Variable Focus Moiré Lenses feature a pair of specially structured diffractive optical elements, fabricated via standard photolithographic techniques. These lenses also consist of a simpler design and construction than alternative liquid, photo-acoustic, or nanomaterial techniques. The simple construction also makes the Moiré lenses insensitive to changes in temperature and vibration resistant. The plates are also [...]
Strong chromatic aberrations Lens efficiency is reduced when its optical power is increased Operates optimally only for a certain wavelength Maximum aperture is limited (approximately 20mm)
The first order diffraction efficiency n1 of a Moiré lens depends on the chosen twisting angle θ, resulting in the corresponding optical power: n1 = (sinc (θ⁄2))2 (1) The total efficiency is a product of the diffraction efficiency and the transmission efficiency nt, which is approximately 96%. For a twisting angle of 45º, the [...]
The surface structure of individual Diffractive Optical Elements of a Variable Focus Moiré Lens are produced by standard photolithography techniques. The resultant pair of elements creates Fresnel zones that can be continuously adjusted to create a continuously variable focal length.
Variable Focus Moiré Lenses function independently of polarization.
To create a custom Variable Focus Moiré Lens, the following is required: Lens Size (Diameter, Square, etc.) Clear Aperture Maximum Thickness Desired Focal Length Range Operating Wavelength Range Desired Efficiency for Maximum Optical Power
n1 = (sinc (θ⁄2))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⁄Aπ (2) Here θ, stands for the current twist [...]
Variable Focus Moiré Lenses can be manufactured for wavelengths from the UV through the IR. The Moiré pattern of the DOEs is required to be designed for a specific wavelength; maximum efficiency is achieved when the structure heights are equal to an integer multiple of the design wavelength (2π phase shift). The limiting factor in [...]