interferometers - INTERFIRE II 1.55



The INTERFIRE II 1.55 has been designed to meet the needs for testing the increasing numbers of optical systems operating at 1.55 micron wavelength. The instrument features a CCD camera with NIR conversion optics and glass lenses and mirrors rather than the III-V material lenses and mirrors that are normally used in IR interferometers. The high resolution near infrared converter between a large format lens and the camera converts the 1.495 - 1.595 micron wavelength band to wavelengths detectable using standard CCD cameras without fading or lag during use. A large format anti-reflection coated input window ensures maximum image resolution is transferred to the attached CCD camera. The camera system offers excellent signal-to-noise resulting in high sensitivity. The better the signal to noise in the image, the better the quality of images of fringes that can be acquired. This in turn gives more accurate measurements

Optical systems designed for use in the near infrared at 1.55 microns are highly popular because the radiation at this wavelength is partially eye-safe. Applications include ranging systems, designation systems and scene illumination systems for surveillance. This wavelength is also used extensively in the communications industry.




Twyman-Green Unequal Path Interferometer


1.55 microns


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


30 kg approx

Laser source type

High performance diode laser

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




Copyright 2006 Precision Optical Engineering. All rights reserved