Inner surface profile measurement of a cylindrical object by an oblique incidence and multiple-wavelength interferometer

准直线光束以倾斜入射角入射到流体动力轴承的内表面中，该流体动力轴承的内径和长度分别为3mm和3. 5 mm。选择从内表面沿指定方向反射的光以获得相位分布与内表面轮廓成比例的光场。该光场与使用可调谐外腔激光二极管的多波长干涉仪中的参考光场干涉。该方法可以测量内表面深度为5μm左右的沟槽的宽度，误差小于0. 3μm。

A collimated line beam is incident at an oblique incident angle into an inner surface of a hydrodynamic bearing whose inner diameter and length are 3 mm and 3. 5 mm, respectively. Lights reflected in specified directions from the inner surface are selected to obtain an optical field whose phase distribution is proportional to the inner surface profile. This optical field interferes with a reference optical field in a multiple-wavelength interferometer using a tunable external cavity laser diode. Shapes of grooves with depth of about 5μm on the inner surface can be measured with an error less than 0. 3μm.