|  | G |
SECTION G — PHYSICS

|  | G |
Note(s) In this section, the following term is used with the meaning indicated: "variable" (as a noun) means a feature or property (e.g., a dimension, a physical condition such as temperature, a quality such as density or colour) which, in respect of a particular entity (e.g., an object, a quantity of a substance, a beam of light) and at a particular instant, is capable of being measured; the variable may change, so that its numerical expression may assume different values at different times, in different conditions or in individual cases, but may be constant in respect of a particular entity in certain conditions or for practical purposes (e.g., the length of a bar may be regarded as constant for many purposes). Attention is drawn to the definitions of terms or expressions used, appearing in the notes of several of the classes in this section, in particular those of "measuring" in class Fulltext... Hierarchy... Expanded...G01 and "control" and "regulation" in class Fulltext... Hierarchy... Expanded...G05. Classification in this section may present more difficulty than in other sections, because the distinction between different fields of use rests to a considerable extent on differences in the intention of the user rather than on any constructional differences or differences in the manner of use, and because the subjects dealt with are often in effect systems or combinations, which have features or parts in common, rather than "things", which are readily distinguishable as a whole. For example, information (e.g., a set of figures) may be displayed for the purpose of education or advertising (Fulltext... Hierarchy... Expanded...G09), for enabling the result of a measurement to be known (Fulltext... Hierarchy... Expanded...G01), for signalling the information to a distant point or for giving information which has been signalled from a distant point (Fulltext... Hierarchy... Expanded...G08). The words used to describe the purpose depend on features that may be irrelevant to the form of the apparatus concerned, for example, such features as the desired effect on the person who sees the display, or whether the display is controlled from a remote point. Again, a device which responds to some change in a condition, e.g., in the pressure of a fluid, may be used, without modification of the device itself, to give information about the pressure (Fulltext... Hierarchy... Expanded...G01L) or about some other condition linked to the pressure (another subclass of class Fulltext... Hierarchy... Expanded...G01, e.g., Fulltext... Hierarchy... Expanded...G01K for temperature), to make a record of the pressure or of its occurrence (Fulltext... Hierarchy... Expanded...G07C), to give an alarm (Fulltext... Hierarchy... Expanded...G08B), or to control another apparatus (Fulltext... Hierarchy... Expanded...G05). The classification scheme is intended to enable things of a similar nature (as indicated above) to be classified together. It is therefore particularly necessary for the real nature of any technical subject to be decided before it can be properly classified.

INSTRUMENTS

|  | G02 |
OPTICS (making optical elements or apparatus Fulltext... Hierarchy... Expanded...B24B, Fulltext... Hierarchy... Expanded...B29D 11/00, Fulltext... Hierarchy... Expanded...C03, or other appropriate subclasses or classes; materials per se, see the relevant places, e.g. Fulltext... Hierarchy... Expanded...C03B, Fulltext... Hierarchy... Expanded...C03C)

|  | G02 |
Note(s) In this class, the following expression is used with the meaning indicated: "optical" applies not only to visible light but also to ultra-violet or infra-red radiations. [4]

|  | G02F |
DEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH IS MODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THE DEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY, COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g. SWITCHING, GATING, MODULATING OR DEMODULATING; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF; FREQUENCY-CHANGING; NON-LINEAR OPTICS; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS (optical transfer means between sensing member and indicating or recording part in connection with measuring Fulltext... Hierarchy... Expanded...G01D 5/26; devices in which mathematical operations are carried out with optical elements Fulltext... Hierarchy... Expanded...G06E 3/00; electrical signal transmission systems using optical means to convert the input signal Fulltext... Hierarchy... Expanded...G08C 19/36; information-recording by electric or magnetic means and reproducing by sensing optical properties Fulltext... Hierarchy... Expanded...G11B 11/00; static stores using optical elements Fulltext... Hierarchy... Expanded...G11C 13/04; transmission systems employing electromagnetic waves other than radio waves, e.g. light, infra-red radiation, Fulltext... Hierarchy... Expanded...H04B 10/00; optical multiplex systems Fulltext... Hierarchy... Expanded...H04J 14/00; pictorial communication, e.g. television Fulltext... Hierarchy... Expanded...H04N) [2,4]

