Patent Application
20070285813
The present invention relates to adjustable pinholes for use in laser scanning microscopes.
A scissors-like shutter mechanism for a pinhole has been described in U.S. Patent Application 2003/0184882 A1, published on Oct. 2, 2003.
In such mechanisms, above all, the accuracy at the sites of the angles, which lie mutually opposite and which must move about an axis of rotation, poses a serious problem in the fabrication of pinhole apertures with reproducible and light-tight shutting and exact quadratic form.
The problem lies in the fabrication of high-precision pinholes which can shut in a light-tight manner, and whose apertures exhibit a quadratic form from size zero onwards.
The special advantages of the present invention lie in the quasi-monolithic and very flat design with a “sandwich” style of construction, whereby, according to the invention, the optical position measurement unit can also be integrated directly into it. Regulation of the pinhole position can be done with a closed measurement circuit without hysteresis effects. The invention can be realized with a number of materials, among others, with silicon wafer material. Thus, an already miniaturized design can be miniaturized even further. Energy consumption for the actuation is low. Production costs are very low.
The basic module consists of at least one monolithic planar structure, which comprises at least one sharp edge, built in the interior, and held by elastic joints, and preferably containing at least two triangles, situated in a fixed spatial relationship with mutually opposite orientation, which serve the purpose of controlling the position (Optical Position Measurement Unit OPM).
Further, the position control comprises flat structures, preferably of the same material as that used in the basic modules, which include small sources of light (for example LEDs) or receivers with adapted dimensions, and are plugged in the sandwich structure of the basic modules. Further details about the function of the OPM will be presented in the following description.
The sharp edges of the basic modules are mutually parallel and can be slanted, so as to achieve better closure.
The mechanical arrangement of the integrated mobile elements, preferably a parallelogram attachment in this case, ensures parallelism of both of the edges, which are mutually displaceable. The movement of the edges takes place by means of miniaturized magnetic actuators, preferably, but not exclusively, of a moving magnet type, whereby, within an electrical coil, one or more permanent magnets, or a different type of electromagnetic actuator, are arranged in a displaceable manner.
Thereby, it is of advantage, if the magnetic actuators are arranged on the same planar structure as the edges and move the edges. The coupling of the movable edges with the optical position measuring units enables a manipulation of the edges by means of a closed control circuit. With a pinhole according to the invention, at least the following specifications can be realized:
apertures with a 3-300 μm diameter;
a drift-free movement range of ±300 μm;
reproducibility of the position and opening of an edge less than 500 nm;
compact build in an area smaller than 50×50 ×20 nm;
accuracy of an edge smaller than 0.8 μm;
a high degree of stiffness of the edges (small axial overlap error);
independence of the wavelength within the range of at least 350-800 nm, as well as in IR and UV range; and
a set-up time less than one second.
In the following, the invention is described in detail on the basis of the schematic diagrams.
In describing preferred embodiments of the present invention illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner to accomplish a similar purpose.
A planar structure S of the basic component consists of an external frame R in which narrow elastic frames ST are incorporated, which exhibits recesses RE at their joints in order to keep the junction points small and elastic.
The frames ST hold two elongated inner base plates G1 and G2, on which the two edges Sc1 and Sc2 are fastened with their parallel edges lying opposite to each other. On the base plates G1 and G2, magnets M of an electromagnetic actuator Ac are fixed sideways, which project into an electric coil SP fastened on the frame R.
Through electrical regulation, the magnets move into the coils and cause therewith the movements of the edges Sc1, Sc2 against each other in the direction of the arrow Ar.
The elastic frames ST move perpendicular to their longitudinal direction and are elastic at their joints RE in that direction, while the arrangement perpendicular to the direction of the movement of the edges exhibits a high degree of stiffness. With reference to
If two planar basic modules are joined as in
In
Behind the triangles D1, D2 with mutually opposite orientation, which are arranged in a row perpendicular to the direction of the displacement (arrow), a slit AP, oriented at a right angle to the direction of the displacement is arranged (there can also be two slits), which are illuminated by one, or preferably two, LEDs L1, L2, for each of the triangular aperture.
Due to the movement of the edges, the transmission area of the triangles D1, D2 changes with respect to the slit or the slits AP. This means a change in the quantity of light, which is registered, separately for each triangle, by the two detectors DE1, DE2 located on the other side, opposite the source of light.
The difference in the quantity of light forms the control signal which is proportional to the path of the displacement X, while the sum of the detector signals remains the same and hence ensures that the signal is independent, in first approximation, of the fluctuations in the quantity of light.
Through the registration of the control signals in the X and Y direction, the information about the state of the opening of the pinhole is obtained. The calibration of the adjustment device can be done by means of external measurements or directly in a laser scanning microscope (LSM).
The position detection element can naturally be also realized by means of other types of non-optical sensors, such as, a capacitive, an inductive, or an electromagnetic sensor, as long as an electrical feedback signal is made available by means of the position detection element.
In
All planar elements are positioned and fixed using pins (not shown). All elements can be realized by means of diverse types of processing methods using various materials, in particular, metallic materials, ceramic materials, semiconductors and synthetic materials.
It is to be understood that the present invention is not limited to the illustrated embodiments described herein. Modifications and variations of the above-described embodiments of the present invention are possible, as appreciated by those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10323922.7 | May 2003 | DE | national |
The present patent application is a nationalization of International Application No. PCT/EP2004/004498, filed Apr. 28, 2004, which is based on, and claims priority from, German Application No. DE 103 23 922 A1, filed May 22, 2003, both of which are incorporated herein by reference in their entireties.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP04/04498 | 4/28/2004 | WO | 4/5/2007 |
