Project name Interferometer development
Client / customer Control Systems Technology, TU/e
Partner VSL - Dutch Metrology Institute
Description Development of a Differential Plane-Mirror Interferometer (DPMI). The interferometer is designed for the Nanostage3D translation stage but can be used as a stand-alone interferometer as well.

Figure 1 gives the beam layout of the DPMI. A polarizing beamsplitter divides the incoming two-frequency laser beam into a reference beam and a measurement beam. Each beam is then reflected twice by its respective mirror before being recombined and coupled into a fiber-optic detector. Beamsplitters and wave plates separate the first and second pass.

The optical length of the measurement beam and the reference beam are identical for maximum thermal stability. The DPMI measures only the relative translations along the mirror normal, this measurement is not influenced by other movements of the mirror or movements of the interferometer itself.

The overall dimensions of the DPMI optics are 58 x 48 x 10 mm (figure 2). When used with Zygo® ZMI4004 measurement electronics the resolution is 0.15 nm.

Part of the development process is the design and fabrication of assembly tooling (figure 3).
Summary (PDF) -

1: optical layout 2: components 3: assembly tooling

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