interferometers - INTERFIRE II 850 nm



The INTERFIRE II 850 nm utilises two laser diode sources, one as a marker beam and one for the measurements at 850 nm. These are coupled into a fibre optic to give very precise alignment. The laser diodes supply plenty of power, but the sensitivity of the camera is sufficient that they can be operated at relatively low power.

The new instrument has all the functional capabilities of the INTERFIRE II family, with a 35 mm aperture, zoom and focus systems and remote control. External beam expanders are also available for the instrument. The system is also fully compatible with phase shift measurement accessories. The high sensitivity ensures reliable fringe acquisition.





Twyman-Green Unequal Path Interferometer


850 nanometres


675mm (l) x 260mm (w) x 280 mm (h)


30 kg approx

Laser source type

    Head dimensions

    Head weight

High performance diode laser

150mm (l) x 81mm (w) x 64mm (h)

1 kg approx

Clear aperture

Nominally 35mm (greater than 31.5 mm guaranteed). Expandable with accessories

Fringe detection

Focal plane array with fringe contrast adjustments


CCIR compatible or as specific user requirements


Integral co-linear visible HeNe laser

Optical zoom

Continuously variable x1 - x3

Remote control

Full control of reference mirror tilt/tip

Diode & HeNe lasers -on/off, standby,

aperture focusing, optical zoom,

phase shifting fringe analysis

Accuracy (PV)

STATIC: l/20     PHASE: l/50

Repeatability (PV)

STATIC: l/50     PHASE: l/1000

Data acquisition time

STATIC: 0.04 sec     PHASE: 0.167 - 1.33 sec

Minimum hardware

Pentium© computer with maths processor,

vacant expansion slot for framegrabber board



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