Documentation dedicated to the typical application of Displacement Measuring Interferometer (DMI). In other words, the high precision measurement equipment. From basic theory to typical problems that course measurement errors.

## Applications

### Positioning

The linear positioning measurement. It is the most advanced option of linear measurements. After all, it is also the most common form of laser interferometer measurements performed on machines. To clarify, the laser system measures linear positioning accuracy, repeatability and backlash. In short, system compares the position to which the machine moves with the true position measured by the interferometer.

### Velocity

Velocity measurements are performed with the use of linear optics. For example, this measurements can be used to get the motor movement characteristic. The System enables to measure velocity in different units. For instance, the value of velocity is sampled every 40ms.

### Straightness

In order to gain basic information about the machine axis geometry use the straightness measurements. With this option user can measure machine base straightness on all important surfaces of the base. For instance, check the movement of the measured machine’s element in space.

### Squareness

The squareness measurement is used to characterise the measured machine geometry. In other words, the squareness of axes. Firstly, determine the measurement technique. It can be either 3D or Wollaston straightness measurement. Above all, in order to obtain the proper results, two measurements with the use of a right angle etalon are necessary.

### Paralelism

The parallelism measurement is used to characterize the measured machine geometry. For example, the parallelism of axes. Performed the measurement with 3D or Wollaston straightness technique. Moreover,  to obtain the proper results, make two measurements with the right angle etalon. From obtained axes straightness data software calculates and draws parallelism.

### Dynamic

For characterisation of subtle machine movement use dynamic measurements. The laser measurement system HPI-3D is capable of characterising the tested machine. During measurements the system takes with up to 1 000 samples per second in the Bluetooth mode. Moreover, up to 100 000 samples per second in the USB mode. In the same vein, both modes provide 100 pm measurement resolution. Dynamic measurements are performed with the use of linear optics, angular, or Wollaston optics. The System enables to perform dynamic measurement of distance, velocity, acceleration, angle or straightness in different units.