EP1399772A2 - Microscope tube - Google Patents

Abstract

The invention relates to a microscope tube consisting of: a housing (1) comprising a lower housing part (3) and an upper housing part (2), an incident lens group (9) fixed to the lower housing part (3) which is embodied for coupling to an infinite optical path of a microscope, a tube lens (12), fixed within the upper housing part, which rests with the incident lens group (9) on a mutual optical axis (OA1) and which gathers the rays supplied by the incident lens group (9) into an intermediate image, so that a finite optical path is formed between the tube lens (12) and the intermediate image; and a prism unit (13) which is fixed in the upper housing part (2)after the tube lens (12) and which deflects the further optical path (OA2) at a set angle of between 65 DEG and 75 DEG . Said prism unit is located in the finite optical path so that the intermediate image can be observed without further intermediate imaging, by means of a binocular lens group (4) which can be mounted on the upper part of the housing (2). The upper housing part (2) and the lower housing part (3) can be moved relative to each other along the optical axis (OA1).

Description

 microscope

The invention relates to a microscope tube, which is designed for coupling to an infinite beam path of a microscope and has a tube lens that generates an intermediate image that can be viewed via binocular optics.

Such microscope tubes are known. For example, DE 195 138 70 A1 describes a microscope tube with a tube lens, which transmits the image into an intermediate image plane of an eyepiece and has a corresponding deflection device in order to enable easy viewing of the image via a binocular lens. This microscope tube is designed such that the angle by which the beam path is deflected can be adjusted over a wide angular range by means of a prism and a rotatable mirror. This makes it possible to adjust the viewing angle from which a viewer can see into the microscope tube.

With such an adjustment of the viewing angle, the height of the tube viewing also changes automatically. In order to compensate for this, an intermediate tube is provided as a modular, separate component in DE 198 285 48 A1, which can be connected upstream of the microscope tube carrying the binocular optics in the infinity beam path of a microscope. This intermediate tube allows height adjustment, so that in combination with the tube known from DE 195 138 70 A1 with adjustable viewing angle, both the angle and the height of the tube viewing can be adjusted over a wide range.

However, this concept of creating a tube insight that is as ergonomic as possible has the disadvantage that the microscope tube known from DE 195 138 70 A1 with a variable viewing angle is dependent on tube lenses with a relatively large focal length, since additional optical reflections are required to pivot the observer's insight. which inevitably extends the optical path length. DE 195 138 70 A1 therefore provides special tube lenses, but this is not always desirable. If one would like to do without such special tube lenses, an additional intermediate image can alternatively be realized, which, however, considerably increases the depth of the microscope tube. Again, this can be ergonomically disadvantageous, since the position of the view into the microscope tube can sometimes be at a relatively large distance from the focusing setting wheels of the microscope. The invention is therefore based on the object of creating a microscope tube which is ergonomic and which can also be used with tube lenses having a short focal length.

This object is achieved by a microscope tube with an entrance optic, which is designed for coupling to an infinite beam path of a microscope, a tube lens, which brings bundles of rays supplied by the spaced entrance optics together in an intermediate image, so that a finite light beam path is formed between the tube lens and the intermediate image, and a prism unit arranged downstream of the tube lens, which deflects the further beam path by a fixed angle between 65 ° and 75 ° and lies in the finite beam path in such a way that the intermediate image can be viewed without further intermediate images with binocular optics that can be attached to the upper part of the housing, with a height adjustment device being provided the distance between the entrance optics and the tube lens is adjustable.

The invention therefore turns away from the previously usual procedure, in which a microscope tube that was as universally adjustable as possible was sought. Instead, a fixed viewing angle of approximately 20 ° is now provided, which is combined with a height adjustment. Such a fixed viewing angle was recognized as ergonomically more favorable, since the wide adjustability of the viewing angle according to the prior art regularly led to incorrect settings by the users. In order to be able to optimally select the height of the tube insight, this fixed viewing angle in the microscope tube is combined with an integrated height adjustment device. This combination according to the invention - selection of a fixed viewing angle close to 20 ° and the greatest possible adjustability of the altitude - makes it possible to avoid the solution, which is more complex in terms of construction and production technology, with a modular intermediate tube. The integration of the height adjustment device in the microscope tube housing achieves manufacturing advantages, so that such a microscope tube is less expensive.

