(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 precision. The maximum diameter is limited by the measuring field or by the charcteristics of repeatability and linearity. The minimum diameter is determined by the focusing of the beam (spot size).
  This is the square area within which the part being measured must be placed to obtain the specified accuracy. The two sides are the heights of the areas scanned by the laser beam and they are parellel to the directions of the laser beams. The positioning of the product outside the measuring field will induce an error condition or will worsen the gauging performance.
  This is the minimum diameter change detectable by the gauge. This is normally determined by the software which processes the signal of the gauge but in any case it must be consistent with the repeatability: a much higher resolution is useless. The two axes have the same resolution.
  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 an ambient 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. The repeatability is the same for both axes and it is related to the mean diameter (X+Y)/2.
The 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 change in diameter being measured, within the range of the measurable diameters,
  • a displacement of the part 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 the average diameter (X+Y)/2 of a master located in the centre of the measuring field, for any diameter included between the minimum and the maximum specified values.

 

maximum measuring error of the average diameter (X+Y)/2, when a master is moved along the two X and Y axes crossing in the centre of the field. Checked with a specified diameter value.
  This is the plane scanned by the laser beam axis.
  This is the frequency at which the laser beam explores the measuring field. At every scan one reading is taken on both axes; 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 or the diameter of the circle where the laser beam is focused (99% of power), in the point of maximum focalisation, that is in the centre of the measuring field.

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) determines the laser beam thickness and the minimum measurable diameter.
 

This is defined by the coordinates h and d, which determine the position of the centre of the square measuring field.

Only for ALS13XY
The focusing point might not overlap exactly with the centre of the measuring field, because, due to manufacturing reasons, a tolerance is allowed between these two positions:
± 0,5 mm for ALS13XY/100/B model,
± 1 mm for ALS13XY/100/A model.
When measuring a diameter very close to the minimum specified value, it is necessary to place the part exaclty in the focusing point; to do this plug an oscilloscope to the gauge test connector and adjust the part position until the lowest peak of the video signal (part shadow) reaches its minimum value, which must be anyway very close to zero.

Only for ILS13XY
The focusing point might not overlap exactly with the centre of the measuring field, because, due to manufacturing reasons, a tolerance is allowed between these two positions, and namely:
± 0,5 mm for ILS13XY/100/B model,
± 1 mm for ILS13XY/100/A model.
When measuring a diameter very close to the minimum specified value, it is necessary to place the part exactly in the focusing point; to do this connect a Handheld Terminal or a PC to the gauge and use the CALIBRATION / CENTERING Submenu.

  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 a number of scans equal to 4 times the previous case. The averaging rate is equal to the programmed measuring time: the newest scans continuously replace the oldest ones, so as to mantain 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 scans averaged is equal to the product of the programmed measuring time by the scanning frequency. The specified measuring time is related to the measurement along both axes. 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).