Ophthalmic microscope with at least one controlled manual degree of freedom

Abstract

An ophthalmic microscope comprises a first assembly with a base (1) and a stage (2), a second assembly with a pivot arm (3) and a microscope device (8), and a third assembly with a pivot arm (4) and a light source (9). The assemblies are pivotable to each other at a hinge (30). An electric control motor (38a, 38b, 38c) and a position sensor (46a, 46b) are incorporated in the hinge (30). A brake controller (50) of the microscope is adapted to interrupt the manual mutual displacement of the assemblies in response to a signal from the position sensor (46a, 46b) in order to assist a user in correctly aligning the assemblies.

Description

Technical Field

[0001] The present invention relates to an ophthalmic microscope having a support, a microscope apparatus, at least first and second components that are manually movable relative to each other, and a position sensor arranged to measure the relative position between the first and second components. Background Technology

[0002] US2011 / 0001931 describes a slit-lamp microscope that can be manually moved relative to its support in two horizontal directions.

[0003] The device is equipped with an electrically controlled brake to brake any movement along these degrees of freedom. The user operates the brake by actuating a switch on the device.

[0004] EP2721995 describes another slit-lamp microscope with a setup state acquisition section that includes a position sensor for measuring the illumination angle. Summary of the Invention

[0005] The problem to be solved by the present invention is to provide an ophthalmic microscope of this type with increased ease of use.

[0006] This problem is solved by the ophthalmic microscope of claim 1.

[0007] Therefore, an ophthalmic microscope includes at least the following components:

[0008] - Microscope equipment: Microscope equipment typically includes a lens system for magnifying images of the eye. It may further include a camera and / or an eyepiece.

[0009] - At least the first and second components: These two components are capable of being moved manually relative to each other, for example, by providing suitable linear or pivot bearings between them.

[0010] - A position sensor having a first sensor component arranged to measure the relative position between the first and second components: this first sensor component may include, for example, an angle or linear sensor. It generates an electronic signal indicating the relative position of the two components.

[0011] - Electrically controlled brake. This brake includes a main brake component disposed between the first and second components.

[0012] - A brake controller, which is connected to a position sensor and a brake and is adapted to operate the brake based on the readings of the position sensor.

[0013] This design of the microscope makes it possible to actuate the brakes based on the positions of two mutually movable components. Therefore, even if the user manually moves the components, the device can help position them correctly.

[0014] Advantageously, the "first component" is the base of the device or a platform that is translated and mounted to the base.

[0015] The “second component” may include, for example, a microscope or a light source for a microscope.

[0016] In critical applications, the first and second components can pivot relative to each other. This is a common degree of freedom in ophthalmic microscope components, and mechanizing this degree of freedom is expensive. Therefore, the assisted manual placement of the components provides a significant advantage to the user.

[0017] In an advantageous embodiment, the microscope includes a third component, which may include, for example, a light source that is manually movable relative to the first and second components. In this case, the brake includes an auxiliary brake member disposed between the first and third components to generate an electrically controllable braking force between them. Additionally, the position sensor includes a second sensor member arranged to measure the relative position between the first and third components.

[0018] The second sensor component can directly measure between the first and third components, or it can measure the relative position between the second and third components, thereby indirectly determining the relative position between the first and third components by combining it with the readings of the first sensor component.

[0019] The brake may also include two auxiliary brake components, one of which is disposed between the first and third components, and the other of which is disposed between the second and third components. This allows any two of the three components to be fixed to each other so that they can be moved relative to the remaining components as a common unit.

[0020] The brake controller can be adapted to calculate the timing of brake actuation based on desired relative positions. Specifically, the controller may include one or more storage locations for storing one or more desired brake positions. Current readings from position sensors are compared to these brake positions(s) to assist braking at those positions.

[0021] To improve braking accuracy, the brake controller can also be adapted to perform the following steps:

[0022] - Determine the speed of movement between components; and

[0023] - The actuation time of the actuator is calculated based on the desired relative position and the speed of movement.

[0024] This allows for at least partial compensation of the speed-dependent braking distance of the microscope.

[0025] The brake controller can also be adapted to calculate the time delay between (1) the actuation of the brake and (2) the stopping of the motion between the components. This time delay can then be used to determine a more accurate actuation time of the brake.

[0026] As described below, this allows for the determination of the device's status and / or how it is used, which in turn helps improve the timing of the braking process. In particular, the brake controller can be adapted to:

[0027] - Use multiple past measurements of the braking process to derive at least one parameter describing the braking distance of the brake.

