Optical probe for surface texture measurement Available from Horstmann Metrology, the LaserSurf non-contact optical probe is a high resolution optical measuring instrument designed to measure surface texture without contact.

It uses a laser light system with a spot size of 1.5/~m and a height resolution of 0.01 /~m. A complete system consists of the optical probe, a traverse mechanism and a parameter display unit. The display unit may optionally comprise a computer- controlled data acquisition and display unit.

The probe system consists of a measuring head and control unit and

is supplied for retrofit or as part of the complete system. In the retrofit role the probe can be attached to the existing surface measuring instrument using one of the special adapters.

Contained within the measuring head is a moveable lens which focuses the laser light onto the surface allowing photodiodes to detect the size of the reflected spot. A complex loop control loop acts to maintain the minimum spot size (1.5/~m), as the surface is traversed, by continuous adjustment of the lens. From this control loop the surface profile signal is derived and is available directly from the instrument.

Optical micrometer for on-line measurement For the on-line measurement of dimensions during production processes and optical micrometer has been launched by GWl.

The RS1500 series has a sensing head which produces a parallel light flux, and which is then cast onto a 2048 bit CCD image sensor. Interruption of the light casts a shadow on the sensor which is then able to determine the dimension of the object. ]'he measuring range is 0 99.99 mm in three switched stages, with a sampling rate of 250 s 1 and a resolution of

10 tim. Display of the measured variable

is presented on a bright four-digit LED meter, updated every 2 s. The RS1 500 is also equipped with an upper and lower digital comparator, and BCD outputs.

The wide and varied applications include diameter measurement on extruding machines, simultaneous X and Y axis measurement, sheet width, object height, and positioning.

Graham & White Instruments Ltd, 135 Hatfield Road, St Albans, Hertfordshire ALl 4LZ, UK

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The control unit for Horstmann "s LaserSurf has an LED bargraph to indicate the position of the head relative to the surface

Alternatively, a version of the instrument is available which provides an on-line R a value for immediate assessment of the surface finish.

The operation of the control loop is dependent on the reflection of light from the material surface. A second control loop acts to keep the returned light level constant by varying the intensity of the laser output. Surface reflectivity of a minimum of 5% is required for the control loop to operate.

In setting up the system, as the measuring head is lowered toward the surface, an audible signal is used to indicate when the head reaches the correct operating position. An LED bargraph indicates the position of the head relative to the surface and a control button is provided so that the height may be set to zero.

With a 1.5/~m spot size the resolution is said to be 0.01 /~m with a head-to-specimen working distance of 1 mm. The working range is _+ 500/~m with a full accuracy range of _+ 100 #m. The traverse speed is 0.05 to 0.5 mm s

Horstmann Metrology, Sharp Road, Parkstone, Poole BH12 4BG, UK

The optical micrometer from GWl can be used during production processes for the measurement of dimensions

The optical head of Horstmann "s LaserSurf has a spot size of 1.5 l~m and achieves a height resolution of O. O01 iLm

248 OCTOBER 1989 VOL 11 NO 4