Fig. 1. Schematic of an SSOCT system

Fig. 2. Schematic of a one-order CDG

Fig. 3. Energy distribution of the first order diffraction ring on the back focal plane of F₄

Fig. 4. Axial energy distributions of Bessel beam center spot at different distances from F₅ back focal plane under different filtering conditions

Fig. 5. Graphic representations of δ^(1/2)(x) and δ^(1/2)(-x)

Fig. 6. Energy distributions of the first-order diffraction ring. (a) a=b; (b) a=-b

Fig. 7. Relationship between duty ratio T₀ and diffraction efficiency η

Fig. 8. Comparison of two CDG configurations. (a) Radial energy distributions of the first order diffraction ring; (b) axial energy distribution of central spot under the condition of CDG-A; (c) axial energy distribution of central spot under the condition of CDG-B; (d) normalized axial energy distributions of central spot

Fig. 9. Illumination field at the sample position

Fig. 10. Energy distribution of the first order diffraction ring

Fig. 11. Axial point spread function

Fig. 12. Microbeads imaging. (a) Image of 2 μm microbeads; (b)--(d) lateral point spread functions in different regions

Fig. 13. OCT images measured by the OCT system. (a) Fingernail; (b) multilayer white tape