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PrismMaster High Precision Automatic Goniometer
The system also includes an autocollimator mounted on a tillable base. Unlike other goniometers which are using a visual autocollimator, the PrismMaster is equipped with a computerized autocollimator featuring a resolution of 0.1 arcsec. The autocollimator image is taken by a CCD-camera and further processed via framegrabber, PC and specific software.
The fine rotary adjustment of the table is given by a high precision micrometer. A digital display provides an angle indication with a resolution of 0.36/0,036 arcsec. The software provides easy operation, records of measurement data to a file and print out of the measurement certificate.
For more information, download the PrismMaster brochure.
Since the PrismMaster is using a computerized autocollimator no precise, difficult and time consuming alignment procedures are necessary.
The tilt table is simply rotated until the autocollimator is approximately square to the first surface of the prism or polygon. To achieve this, the operator is rotating the table until the reflected image of the autocollimator appears on the PC-monitor within a defined range area. The same procedure is repeated to obtain a reading from the second surface of the prism. The tiresome and difficult visual alignment becomes obsolete.
This is not only incomparably easier and comfortable for the operator, but very important for the overall accuracy of the instrument. In other goniometers the overall accuracy - even when using an accurate encoder- is decisively limited by the ability of the operator to visually and repeatedly align the autocollimator perfectly square to the sample surface. Certainly the alignment error can be reduced repeating the measurement several times and calculating the mean value, however, this is inefficient and dependent on the ability and the degree of tiredness of the operator.
Measurement in reflection mode
The measurement starts using the mouse or pressing a PC-key. The position of the autocollimator reticle and of the rotary encoder is automatically recorded. Following up the angle indication on the digital display, the table is rotated until the reflected image on the second surface of the prism appears on the monitor within the range area. This range area is designated by a red coloured rectangle on the PC-Monitor. A mouse click completes the measurement and the angle value is displayed on the monitor.
Measurement in transmission mode
For measurements in transmission mode the PrismMaster uses a tillable mirror attached to the tilt table of the goniometer. The tilt table is rotated until the mirror is approximately square to the autocollimator i.e. the reflected image is seen on the monitor within the range area. This reference position is recorded.
The tilt table is rotated at the expected angle following the angular indication of the digital display. The sample is placed on the table and positioned so that the reflected image goes through the prism and returns to the autocollimator. Since the beam is reflected by the mirror a double measurement sensitivity results.
The PrismMaster is available in several versions:
Precision Rotary Table
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