In addition, by choosing the fixed viewing angle and dispensing with angle adjustment mechanisms that are prone to incorrect adjustment, the microscope tube is smaller, in particular shorter. This avoids an unergonomically large distance between the tube view and the focusing knobs of a microscope.

The prism unit provided in the housing effects the beam deflection required for the ergonomically favorable viewing angle. Here a deflection angle, which is defined as a supplementary angle between the original optical axis and after the deflection of the present optical axis, between 65 ° and 75 ° has proven to lead to a particularly ergonomic viewing angle.

In a particularly expedient development, the invention provides a microscope tube with a housing, which has an upper housing part and a lower housing part, in which the entrance optics is attached while the upper housing part carries the tube lens, which lies with the entrance optics on a common optical axis, the upper housing part and lower housing part being displaceable relative to one another along the optical axis. This two-part housing is particularly small and advantageously accommodates the height adjustment device.

The microscope tube according to the invention has the further advantage that different prism units can be used without major structural changes to the other components.

Since microscope tubes with reversed image positions have so far been used primarily in the biomedical application of microscopes, this has led to a familiarization effect. This

Users therefore prefer microscope tubes with an inverted image position. For such applications, therefore, a microscope tube with a prism unit is preferably provided, which by a

Double reflection does not change the image position. A prism unit having a first and a second prism, which are spaced apart by an air gap, is particularly expedient, the beam bundle entering the first prism first totally reflecting on its surface assigned to the air gap and then on an adjacent, mirrored surface reflected second prism.

Such a prism structure has the advantage that the resulting optical path length is extremely short. It can therefore also be used advantageously for tube lenses with a short focal length.

If this boundary condition does not exist, other prism arrangements can of course also be used which use an even number of reflections for the deflection.

For applications in material testing, users often prefer an upright, correct image position so that the direction of displacement of a specimen matches the image movement. A prism unit is therefore advantageous for such an application, which combines a unique reflection for reversing the height with a corresponding device for reversing the side. This is achieved in a particularly simple manner by a prism unit which effects an image position inversion and, for this purpose, has a pair of reflective roof surfaces which, as is known, results in a page reversal.

The height adjustment device must make the distance between the tube lens and the entrance optics, with which the bundles of rays are picked up from the infinite beam path of the microscope, variable, whereby the optics downstream of the tube lens always remain at a fixed distance from the tube lens. This is particularly easy to achieve, in particular in the case of afocal entrance optics, which are preferred for image correction reasons, by designing the housing in which a lower housing part can be telescopically pushed into an upper housing part if the lower housing part carries the entrance optics and the upper housing part carries the tube lens including subordinate optics , Known guide rods can be used to guide the unit carrying the entrance optics and the unit carrying the tube lens including the downstream optics. Particularly precise guidance is achieved with a recirculating ball bearing guide, in which a guide carriage preferably runs on a guide rail. Such a recirculating ball guide has the further advantage that inexpensive standard components can be used.

There are only minimal requirements for the drive of the height adjustment device if the mutual position is guaranteed by the guide. Low precision then only affects the convenience of height adjustment, but not the optical properties of the microscope tube. A particularly simple mechanism with relatively high adjustment accuracy is achieved with a rack and pinion drive. This can be designed such that a toothed wheel rotatably attached to the upper housing part engages on a toothed rack attached to the lower housing part. Of course, the position of the gear and rack can also be reversed.

It has generally proven to be advantageous if, in the case of a microscope tube with a height adjustment device, a height position once set cannot be inadvertently readjusted. In principle, any suitable fixation mechanism that counteracts an adjustment of the distance between the entrance optics and the tube lens is suitable for this purpose; For example, appropriate closures are conceivable that block the adjustment mechanism, such as locking levers or the like. An adjustment mechanism that does not have to be blocked separately, but in which a certain force must always be overcome for adjustment, is particularly expedient. A particularly simple embodiment in this regard is a slip clutch which inhibits the height adjustment mechanism of the entrance optics and tube lens.

In the case of an adjustment mechanism driven by a rotatable shaft, such a slip clutch will advantageously be provided between the shaft and a housing part in which the shaft is held. In a particularly inexpensive to manufacture realization, a shaft rotatably held in a housing part is provided, the rotation of which drives the mutual displacement of the entrance optics and the tube lens, a non-rotatably seated slider on the shaft, which is tensioned on a sliding surface attached to the housing part, so that a the rotation of the shaft inhibiting slip clutch is formed. This design requires few moving parts and only a few friction linings. The friction linings can have Teflon particularly advantageously, since they are particularly wear-resistant.