[0028] - Calculate the actuation time of the brake based on these parameters.

[0029] Therefore, the prediction of braking distance can be adapted, for example, to the state of the hand force and / or brakes used by the user to operate the equipment. Attached Figure Description

[0030] The invention will be better understood when considered in the following detailed description, and objectives other than those described above will become apparent. This description refers to the accompanying drawings, in which:

[0031] Figure 1 A side view of a slit-lamp microscope is shown.

[0032] Figure 2 A top view of the microscope is shown (with the slit lamp arm pivoted relative to the microscope's optical axis).

[0033] Figure 3 A cross-sectional view of the hinge is shown, and

[0034] Figure 4 A circuit block diagram of some components of the brake controller is shown. Detailed Implementation

[0035] Overview

[0036] Figure 1 and 2 Examples of ophthalmic microscopes, particularly slit-lamp microscopes, are shown.

[0037] The microscope has a base 1 that rests on, for example, a table, a translational stage 2 mounted on the base 1, a first arm 3, and a second arm 4.

[0038] The stage 2 can be linearly displaced relative to the base 1 along the horizontal x and z directions.

[0039] Arms 3 and 4 are mounted to stage 2 and pivot about a common vertical pivot 5 (i.e., an axis parallel to the vertical direction y).

[0040] Advantageously, arms 3 and / or 4 are manually operated, i.e., their angular positions are manually changed, and they are not equipped with electric actuators for changing their angular positions. However, they may also be equipped with electric angular actuators to operate them automatically in addition to manually.

[0041] The device may also include a headrest 7 mounted on the base 1 to receive the patient's head.

[0042] Arm 3 carries the microscope equipment 8, and arm 4 carries the light source 9.

[0043] The microscope 8 has an optical axis 12. It may include an entrance objective 14 that projects the image of the eye 10 onto a camera 16 and / or an eyepiece 18. A beam splitter 20 may be arranged to split the light between these components.

[0044] The light source 9 may be, for example, a slit lamp known to those skilled in the art, adapted to project a slit-shaped beam onto the eye 10 to be examined. In this embodiment, the light source 9 includes a light generator 22, a spatial light modulator or an adjustable mechanical slit 24, and an imaging optics 26.

[0045] The light generator 22 may include, for example, several units that emit different wavelengths, such as in the red, green, blue, and infrared ranges of the spectrum. These units can be individually controlled to change the color of the light source 22. The imaging optics 26 projects light from the modulator 24 onto the front surface of the eye 10, for example, via a mirror 28 mounted to the arm 4.

[0046] The light source 9 can be positioned above or below the reflector 28.

[0047] The device also includes a hinge 30 connecting the arms 3 and 4 and the platform 2, as well as a brake controller 32 for operating the brakes of the device. These components are described in more detail below.

[0048] Hinge design

[0049] Figure 3 A schematic cross-sectional view of hinge 30 along pivot 5 is shown. In this view, sections with the same shading pattern indicate sections that are rigidly connected to each other.

[0050] The purpose of hinge 30 is to pivotally connect the first, second, and third components of the microscope to each other. In this embodiment, the first component is the stage 2, the second component is the first arm 3 with microscope equipment 8, and the third component is the second arm 4 with illumination source 9.

[0051] These three components pivot about pivot 5 relative to each other.

[0052] The hinge 30 includes “first hinge members” 32a, 32b, 32c that are rigidly connected to the stage 2 (or base 1) (i.e., the first component of the microscope).

[0053] It also includes a “second hinge member” 34 that is rigidly connected to the arm 3 (i.e., the second component of the microscope).

[0054] It also includes a “third hinge component” 36a-36d that is rigidly connected to arm 4 (i.e., the third component of the microscope).

[0055] For embodiments of the invention where components pivot, the term "rigid" connection should be understood as "non-pivoting" connection.

[0056] The hinge 30 also includes a brake having a main brake component 38a and one or two auxiliary brake components 38b, 38c.

[0057] The main brake component 38a includes a first coil component 40a and a first brake disc 42a, which are arranged to generate frictional braking force between the first hinge components 32a-32c and the second hinge component 34.

[0058] In the illustrated embodiment, the first coil member 40a is connected to the first hinge members 32a-32c and the first brake disc 42a is connected to the second hinge member 34, but the opposite arrangement can also be used.

