In-Situ Evaluation of the Pitch of a Reflective-Type Scale Grating by Using a Mode-Locked Femtosecond Laser

Major modifications are made to the setup and signal processing of method in-situ measurement pitch a diffraction grating based on angles diffracted optical frequency comb laser emanated from grating. In method, improvement uncertainty can be expected since every mode in utilized. Instead employing Fabry-Pérot etalon for separation neighboring modes group beams, weight-of-mass is introduced detect light wavelength Littrow configuration. An attempt also reduce influence non-uniform spectrum employed through normalization operation. addition, an alignment technique with employment retroreflector precise components setup. Furthermore, mathematical model by proposed established, theoretical analysis carried out guide expression (GUM).