Test of accuracy of positioning of AMBER-SPG-DIU
We put the DIU module in a suitable dewar for cooling it to the working temperature (Fig. 1). Reflecting a laser beam on a mirror fixed on the module we could evaluate the accuracy of positioning of the device (Fig. 2 and 3).
Fig 1 (The DIU module in test dewar)
Fig 2 (details of DIU with reflecting mirrors, one fixed on DIU)
Fig 3 (Laser and dewar)
The accuracy in reproducing a position was tested controlling the position of the reflected laser beam by means of a light sensor (Fig. 4). The sensibility of this setup is about few arcseconds of movement of the wheel of DIU. The device is working fine for speed lower than 1000 motor steps/second.
Fig 4 (Detail of the sensor with the reflected beam)
Fig 5 (Light sensor and computer for acquisition)