[0059] The auxiliary brake component 38b includes a second coil component 40b and a second brake disc 42b, which are arranged to generate frictional braking force between the second hinge component 34 and the third hinge components 36a-36d.

[0060] In the illustrated embodiment, the second coil member 40b is connected to the second hinge member 34 and the second brake disc 42b is connected to the third hinge members 36a-36d, but the opposite arrangement can also be used.

[0061] The auxiliary brake component 38c includes a third coil component 40c and a third brake disc 42c, which are arranged to generate frictional braking force between the first hinge components 32a-32c and the third hinge components 36a-36d.

[0062] In the illustrated embodiment, the third coil member 40c is connected to the first hinge members 32a-32c and the third brake disc 42d is connected to the third hinge members 36a-36d, but the opposite arrangement can also be used.

[0063] Brake components 38a, 38b, and 38c can be actuated individually and independently.

[0064] The coil components 40a, 40b, 40c and the brake discs 42a, 42b, 42c are advantageously arranged in a ring and coaxial arrangement around the pivot 5.

[0065] The brake discs 42a, 42b, and 42c are made of ferroelectric material, and when current is transmitted through them, they are attracted to their respective coil members 38a, 38b, and 38c. In the illustrated embodiment, this attraction generates a frictional force that brakes the movement between the two respective hinge members.

[0066] The hinge 30 also includes a main pivot bearing 44a that pivotally connects the first hinge components 32a-32c and the second hinge component 34. Its axis of rotation coincides with the pivot 5.

[0067] Hinge 30 also includes two auxiliary pivot bearings 44b and 44c. The second pivot bearing 44b connects the second hinge member 34 to the third hinge members 36a-36d, and the second pivot bearing 44c pivotally connects the first hinge members 32a-32c to the third hinge members 36a-36d. The second pivot bearings 44b and 44c are again coaxial with pivot 5.

[0068] The hinge 30 also includes a position sensor having first and second sensor components 46a, 46b.

[0069] The first sensor component 46a is arranged between the first hinge components 32a-32c and the second hinge component 34. It is adapted to measure the relative pivoting position between the two hinge components.

[0070] The second sensor component 46b is arranged between the first hinge components 32a-32c and the third hinge components 36a-36d. It is adapted to measure the relative pivoting position between the two hinge components.

[0071] The first and second sensor components 46a and 46b can be magnetic angular position sensors.

[0072] exist Figure 3 In one embodiment, the first component of the microscope (i.e., the stage 2 and / or the base 1) is connected to a first position of the hinge 30. Figure 3 The lower end of the hinge 30). The second component of the microscope (i.e., the arm 3 and the microscope device 8) is installed in the second position of the hinge 30. Figure 3 The middle section of the hinge). The third component of the microscope (i.e., arm 4 and light source 9) is mounted to the third position of hinge 30 (the middle section of the hinge). Figure 3 (The top of the middle hinge).

[0073] The second position is located between the first and third positions along pivot 5. When using this type of design, the first hinge members 32a-32c or the third hinge members 36a-36d advantageously include an axis extending through the second hinge member 34, which allows direct interaction between the first and third hinge members.

[0074] exist Figure 3 In one embodiment, the shaft 36c is formed by a third hinge member, which allows the auxiliary brake member 38c and / or the second sensor member 46b to be mounted at a first position on the hinge 30.

[0075] In other words, the shaft is connected to the first or third component of the microscope on one side and to one of the actuator component and / or sensor component on the other side.

[0076] Shaft 36c is hollow and can accommodate cables, for example, connected to brake components 38a-38c, microscope equipment 8, and / or light source 9.

[0077] In the illustrated embodiment, pivot bearings 44a, 44b, and 44c are roller bearings. Such roller bearings have very low friction when the brake is deactivated. This may not always be desirable. Therefore, one or more friction dampers 45a, 45b can be provided to dampen movement between at least one pair of components.

[0078] One or more friction dampers are designed to apply permanent friction between components, which is much greater than the rolling resistance of roller bearings, in particular at least 100 times greater.

[0079] In the illustrated embodiment, a first friction damper 45a is provided for damping movement between the first and second components, while a second friction damper 45b is provided for damping movement between the first and third components.

[0080] More generally, the device comprises a combination of at least one roller bearing and at least one friction damper located between at least two components.

