Liquid crystal devices

90.13 Liquid crystal devices not constituting articles provided for more specifically in other headings; lasers, other than laser diodes; other optical appliances and instruments, not specified or included elsewhere in this Chapter. 9013.10 - Telesco 9013.20 - Lasers, other than laser diodes - Other devices, appliances and instruments - Parts and accessories 90 13.80 90 13.90 ic si hts for fitting to arms; periscopes; telescopes designed to form arts o rnac ines, appliances, instruments or apparatus of this Chapter or Eection XVI ? k In accordance with Cha ter Note 5, measurin or checking optical ap liances, instruments and machines are excluded om this heading antfall in headlng 90.31. &a ter Note 4, however, classifies certain refracting telescopes m this heading and not in heat?ing 90.05. It should, moreover, be noted that optical instruments and appliances can fall not only in headin s 90.01 to 90.12 but also in other headings of this Chapter (in particular, heading 90.15, 0.18 or 90.27). This heading includes : % B (1) Liquid crystal devices consisting of a liquid crystal layer sandwiched between two sheets or plates of glass or plastics, whether or not fitted with electrical connections, presented in the piece or cut to special shapes and not constituting articles described more specifically in other headings of the Nomenclature. Lasers. These produce or am lify electro-mapetic radiation in the wavelength range between 1 nanometre and 1 mi limetre (ultra-violet, visible light and infia-red regions of the spectrum), by the rocess of controlled stimulated emission. When the lasing medium (e.g., crystals, ases, iquids, chemical products) is excited by the light from an electric source or by t e reaction fkom another source of energy, the light beams which are produced inside the lasing medium are repeatedly reflected and amplified in such a way that a coherent light beam (visible or invisible) is emitted from one end which is partly transparent. fl P In ,addition to the lasing medium, the ener source (pumping system) and the resonant optical cavity (reflector system), i.e., the asic elements combined in the laser head (possibly with Fabry-Perot interferometers, interference filters and spectroscopes), lasers generally also incorporate certain auxiliary com onents (e.g., a power supply unit, a cooling system, a control unit and, in the case of i e gas laser, a gas sup ly system or, in the case of liquid lasers, a tank, fitted with a pump for the dye solutions!. Some of these auxiliary components may be contained in the same housing as the laser head compact laser) or may take the forin of se arate units, connected to the laser head by ca les, etc. (laser system). In the latter case J e units are classified in this heading pronded they are presented together. % Lasers are classified in this heading not on1 if they are intended to be incorporated in machines or ap liances but also if they can e used independently, as compact lasers or laser systems, or various purposes such as research, teaching or laboratory examinations, for example, laser pointers. P B However, the heading excludes lasers which have been adapted to perform quite s ecific functions by adding ancillary equipment consisting of special devices (e.g., work-tables, wor -holders, means of feeding and posihor+g wor ieces, means of observing and checking the progress of the operation, etc.) and whrch, there ore, are identifiable as working machines, medical apparatus, control ap aratus, measurin apparatus, etc. Mac.hines and appliances incorporating lasers are also excluded goom the headin fnsofar as then clasafication is not specified in the Nornencl?ture, they should be classified with e machines or appliances having a simlar function. Examples Include : I: ? tii (i) Machine-tools for working any materials by removal of material by laser (e.g., metal, glass, ceramics or plastics) (heading 84.56). (ii) Laser soldering, brazing or welding machines and apparatus, whether or not capable of cutting (heading 85.15). (iii) Instruments for levelling (aligning) pipes by means of a laser beam (heading 90.15). (iv) Laser apparatus specially used for medical purposes(e.g., in ophthalmological operations) (heading 90.18). Subject to the provisions of Notes 1 and 2 to this Cha ter, arts and accessories for lasers, for example, laser tubes, are also classified in this heat8ng. Eowever, this headin does not include electric flash lamps used for umping, such as xenon lam s, iodine amps and mercury va our lamps (heading 85.34, laser diodes (heading 85. 1) and laser crystals (e.g., mbies7, laser mirrors and lenses (heading 90.01 or 90.02). f a (3) Hand magnifyin glasses and magnifiers (e.g., pocket type or those for office use), and thread counters (t ese magnifiers may be fitted or combined with an illuminating lamp, they remain in this headin if the lamp enhances the use of the magnifier); binocular magnifjm lasses (genera ly on supports) which, unlike stereoscopic microscopes of heading are fitted with eyepieces but not with an objective. % &.A, (4) P " Door-eyes '' for viewing through doors; also similar articles fitted with an optical system. (5) Telescopic si hts for wea ons, refracting or reflecting, presented se arately; optical devices suitab e for use wi arms and mounted thereon or presented wi the firearms on which they are designed to be mounted, are classified with the arm, see Note 1 (d) to Chapter 93. k tR (6) Telescopes of a kind designed to form parts of instruments of other headings of this Chapter (e.g., telescopes forming parts of surveying instruments) or of machines of Secbon XVI. (7) Fibrescopes for industrial use. Fibrescopes for medical purposes (endoscopes) are excluded (heading 90.18). viewin Of incorporatingtwo xed pictures which are B (9) Kaleidoscopes, other than toy kaleidoscopes (Chapter 95). (10) Magnaying periscopes for submarines or tanks; and non-magnifying periscopes (e.g., for trenches). (11) Mounted glass mirrors, o tically worked, which are unsuitable for fittin to instruments or apparatus for exam le, certain rear-view mirrors, chimney or gain inspection mirrors, and speci mirrors or wind-tunnel observations). !? Rear-view or other mirrors, not optically worked (including shaving mirrors, whether or not magnifymg) are excluded (heading 70.09 or 83.06). (12) Optical lightbeam signalling a aratus, for the long-distance transmission of optical signals (for example, in rnorse c o g . (13) Slide viewers fitted with a single magnifying lens and used for examining photographic slides. PARTS AND ACCESSORIES Subject to the provisions of Notes 1 and 2 to this Cha ter (see the General Ex lanatory Note), parts and accessories of apparatus or appliances of this eading remain classifie here. R i' -