Fig. 1. Picometer accuracy measurement using a laser interferometer

Fig. 2. Principle of weak chaos measurement using a laser interferometer

Fig. 3. Principle of 3D-locking using orthogonal laser interferometers for high precision measurement of targeted point P(x, y, z) which is moved in two dimensions

Fig. 4. Grating with N periods of d and laser interference field can be measured with a laser interferometer

Fig. 5. Schematic of configuration for grating period measurement system

Fig. 6. Picometer comb is made by using twice-exposed holography with picometer difference between the periods of the two interference field

Fig. 7. Interference fringes can be used to measure the period difference of picometer comb due to the reverse relation between the period T of the interference field and the period difference Δd in picometer level

Fig. 8. Interference fringes produced by a picometer comb. (a) Actual pattern collected by the photodetector; (b) simulation pattern