A locking mechanism, in particular in the form of a slip clutch, has the advantage that the selected altitude remains largely independent of the weight of the microscope tube or the weight that is placed on the microscope tube by a camera, for example. In the case of a microscope with a vertically aligned optical axis, the tube lens together with the downstream optics, in particular together with the eyepiece, is usually moved upwards in order to enlarge the distance between the entrance optics and the tube lens. A different force is then required to increase the distance than to reduce the distance between the entrance optics and the tube lens. In order to compensate for this ergonomically disadvantageous effect, it is expedient to clamp a spring unit between the holder carrying the entrance optics, for example the lower housing part, and the holder carrying the tube lens with the downstream optics, for example the upper housing part, which for largely forceless adjustment of the distance of the between the entrance optics and tube lens in both directions.

The angle by which the prism unit deflects the beam path can be freely selected between 65 ° and 75 ° in the range according to the invention. A deflection angle close to or equal to 70 ° has proven to be particularly ergonomic, so that a viewing angle close to or equal to 20 ° is achieved when the optical axis is vertical.

Cameras are often attached to microscopes to record images. It is particularly expedient that the camera then lies in the intermediate image plane of the tube lens. In principle, this could be done by attaching the camera to the eyepiece. However, it has proven to be more advantageous that the prism unit can be moved out of the beam path and a camera connection is provided, via which the intermediate image can be recorded with a camera attached to the camera connection when the prism unit is moved out, so that the intermediate image is imaged directly into a camera. The eyepiece can then remain in position with the camera installed and does not have to be removed.

The invention is explained in more detail below by way of example with reference to the drawing. The drawing shows:

1 is a perspective view of a microscope tube from above,

2 is a perspective view of the microscope tube from below, FIG. 3 is a longitudinal sectional view along the optical axis through the microscope tube,

4 shows a cross section through the microscope tube in the plane of a height adjustment mechanism,

5 shows a further longitudinal sectional illustration of the microscope tube in the plane of the optical axis and of the adjustment mechanism, FIG. 6 is a schematic illustration of a prism unit of the microscope tube and

7 shows an optional configuration of the prism unit. Figure 1 shows a perspective view of a microscope tube, which is intended for mounting on a tripod of a microscope. The microscope tube has a two-part housing with an upper housing part 2 and a lower housing part 3. A binocular part is attached to the upper housing part 3, which, as will be explained in more detail later, grants a viewing angle of 20 ° when the housing 1 of the microscope tube is mounted on a microscope with a vertically extending axis. In the binocular part 4, two eyepiece inserts 5 and 6 are inserted, the distance between which can be adjusted to the eye relief of the user.

The housing 1 of the microscope tube is adjustable in such a way that the lower housing part 3 can be pushed telescopically into the upper housing part 2. This telescopic movement is actuated via a height adjustment wheel 7. On the top of the housing 1, a cover 8 can also be seen, which is provided for a camera connection to be explained.

Figure 2 shows the microscope tube in perspective from below. An entry optic 9 is provided in the bottom of the lower housing part 3, via which radiation from the infinite beam path of the microscope can be coupled. For attachment to the microscope stand, the lower housing part 3 also has threaded holes 10 on its base, via which the housing 1 can be screwed to the microscope stand.

Figure 3 shows a sectional view of the inner structure of the microscope tube. The entrance optics 9, which is arranged in the bottom 17 of the lower housing part 3 designed as a backdrop, come to rest on the optical axis OA1 of the microscope when the microscope tube is fastened on a microscope stand. The entrance optics 9, which in the present example is made up of two lenses, is afocal, i.e. it extends the telecentric area in the infinity beam path of the microscope.

Downstream of the entry optics 9 is a tube lens 12 which is fastened in a prism holder which carries a prism unit 13 arranged downstream of the tube lens 12. The tube lens 12 brings the tufts of rays, which are guided by the entry optics 9 in the infinity beam path, to an intermediate image, which is then visible through the binocular part 4. The prism unit 13 causes the beam path to be deflected by an angle of 70 °. The structure of the prism unit 13 will be explained in more detail later with reference to FIG. 6.