[0081] Advantageously, a roller bearing 44a and a friction damper 45a are present between the first and second components, and a roller bearing 44c and a friction damper 45b are present between the first and third components. In a particularly advantageous embodiment, a roller bearing 44b is present between the second and third components, but without a friction damper, which makes it easier to move the second or third component relative to the first component without moving the third or second component respectively.

[0082] Braking operation

[0083] The microscope includes a brake controller 50, which in Figure 4 It is shown schematically in the diagram.

[0084] It may include a microcontroller or microprocessor, which may be, for example, part of the microscope's control unit. It is programmed to perform the various braking functions described below.

[0085] The brake controller 50 is connected to the position sensor, i.e., to the sensor components 46a and 46b, which allows it to determine the current relative positions of the three microscope components.

[0086] It is also connected to brake components 38a, 38b, and 38c to operate them.

[0087] The brake controller 50 is also connected to a display 52 suitable for displaying operating instructions and / or status information to the user.

[0088] Below, we describe some of the functionalities that can be implemented in the brake controller 50.

[0089] Actuation time

[0090] The first functionality involves supporting users to move microscope components to a predefined relative position.

[0091] In this functionality, the storage section 54 of the brake controller 50 can maintain at least one “desired mutual position” between the two components of the microscope.

[0092] The brake controller 50 can now be equipped to compare this desired mutual position with the current mutual position between the two components. If a mismatch exists, the brake controller 50 displays on the display 52 the direction of displacement for moving one of the components to the desired mutual position.

[0093] For example, the desired relative position could be, for instance, an angle of 37.2° between the stage 2 and the first arm 3. For example, the first sensor component 46a indicates that the current relative position (i.e., the current angle) is 33.5°. One or both of these figures can be displayed on the display 52.

[0094] Next, the brake controller 50 determines the direction to move arm 3 from its current position to the desired position. This direction is then displayed, for example, by highlighting one of two arrows 56a and 56b on the display 52.

[0095] By displaying the direction of displacement in this way, users can be assisted in manually moving one of the components to the correct direction.

[0096] The brake controller 50 can then assist the user in properly braking the moving component at the correct time so as to stop the movement at the desired position. To do this, it calculates the timing for actuating the brake (i.e., at least one of its brake components 38a, 38b, 38c).

[0097] In the simplest method, the actuation time of the brake can be the time it takes for the current position to match the desired position. However, this can lead to poor matching because the brake has a certain braking distance and can therefore stop at a position beyond the desired position.

[0098] A more accurate algorithm takes into account the speed of movement between the two components.

[0099] Let us assume x0 is the desired mutual position, and x(t) is the current mutual position. In this case, the actuation time t0 for the actuating brake should be the time when x0 – x(t0) equals the expected braking distance D of the microscope, that is,

[0100] x0–x(t0)=D (1)

[0101] The braking distance D is not a constant. More precisely, it is typically a function of the current velocity of the motion, v(t) = dx(t) / dt, and the brake's reaction time, Δt. It can also be a function of the force exerted by the user on the moving component (a stronger force will increase the braking distance). Therefore...

[0102] D=D(Δt,v,u), (2)

[0103] Where u is a user-dependent parameter.

[0104] In a specific example, the braking distance D can be approximated by the following formula.

[0105] D=Δt·v+u (3)

[0106] The velocity v in equations (2, 3) can be calculated from the measurements of position sensors 46a and 46b. Parameters Δt and u can be obtained in various ways:

[0107] - The time delay Δt can be considered a device-specific delay, for example, which can be obtained from calibration measurements at the manufacturer's site. However, it can vary over time, for example, due to wear or contamination of the brakes, and therefore it advantageously originates from previous braking processes as described below.

[0108] The parameter u can be assumed to be a constant and determined using calibration measurements from the manufacturer's field of study using samples from typical users. However, since it depends on how a given user operates the equipment, it is best to also derive it from previous braking procedures (advantageously performed by the same user as the current user of the microscope), as described below.

[0109] If one or more of the parameters Δt and u are to be derived from the previous braking process, then the brake controller 50 is advantageously adapted to perform the following steps:

[0110] -Measure the braking distance D and the speed v(t0) when the brake is applied for multiple past braking processes.

[0111] - Store the braking distance and speed obtained in this way.

[0112] - Using a model for braking distance D(Δt,v,u) as a function of velocity v(t0), take one or more unknown parameters as model parameters and fit these model parameters to the stored braking distance and velocity.

