Digital microscope comprising pivoting stand, method for calibration and method for automatic focus and image center tracking for such a digital microscope
09817223 · 2017-11-14
Assignee
Inventors
Cpc classification
G02B21/365
PHYSICS
F16M11/046
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16M11/18
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16M11/2021
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16M2200/021
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
International classification
F16M11/04
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16M11/18
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16M11/20
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Abstract
A digital microscope having a pivoting stand, a method for calibrating said stand and a method for automatic focus tracking and image center tracking upon actuation of the pivoting stand. The pivoting stand includes an angle sensor for determining a current pivot angle of the pivot arm (07). The current pivot angle is processed in the control unit to execute automatic focus tracking and/or center tracking upon actuation of the pivot arm (07). Calibration is performed using two pivot angles, wherein deviating focus and image center positions are ascertained, and a pivot-angle-dependent function for focus and the image center position is ascertained therefrom.
Claims
1. A digital microscope comprising an optical unit, which comprises at least one objective and an image processing unit, wherein a longitudinal axis of the objective defines an optical axis; a pivoting stand having a pivot arm that is pivotable around a pivoting axis, and on which a support is arranged for holding the optical unit; a specimen stage which is adjustable in at least two mutually perpendicular displacement axes, wherein one of the displacement axes is aligned parallel with the pivoting axis; a control unit for controlling and positioning optical unit, pivot arm and specimen stage; wherein the support and the specimen stage are displaceable; and wherein the pivoting stand comprises an angle sensor for determining a current pivot angle of the pivot arm, wherein the angle sensor comprises two inertial sensors, each of which is disposed on a plate so as to be movable relative to each other, wherein the current pivot angle is processed in the control unit, in order to execute an automatic focus tracking and center tracking upon actuation of the pivot arm.
2. The digital microscope according to claim 1, wherein the support can be moved by a motorized mechanism in the direction of the optical axis.
3. The digital microscope according to claim 1, wherein the specimen stage can be moved by a motorized mechanism in a vertical direction.
4. The digital microscope according to claim 1, wherein the pivot arm is arranged locked in a first position having a pivot angle of ZERO.
5. The digital microscope according to claim 1, wherein the pivoting stand comprises a high torque magnet brake with which the pivot arm can be fixed in any pivot position.
6. A method for calibrating a pivoting axis and an image center in a digital microscope according to claim 1, comprising the following steps: adjusting a first pivot angle of the pivot arm; bringing a calibration marking located on the specimen stage into focus by moving the support along the optical axis or by moving the specimen stage in a vertical direction; centering the calibration marking with the optical axis by moving the specimen stage along two axes that are perpendicular to the optical axis when the pivot arm is in an upright position; detecting and storing all first axial positions of the specimen stage and the support and of the first pivot angle; pivoting the pivot arm to a second pivot angle; bringing the calibration marking into focus for a second time; centering the calibration marking for a second time; detecting and storing all second axial positions of the specimen stage and the support and of the second pivot angle, determining a relative focus difference and a relative pivoting axis difference from the first and second axial positions; ascertaining a pivot-angle-dependent function for actuating a control unit of the digital microscope for the purpose of correcting the relative focus difference and the relative pivoting axis difference.
7. The method according to claim 6, wherein the second pivot angle is determined relative to the first pivot angle, wherein the first pivot angle is defined as a reference position.
8. The method according to claim 6, wherein the control unit actuates the specimen stage and the support in order to shift a point of origin of a perpendicular system of coordinates formed by the optical axis when the pivot arm is in the upright position and the displacement axes in such a way that it coincides with the position of the calibration marking.
9. The method for automatic focus tracking and image center tracking in a digital microscope having the features of claim 1 upon actuation of the pivot arm, the method comprising: detecting a pivot angle of the pivot arm; and automatically adjusting a focus distance and an image center position based on the detected pivot angle.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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(15) The present disclosure is susceptible of various modifications and alternative forms, and some representative embodiments have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the inventive aspects are not limited to the particular forms illustrated in the drawings. Rather, the disclosure is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure as defined by the appended claims.
