Disclosed is a thermo-mechanical actuator (100) comprising a piezo¬electric module (110), the piezo-electric module comprising at least one piezo-electric element (120), wherein the thermo-mechanical actuator is configured to: receive a thermal actuation signal (132) for controlling a thermal behaviour of the piezo-electric module, or provide a thermal sensing signal (132) representative of a thermal state of the piezo-electric module, and, wherein the thermo-mechanical actuator is configured to: receive a mechanical actuation (134) signal for controlling a mechanical behaviour of the piezo-electric module, or provide a mechanical sensing signal (134) representative of a mechanical state of the piezo-electric module.

The present invention provides a deformation apparatus that deforms a surface of a member, the apparatus comprising: a plurality of actuators each of which is configured to apply a force to the member to deform the surface; a measurement device configured to measure an induced electromotive force generated in a first actuator of the plurality of actuators; and a controller configured to control the plurality of actuators, wherein the controller causes the measurement device to measure a temporal variation of an induced electromotive force in the first actuator while vibrating the member by using a second actuator, of the plurality of actuators, which is different from the first actuator, converts the measured temporal variation of the induced electromotive force into a frequency spectrum, and detects an abnormality in the first actuator based on the frequency spectrum.

A mirror arrangement (30) includes: a substrate (31), which has a front side (31a) having a mirror face (32a) for reflecting radiation (5), and a rear side (31b) facing away from the front side (31a), as well as at least one actuator (27) arranged to generate deformations of the mirror face (32a). The at least one actuator (27) is secured on the rear side (31b) of the substrate (31), and the mirror arrangement (30) has a hydrogen barrier (38) which is configured to protect a hydrogen-sensitive material (M) on the rear side (31b) of the substrate (31), in particular on the at least one actuator (27), from the attack by hydrogen (37) from the surroundings (36) of the mirror arrangement (30). An associated optical arrangement, in particular an EUV lithography apparatus (1), incorporating such a mirror arrangement (30) is also disclosed.

The disclosure provides a method that includes filling a cavity in a substrate with a second material, wherein the substrate includes a first material. The method also includes using galvanic and/or chemical deposition of a third material to apply an overcoating to a first surface of the substrate in a region of the cavity. The method further includes removing the second material from the cavity. In addition, the method includes, before or after removing the second material from the cavity, applying a reflective layer to the overcoating. The disclosure also provides related optical articles and systems.

The invention relates to an object positioning system including: an actuator system and a measurement system. The actuator system comprises an actuator made of a material with predominantly electrostrictive properties and substantially no net polarization in absence of an electric field. The actuator system is configured to apply an electric field to the actuator, which electric field comprises a bias electric field and an actuation electric field superimposed on the bias electric field, a field strength of said actuation electric field being equal to or smaller than a field strength of the bias electric field. The measurement system is configured to measure an electrical property of the actuator which is representative for a mechanical state of the actuator. The measurement system comprises a bridge circuit including an actuator and a reference element having electrical properties matched to the electrical properties of the actuator.

A mirror that has a mirror substrate (12), a reflection layer stack (21) reflecting electromagnetic radiation incident on the optical effective surface (11), and at least one piezoelectric layer (16) arranged between the mirror substrate and the reflection layer stack and to which an electric field for producing a locally variable deformation is applied by way of a first electrode arrangement and a second electrode arrangement situated on alternate sides of the piezoelectric layer. In one aspect, both the first and the second electrode arrangements have a plurality of electrodes (20a, 20b), to each of which an electrical voltage relative to the respective other electrode arrangement can be applied via leads (19a, 19b). Separate mediator layers (17a, 17b) set continuous electrical potential profiles along the respective electrode arrangement, and where said mediator layers differ from one another in their average electrical resistance by a factor of at least 1.5.

A mirror arrangement (30) includes: a substrate (31) with a front side (31a) having a mirror face (32a) reflecting radiation (5), and a rear side (31b) facing away from the front side and on which at least one actuator (27) generating deformations of the mirror face is arranged. A water vapor (36)-sorbing material (33, 42) is formed on the rear side (31b) and forms an adhesive layer (33) for securing the actuator. The layer extends into interspaces (35) between the actuators (27). A surface (33a, 42a) of the water vapor-sorbing material is covered at least partly by a coating (37) which forms a water vapor diffusion barrier.

A mirror having a mirror substrate (12, 32, 52), a reflection layer stack (21, 41, 61) reflecting electromagnetic radiation having an operating wavelength that is incident on the optical effective surface (11, 31, 51), and at least one piezoelectric layer (16, 36, 56), arranged between the substrate and the reflection layer stack and to which an electric field producing a locally variable deformation is applied. A first electrode arrangement (20, 40, 60) situated on the side of the piezoelectric layer faces the reflection layer stack, and a second electrode arrangement (14, 34, 54) is situated on the side of the piezoelectric layer facing the mirror substrate. Optionally, a bracing layer (98) is provided, which limits sinking of the piezoelectric layer (96) into the mirror substrate (92) when an electric field is applied, in comparison with an analogous construction lacking the bracing layer, thereby increasing the piezoelectric layer's effective deflection.

A method for calculating a spatial map associated with a component, the spatial map indicating spatial variations of thermal expansion parameters in the component, the method comprising: providing or determining a temperature distribution in the component as a function of time; calculating the spatial map associated with the component using the provided or determined temperature distribution in the component and optical measurements of a radiation beam that has interacted directly or indirectly with the component, the optical measurements being time synchronized with the provided or determined temperature distribution in the component.

The present invention provides a deformation apparatus that deforms a surface of a member, the apparatus comprising: a plurality of actuators each of which is configured to apply a force to the member to deform the surface; a measurement device configured to measure an induced electromotive force generated in a first actuator of the plurality of actuators; and a controller configured to control the plurality of actuators, wherein the controller causes the measurement device to measure a temporal variation of an induced electromotive force in the first actuator while vibrating the member by using a second actuator, of the plurality of actuators, which is different from the first actuator, converts the measured temporal variation of the induced electromotive force into a frequency spectrum, and detects an abnormality in the first actuator based on the frequency spectrum.