Dual-laser interferometer cuts costs

The high-performance Twyman Green infra-red Interfire interferometer system can now be supplied with two separate laser systems.

The high-performance Twyman Green infra-red Interfire interferometer system can now be supplied with two separate laser systems.

This means that a single interferometry unit can now be used for measurements at two different wavelengths without the need to buy two complete systems.

Typical applications include the measurement of wavefront aberration of thermal imaging lens and mirror systems, optical homogeneity of IR materials and flatness of optical surfaces.

Although the Interfire 3-5 and Interfire 10.6 single-laser interferometry systems are still available for applications in the 10.6 or 3-5um wavebands, the new dual-laser system offers considerable cost saving benefits for users who wish to make measurements in both regions of the spectrum.

The new system consists of the interferometer, remote control handset and a choice of two lasers.

In general, a CO2 laser is used for measurements at 10.6um, and a variety of lasers is available within the 3-5um range, although a popular choice is the 3.39um HeNe laser.

The system is designed for applications where measurements at any given wavelength are made over a reasonable period of time as switching between wavelengths requires replacement of one laser by the other.

The Interfire is a laser unequal path interferometer designed for convenience and ease of use.

It is a portable integrated system, easily set up for use, yet compact enough to be stowed easily in a cupboard.

The system features a collinear HeNe laser (visible) for ease of alignment of the external optics under test.

The long coherence length of the laser source allows unequal paths in the test and reference arms.

The length of the test arm needs no adjustment and is wholly contained within the instrument.

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