|  | G02F 1/00 |
Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics (thermometers using change of colour or translucency Fulltext... Hierarchy... Expanded...G01K 11/12, using changes in fluorescence Fulltext... Hierarchy... Expanded...G01K 11/32; light guide devices Fulltext... Hierarchy... Expanded...G02B 6/00; optical devices or arrangements using movable or deformable elements for controlling light independent of the light source Fulltext... Hierarchy... Expanded...G02B 26/00; control of light in general Fulltext... Hierarchy... Expanded...G05D 25/00; visible signalling systems Fulltext... Hierarchy... Expanded...G08B 5/00; indicating arrangements for variable information by selection or combination of individual elements Fulltext... Hierarchy... Expanded...G09F 9/00; control arrangements or circuits for visual indicators other than cathode-ray tubes Fulltext... Hierarchy... Expanded...G09G 3/00; control of light sources Fulltext... Hierarchy... Expanded...H01S 3/10, Fulltext... Hierarchy... Expanded...H05B 33/08, Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...H05B 35/00-H05B 43/00) [2,4]

|  | G02F 1/00 |
Note(s) This group covers only: devices or arrangements, e.g. cells, the optical operation of which is modified by changing the optical properties of the medium of the devices or arrangements by the influence or control of physical parameters, e.g. electric fields, electric current, magnetic fields, sound or mechanical vibrations, stress or thermal effects; [2] devices or arrangements in which the electric or magnetic field component of the light beams influences the optical properties of the medium, i.e. non-linear optics; [2] control of light by electromagnetic waves, e.g. radio waves, or by electrons or other elementary particles. [2]

|  | G02F 1/01 |
· | for the control of the intensity, phase, polarisation or colour (Fulltext... Hierarchy... Expanded...G02F 1/29 takes precedence; polarizing elements per se Fulltext... Hierarchy... Expanded...G02B 5/30; static storage per se Fulltext... Hierarchy... Expanded...G11C; image tube screens acting as light valves by shutter operation Fulltext... Hierarchy... Expanded...H01J 29/12; such screen acting by discoloration Fulltext... Hierarchy... Expanded...H01J 29/14) [2]

|  | G02F 1/015 |
· · | based on semiconductor elements with at least one potential jump barrier, e.g. PN, PIN junction (Fulltext... Hierarchy... Expanded...G02F 1/03 takes precedence) [3]

|  | G02F 1/025 |
· · · | in an optical waveguide structure [5]

|  | G02F 1/03 |
· · | based on ceramics or electro-optical crystals, e.g. exhibiting Pockels or Kerr effect [2,4]

|  | G02F 1/035 |
· · · | in an optical waveguide structure [5]

|  | G02F 1/05 |
· · · | with ferro-electric properties (Fulltext... Hierarchy... Expanded...G02F 1/035, Fulltext... Hierarchy... Expanded...G02F 1/055 take precedence) [2,5]

|  | G02F 1/055 |
· · · | the active material being a ceramic (Fulltext... Hierarchy... Expanded...G02F 1/035 takes precedence) [4,5]

|  | G02F 1/07 |
· · | based on electro-optical liquids exhibiting Kerr effect [2]

|  | G02F 1/09 |
· · | based on magneto-optical elements, e.g. exhibiting Faraday effect [2]

|  | G02F 1/095 |
· · · | in an optical waveguide structure [5]

|  | G02F 1/11 |
· · | based on acousto-optical elements, e.g. using variable diffraction by sound or like mechanical waves (acousto-optical deflection Fulltext... Hierarchy... Expanded...G02F 1/33) [2]

|  | G02F 1/125 |
· · · | in an optical waveguide structure [5]

|  | G02F 1/13 |
· · | based on liquid crystals, e.g. single liquid crystal display cells (liquid crystal materials Fulltext... Hierarchy... Expanded...C09K 19/00) [2]

|  | G02F 1/133 |
· · · | Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements (arrangements or circuits for control of liquid crystal elements in a matrix Fulltext... Hierarchy... Expanded...G09G 3/36) [3]

|  | G02F 1/1333 |
· · · · | Constructional arrangements (Fulltext... Hierarchy... Expanded...G02F 1/135, Fulltext... Hierarchy... Expanded...G02F 1/136 take precedence) [5]

|  | G02F 1/1335 |
· · · · · | Structural association of optical devices, e.g. polarisers, reflectors or illuminating devices, with the cell [5]

|  | G02F 1/1337 |
· · · · · | Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers [5]

|  | G02F 1/1339 |
· · · · · | Gaskets; Spacers; Sealing of the cell [5]

|  | G02F 1/1341 |
· · · · · | Filling or closing of the cell [5]

|  | G02F 1/1343 |
· · · · · | Electrodes [5]

|  | G02F 1/1345 |
· · · · · | Conductors connecting electrodes to cell terminals [5]

|  | G02F 1/1347 |
· · · · · | Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells [5]

|  | G02F 1/135 |
· · · · | Liquid crystal cells structurally associated with a photoconducting or a ferro-electric layer, the properties of which can be optically or electrically varied [3]

|  | G02F 1/136 |
· · · · | Liquid crystal cells structurally associated with a semi-conducting layer or substrate, e.g. cells forming part of an integrated circuit (Fulltext... Hierarchy... Expanded...G02F 1/135 takes precedence) [5]

