Fig. 1. Principle of absolute linear-angular positioning. (a) Schematic diagram of the overall scheme. The inset shows the absolute code that reflects the linear-angular displacements. (b) Principle of absolute code formation. (c) The mapping relationship between x−τ position and absolute code.

Fig. 2. Design and fabrication of the metasurface array device. (a) Schematic of the unit cell. (b) Planar and sectional design of the unit cell. (c) Graph depicting the relationship among w, wavelength, and reflectance. (d) Graph depicting the relationship among incident angle θ, wavelength, and reflectance. (e) SEM characterization of different subunits.

Fig. 3. Experimental setup. (a) Photograph of the experimental setup. (b) Clamping setup of the metasurface array reflector. (c) Photograph of the metasurface array reflector. (d) Interface of the two-DOF synchronous control system. (e) Images captured by the CCD at three distinct linear-angular positions.

Fig. 4. Sensitivity characterization of different subunits to linear and angular responses when (a) Δx = 50 µm, (b) Δτ = 170 µrad, (c) Δx = 10 µm, and (d) Δτ = 85 µrad.

Fig. 5. Linear-angular single-step operation experiment. (a) Schematic of the four positions. (b) Schematic of the movement paths. (c) Similarity variation trend with the four positions as templates.

Fig. 6. 2D position Tracking. (a) Establishment of the TN. (b) Template naming convention and schematic for pose absolute code matching. (c) Reference values for 2D position template numbers. (d) Matching results between the measured position and the template. (e)–(g) Comparison of reference template numbers and actual template numbers obtained from matching under three routes (e) L₁, (f) L₂, and (g) L₃.

Fig. 7. 2D absolute positioning. (a) Overall positioning point distribution results. (b) Tracking accuracy of each position point.