(Click on item of Interest Below)
 

  This is the range of diameters that are measurable by the laser gauge, in accordance with the specified characteristics of accuracy. The maximum diameter is limited by the measuring field or by the characteristics of repeatability and linearity. The minimum diameter is determined by the focusing of the beam (spot size).
 

This is given by the height of the area scanned by the laser beam: to be measured, the part must be included within the measuring field.
 

The axis of the part, being at the same time perpendicular to the scanning plane, must lie on this plane, to achieve the best linearity performance, as specified.

  This is the plane scanned by the laser beam axis.
 

It is located on the measuring plane, in the middle of the measuring field. This is defined by the coordinates h and d, which determine the centre line of the measuring field and the location of the measuring plane, respectively.

  This is the minimum diameter variation that the gauge can detect. This is normally determined by the software that processes the signal of the gauge, but in any case it must be consistent with repeatability: a much higher resolution is useless and meaningless.
  This is the maximum variation of the measured diameter, with the part firmly placed at the same position in the measuring field. The specified value is given with a temperature of 20°C ±1°C and for a measuring time of 1 second, unless otherwise stated. The confidence level is at ±3s, corresponding to the 99.7% of measurements. Repeatability improves for diameters smaller than the maximum one and worsens with a shorter measuring time, being inversely proportional to the square root of the measuring time (i.e. a four times longer time will halve the repeatability value).

 

This is the maximum error caused by:

  • a variation in diameter, within the range of measurable diameters;
  • a displacement of the part in the measuring plane, within the measuring field;
  • a lateral displacement of the part out of the measuring plane, within the measuring field.

The axis of the piece must be perpendicular to the scanning plane, to avoid any error due to the tilt.
As the linearity errors are systematic ones, they can be corrected by re-calibrating the gauge with a master placed in the actual measuring position.

maximum measuring error of a master located in the centre of the measuring field, for any master whose diameter is included between the minimum and the maximum specified values.

maximum measuring error, when a master is moved up and down within the measuring field, keeping its axis on the measuring plane. Checked with a specified diameter value.

maximum measuring error, when a master is moved sideways within the measuring field, its axis being out of the measuring plane. Checked with a specified diameter value. It is given as µm of error for each mm of lateral displacement.
  Due to the design tolerances of the rotating mirror and of the scanning motor, the scanning plane might be affected by a lateral oscillation, whose maximum peak-to-peak amplitude is specified.
  This is the frequency at which the laser beam explores the measuring field. At every scan one reading is taken; however, this single shot hasn't the specified repeatability.
  This is the uniform translation speed at which the laser beam explores the measuring field.
 

This is given by the axes of the ellipse where the laser beam is focused (99% of power), on the measuring plane.

The horizontal dimension (l) corresponds to the laser beam width and determines the minimum length of the details that can be checked on the part; the vertical dimension (s) corresponds to the laser beam thickness and determines the minimum measurable diameter.
  it is performed over a number of scans equal to the product of the programmed measuring time by the scanning frequency. Each average is performed over a new group of scans.
  it is performed over 4 times the number of scans in the previous case. The averaging rate is equal to the programmed measuring time: the newest scans continuously replace the oldest ones, so as to maintain the total number unchanged.
 

This is the minimum time for the simple average, which is necessary to get the specified repeatability, for all the measurable diameters. The number of averaged scans is equal to the product of the programmed measuring time by the scanning frequency. A measuring time shorter than specified worsens the repeatability value.
 

Typical value. It states the measurement drift due to the room temperature change, when measuring a master with null coefficient of expansion (INVAR).

For ILS200 model
Typical value when measuring with one laser beam. It states the measurement drift due to the room temperature change, when measuring a master with null coefficient of expansion (INVAR). When measuring between two beams, the reding error expressed in mm / °C is given by the relationship below, where F is in mm:
DF/DT=1,8104-0,01884*F