Abstract: A device for optically measuring and/or testing oblong products moving in a longitudinal direction. The device includes a plurality of cameras arranged in a plane perpendicular to the longitudinal direction, and distributed around the longitudinal direction. Each of the cameras has a fixed focus. The device further includes a displacing device adapted to displace each of the cameras simultaneously and jointly over the same distance toward the surface of the oblong product to focus on the oblong product, wherein the device defines a center that is located in the plane.

Abstract: A method of measuring a dimension and/or position of an object located in a measuring field, includes projecting a fan-shaped reference wave onto a holographic optical element having a first interference pattern and a second interference pattern; forming a first parallel partial wave front from the fan-shaped reference wave using the first interference pattern, the first parallel partial wave front entering the measuring field; and forming a second parallel partial wave front from the fan-shaped reference wave using the second interference pattern, the second parallel partial wave front entering the measuring field; wherein the measuring field is located behind the holographic optical element, and the first parallel partial wave front and the second parallel partial wave front intersect in the measuring field. A method of making a holographic optical element is also disclosed.

Abstract: A method of measuring a dimension and/or position of an object located in a measuring field, includes projecting a fan-shaped reference wave onto a holographic optical element having a first interference pattern and a second interference pattern; forming a first parallel partial wave front from the fan-shaped reference wave using the first interference pattern, the first parallel partial wave front entering the measuring field; and forming a second parallel partial wave front from the fan-shaped reference wave using the second interference pattern, the second parallel partial wave front entering the measuring field; wherein the measuring field is located behind the holographic optical element, and the first parallel partial wave front and the second parallel partial wave front intersect in the measuring field. A method of making a holographic optical element is also disclosed.