Position & Angle Measurement Displacement Measuring Interferometers

ZMI™ Displacement Measuring Interferomter system.

Displacement Measuring Interferometer systems (DMI) measure relative position of a "target" to a very high degree of precision, making them ideally suited to provide feedback to a motion control system. A typical OEM application for this technology is in photolithography equipment where it measures stage position and sends the data to the precision motion control system, making possible ultra-precise positioning of the stage.

Some processes that benefit from this level of precision are: machine tool calibration, X-Y stage control in semiconductor photolithography, stage control and triggering in memory repair and wafer inspection, machine tool calibration, and diamond turning. Many different interferometer configurations are possible, with each designed to accomplish a specific type of measurement.

Angle Interferometer

Displacement Measurement - Useful for measuring limited distances with extreme precision. At right is a basic single-pass configuration for measuring linear displacement. Since the measurement beam makes only one pass to the target, this design allows for the maximum range of travel. A two-pass configuration has half the range of a single-pass.

Angle Measurement - Measures changes in the angle of the target mirror with extreme precision. Shown is a DPMI configuration (Differential Plane Mirror Interferomter). The angular displacement reference mirror has two holes that are positioned such that the second pass of the beams is directed to the opposite mirror it reflected from on the first pass. The resultant output is an angular displacement whose resolution is based on the separation between the beams on the target mirror (less than 0.1 arc second).

ZYGO's ZMI™ Series of products are the industry leaders in displacement and angle measuring interferometer systems for your OEM application.

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