|  | G02F 1/137 |
· · · | characterised by a particular electro- or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction, dynamic scattering [3]

|  | G02F 1/139 |
· · · · | based on orientation effects in which the liquid crystal remains transparent [6]

|  | G02F 1/141 |
· · · · · | using ferroelectric liquid crystals [6]

|  | G02F 1/15 |
· · | based on electrochromic elements [5]

|  | G02F 1/153 |
· · · | Constructional arrangements [5]

|  | G02F 1/155 |
· · · · | Electrodes [5]

|  | G02F 1/157 |
· · · · | Structural association of optical devices, e.g. reflectors or illuminating devices, with the cell [5]

|  | G02F 1/161 |
· · · · | Gaskets; Spacers; Sealing of the cell; Filling or closing of the cell [5]

|  | G02F 1/163 |
· · · | Operation of electrochromic cells; Circuit arrangements [5]

|  | G02F 1/167 |
· · | based on electrophoresis [5]

|  | G02F 1/17 |
· · | based on variable absorption elements (Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...G02F 1/015-G02F 1/167 take precedence) [2,5]

|  | G02F 1/19 |
· · | based on variable reflection or refraction elements (Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...G02F 1/015-G02F 1/167 take precedence) [2,5]

|  | G02F 1/21 |
· · | by interference [2]

|  | G02F 1/225 |
· · · | in an optical waveguide structure [5]

|  | G02F 1/23 |
· · | for the control of the colour (Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...G02F 1/03-G02F 1/21 take precedence) [2]

|  | G02F 1/25 |
· · · | as to hue or predominant wavelength [2]

|  | G02F 1/29 |
· | for the control of the position or the direction of light beams, i.e. deflection (static stores with electric or magnetic read-in and optical read-out Fulltext... Hierarchy... Expanded...G11C; lasers provided with means to change the location from which, or the direction in which, laser radiation is emitted Fulltext... Hierarchy... Expanded...H01S 3/101) [4]

|  | G02F 1/295 |
· · | in an optical waveguide structure (Fulltext... Hierarchy... Expanded...G02F 1/313, Fulltext... Hierarchy... Expanded...G02F 1/335 take precedence) [5]

|  | G02F 1/31 |
· · | Digital deflection devices (Fulltext... Hierarchy... Expanded...G02F 1/33 takes precedence) [2]

|  | G02F 1/313 |
· · · | in an optical waveguide structure [5]

|  | G02F 1/315 |
· · · | based on the use of controlled total internal reflection [3]

|  | G02F 1/33 |
· · | Acousto-optical deflection devices [2]

|  | G02F 1/335 |
· · · | having an optical waveguide structure [5]

|  | G02F 1/35 |
· | Non-linear optics (optical bistable devices Fulltext... Hierarchy... Expanded...G02F 3/02; lasers using stimulated Brillouin or Raman effect Fulltext... Hierarchy... Expanded...H01S 3/30) [2,5]

|  | G02F 1/37 |
· · | for second-harmonic generation [2]

|  | G02F 1/39 |
· · | for parametric generation or amplification of light, infra-red, or ultra-violet waves (electrical parametric amplifiers Fulltext... Hierarchy... Expanded...H03F 7/00) [2]

|  | G02F 2/00 |
Demodulating light; Transferring the modulation of modulated light; Frequency-changing of light (Fulltext... Hierarchy... Expanded...G02F 1/35 takes precedence; photoelectric detecting or measuring devices Fulltext... Hierarchy... Expanded...G01J, Fulltext... Hierarchy... Expanded...H01J 40/00, Fulltext... Hierarchy... Expanded...H01L 31/00; demodulating laser arrangements Fulltext... Hierarchy... Expanded...H01S 3/10; demodulation or transference of modulation of modulated electromagnetic waves in general Fulltext... Hierarchy... Expanded...H03D 9/00) [2]

|  | G02F 2/02 |
· | Frequency-changing of light, e.g. by quantum counters (luminescent materials Fulltext... Hierarchy... Expanded...C09K 11/00) [2]

|  | G02F 3/00 |
Optical logic elements (electric-pulse generators using opto-electronic devices as active elements Fulltext... Hierarchy... Expanded...H03K 3/42; logic circuits using opto-electronic devices Fulltext... Hierarchy... Expanded...H03K 19/14); Optical bistable devices [5]

|  | G02F 3/02 |
· | Optical bistable devices [5]

|  | G02F 7/00 |
Optical analogue/digital converters

|  | G02F 7/00 |
Note(s) This group covers only converters based in substantial manner on elements which are provided for in group Fulltext... Hierarchy... Expanded...G02F 1/00. [4]