Measuring head in or for a densitometer
First Claim
1. In or for a densitometer, a measuring head comprising a light source, a photoelectric transducer and an optical system for providing a light path between the source and the transducer via a location at which an object to be measured is received, the optical system including means to form a defined spot of light at said location to illuminate an area of an object received thereat and means to guide light from the illuminated area to the transducer;
- the improvement comprising means in said light path to provide at the transducer a light intensity response across the spot that follows a bell-shaped curve having its maximum at the center of the spot and being symmetrical about the spot center.
1 Assignment
0 Petitions
Accused Products
Abstract
A measuring head for a densitometer comprises a light source and an optical system for forming a spot of light of defined size on the surface of an object under test. The optical system guides the reflected or transmitted light, depending on the type of densitometer, from the area of the spot to a photoelectric measuring transducer. The light intensity distribution across the spot as seen by the transducer is weighted to have a bell-shaped curve with its maximum at the center of the spot. The weighting may be done in the optical path from the spot area to the transducer or, as described, in the path between the source and spot area by means of a filter comprised of a plano-convex transparent lens and a plano-concave lens of neutral grey glass. The lenses have the same index of refraction and the same curvatures and are joined to form a plane parallel plate having a maximum transmissivity on its axis, the transmissivity decreasing radially from the axis. The head finds particular use for measuring raster-like material such as offset printing.
8 Citations
19 Claims
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1. In or for a densitometer, a measuring head comprising a light source, a photoelectric transducer and an optical system for providing a light path between the source and the transducer via a location at which an object to be measured is received, the optical system including means to form a defined spot of light at said location to illuminate an area of an object received thereat and means to guide light from the illuminated area to the transducer;
- the improvement comprising means in said light path to provide at the transducer a light intensity response across the spot that follows a bell-shaped curve having its maximum at the center of the spot and being symmetrical about the spot center.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
Specification