DETAILED DESCRIPTION OF ILLUSTRATED EXAMPLES
(16)
(17)
(18) For purposes of orientation, a spatial system of coordinates is established, which comprises, as viewed from the illustration plane of
(19) Pivoting stand 01 comprises a stand base 02, on which a pedestal 03 is mounted, in which a bearing is integrated for an articulated part 06, which is capable of pivoting about a pivoting axis 04 and on which a pivot arm 07 is fixedly arranged. On pivot arm 07, a preferably motorized upper Z-guide 08 is arranged, via which a support 09, which holds an optical unit 11, can be moved in the Z-position relative to a reference position Z.sub.Ro. Reference position Z.sub.Ro of (motorized) upper Z-guide 08 is indicated relative to pivoting axis 04 and results from a defined movement into position via a suitable sensor device during the initialization process of (motorized) upper Z-guide 08. This sensor device is formed, for example, by a target which is moved along during Z-movement, and a hybrid coupler (a photoelectric barrier) mounted so as to remain stationary, which halts Z-movement during the initialization process as soon as the movement of the target into the hybrid coupler alters the switching state of the hybrid coupler. Alternatively, other technical solutions that are known to a person skilled in the art and are sufficiently reproducible may also be used as the sensor device. For example, a Hall sensor and a magnet may also be used, in which case the Hall sensor replaces the hybrid coupler and the magnet replaces the target. The reproducibility that can be achieved with the sensor device as the maximum deviation from the actual reference position is several orders of magnitude smaller than could be ensured through calibration processes or with typical manufacturing inaccuracies and cost-optimized production.
(20) With a sufficiently precise (motorized) upper Z-guide 08, as can be assumed in digital microscopes, the Z-positions therefore also have correspondingly small deviations relative to reference position Z.sub.Ro.
(21) In
(22) The first Z-position Z.sub.o1 is characterized in that a specimen detail 13, located on the upper side of a specimen 14, is imaged in sharp focus on an image sensor, not shown, with pivot arm 07 in the vertical position, wherein the Z-coordinates of specimen detail 13 and of pivoting axis 04 are not identical.
(23) A preferably motorized lower Z-guide 16 is mounted on stand base 02, although motorized lower Z-guide 16 could also alternatively be mounted on pedestal 03. The back side of pivoting stand 01 is preferably covered by a dust cover 17.
(24) On (motorized) lower guide 16, which is variable relative to a reference position Z.sub.Ru in terms of the Z-position (see
(25) According to
(26) According to
(27) In practical terms, according to
(28) On the Y-axis of (motorized) specimen stage 18, a first Y-position Y.sub.1>0 is set relative to reference position Y.sub.R, in which, when pivot arm 07 is aligned vertically, specimen detail 13, which is positioned centered in relation to the entire area of movement of specimen stage 18 in the Y-direction, of specimen 14, which is placed on upper surface 21 of reflected light insert plate 20, should be located at the center of the image. Since the deviations which also occur here in practical terms are not relevant for the view according to the invention, the deviations have not been shown in
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(30) Pivot arm movement is blocked by a high torque magnetic brake disposed around pivoting axis 04 and not described in greater detail here. The blocking can be removed for as long as pressure is applied to a button 23 according to
(31) Because, in principle, the focusing process can be implemented via both (motorized) upper Z-guide 08 and (motorized) lower Z-guide 16, the Z-coordinates of pivoting axis 04 can deviate relative to the Z-coordinates of specimen detail 13, even when specimen detail 13 is located in the specimen plane.
