The sensor is made in two versions: Probe tip angle is either 50 degrees or 57 degrees. The value is stamped on the probe tip.
The rangeability of the two sensor versions is described in the following figure. The shaded area shows the span for a typical mechanical zero setting. By mechanical zero adjustment the shaded area can be moved right (holder moved outwards) or left within the borders of the rectangle. For example, the 57 degree version can measure up to R.I. 1.530. If the desired measurement range cannot be achieved with the sensor version in use, the sensor has to be exchanged. The standard span in the following figure is based on an objective lens focal length f=10.
