Optical distance sensor

US5448359A · kind A · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Anton Schick · Taufkirchen, DE
• Richard Schneider · Livonia, US
• Michael Stockmann · Munich, DE

Key dates

• Filing date: Jun 17, 1994
• Grant date: Sep 5, 1995
• Expiry date: Jun 17, 2014

Classification

• Technology area (CPC G): Physics
• CPC primary: G01B11/0608
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

In order to set up a height raster image for the inspection of complex units, for example of equipped printed circuit boards, optical distance sensors are employed. In this case, the known triangulation method or the likewise known confocal principle is employed. A sensor which permits a complete inspection in an acceptable time must cope with an appropriately high data rate. To this end, a distance sensor is described, which at the same time exhibits a high resolution and a low sensitivity in relation to secondary light reflexes. The essential features reside in: 1) a measurement beam (19) which is shaped to be substantially larger than the illumination beam (18) with respect to the diameter; 2) an approximately equal diameter of the two beams at the measurement location, the illumination beam (18) exhibiting a greater depth of focus (T) than the measurement beam (19), 3) a beam splitting unit (154) for splitting the measurement beam (19) with approximately point photodetectors which are disposed in each partial beam and which are disposed one behind the other in the direction of the partial beams and the respective height level within the depth of focus (T) is recognizable by the…