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(33) In contrast to the usual mathematical approach, however, the amounts here contain a sign that contains the directional information relative to the drawing. A negative sign for such a unidimensional variable in the calculation indicates in
(34) The position of pivoting axis 04 relative to ideal pivoting axis 26 or specimen detail 13 is described by the vector MI. This vector can also be broken down into vectors MIX and MIZ, arranged parallel to the coordinate axes, with vector MIZ ending at point MAZ and vector MIX beginning at point MAZ. Working distance a.sub.L between the specimen plane and end face 22 of objective 12 when pivot arm 07 is in the vertical alignment, not shown in
(35) Pivoting pivot arm 07 around angle w2 causes the vectors to rotate accordingly about pivoting axis 04. In so doing, vector MIX becomes vector MIX′, vector MIZ becomes vector MIZ′, vector A becomes vector A′, vector AL becomes vector AL′ and point MAZ becomes point MAZ′. In addition, specimen plane OE is pivoted about pivoting axis 04, resulting in a pivoted specimen plane OE′. Vectors MIZ′ and A′ lie on pivoted optical axis OA′. At penetration point 27 where pivoted optical axis OA′ passes through pivoted specimen plane OE′, vector dF ends, which is a measurement of defocusing and which begins with laterally offset specimen detail OD′.
(36) According to
A=A′
AL=AL′
MIX=MIX′
MIZ=MIZ′
Ā=
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(39) After conversion, the following results:
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(41) With these signed unidimensional variables MIX and MIZ, the position of pivoting axis 04 relative to ideal pivoting axis 26 is clearly described as a function of pivot angle w2 and can therefore be presumed to be known once these variables MIX and MIZ have been calculated and stored in the control unit, which can be integrated, for example, in the operating and display unit. All calculated data can be stored in the control unit and further used as needed.
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(43) In contrast to the representation of
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(45) From signed unidimensional variables dF and dx, factoring in pivot angle w2, the likewise signed unidimensional variables MIX and MIZ can be determined according to the above calculation procedure. The present signed unidimensional variables MIX and MIZ fully describe the position of pivoting axis 04 relative to the ideal pivoting axis 26.
(46) Using the correction operation according to the invention, it is possible to compensate for any pivot angle by further converting the previously calculated variables for lateral specimen offset dx and defocusing distance dF. To accomplish this, based on the current pivot angle w.sub.K, in the correction operation the variables dx.sub.K and dF.sub.K, which counteract the specimen offset and the defocusing distance, are calculated in the control device. The correction variables w.sub.K, dx.sub.K and dF.sub.K which are each valid for any pivot angle are not shown in the figures.
(47) From the relationships for determining signed variables MIX and MIZ according to
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(49) The relationship X.sub.K=X1−dx.sub.K results in an X-position X.sub.K of the X-axis of the (motorized) specimen stage 18 relative to reference position X.sub.R, in which a specimen 14 placed on upper surface 21 of reflected light insert plate 20, centered relative to the entire movement range of specimen stage 18 in the X-direction, with pivot arm 07 aligned vertically, is located with a specimen detail 13 again at the image center after the pivoting of pivot arm 07 about pivot angle w.sub.K in the correction operation according to the invention.
(50) The relationship Zo.sub.K=Zo1−dF.sub.K results in a Z-position Zo.sub.K of the (motorized) upper Z-guide 08 relative to reference position Z.sub.Ro, in which specimen detail 13 is sharply imaged with pivot arm 07 pivoted about pivot angle w.sub.K in the correction operation according to the invention.
(51) Depending on the current pivot angle w.sub.K in the correction operation according to the invention, (motorized) specimen stage 18 is automatically positioned in the corresponding X-position X.sub.K relative to reference position X.sub.R and (motorized) upper Z-guide 08 is automatically positioned in the corresponding Z-position Zo.sub.K relative to reference position Z.sub.Ro via the control device, so that specimen detail 13 is located at the image center and is imaged in focus with each current pivot angle w.sub.K following the correction according to the invention.
