Our PT-Series optical interference testing rig for applanation
tonometers consists of an automated laser based testing device
equipped with a USB interface for coupling to a PC, plus signalprocessing
software running on standard PCs/notebook
computers. Its flexibility of configuration allows its use with various
types of tonometers. The buckling force set on the tonometer to
be tested is automatically recorded over its full travel. Detecting
the limits of the tonometer's travel allows outputting both its
buckling force characteristic curve over its full travel and the
buckling force at the midpoint of its travel, as stipulated by testing
The force sensor employed is an optical interferometric device
with a measurement range of 100 mN and a resolution of
0.01 mN. To test a tonometer, the tonometer is driven up against
this force sensor by an electromechanical drive, where the
measured buckling force characteristic curve is employed
internally for controlling the motions of the drive and detecting the
limits of the tonometer's travel. The measured value of the
buckling force at the midpoint of the travel is then compared with
the prescribed tolerance range and displayed either in green,
indicating that it falls within that range, or in red, indicating that it
falls outside that range. A complete series of measurements,
including printing the calibration certificate, takes less than five
minutes, thanks to the fully automated test procedures of the rig.
The facilities provided for calibrating its optical interference force
sensor using standard weights allow tracing its calibration back to
national reference standards.
• Allows making orientation independent force
measurements by laser interferometric force
sensor over the full measurement range while
maintaining compliance with tolerated error limits.
• Provides automated test procedures complying
with ISO 8612 testing regulations for
applanation tonometers (determinations of
both buckling forces at the midpoints of their
travels and hysteresis).
• Diagram of tonometers' buckling-force characteristic
curves over their full travels
• The first rig to allow the testing of tonometers
over the full prescribed temperature range of
15°C to 30°C.
• Testing, including setup, takes only about
• Printout of a calibration certificate
• Calibration using standard weights allows tracing
its calibration back to national standards.
• The rig is portable, and thus may be used onsite
e.g. at hospitals or ophthalmologists' offices.
• Certification by German calibration authorities
has been granted.
Suitable for use with all types of applanation tonometers.
Measurement range: 0 ... 10 g (100 mN)
Resolution: 1 mg (0.01 mN)
0.1 mg internally
Standard calibration error
of the force sensor employed: < 0.5 mg (0.005 mN)
Test duration: ¡¤¤µ min
Laser Safety Class
acc. DIN EN 60825-1 2M
Dimensions (H x W x D)
• Testing rig: 360 mm x 390 mm x 190 mm
• Electronics module: 150 mm x 240 mm x 400 mm
• Conducting metrological accuracy checks on
applanation tonometers in accordance with
?11, section 3, MPBetreibV, both in the
laboratory and on-site at remote locations.
• Testing tonometers for compliance with the
EN ISO 8612 testing standard.
• Quality control testing during tonometer