[0113] Depending on the model used for the braking distance D(Δt,v,u) as a function of velocity v(t0), it is possible to use a linear fitting algorithm (e.g., for the model of equation (3)) or a nonlinear fitting algorithm.

[0114] If at least one parameter (such as parameter u) will vary between users, then the brake controller 50 is equipped with a suitable input component 58 for inputting a user-specific ID. In that case, the brake controller 50 determines a different set of parameters for different users.

[0115] The determination of one or more parameters can be refined automatically, for example, after each braking process.

[0116] Release brake

[0117] The brake can be released manually, for example, by providing a brake release input 60, such as a button or an area on a touchscreen. The brake is released when the user operates this input.

[0118] In another embodiment, the brake controller 50 may be adapted to perform the following steps:

[0119] a) Detect the increase in force acting on brakes 38a, 38b, and 38c while brakes 38a, 38b, and 38c are activated.

[0120] b) During this increase, release brakes 38a, 38b, and 38c.

[0121] In this way, the user can easily overcome the force of the brake to push one of the components, in which case the brake is released.

[0122] Steps a) and / or b) can be suppressed for a given time, for example, 1 second after the brake is actuated, or before the component has stopped, in order to ensure that the force is an intentional effort to remove the component from its position after the braking process is completed.

[0123] The detection in step a) can be performed, for example, by means of a dedicated force sensor. However, if the position sensors 46a and 46b have sufficient resolution, they can be used to detect elastic deformation in the hinge 30 caused by forces applied to one or more components, and thus can be used to detect forces without a dedicated force sensor.

[0124] Tactile marking of location

[0125] While the user moves one of the components, the brake can also be briefly activated during a "tapping" operation. This will generate tactile feedback for the user, indicating certain preferred relative positions of the components, such as axial alignment or alignment at certain angles.

[0126] To achieve this, the brake controller 50 can be adapted to activate and automatically deactivate the brakes 38a, 38b, 38c for a duration of less than 1 second, particularly less than 0.5 seconds. On the other hand, the activation duration is advantageously at least 0.1 seconds, because a much slower activation may not be sufficient to generate an interruption effect that the user can take action against.

[0127] For example, the duration can be given as follows:

[0128] - It can be a fixed time.

[0129] - It can depend on signals from position sensors 46a, 46b. For example, if the brake controller 50 detects that the speed v(t) drops rapidly after the brake is actuated (e.g., drops by more than a given percentage within a given time), then it can keep the brake active, assuming the user has released the component and wants to stop at this position. Otherwise, it releases the brake, assuming the user has not yet released the component, does not want to stop at the given position, and wants to continue moving the component.

[0130] This tactile feedback, achieved through a temporary actuation brake, eliminates the need for mechanical feedback components (such as mechanical indexing mechanisms).

[0131] Group operations

[0132] The brake controller 50 may also be equipped to group two of the three components together while allowing the remaining components to move freely relative to that group.

[0133] For example, brake controller 50 may be adapted to operate brakes 38a, 38b, 38c in at least one, and particularly at least two, of the following modes:

[0134] - Actuates the first brake component 38a while simultaneously deactivating the second brake component 38b and the third brake component 38c. In this case, the first and second components ( Figure 3 In the embodiment, the relative positions of the base 2 and arm 3 remain fixed, while the third component (arm 4) can be moved.

[0135] - Actuate the second brake component 38b while deactivating the first brake component 38a and the third brake component 38c. In this case, the relative positions of the second and third components (arms 3 and 4) are fixed, and the two components can be moved as a group relative to the first component (base 2).

[0136] - Actuate the third brake component 38c, while deactivating the first brake component 38a and the second brake component 38b. In this case, the relative positions of the first and third components (base 2 and arm 4) are fixed, while the second component (arm 3) can be moved relative to them.

[0137] In other words, the brake controller 50 can be adapted to keep one brake component active while keeping two other brake components deactivated, and advantageously, the user can select which brake component to be activated.

[0138] notes

[0139] In the illustrated embodiment, the brake components are brought into their braking state by feeding current through them. In other words, if there is no current flowing through the microscope, the brake is released. This allows for a compact design of the device and / or reduces power consumption in the non-braking state.

[0140] In another embodiment, the brake components can be designed to enter their non-brake state by sending an electric current through them. This can be achieved, for example, by brake components having two rings pushed against each other by spring components, wherein an electromagnet can be activated to act against the force of the spring. This design allows the microscope to be locked in an unused state without current and reduces power consumption in the braked state.

