Abstract: Using of existing laser interferometer the two angular deviations, i.e. the rotations around the axes vertical to the displacement movement direction, can be already easily measured. But the rotation around the displacement movement axis(roll angle) , especially for large range movement, there has been no effective measurement method. Toward to high precision positioning stages, we have developed a high precision micro roll measurement interferometer, which uses a special differential plane mirror interferometer combining a wedge prism and a wedge reflector assembly. It does not need a large reference mirror, but it can quickly and efficiently measure the roll angle of each kind of precision linear positioning stages and achieve both high measurement resolution and practicability. Also it can be directly traced to meter definition without calibration. Experimental results show that the roll angle interferometer with such four optical symmetry paths can effectively eliminate the influences of other DOF motion. By using of normal phase meter with 2π/360 subdivision, the roll angle measurement resolution is about 1". By using of high precision phase meter with 2π/36 000 subdivision, the roll angle measurement resolution will reach 0.01".

Key words: heterodyne interferometer, polarizing splitting, roll angle