Moire Lens (Focus Tunable Lens)

  • Update:Feb 12, 2021
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Two specifically structured DOEs are cascaded to obtain various optical elements like lenses, axicons or spiral phase plates. Their optical power is continuously adjustable, simply by rotating the DOEs with respect to each other.

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Two specifically structured DOEs are cascaded to obtain various optical elements like lenses, axicons or spiral phase plates. Their optical power is continuously adjustable, simply by rotating the DOEs with respect to each other.

tunable lens

Tunable Lens

With the Moiré lens a laser beam can be variably focused or objects at variable distance can be imaged sharply. By rotating two DOES (Diffractive Optical Element) against each other, the focal length of the lens changes.

Tunable Axicons

Our tunable axicons make it easy to create high-quality Bessel-like beams. The output parameters of the beam can be tuned by rotating two DOES (Diffractive Optical Element) against each other.  

Moire Lens

tunable lens, moire lensThe Moire lens is an innovation in the field of focus tunable lenses. It shows some useful advantages compared to other lenses:

A combination of two Moire lenses can be used to create a variable magnification lens. It represents the potentially most compact zoom optics (especially suitable for smartphone- or thermal-cameras).

Tunable Phase Shifters & Helical Beam

Through special DOE design it is possible to produce tunable optical phase shifters. The same principle can be used to generate helical wavefronts (OAM). This beam resembles a corkscrew, with propagation of the wavefront.

By turning the DOE’s against each other, phase shifters and helical beam converters can be tuned easily.

From UV/VIS to IR to Terahertz radiation: For each wavelength the optimal substrate is selected for our customers. All components can be produced with apertures up to 25 mm.

Application Fields & Markets

In summary,: special high-end applications as well as numerous low-end mass products. Offset optical power can be implemented, optical efficiency up to 90%, chromatic aberrations computationally reducible, combination with “standard” optics (e.g. glass lenses) permits compensation of dispersion effects.

1. Electronically Tunable Moiré  Lens STD-MIE-20-1064
Optical power of the diffractive lens can be tuned electronically.

moire lens, focus tunable lensOptical specifications:

Mechanical specifications:

Operational specifications:

moire lens, tunable lensPerformance:

Electrical specifications:

Communications:

2. Manually Tunable Moiré Lens STD-MI-10-532
Optical power of the diffractive lens can be tuned by rotating the rear ring.

moire lens, focus tunaable lensOptical specifications:

Mechanical specifications:

Operational specifications:

3. Application Fields & Markets

In summary, special high-end applications as well as numerous low-end mass products. Offset optical power can be implemented, optical efficiency up to 90%, chromatic aberrations computationally reducible, combination with “standard” optics (e.g. glass lenses) permits compensation of dispersion effects.

Tunable Lens
The Moiré Lens enables dynamical focusing. Applications cover

moire lens, focus tunable lens moire lens, focus tunable lens

Tunable Axicon
Generate a tunable axicon with the Moiré Lens to dynamically modulate self-healing beams. Applications cover:

Tunable Phase Shifter
The Moiré Lens principle enables the realization of an infinity phase shifter. Applications cover:

moire lens, focus tunable lens moire lens, focus tunable lens

Tunable Helical Beam
With the Moiré Lens the steepness of a staircase-like phase front can be adjusted to produce a ring focus of variable diameter. Applications cover:

4. Questions and Answers

1. What are the advantages of Variable Focus Moiré Lenses?

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 thin, lightweight, and can be fabricated from a variety of materials including those which transmit in the UV or IR spectral regions. Focusing over a wide focal length range is achieved by a simple rotation of the plates, yielding aberration free spots when used with monochromatic illumination.

2. Are there any disadvantages of Variable Focus Moiré Lenses?

3. What is the efficiency of Variable Focus Moiré Lenses?

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 diffraction efficiency is around 65%, therefore the total efficiency is approximately 62%.

4. How are Variable Focus Moiré Lenses manufactured?

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.

5. How does Polarization affect the performance?

Variable Focus Moiré Lenses function independently of polarization.

6. What specifications are required to create a custom Variable Focus Moiré Lens?

To create a custom Variable Focus Moiré Lens, the following is required:

7. What optical power range and Numerical Aperture (NA) does a Variable Focus Moiré Lens provide?

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 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 = ±π⁄2) is higher than 80%. For this lens with an aperture of the optical power range is as follows:

D = ±1⁄(2A) = ±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).

8. What wavelengths are available?

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 the DOE design is the transmission properties of the substrate. Fused Silica is commonly used for UV or visible applications, whereas Germanium is a common choice for IR applications.

Focus Tunable Lenses

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