortion temperatures as well 

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Optical Applications. Vitreous siUca is ideal for many optical appHcations because of its excellent ultraviolet transmission, resistance to radiation darkening, optical polishing properties, and physical and chemical stabiUty. It is used for prisms, lenses, cells, wiadows, and other optical components where ultraviolet transmission is critical. Cuvettes used ia scatter and spectrophotometer cells are manufactured from fused siUca and fused quart2 because of the transmissive properties and high purity (222). 

The design and operation of an NIR probe is similar to that of conventional UV-visible OFCD reported in the literature.(21) These probes consist of a light source, a bifurcated fiber, an NIR dye, a polymer matrix, a detector, and other optical components. 

Figure 12.1 shows the classic L-format of the most commonly used fluorescence spectrometer configuration which is topologically the same for the measurement of both steady-state spectra and lifetimes. The source and detector options of relevance to IR fluorescence measurements are discussed in Sections 12.3 and 12.4, respectively. The other optical components comprised of the lenses for focusing and collection and monochromators for wavelength selection contain few peculiarities in the near-IR as... 

The small divergence of the laser beam, which is limited only by diffraction and by optical inhomogeneities of the laser medium or other optical components in the laser cavity, has several advantages for spectroscopists ... 

Sample handling is simplified as glass can be used for windows, lenses, and any other optical components. In addition, the laser source is easily focused on small sample area. Very small samples can be investigated without time-consuming preparation. It is also possible for the source radiation to be transmitted through optical fibers. The fiber-optic probe can be in contact with the sample or immersed in it. The probe consists of input fibers surrounded by several collection fibers that transport the scattered radiation to the monochromator. This makes it possible to collect spectra directly under relatively adverse conditions. 

PROBLEM 21.7 Silica glasses used in lenses, laser mirrors, and other optical components can be made by the sol-gel method. One step in the process is the hydrolysis of Si(OCH3)4. Write a balanced equation for the reaction. 

Precision alignment and attachment of optical fibers to couple them with lenses, transmitter and receiver components, and laser diodes is stiU largely a manual, labor-intensive process. Optical fibers must be aligned to insure that the optimum amoimt of light is transmitted between the fiber on the outside and the laser, photodiode, or other optical component on the inside of a package. Alignment may be active or passive. ... 

Transparent amorphous polymers such as poly(methyl methacrylate) (PMMA) have been found to be useful materials for polymer optical fibers (POFs) (1,2), waveguides (3), lenses (4), optical disks (5), and other optical components because of their excellent mechanical properties and easy processing. Many recently developed optical applications utilizing polarization techniques need optical polymers for maintaining more accurate polarization. However, applications of optical polymers are limited by birefringence which occurs in the process of device fabrication. 

Hysol UV 702 0.24 100/ glass/ stainless 10—20 secs (6 mW/cm 365 nm) N/A Bonding of lenses, prisms, v-grooves and other optical components with small gaps (<25 pm)... 

A waveguide works on a similar principle to optical fibers, so most fiber-optic detection methods can be transplanted to waveguide-based biosensors [6]. Compared with optical fibers, the waveguide is more easily integrated with other optical components (e.g., grating, interferometer) and can be integrated into miniaturized detection devices such as microfluidic chips. 

Plastic and pulp products (paper) are two obvious choices for flexible substrates. Both are relatively inexpensive and readily available commercially. The first obvious difference between them from a product point of view is transparency. Paper is usually opaque, where plastic can be clear. The latter is often useful for displays, mirrors, and other optical components. 

Sensitive area compatible with other optical components. 

The basic building block for any optical fiber system is the optical fink, that is, all of the components necessary to take the desired electrical signal and modulate it onto an optical carrier, the fiber and other optical components to convey the optical signal from source to destination, and the components required to recover the desired electrical signal from the optical carrier. In this section the components that make up the optical transmitter wfil be reviewed. 

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