[0141] In the above embodiment, there are three movable components. However, the microscope may also include only two movable components, or it may include more than three components.

[0142] In the example shown, the components pivot relative to each other, and the brake is adapted to brake the pivotal movement between the components. However, the invention can also be used for other types of relative displacement. For example, it can be used to brake linear displacement between components of a microscope, such as the displacement of stage 2 relative to base 1 in the x and / or z directions or the vertical displacement of components along the y direction (such as the vertical displacement of headrest 7).

[0143] The microscope described herein assists the user in properly aligning various components, for example, in order to establish or reproduce the desired measurement configuration.

[0144] While presently preferred embodiments of the invention have been shown and described, it should be clearly understood that the invention is not limited thereto, but may be practiced and implemented differently in other ways within the scope of the following claims.

Claims

1. An ophthalmic slit lamp microscope, comprising: a microscope device (8), at least a first assembly (1, 2) and a second assembly (3, 8; 4, 9) which are manually pivotable relative to each other, and a position sensor (46a, 46b) having a first sensor member (46a) arranged to measure a relative position between the first and second assemblies (1, 2; 3, 8; 4, 9), an electric control brake (38a, 38b, 38c) having a main brake member (38a) arranged between the first and second assemblies (1, 2; 3, 8; 4, 9), and a brake controller (50) connected to the position sensor (46a, 46b) and to the brake (38a, 38b, 38c) and adapted to operate the brake (38a, 38b, 38c) in dependence of a reading of the position sensor (46a, 46b).

2. The microscope of claim 1, wherein the first assembly (1, 2) is a base (1) of the microscope or a stage (2) translationally mounted to the base (1).

3. The microscope of any one of claims 1 or 2, wherein the second assembly (3, 8; 4, 9) comprises the microscope device (8).

4. The microscope of any one of claims 1 or 2, wherein the second assembly (3, 8; 4, 9) comprises a light source (9).

5. The microscope of any one of claims 1 or 2, having a hinge (30) connecting the first and second assemblies (1, 2; 3, 8; 4, 9), wherein the hinge (30) comprises: a first hinge member (32a, 32b, 32c) rigidly connected to the first assembly (1, 2), a second hinge member (34) rigidly connected to the second assembly (3, 8; 4, 9), and a main pivot bearing (44a) having a pivot shaft (5) and connecting the first and second hinge members (32a, 32b, 32c; 34).

6. The microscope of claim 5, wherein the hinge (30) further comprises a first coil member (40a) and a first brake disc (42a) arranged around the pivot shaft (5) and positioned to generate a friction brake force between the first and second hinge members (32a-32c; 34) in dependence of an electric current in the first coil member (40a).

7. The microscope of any one of claims 1 or 2, further comprising: a third assembly (4, 9) which is manually movable, in particular pivotable, relative to the first assembly (1, 2) and relative to the second assembly (3, 8), wherein the brake (38a, 38b, 38c) comprises an auxiliary brake member (38b, 38c) arranged between the first and third assemblies (1, 2; 4, 9) and / or between the second and third assemblies (3; 4), and the brake controller (50) is connected to the auxiliary brake member (38b, 38c) and adapted to operate the auxiliary brake member (38b, 38c) in dependence of a reading of the position sensor (46a, 46b). The position sensor (46a, 46b) comprises a second sensor member (46b) arranged to measure the relative position between the first and third assemblies (1, 2; 4, 9).

8. The microscope of claim 5, further comprising a third assembly (4, 9) manually movable, in particular pivotably movable, relative to the first assembly (1, 2) and relative to the second assembly (3, 8), wherein the brake (38a, 38b, 38c) comprises an auxiliary brake member (38b, 38c) arranged between the first and third assemblies (1, 2; 4, 9) and / or between the second and third assemblies (3; 4), and the position sensor (46a, 46b) comprises a second sensor member (46b) arranged to measure the relative position between the first and third assemblies (1, 2; 4, 9), wherein the hinge (30) comprises a third hinge assembly (36a-36d) rigidly connected to the third assembly (4, 9), and an auxiliary pivot bearing (44b, 44c) connecting the first or second hinge member (32a-32c; 34) and the third hinge member (36a-36e).

