NOVELTY - The trough collector comprises a focal area and an absorber tube (7) arranged in the focal area, where the absorber tube has an insulating area, which extends from its outer surface to the inside and encloses a transport channel that runs through the absorber tube along its length and carries a heat transporting medium and is penetrated by thermal openings that extend radially from an outer side through the insulating area to the transport channel. The thermal openings comprise a constriction for a radiation (6) passing through the opening. The focal area is located in the constriction.    USE - The trough collector is useful: in solar power plants; and for the production of heat.    ADVANTAGE - The trough collector is capable of simply and economically producing heat with high efficiency.    DETAILED DESCRIPTION - The trough collector comprises a focal area and an absorber tube (7) arranged in the focal area, where the absorber tube has an insulating area, which extends from its outer surface to the inside and encloses a transport channel that runs through the absorber tube along its length and carries a heat transporting medium and is penetrated by thermal openings that extend radially from an outer side through the insulating area to the transport channel. The thermal openings comprise a constriction for a radiation (6) passing through the opening. The focal area is located in the constriction. The thermal openings continuously expand itself against inside after the constriction, and are formed as a connecting channel extending itself from the outer surface of the absorber tube to the transport channel, where the connecting channel continuously extends itself against the inside behind the constriction and is formed with reflective walls so that the radiation completely reaches the transport channel without absorption at the reflecting walls. The trough collector comprises focal line areas. Each focal line areas of the thermal opening is associated, where the focal line areas are formed as a slit-shaped connecting channel that extends itself over the length of the absorber tube between an outerworld and the transport channel. The constriction of the thermal openings is present itself on the outer surface of the absorber tube and then extends itself against the inside of the connecting channel, which expands itself both the inside and outside. The constriction is provided on the inside of the insulating area. The trough collector comprises rows of focus point areas lying next to each other, where each focal point is associated with a single thermal opening formed as the connecting channel and is separated from remaining thermal openings by the insulating area. Portions of an inner wall of the connecting channel are formed such that the concentrated radiation reflects against the transport channel. The trough collector comprises a linear concentrator, which is divided into sections passing parallel to each other. The thermal openings are formed as a retainer for photovoltaic cells. An INDEPENDENT CLAIM is included for an absorber tube for a trough collector.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a trough collector.    Pressure cell (2)    Upper flexible membrane (3)    Lower flexible membrane (4)    Radiation (6)    Absorber tube. (7)