WO2010017944A1

WO2010017944A1 - Microscopy arrangement with a unit for calculating the focal depth and focus offset determined therefrom

Info

Publication number: WO2010017944A1
Application number: PCT/EP2009/005789
Authority: WO
Inventors: Martin Fanenbruck; Joachim Steffen
Original assignee: Carl Zeiss Surgical Gmbh
Priority date: 2008-08-15
Filing date: 2009-08-10
Publication date: 2010-02-18
Also published as: DE102008041290A1

Abstract

The invention relates to a microscopy arrangement (100) for viewing an object (108) or an intermediate image (126, 127) created of an object (108), particularly in microsurgery. The microscopic arrangement (100) comprises a lens arrangement (102) with an object plane (195) for arranging the objects (108) or the intermediate image (126, 127) to be viewed. The microscopy arrangement (100) comprises a focus offset adjustment unit (190) that provides a focus offset signal to an adjustment unit for the lens arrangement (101) in order to defocus the lens arrangement (101) relative to the focusing condition in a defined way. According to the invention, a depth of focus calculation unit (160) is provided that is connected to the focus offset adjustment unit (190) and that calculates a focus depth value from set parameters of the microscopy arrangement (100) when activated. The focus offset adjustment unit (160) generates a focus offset signal corresponding to a focus offset for the lens arrangement (102), said offset being a fraction of the calculated focus depth value in the direction of the lens arrangement (101) or in the direction of the object plane (200).

Description

MICROSCOPY ARRANGEMENT WITH UNIT - FOR CALCULATING THE DEPTH SHARP AND FOCUS SUBSTANCE THEREOF

The invention relates to a microscope arrangement for viewing an object or an intermediate image generated by an object, in particular in microsurgery, which has an objective arrangement with an object plane for arranging the object to be viewed and contains a focus offset adjustment unit which transmits a focus offset signal to a subject Adjusting unit for the lens assembly outputs to defocus the lens assembly defined relative to a Fokussierzustand.

A microscopy arrangement of the aforementioned type is known from JP 2006 122 232 A2 and from DE 10 2005 011 781 Al. There are surgical microscopes are described with a focusable main lens system in which the setting of a defined focus offset is provided by an observer.

Operations on the human eye, for example cataract surgery, are typically performed using a surgical microscope. The human eye is a spatially extended organ that is accessible to an operator only from the side of the cornea. In the course of an operation, therefore, there is a need for an operator to see different levels in the eye sharply.

The visual depth of field ST of a microscope arrangement is dependent, on the one hand, on its magnification β, but on the other hand also on the numerical aperture NA for the imaging beam path, which penetrates the microscope main objective system. In addition, the depth of field ST is influenced by the wavelength λ of the observation light in the imaging beam path. According to Berek, the following relationship applies to the visual depth of field ST:

_{ST =} ^Q M ₊ > ^{34 mm}

NA 'ßNA In order to allow an operator with a surgical microscope to observe an object area with good depth of field, surgical microscope systems are known, which have adjustable aperture stops, which are arranged in the observation beam paths. Such surgical microscope system as the Carl Zeiss OPMI ^® Pentero.

By reducing the diameter of the apertures of the aperture stops, the depth of field ST of the observation image can be increased. However, the reduction in the apertures of the aperture stops is generally associated with a loss of image brightness.

Increasing the magnification for the imaging beam path in a surgical microscope has a twofold effect on the depth of field: According to the Berek relation, the depth of field ST decreases with increasing magnification β. However, increasing the magnification β simultaneously causes a reduction in the numerical aperture NA of the imaging beam path that passes through the microscope main objective. Increasing the magnification of the microscope thus also results in a loss of image brightness.

In commercially available surgical microscope systems, which enable a stereoscopic observation of an object area with imaging beam paths that pass through a common microscope main objective, the visual depth of field for a magnification factor β> 10 is only about 2 mm or less.

However, neurosurgery and ophthalmic surgery often operate under a surgical microscope at up to 30x magnification. If tissue surfaces are considered to be uneven and scatter the light strongly, a shallow depth of field of a corresponding optical imaging system is very disadvantageous. In the field of neurosurgery, it is known to visualize tumor-affected tissue by means of fluorescent dye in a surgical microscope. For this purpose, the patient is injected via the bloodstream, a fluorescent dye, which is excited by the illumination system of the surgical microscope for fluorescence. A corresponding surgical microscope which is suitable for the observation of fluorescent light is described, for example, in WO 2007/090591 A1. The fluorescence image of the object area is relatively faint compared to an observation image based on normal scattered light. This requires that in surgical microscopes, which are operated in fluorescence mode, only comparatively large numerical apertures can be set for the imaging beam paths.

The object of the invention is to provide a microscopy arrangement, with which an intermediate image or image for an observation person with high depth of field is produced even when observing an uneven object area.

This object is achieved by a microscopy device of the type mentioned above in which a depth-of-field calculation unit is provided, which is connected to the focus offset adjustment unit and which calculates a depth of field value when activated from adjustment parameters of the microscope arrangement, wherein the focus offset adjustment unit generates a focus offset signal, which corresponds to a focus offset for the objective arrangement by a fraction of the calculated depth of field depth in the direction of the objective arrangement or in the direction of the object plane.

