VARIABLE FOCUS MOIRE LENSES
Continuous and exact variation of focal length within a wide focal length range
Aberration-free for monochromatic light
Suitable for high power applications
Scalable in aperture and spectrum (from UV to IR)
Thin and lightweight
Temperature-independent (between -20°C and 70°C)
Variable Focus Moiré Lenses consist of specially structured cascaded Diffractive Optical Elements (DOEs). These lenses are continuously adjustable over a wide focal length range by simply rotating the elements. Variable Focus Moiré Lenses exhibit aberration-free performance with monochromatic illumination and can be adapted for wavelengths from the UV to the IR. Typical applications include laser optical assemblies such as variable beam expanders, or as elements within a zoom lens, eliminating the need for complicated translating optomechanics.
Due to the Moiré effect a mutual rotation of the DOEs lead to a lens of certain refractive power, depending on the rotation angle φ.
The DOEs possess a surface structure that shifts the phase of monochromatic light in the range between 0 and 2π. The superposition of the complementary structured DOEs have the same effect as a corresponding Fresnel lens.
Rotating the 2nd element in the Variable Focus Moiré Lens assembly with respect to the first provides continuous focusing of the light source. The assembly spans negative and positive focal lengths, over a range of ±25 diopters.