Methods of fabricating optical lenses and mirrors, systems and composite structures based on diffractive waveplates, and fields of application of said lenses and mirrors that include imaging systems, astronomy, displays, polarizers, optical communication and other areas of laser and photonics technology. Diffractive lenses and mirrors of shorter focal length and larger size, with more closely spaced grating lines, and with more exacting tolerances on the optical characteristics, can be fabricated than could be fabricated by previous methods.

Embodiments of the disclosure are generally directed to systems and methods for switchable electroactive devices for head-mounted displays (HMDs). In particular, a method may include (1) applying an electric field to an electroactive element of an electroactive device via electrodes of the electroactive device that are electrically coupled to the electroactive element to compress the electroactive element, which comprises a polymer material defining nanovoids, such that an average size of the nanovoids is decreased and a density of the nanovoids is increased in the electroactive element, wherein the electroactive device is positioned at a distance from a user's eye, and (2) emitting image light from an emissive device positioned such that at least a portion of the image light is incident on a surface of the electroactive device facing the user's eye.

An example device includes a nanovoided polymer element, which may be located at least in part between the electrodes. In some examples, the nanovoided polymer element may include anisotropic voids, including a gas, and separated from each other by polymer walls. The device may be an electroactive device, such as an actuator having a response time for a transition between actuation states. The gas may have a characteristic diffusion time (e.g., to diffuse half the mean wall thickness through the polymer walls) that is less than the response time. The nanovoids may be sufficiently small (e.g., below 1 micron in diameter or an analogous dimension), and/or the polymer walls may be sufficiently thin, such that the gas interchange between gas in the voids and gas absorbed by the polymer walls may occur faster than the response time, and in some examples, effectively instantaneously.

Example methods include depositing a precursor layer onto a substrate where the precursor layer includes droplets comprising a polymerizable material, inducing a phase inversion in the precursor layer to obtain a modified precursor layer including droplets of a non-polymerizable liquid within a polymerizable liquid mixture, and polymerizing the polymerizable liquid mixture to obtain a nanovoided polymer element. Examples include devices fabricated using nanovoided polymer elements fabricated using such methods, including electroactive devices such as actuators and sensors.

An optical element includes a nanovoided polymer layer having a first refractive index in an unactuated state and a second refractive index different than the first refractive index in an actuated state. Compression or expansion of the nanovoided polymer layer, for instance, can be used to reversibly control the size and shape of the nanovoids within the polymer layer and hence tune its refractive index over a range of values, e.g., during operation of the optical element. Various other apparatuses, systems, materials, and methods are also disclosed.

An optical device comprising an optical hydrogel with select regions that have been irradiated with laser light having a pulse energy from 0.01 nJ to 50 nJ and a wavelength from 600 nm to 900 nm. The irradiated regions are characterized by a positive change in refractive index of from 0.01 to 0.06, and exhibit little or no scattering loss. The optical hydrogel is prepared with a hydrophilic monomer.

Techniques are described for forming a gradient index (GRIN) lens for propagating an electromagnetic wave comprising receiving, by a manufacturing device having one or more processors, a model comprising data specifying a plurality of layers, wherein at least one layer of the plurality of layers comprises an arrangement of one or more volume elements comprising a first dielectric material and a second dielectric material, wherein the at least one layer of the plurality of layers has a dielectric profile that is made up of a plurality of different effective dielectric constants of the volume elements in the layer, and generating, with the manufacturing device by an additive manufacturing process, the GRIN lens based on the model.

A display device includes a scanned projector for projecting a beam of light, and a diffraction grating for dispersing the light at a plurality of angles into a waveguide, wherein at least a portion of the diffraction grating includes a nanovoided polymer. Manipulation of the nanovoid topology, such as through capacitive actuation, can be used to reversibly control the effective refractive index of the nanovoided polymer and hence the grating efficiency. The switchable grating can be used to control the amount of diffraction of an incident beam of light through the grating thereby decreasing optical loss. Various other methods, systems, apparatuses, and materials are also disclosed.

In some examples, a device includes a nanovoided polymer element, a planarization layer disposed on a surface of the nanovoided polymer element, a first electrode disposed on the planarization layer, and a second electrode. The nanovoided polymer element may be located at least in part between the first electrode and the second electrode. The planarization layer may be located between the nanovoided polymer element and the first electrode.

An illumination device includes at least one light source and at least one optical component formed by a stack of at least two biconvex cylinder lenses, each lens having an optical axis perpendicular to a stacking direction of the optical component. The optical component is manufactured using a 3D printing process using fused deposition modeling.