9. The microscope of claim 8, having a hinge (30) connecting the first and second assemblies (1, 2; 3, 8; 4, 9), wherein the hinge (30) comprises: a first hinge member (32a, 32b, 32c) rigidly connected to the first assembly (1, 2), a second hinge member (34) rigidly connected to the second assembly (3, 8; 4, 9), and a main pivot bearing (44a) having a pivot (5) and connecting the first and second hinge members (32a, 32b, 32c; 34), a first coil member (40a) and a first brake disc (42a) arranged around the pivot (5) and positioned to generate a friction brake force between the first and second hinge members (32a-32c; 34) depending on an electric current in the first coil member (40a), and a second coil member (40b) and a second brake disc (42b) arranged around the pivot (5) and positioned to generate a friction brake force between the second and third hinge members (34, 36a-36d) depending on an electric current in the second coil member (40b).

10. The microscope of claim 9, further comprising a third coil member (40c) and a third brake disc (42c) arranged around the pivot axis (5) and positioned to generate a friction brake force between the first and third hinge members (32a-32c; 36a-36d) depending on an electric current in the third coil member (40c).

11. The microscope of claim 7, wherein the brake (38a, 38b, 38c) comprises two auxiliary brake members (38b, 38c), wherein one auxiliary brake member (38c) is arranged between the first and third assemblies (1, 2; 4, 9) and the other auxiliary brake member (38b) is arranged between the second and third assemblies (3, 8; 4, 9).

12. The microscope of claim 8, having a hinge (30) connecting the first and second assemblies (1, 2; 3, 8; 4, 9), wherein the hinge (30) comprises: a first hinge member (32a, 32b, 32c) rigidly connected to the first assembly (1, 2), a second hinge member (34) rigidly connected to the second assembly (3, 8; 4, 9), and a main pivot bearing (44a) having a pivot axis (5) and connecting the first and second hinge members (32a, 32b, 32c; 34), wherein the first assembly (1, 2) is connected to a first position of the hinge (30), the second assembly (3, 8) is connected to a second position of the hinge (30), and the third assembly (4, 9) is connected to a third position of the hinge (30), wherein the second position is located between the first and third positions, and wherein the first hinge member (32a-32c) or the third hinge member (36a-36d) comprises a shaft (36c) extending through the second hinge member (34).

13. The microscope of any one of claims 1 or 2, wherein the brake controller (50) is adapted to calculate an actuation time (to) to actuate the brake (38a, 38b, 38c) depending on a current mutual position (x) and a desired mutual position (xo).

14. The microscope of claim 13, wherein the brake controller (50) is adapted to: determine a velocity (v) of a movement between the first and second assemblies (1, 2; 3, 8; 4, 9), and calculate a time (to) to actuate the brake (38a, 38b, 38c) depending on the desired mutual position (xo) and the velocity (v) of the movement.

15. The microscope of claim 14, wherein the brake controller (50) is adapted to: calculate a brake distance (D) to actuate the brake (38a, 38b, 38c) to stop the movement between the first and second assemblies (1, 2; 3, 8; 4, 9), using the braking distance (D) to determine the actuation time (t0).

16. The microscope of claim 15, wherein the brake controller (50) is adapted to: - calculate an actuation time (t0) for actuating the brake (38a, 38b, 38c) from the current mutual position (x) and the desired mutual position (x0), - use a plurality of past measurements of the braking process to derive at least one parameter (At, u) describing a braking distance (D) of the brake (38a, 38b, 38c), - calculate the actuation time (t0) from the parameter (At, u).

17. The microscope of any one of claims 1 or 2, wherein the brake controller (50) is adapted to: - detect an increase of a force acting on the brake (38a, 38b, 38c) when the brake (38a, 38b, 38c) has been activated, and - release the brake (38a, 38b, 38c) upon such increase, and in particular wherein a position sensor (46a, 46b) is used to detect the force.

18. The microscope of any one of claims 1 or 2, wherein the brake controller (50) is adapted to activate and automatically deactivate the brake (38a, 38b, 38c) for a duration of less than 1 second, in particular less than 0.5 seconds.

19. The microscope of any one of claims 1 or 2, further comprising a display (52), and wherein the brake controller (50) is adapted to: - determine a current position (x) between the first and second components in relation to a desired mutual position (x0), and - indicate on the display (52) a direction of displacement for moving one of the first and second components to the desired mutual position (x0).

20. The microscope of any one of claims 1 or 2, comprising a roller bearing (44a, 44b, 44c) and a friction bearing (45a, 45b) between the first and second components (1, 2; 3, 8; 4, 9).

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