The focal plane of the microscope assembly is defined as being moved into or out of the object to be examined. By displacing the focal plane of the microscopy device out of the object to be examined in the direction of its main object system, object structures with deposition from the focal plane of the microscope device in the depth of field of the microscope device can be detected in a section in which, in the case of a conventional adjustment of the system, in particular in the case of an uneven Object area no longer all object structures, can be seen sharply. This is particularly advantageous in the field of neurosurgery in minimally invasive procedures, in the context of which small Trepanationsöffnungen be prepared. Here narrow and deep channels are created in which surgery is performed. When operating in such narrow and deep canals, there is a need for the surgeon to be able to see not only the front section of surgical instruments with a microscope in the form of a surgical microscope, but also a center section of these instruments, such as when inserted in a trephine opening. The shifting of the focal plane of the microscope arrangement here ensures that a corresponding instrument can be precisely guided in a narrow surgical channel even under optical imaging conditions in which enlarging the depth of field by dimming the observation beam paths of the microscope assembly is not possible due to insufficient light.

In the field of ophthalmology, shifting the focus plane toward the object being examined allows for rapid, sharp viewing of different planes of a patient's eye after the microscope assembly has been focused on the cornea of the patient's eye.

In a development of the invention, the adjustment parameters comprise the numerical aperture of an imaging beam path of the microscope arrangement. This imaging beam path may be e.g. be designed as a visual imaging beam path for an observer's eye or as a camera imaging beam path.

By including the microscope depth adjusting parameter setting parameter of the microscopic array and the magnification of the imaging beam path of the microscopy device and the observation light wavelength, the Berek relation allows to precisely calculate the maximum depth of an object area accessible to a good depth of field observation.

It is favorable to provide for the calculation of the depth of field a wavelength for observation light range 490 nm to 590 nm, preferably 500 nm. In this way, the depth of field of the microscope assembly for a Optimize object examination with visible light whose spectral composition corresponds to natural sunlight.

In a further development of the invention, the corresponding wavelength is in the range 820 nm to 900 nm. It is preferably 840 nm. In this way, the system is designed for fluorescence observation of the object region with good depth of field using the fluorescent dye indocyanine green (ICG).

In a development of the invention, the wavelength of light entering into the calculation of the depth of field lies in the range from 620 nm to 740 nm, preferably 630 nm or even 704 nm. In this way, the system can be configured for good depth of field when using the fluorescent dye 5AIa or protoporphyrin IX ,

By calculating the depth of field based on the 650 nm wavelength, the system can be optimized for fluorescence observation with the fluorescent dye hypericin.

For the fluorescence dye fluoresce, an optimal depth of field can be achieved with a corresponding microscope arrangement, if the wavelength range 520 nm to 530 nm is taken into account for its calculation. For the use of the fluorescent dye ITC, a wavelength in the range of 540 nm to 560 nm, in particular 550 nm, is favorable for determining the depth of field. By using the wavelength 590 nm, 461 nm, 556 nm, 480 nm, 510 nm, 528 nm or 565 nm for the depth of field calculation, the corresponding microscopy system can be used for the fluorescence examination of the object area with good depth of field using the fluorescent dyes GFP, DAPI, Optimize Rodamin, BFP, GFP, YFP or OFP.

In a further development of the invention, the focus offset for the objective arrangement corresponds to half (50%) of the calculated depth of field value. In this way, a surface area of the object area at a depth corresponding to the calculated depth of field can be sharply observed with good resolution. An advantageous embodiment of the invention is illustrated in the figures and will be described below.

Show it:

1 shows a microscope assembly with depth of field calculation unit and focus offset adjustment unit.

FIG. 2 shows the main objective system of the microscope arrangement in a first focusing state; FIG.

3 shows the main objective system of the microscope arrangement in a second focusing state with focus offset in the direction of the main objective system; and

4 shows the main objective system of the microscope arrangement in a third focusing state with focus offset in the direction of the object plane.

The microscope apparatus 100 in FIG. 1 has a depth-of-field calculation unit 160 and a focus offset adjustment unit 190.

The microscope assembly 100 is designed as a surgical microscope. As a lens arrangement, it comprises a focusable main objective system 101 with an object plane 200, which is penetrated by a left observation beam path 102 and a right observation beam path 103. The microscope assembly 100 includes a stepless zoom system 104. It has a binocular tube 105, which allows an observer with a left observer eye 106 and a right observer eye 107 to stereoscopically view an object region 108.

In the microscope assembly 100, an illumination system 109 with light source 110 is provided. The illumination system 109 includes a filter wheel 111 having different ones Filters for illumination light, which can be pivoted into the illumination beam path 109a.

The illumination beam path 109a is guided to the object area 108 via an object lens 112 and a deflection mirror 113.

The illumination system 109 is assigned a lighting system control unit 140. This serves to control the lamp current for the light source 110 and to adjust the filter wheel 111.

By suitable choice of lamp current and filter wheel setting, the wavelength spectrum and intensity of the illumination light for the object region 108 can be set in a defined manner.

