Abstract: An optical imaging lens includes: a first, second, third, fourth, fifth and sixth lens element. The first lens element has positive refracting power, an object-side surface with a convex part in a vicinity of the optical axis, and a convex part in a vicinity of its periphery, the second lens element has negative refracting power, an image-side surface with a convex part in a vicinity of its periphery, the third lens element has an image-side surface with a concave part in a vicinity of the optical axis, the fourth lens has an image-side surface with a convex part in a vicinity of the optical axis, the fifth lens element has object-side surface with a concave part in a vicinity of the optical axis, and the sixth lens element has an image-side surface with a concave part in a vicinity of the optical axis.

Abstract: Present embodiments provide for an optical imaging lens. The optical imaging lens may comprise five lens elements positioned sequentially from an object side to an image side. By controlling the convex or concave shape of the surfaces of the lens elements and designing parameters satisfying at least one inequality, the view angle of the optical imaging lens may be increased to achieve better optical characteristics.

Abstract: Present embodiments provide for an optical imaging lens. The optical imaging lens may comprise five lens elements positioned sequentially from an object side to an image side. By controlling the convex or concave shape of the surfaces of the lens elements and designing parameters satisfying at least one inequality, the view angle of the optical imaging lens may be increased to achieve better optical characteristics.

Abstract: An optical imaging lens includes: a first, second, third, fourth, fifth and sixth lens element. The first lens element has positive refracting power, an object-side surface with a convex part in a vicinity of the optical axis, and a convex part in a vicinity of its periphery, the second lens element has negative refracting power, an image-side surface with a convex part in a vicinity of its periphery, the third lens element has an image-side surface with a concave part in a vicinity of the optical axis, the fourth lens has an image-side surface with a convex part in a vicinity of the optical axis, the fifth lens element has object-side surface with a concave part in a vicinity of the optical axis, and the sixth lens element has an image-side surface with a concave part in a vicinity of the optical axis.

Abstract: A fluorine compound-containing composite material consists essentially of a metal or polymer matrix and particles or fibers of a polytetrafluoroethylene oligomer having a number average molecular weight of 10,000 or less, the proportion of the number of fluorine atoms to the number of the total atoms at the surface portion of the composite material being 40% or more.

Abstract: A fluorine compound-containing composite material consists essentially of a metal or polymer matrix and particles or fibers of a polytetrafluoroethylene oligomer having a number average molecular weight of 10,000 or less, the proportion of the number of fluorine atoms to the number of the total atoms at the surface portion of the composite material being 40% or more.

Abstract: The present invention provides a recording material containing a carbonaceous powder whose surfaces are modified with a fluorine gas. Even when the recording material of the present invention is stored for a long period of time, a carbonaceous powder such as a graphite powder or carbon black neither coheres nor precipitates. For example, even if the recording material of the present invention is used in a felt pen or a ball-point pen, the carbonaceous powder does not cohere in the container or the pen point, and therefore any clogging does not occur in the pen point and good writing is possible.

Abstract: The present invention provides a recording material containing a carbonaceous powder whose surfaces are modified with a fluorine gas. Even when the recording material of the present invention is stored for a long period of time, a carbonaceous powder such as a graphite powder or carbon black neither coheres nor precipitates. For example, even if the recording material of the present invention is used in a felt pen or a ball-point pen, the carbonaceous powder does not cohere in the container or the pen point, and therefore any clogging does not occur in the pen point and good writing is possible.

Abstract: In oxide film removing equipment for removing a SiO.sub.2 film on a semiconductor substrate by using hydrogen fluoride, a liquid mixture of hydrogen fluoride and methyl alcohol is prepared in a chemical factory beforehand. The liquid mixture of hydrogen fluoride and methyl alcohol is heated to generate azeotropic vapor at a semiconductor works and the vapor is used to remove the SiO.sub.2 film on the substrate. The liquid mixture of hydrogen fluoride and methyl alcohol previously prepared in the chemical factory increases safety during an operation at the semiconductor works.

Abstract: Disclosed is a carbon electrode having low polarizability, comprising a porous carbon block and, contained in the pores thereof, a metal fluoride mixture composed of LiF and a metal fluoride other than LiF. This carbon electrode can easily be obtained by a skillful impregnation method. When such a carbon electrode is used as an anode in electrolyzing an electrolyte comprising a mixed molten salt system of potassium fluoride and hydrogen fluoride in an electrolytic cell, polarization of the anode is extremely low and the anode effect is remarkably suppressed so that the electrolysis can stably be performed while exhibiting not only a high anodic current density but also a low voltage.

Abstract: A method for removing a film on a silicon layer formed on a surface of a substrate includes the steps of: (a) placing a substrate in a reaction chamber to be isolated hermetically from the outside air, and (b) feeding anhydrous hydrogen fluoride and alcohol simultaneously into the reaction chamber. Preferably, the method further includes the step of feeding only alcohol into the reaction chamber prior to and/or subsequent to the step (b). An alcohol layer is formed on the substrate surface, whereby the film can be removed uniformly by anhydrous hydrogen fluoride. A by-product of the reaction is taken out from the system of reaction by means of the alcohol on the substrate. No by-product remains on the substrate after the reaction. Since the silicon layer after the reaction is covered with alcohol, re-growth of a native oxide film thereon is also suppressed and on ionic contamination such as fluorine remains on the substrate surface.