Abstract: A gas detector for simultaneously detecting a kind of gas to be detected and a gas concentration by simultaneously effecting adsorption-measuring type gas detection and optical gas detection. The gas detector comprises a gas detecting element having a gas sensitive thin film disposed on a piezoelectric vibrating element and adapted to generate fluorescence or phosphorescence when irradiated with a light, an oscillating unit for oscillating the piezoelectric vibrating element, a frequency detecting unit for detecting an oscillation frequency of the piezoelectric vibrating element, a light emitting element for irradiating the gas sensitive thin film with light and a light receiving element for receiving the fluorescence or phosphorescence generated from the gas sensitive thin film and adapted to detect the intensity of the fluorescence or phosphorescence. The gas detecting element is disposed in a reaction tank provided with a gas passageway and having a light transmissive window.

Abstract: A self-frequency-doubler laser element having a three-dimensional optical waveguide includes a first transparent insulating substrate having both a DFB grating and a grating reflector formed on one side of the DFB grating, a Nd.sup.3+ -ion-doped thin glass film laid over the first transparent insulating substrate, a thin nonlinear optical film laid over the thin glass film, a second transparent insulating substrate laid over the thin nonlinear optical film, and a thin reflecting film laid over the second transparent insulating substrate, wherein the following conditions are satisfied: nf-ng=0.01 to 0.05, and nf and ng are greater than ns and nc, where ns, ng, nf, and nc are the refractive indices of the first transparent insulating substrate, the thin glass film, the thin nonlinear optical film, and the second transparent insulating substrate, respectively.

Abstract: Novel squarium compounds which have a flat photosensitivity in the wide range from visible ray region to the near infrared ray region as a charge generator and which can be prepared by reacting squaric acid and an aniline derivative, and electrophotographic photoreceptors containing the squarium compounds are disclosed.

Abstract: A photosensor having a photoconductive layer made of built-up monomelecular membranes containing a squarylium pigment represented by the formula (I): ##STR1## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4, which may be the same or different, each represents an alkyl group.

Abstract: A novel squarylium derivative represented by general formula (I) and a process for preparing the same are described: ##STR1## wherein X and Z are defined in the specification. This squarylium derivative exhibits high nonlinearity and is excellent in thermal resistance, light resistance, storage stability and processability, so that it can be used for preparation of nonlinear optical elements.

Abstract: Novel squarium compounds which have a flat photo-sensitivity in the wide range from the visible ray region to the near infrared ray region as a charge generator and which can be prepared by reacting squaric acid and an aniline derivative, and electrophotographic photoreceptors containing them are provided.

Abstract: An optical gas sensor comprises a light emitting element; a photo detecting element; a gas sensing element including a thin film containing an organic pigment, the gas sensing element responding to light emitted from the light emitting element to emit fluorescence or phosphorescence; and a filter for selectively picking up fluoroescence or phosphorescence, the gas sensing element and the filter being disposed in an optical path ranging from the light emitting element to the photo detecting element.

Abstract: A wavelength converting device exhibiting high activity for SHG is disclosed, which comprises a compound represented by formula (I) ##STR1## where Ar represents the residue of a .pi.-electron conjugated molecule; and X represents a hydroxyl group, an alkoxy group, or a halogen atom.

Abstract: Novel squarylium compounds, a process for the production thereof as well as to a photoreceptor for electrophotography containing the squarylium compound are disclosed, said squarylium compounds being represented by formula (I) or (II): ##STR1## wherein X is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; Y is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms a hydroxyl group or an alkoxyl group having 1 to 4 carbon atoms.

Abstract: Novel squarylium compounds, a process for the production thereof as well as to a photoreceptor for electrophotography containing the squarylium compound are disclosed, said squarylium compounds being represented by formula (I) or (II): ##STR1## wherein X is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; Y is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxyl group or an alkoxyl group having 1 to 4 carbon atoms.

Abstract: Novel squarylium compounds, a process for the production thereof as well as to a photoreceptor for electrophotography containing the squarylium compound are disclosed, said squarylium compounds being represented by formula (I): ##STR1## wherein R is a straight-chain alkyl group having 2 or more carbon atoms or --C.sub.2 H.sub.4 X, wherein X is a hydroxyl group, a halogen atom or the group --OR.sub.1 wherein R.sub.1 is an alkyl group having 1 to 6 carbon atoms, or a substituted or unsubstituted phenyl group.

Abstract: Novel squarylium compounds, a process for the production thereof as well as to a photoreceptor for electrophotography containing the squarylium compound are disclosed, said squarylium compounds being represented by formula (I): ##STR1## wherein R is a straight-chain alkyl group having 2 or more carbon atoms or --C.sub.2 H.sub.4 X, wherein X is a hydroxyl group, a halogen atom or the group --OR.sub.1 wherein R.sub.1 is an alkyl group having 1 to 6 carbon atoms, or a substituted or unsubstituted phenyl group.

Abstract: Novel squarium compounds which have a flat photosensitivity in the wide range from visible ray region to the near infrared ray region as a charge generator and which can be prepared by reacting squaric acid and an aniline derivative, and electrophotographic photoreceptors containing the squarium compounds are disclosed.

Abstract: A photosensitive medium for electrophotography which comprises a support having thereon a photoconductive layer comprising an organic photoconductive material and containing in a dispersed state a cyanine pigment which functions as a photoconductor expressed by the following general formula (I) ##STR1## in which A represents ##STR2## wherein B represents an aromatic group, a halogen atom, a nitro group, a cyano group, an acetoxy group, a styryl group, an alkylthio group, an alkoxy group, ##STR3## in which Z represents --O--, --Se--, ##STR4## or --S--, R.sub.1, R.sub.2, R.sub.3 and R.sub.4, which may be the same or different, each represents an alkyl group or an allyl group, Y represents --S--, --Se--, --O--, ##STR5## X represents an anion, and the two benzene nuclei may include a carbocylic ring condensed therewith.

Abstract: An electrophotographic photosensitive material comprising an electrically conductive support having thereon a photoconductive layer containing, as an essential component, an organic photoconductive material, in which the photoconductive layer contains in a dispersed state a quinocyanine pigment represented by the following general formula (I) ##STR1## wherein A is selected from the group consisting of ##STR2## wherein B represents an unsubstituted or substituted alkyl group having 1 to 8 carbon atoms, an unsubstituted or substituted aromatic residue, a quinolinium residue, a halogen atom, a nitro group or a cyano group; R.sub.1 and R.sub.2, which may be the same or different, each represents an unsubstituted or substituted alkyl group having 1 to 8 carbon atoms or an allyl group; X represents an anion, and the two quinoline nuclei may have additional substituents.

Abstract: An electrophotographic photosensitive material comprising an electrically conductive support having thereon a photoconductive layer containing an organic photoconductive material, in which the photoconductive layer contains in a dispersed state a quinocyanine pigment represented by the following general formula (I) ##STR1## wherein R.sub.1 and R.sub.2, which may be the same or different, each represents an unsubstituted or substituted alkyl group having 1 to 12 carbon atoms or an allyl group; X represents an anionic functional group selected from the group consisting of R.sub.3 COO.sup.-, R.sub.4 SO.sub.3.sup.-, R.sub.5 SO.sub.4.sup.- and NO.sub.3.sup.- ; R.sub.3 represents an unsubstituted alkyl group having 1 to 5 carbon atoms, a substituted alkyl group having 1 to 5 carbon atoms in the alkyl moiety thereof, an unsubstituted or substituted phenyl group or a nitrogen-containing heterocyclic group; R.sub.