The rays deflected by the prism unit 13 fall through a binocular opening 18, which is formed in a binocular flange 19, which is fastened to the upper housing part 2 by screws, into the binocular part 4 and can be viewed from there with the help of the eyepiece inserts 5 and 6 in the form of the intermediate image become. On a wall of the lower housing part 3, a guide carriage 14 of a recirculating ball guide is fastened by screws 20 and runs on a guide rail 15 fastened to the upper housing part 2. The recirculating ball guide causes an exact vertical guidance of the lower housing part 3 relative to the upper housing part 2 along the optical axis OA1.

In the maximum extended state, i.e. H. if the guide carriage 14 abuts an adjustable stop (not shown in the drawing), the height d, d. H. the distance between the entrance optics 9 and tube lens 12 is maximum. To reduce the height d, the lower housing part 3 is inserted into the upper housing part 2, which, when the lower housing part 3 is fastened to a microscope stand, has the consequence that the viewing height with which a user of the microscope looks into the eyepiece inserts 5 and 6 decreases.

When the lower housing part 3 is inserted into the upper housing part 2, the wall of the lower housing part runs into the upper housing part. This can be seen, for example, on the backdrop wall 16. So that the lower housing part 3 can be pushed as far as possible into the upper housing part until the entrance optics 9 are at a minimally permissible distance from the tube lens 12, a gap 39 is provided on the back of the binocular flange 19, which is located between the prism unit 13 and the binocular flange 19 and in which the backdrop wall 16 can be placed. The maximum insertion depth of the lower housing part 3 into the upper housing part 2 is thus determined by the distance between the lower edge of the upper housing part 2 and the upper edge of the gap 39. Since this distance is limited by the length of the prism unit 13, which cannot be chosen arbitrarily for optical reasons, the gap 39 is therefore designed for the largest possible adjustment range so that the link wall 16 runs past the prism unit 13 without, however, in the optical Beam path to the binocular part 4, d. H. to coincide with the binocular opening 18.

By adjusting the height, when the lower housing part 3 is firmly attached to a microscope stand, the upper housing part 2 together with the eyepiece part 4 attached to it is raised when the height d is increased. The height adjustment wheel 7, which drives a shaft 25, is provided as the drive. FIGS. 4 and 5 show different sectional representations through the microscope tube 1, each in the plane of this shaft 25.

The shaft 25 is mounted in the upper housing part 1 and carries a driver piece 27, which is fastened in a rotationally fixed manner by means of a grub screw 31. The toothed wheel 32 engages in a toothed rack 30 fastened to the lower housing part 3, so that toothed rack 30 and toothed wheel 32 form a toothed rack drive for changing the height d. In order to make the adjustment as weak as possible, spring units 26 are clamped between the upper housing part 2 and the lower housing part 3, which the own weight of the Compensate upper housing part 2 and the attached binocular part 4. The tension of each spring unit 26 is preferably suitably adjustable in order to enable adaptations to binocular parts 4 of different weights. So that the same conditions prevail during upward and downward movement, the spring units have a very flat spring characteristic curve, which is chosen exactly so that it compensates for the weight of the moving parts, ie the upper housing part 2 together with the attached components.

However, since a camera can optionally be attached to the microscope tube 1 instead of the cover - then the weight to be supported by the spring units increases - a slip clutch unit is additionally provided. In the exemplary embodiment, this has a Teflon plate 28 which sits on a wall of the upper housing part 2. A friction disk 29, which can also be made of Teflon, is pressed onto this Teflon plate via a plate spring 33 lying on the shaft 25. The plate spring 33 is supported on a support plate 34 which is fixed on the shaft 25 and has an adjustable bias so that its holding force is adjustable. Optionally, a clamping screw can also be used, whereby weights of up to 5 kg can be supported using conventional disc spring designs.

The microscope tube 1 is designed so that different prism units can be used. In a first variant, the prism unit shown in FIG. 6 is provided, which has a two-part prism group. It consists of a Bauernfeind prism 21, which acts as a deflection prism. It has a mirror surface 24 on its vertical prism surface. An additional prism 22 lies above an air gap 23 of a few 1/10 mm from the Bauernfeind prism 21 and causes the beam path which passes obliquely through the air gap 23 to emerge from the prism unit on a surface perpendicular to the optical axis OA2. The length of the additional prism 23 allows the optical beam path to be shortened, since light paths covered in glass mean a shorter optical path length than the same distance in an air path. The fact that the air gap 23 is penetrated obliquely by the optical axis OA2 and thus by the beam path is not disadvantageous for the image quality. Since in the Bauernfeind prism 21 a total of two reflections take place at the air gap 23 and at the mirror surface 24, the original image position remains unchanged. In addition, a special glass is used, which enables total reflection through a suitable refractive index and at the same time ensures compliance with the tube lens focal length.

