n1 = (sinc (θ2))2  (1)

Provided that the photolithographic processing unit of the DOE surface is in the wavelength range (which is true outside of the UV range), the optical power (D) of a Variable Focus Moiré lens can be calculated as follows:

D = θ  (2)

Here θ, stands for the current twist angle of the DOEs and A denotes the clear aperture of the lens.

Equation 1 shows that the diffraction efficiency of the Variable Focus Moiré lens for a twist angle of ±90º (θ = ±π2) is higher than 80%. For this lens with an aperture of the optical power range is as follows:

D = ±12A = ±25 Dpt

This means that the optical power of the Variable Focus Moiré lens is inversely proportional to the aperture. The NA has a constant value throughout the modulation of its optical power (NA = 0.24 in example described above).