High-precision high-speed and noninvasive optic distance measurement

In all kinds of optical applications, the precision of central optical distance has significant influence on the desired imaging properties according to the optical design requirements. In this paper, we present a measurement method for the determination of the central distance both in assembled systems and single-lens with high precision, high speed and non-invasive characters. The distance between optical surfaces are optically measured by the mean of swept source domain interferometric system. A fiber-optics system with a central wavelength 1310 nm is built, the central distances of all surfaces within coherence length can be quickly measured at the same time. The system pixel resolution is about 0.1μm calibrated by Mitutoyo standard level-zero gauge and calculated by Fast Fourier Transform (FFT) and zero-padding algorithm. System precision double checked by other gauges is less than 0.3μm. The standard gauge-sets and a lens were measured by this system, the result also verified the high precision. The systematic error is less than 0.3μm and the sensitivity is about 22μm experimentally. The high speed swept light source (100kHz used in system) ensures the quick measuring speed. This measurement method has high precision, high speed, non-invasive and high sensitivity characters, and can be applied in related optical system.