NANOMEFOS (Nanometer Accuracy Non-contact Measurement of Free-form Optical Surfaces)

This paper describes a conceptual measurement machine design, aiming for universal and noncontact form measurement of free-form optical surfaces up to Ø 500 mm with an uncertainty of 30 nm (k = 2). This conceptual design is the result of a M.Sc. graduation assignment done within Eindhoven University of Technology (TU/e) in collaboration with TNO TPD. Recently a PhD study has started at TU/e called NANOMEFOS (Nanometer Accuracy Non-contact Measurement of Free-form Optical Surfaces), to further develop this concept. In this paper, first the requirements and current metrology methods with respect to these requirements will be discussed. Next, the machine concept and the calculation of the error budget will be explained. Finally, a short overview of the current design will be given

NANOMEFOS (Nanometer Accuracy Non-contact Measurement of Free-form Optical Surfaces)

This paper describes a conceptual measurement machine design, aiming for universal and noncontact form measurement of free-form optical surfaces up to Ø 500 mm with an uncertainty of 30 nm (k = 2). This conceptual design is the result of a M.Sc. graduation assignment done within Eindhoven University of Technology (TU/e) in collaboration with TNO TPD. Recently a PhD study has started at TU/e called NANOMEFOS (Nanometer Accuracy Non-contact Measurement of Free-form Optical Surfaces), to further develop this concept. In this paper, first the requirements and current metrology methods with respect to these requirements will be discussed. Next, the machine concept and the calculation of the error budget will be explained. Finally, a short overview of the current design will be given

Extracapsular cataract extraction : the fate of retained lens material and intraocular lenses

The aim of this study was to examine the fate of the lens material that remains in the eye after an extracapsular cataract extraction both with and without insertion of an intraocular lens. Apart from this, the development of precipitates on the intraocular lenses was morphologically investigated in order to get a better understanding of the interactions between eye and intraocular lens. This thesis is divided into a first part covering animal experiments and a second part about morphological studies on human material, i.e. autopsy eyes or explanted intraocular lenses. For obvious reasons it is nearly impossible to obtain human eyes after a short implantation time. Therefore in order to study the early events I had to turn to an animal model. Between these two parts we have summarized our data on human anterior lens capsules obtained from extracapsular cataract extractions

Flexure-based alignment mechanisms : design, development and application

For high accuracy alignment of optical components in optical instruments TNO TPD has developed dedicated,monolithic, flexure-based alignment mechanisms, which provide accuracies below 0.1 µm and 0.1 µrad as well asstabilities down to subnanometer stabilty per minute.High resolution, high stability alignment mechanisms consist of an adjustment mechanism and a locking device.Complex monolithic flexure-based mechanisms were designed to align specific degrees of freedom. They are realizedby means of spark erosion. The benefits of these mechanisms are no play, no hysteresis, high stiffness, a simplifiedthermal design and easy assemblage. The overall system can remain a passive system, which yields simplicity.An actuator is used for positioning. Locking after alignment is mandatory to guarantee sub-nanometer stability perminute. A proper design of the locking device is important to minimize drift during locking.The dedicated alignment mechanisms presented here are based on: (a) the results of an internal ongoing researchprogram on alignment and locking and (b) experience with mechanisms developed at TNO TPD for high precisionoptical instruments, which are used in e.g. a white light interferometer breadboard (Nulling) and an interferometer withpicometer resolution for ESA’s future cornerstone missions "DARWIN" and "GAIA"

Large adaptive deformable membrane mirror with high actuator density

With the future growing size of telescopes, new, high-resolution, affordable wavefront corrector technology with low power dissipation is needed. A new adaptive deformable mirror concept is presented, to meet such requirements. The adaptive mirror consists of a thin (30-50 µm), highly reflective, deformable membrane. An actuator grid with thousands of actuators is designed which push and pull at the membrane"s surface, free from pinning and piston effects. The membrane and the actuator grid are supported by an optimized light and stiff honeycomb sandwich structure. This mechanically stable and thermally insensitive support structure provides a stiff reference plane for the actuators. The design is extendable up to several hundreds of mm's. Low-voltage electro-magnetic actuators have been designed. These highly linear actuators can provide a stroke of 15 micrometers. The design allows for a stroke difference between adjacent actuators larger than 1 micron. The actuator grid has a layer-based design; these layers extend over a large numbers of actuators. The current actuator design allows for actuator pitches of 3 mm or more. Actuation is free from play, friction and mechanical hysteresis and therefore has a high positioning resolution and is highly repeatable. The lowest mechanical resonance frequency is in the range of kHz so a high control bandwidth can be achieved. The power dissipation in the actuator grid is in the order of milliwatts per actuator. Because of this low power dissipation active cooling is not required. A first prototype is currently being developed. Prototypes will be developed with increasing number of actuators

Large adaptive deformable membrane mirror with high actuator density

With the future growing size of telescopes, new, high-resolution, affordable wavefront corrector technology with low power dissipation is needed. A new adaptive deformable mirror concept is presented, to meet such requirements. The adaptive mirror consists of a thin (30-50 µm), highly reflective, deformable membrane. An actuator grid with thousands of actuators is designed which push and pull at the membrane"s surface, free from pinning and piston effects. The membrane and the actuator grid are supported by an optimized light and stiff honeycomb sandwich structure. This mechanically stable and thermally insensitive support structure provides a stiff reference plane for the actuators. The design is extendable up to several hundreds of mm's. Low-voltage electro-magnetic actuators have been designed. These highly linear actuators can provide a stroke of 15 micrometers. The design allows for a stroke difference between adjacent actuators larger than 1 micron. The actuator grid has a layer-based design; these layers extend over a large numbers of actuators. The current actuator design allows for actuator pitches of 3 mm or more. Actuation is free from play, friction and mechanical hysteresis and therefore has a high positioning resolution and is highly repeatable. The lowest mechanical resonance frequency is in the range of kHz so a high control bandwidth can be achieved. The power dissipation in the actuator grid is in the order of milliwatts per actuator. Because of this low power dissipation active cooling is not required. A first prototype is currently being developed. Prototypes will be developed with increasing number of actuators