(52) In a calibration process according to the invention, preferably no specimen is located on specimen stage 18. In this process, a reference mark is brought into focus, which is preferably a component of upper surface 21 of reflected light insert plate 20 or the upper side of upper stage plate 19. Alternatively, a special calibration object may be used for this purpose, which contains the reference mark and which can be reproducibly placed on upper surface 21 of reflected light insert plate 20.
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(54) The determination according to the invention of variable MIZ is then begun as shown in
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(56) The deviation DZ of specimen detail 13 relative to pivoting axis 04 in the Z-direction, which can be used for determining the data for an automatic focus tracking, then corresponds to the negative value for MIZ, i.e. the following are true:
DZ=−MIZ
Z.sub.u1=DZ−Z.sub.Ru<0,
(57) which results in
Z.sub.Ru=−MIZ−Z.sub.u1
(58) Since reference position Z.sub.Ru is given relative to pivoting axis 04, all other Z-positions of (motorized) lower Z-guide 16 that are indicated relative to this reference position Z.sub.Ru can be converted to Z-positions relative to pivoting axis 04. According to
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(60) Since specimen detail 13 being viewed has been moved upward by the amount of variable DZ, the Z-position of (motorized) upper Z-guide 08 must also be moved upward accordingly, so that specimen detail 13 will continue to be located in the specimen plane. According to
(61) As long as the position of pivoting axis 04 relative to an ideal pivoting axis 26, the coordinates of which are fully known, has already been determined and stored once, the position of pivoting axis 04 can be reproduced with sufficient precision due to the provided sufficiently accurate absolute positioning precision, even after the system has been switched off and back on again. According to
(62) If different objective variants are provided, these can be coded, so that the system recognizes which objective is currently being used when the system is switched on and each time the objective is changed, and is able to use this information for further actions. This also includes the automatic correction process according to the invention, which offers a substantial time advantage over the prior art. For this purpose, for each objective that will be supplied with a digital microscope, the focus position for focusing on specimen detail 13 positioned at the height of pivoting axis 04 is preferably set and stored already at the factory. Coding the objectives allows each of the stored values to be uniquely assigned to one objective.
(63) Proceeding from the calibration process, which is preferably carried out at the factory, the data obtained during the calibration process can be used for the automatic correction process according to the invention, which completely takes over the corresponding necessary corrections from the now known position of pivoting axis 04 and the objective currently in use, to compensate for the deviations caused by the pivoting movement, thereby providing the user with a substantial time advantage. This time advantage can be increased even further according to the invention when specimen detail 13 to be viewed is already automatically located at the height of pivoting axis 04 when pivot arm 07 is in the vertical position.
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(67) Advantageously, the calibration processes are carried out via menu-controlled queries. An automatic correction can be provided by using the key signal or can be carried out only after confirmation by the user. Of course, the controller provides for a return to factory settings.
(68) Furthermore, a one-time predetermination of the working distance of the objective in use (advantageous assignment by coding the objective) and the use of the stored, factory-set default Z-position of the motorized upper Z-axis for automatically moving to the specimen detail in the pivoting axis is possible. This can optionally be provided as a selection made via a selection button and/or by activating the key. Of course, autofocus functionalities of the digital microscope system may also be used for focusing.
(69) All of the above statements relate to an optical axis (OA) of the imaging system, via which a specimen detail (13) arranged therein and in the specimen plane is always imaged at the image center, independently of other influences. However, the remaining imprecisions of the imaging system may lead, in practical terms, to a zoom center which deviates from the image center, and which is held stationary in the image when the zoom factor is changed. This then always corresponds to the position of the optical axis (OA), i.e. the calibration and correction processes according to the invention would then have to relate to this zoom center in the image and not to the image center. The specimen detail (13) would therefore have to be positioned on a target marking in the image in each case, which marking is arranged at the zoom center and not at the image center. The term “centering the calibration marking with the optical axis (OA)” also covers this case.
(70) Of course, the scope of protection of this application also comprises the corresponding use of target marks in the image which deviate from the image center.