Optionally to the prism group of FIG. 6, the prism shown schematically in the perspective illustration of FIG. 7 can also be used, which causes an image inversion, ie a reversal of the image position with regard to height and side orientation. The prism unit is designed as a one-piece roof surface prism 38 which has an entry surface 36 perpendicular to the optical axis OA1 and an exit surface 37 perpendicular to the optical axis OA2. Two mirrored roof surfaces 38 effect the corresponding beam deflection. Since the beam path in the roof surface prism 35 only once reflected, there is a height inversion. The two roof surfaces 38 result in a side reversal at the same time.

Both prisms deflect the beam path by approximately 70 °, so that the optical axis OA2 extends at an angle of approximately 20 ° to the horizontal when the optical axis OA1 is aligned vertically.

The prism units 13 of Figures 6 and 7 are designed so that they can be used as interchangeable modules. Thus, one and the same microscope tube can, depending on the user's request, either show a correct image in the right side and height or a correspondingly inverted image on the binocular part 4. Extensive optical or mechanical changes are not necessary.

In order to fasten a camera instead of the cover 8, a fastening device (not shown) is provided, the prism unit 13 also sits on a carriage (not shown) in order to be able to move it out of the beam path if an image is to be recorded with the camera ,

Claims

claims 1. microscope tube with an entry optic (9) which is designed for coupling to an infinite beam path of a microscope, - A tube lens (12) which from the spaced entry optics (9) brings bundles of rays together in an intermediate image, so that a finite light path is formed between the tube lens (12) and the intermediate image, and - One of the tube lens (12) downstream prism unit (13), which deflects the further beam path (OA2) by a fixed angle between 65 ° and 75 ° and lies in the finite beam path so that the Intermediate image can be viewed without further intermediate images with binocular optics (4) which can be attached to the upper housing part (2), wherein - An integrated height adjustment device (2, 3) is provided, with which the distance between the entrance optics (9) and tube lens (12) is adjustable. 2. microscope tube according to claim 1, with a housing (1) having a lower housing part (3) and an upper housing part (2), the entrance optics (9) on the lower housing part (3) and the tube lens on the upper housing part (2) is attached, The tube lens (12) and entrance optics (9) lie on a common optical axis (OA1) and the upper housing part (2) and lower housing part (3) can be moved relative to one another along the optical axis (OA1). 3. microscope tube according to claim 1 or 2, wherein the prism unit (13) has a first and a second prism (21, 22) which are spaced apart by an air gap (23), the first prism (21) entering beam bundle first of its surface assigned to the air gap (23) is totally reflected and then reflected on an adjacent, mirrored surface (24) towards the second prism (22). 4. microscope tube according to claim 1 or 2, wherein the prism unit (13) causes an image position inversion and for this purpose has a pair of reflective roof surfaces (38). 5. microscope tube according to one of the above claims in connection with claim 2, wherein the housing lower part (3) in the housing upper part (2) is telescopically insertable. 6. microscope tube according to one of the above claims, wherein the height adjustment device a Recirculating ball guide (14, 15) for guiding the entrance optics (9) and tube lens (12). 7. microscope tube according to one of the above claims, wherein the height adjustment device has a rack and pinion drive (30, 32). 8. Microscope tube according to one of the above claims, the beam path of which is deflected by an angle close to or equal to 70 °, so that when the optical axis (OA1) of the tube lens 12 is vertical, an angle of view close to or equal to 20 ° is achieved. 9. microscope tube according to one of the above claims, wherein the prism unit (13) can be moved out of the beam path and a camera connection (8) is provided, via which the intermediate image with one moved out of the beam path with a prism unit (13) on the camera connection (8 ) attachable camera is recordable. 10. microscope tube preferably according to one of the above claims, in which a height adjustment device has a slip clutch. 11. microscope tube according to claims 2 and 10, with a shaft (25) rotatably held on the upper housing part (2), the rotation of which drives the mutual displacement of the upper housing part (2) and lower housing part (3), a non-rotatable slide disc (29 ) is seated, which is acted upon by a slip covering (28) attached to the upper part of the housing, so that a slip clutch which inhibits the rotation of the shaft (25) is formed. 12. microscope tube according to one of the above claims, wherein the height adjustment device has a prestressed spring unit (26).