Cortex Technical R&D Ltd.

Diameter Gauges

Laser Scanning and Diffraction Diameter Gauges

The DG (Scanning Laser Gauge) and WG (Laser Wire Gauge) type instruments can measure the outside diameter of cylindrical objects, such as rods, tubes, cables, wires or fibres. The measurement is fast (up to 200 measurements/sec), precise and contact-free. The diameter range spanned by these instruments is 10 m m to 50 mm.

Both instrument types (DG and WG gauges) are similar in that they basically consist of a Measuring Head with built-in DSP based signal pre-processor and an industrial PC based Control Unit with a keypad and a large bright fluorescent alphanumeric display (standard) or graphical LCD display (option). One control unit can handle one or two measuring heads, depending on the application. The layout of these heads is similar in that there is a sender and a receiver part, and the object to be measured is placed between them.

The WG Laser Wire Gauges have a stationary laser beam. The object to be measured is placed into the laser beam and diffracts (scatters) the light beam. The diffraction pattern is detected in the receiver head via a one dimensional CCD light sensor, digitised and evaluated by the DSP pre-processor to obtain the diameter of the object. This principle is especially suited for objects of small diameter, such as wires or fibres.

The sender part of the DG Scanning Laser Gauges produces a scanning (moving) laser beam (vertical line) and the object to be measured is placed into this beam and its “shadow” is detected at the receiver part. This principle is used for measuring larger diameters.

The typical application of the WG Laser Wire Gauges is the measurement of very thin objects, such as copper, tungsten and molybdenum wires. The typical diameter ranges are 10 - 300 m m (although diameters up to 2 mm can be measured with a special software).

The application of the DG Scanning Diameter Gauges are widespread. Two types of gauges are available: the DG1 Gauge performs precise measurements with 0.1 m m resolution and works in the 50 m m - 10 mm measuring range (20 mm on request), while the DG50 Gauge has a resolution of 1 m m and a 1 - 50 mm measuring range. The main application of the DG1 Gauge is the QC of wires and cables or small machined parts during or after the manufacturing stage. The DG50 Gauge can be used for similar measuring purposes for diameters up to 50 mm in harsh industrial environments.

(C) 1999. Cortex Ltd.