The microscope assembly 100 further comprises a filter wheel 151 and a filter wheel 152 with corresponding filter wheel control units 153 and 154. By adjusting the filter wheels 151, 152, different filters for observation light between the main lens system 101 and the controllable zoom system 104 in the left and right observation beam path 102, 103 are pivoted. This makes it possible, in particular, to operate the microscope arrangement 100 in a fluorescence mode in which the object area 130 is marked with a suitable fluorescent dye which is excited to fluorescence with light of suitable wavelength from the illumination system 109. By means of the filter wheels 111 and 151 and 152 such filters are switched into the beam paths for illumination and observation light, which suppress illumination light in the spectral range of the wavelength of fluorescent light and filter the observation light in the wavelength range of the excitation band for fluorescence, it is possible by means of the microscope assembly 100th visualize fluorescent structures in the object area 108 with good contrast.

In the microscope assembly 100, a camera unit 114 and a camera unit 115 are provided. The camera 114 is via a beam splitter 1 16 image information from the left observation beam 102 supplied. The camera unit 115 is associated with a beam splitter 117 in the right observation beam path 103.

Furthermore, the microscope arrangement comprises display units 118 and 119, which enable beam splitter 120 and 121 to mirror image information into the left and right observation beam paths 102, 103.

Between the beam path 116 and 117 and the controllable zoom system 104, there is an adjustable aperture stop 122 and 123 in the left and right viewing beam paths 102, 103. In addition, the camera unit 114 is assigned a controllable aperture stop 124. Accordingly, an aperture stop 125 is located in the imaging beam path for the camera unit 115.

In the binocular tube 105 of the microscope assembly 100 is in the left and right observation beam 102, 103 each have an intermediate image 126, 127 which is imaged via an eyepiece lens 128, 129 in the binocular tube 105 to infinity.

The intermediate image 125, 126 in the binocular tube 105 of the object region 108 is perceived as a sharp image by an observer via a depth-of-field region 130.

The depth-of-field region 130 for the respective observation beams 102, 103 is of the numerical aperture NAiO ₂ , NA ₁₀₃ for the observation light in the left and right observation beam paths 102, 103 determined by the object-side aperture angle, from the magnification set by the zoom system 104 and the focusable main lens system 101 ßio ₂ , ßio3 and the wavelength λ of the observation light determined.

The depth of field of the observation image captured by the camera units 114 and 115 depends on the numerical aperture NAi 33, NAi 34 of the imaging beam path 133, 134 with object-side opening angles 135, 136, respectively Cameras 1 14, 1 15, the optical magnification ßiu, ßπs of the camera image and the wavelength of the light λ in the imaging beam path to the cameras.

In the microscope apparatus 100, a depth of field calculation unit 160 is provided. The depth-of-field calculation unit 160 is connected via a data line 161 to a control unit 162 for a zoom system 104 and via a data line 163 to a control unit 164 for the focusable main objective system 101. By means of the data lines 141 and 142, the depth-of-field calculation unit 160 is supplied with the setting information of the main lens system 101 and the zoom system 104.

The microscope assembly further includes data lines 165, 166, 167 and 168 to control units 170, 171, 172 and 173 for the aperture stops 122 and 123 in the left and right viewing beam paths 102 and 103 and the aperture stops 124 and 125 for the camera units 114 and 115 receives the depth-of-field calculating unit 140 in accordance with the aperture aperture diameter setting of the aperture stops 122, 123, 124, and 125.

Setting information to the lighting system 109 is supplied to the depth-of-field calculation unit 160 via a data line 181 from the lighting system control unit 140.

Further, the microscope assembly includes data lines 182 and 183 which are provided for transmitting information regarding the setting of the filter wheels 151 and 153 in the observation beam paths to the depth-of-field calculation unit 160.

The depth-of-field calculation unit 160 includes an operation unit 191 and a display unit 192. By means of the operation unit 191, it can be set by an observer in a calculation mode. In this calculation mode, in the depth of field calculation unit 160, the depth of field ST _{ZB I2} 6 and STZBI27 of the intermediate images 126 and 127 in the binocular tube 125 and the depth of field STKIU or ST _KH S determines the images captured by the camera 114 and 115 according to the following relationship:

- ^{0 5λ} 0.34mm

N ₁₀₂ ] ² P ₁₀₁ NA ₁₁

The determined values for the respective depths of field are displayed on the display unit 192. In this way, an observer is able to configure the illumination system, zoom system and aperture stops for optimum depth of field.

The depth-of-field calculation unit 160 is associated with a user-operable focus offset adjustment unit 190 that can be operated in a first and a second operating state: Upon actuation of the focus offset adjustment unit 190 in the first operating state, this sends an actuating signal to the control unit 164 for the main objective system 101 from, around the focus F of the main lens system 102 by a selectable amount Fi = Q x ₁ ST ₂₅₁₂₆ or

x ₁ ST ₂₅₁₂₇ or Fi = α x 5T ₁₀₁₄ or

Fi = ax 5T ^ ₁₁₅ in the direction of the arrow 198 to move out of the object area 108, where 0 <a ≤ 1, and preferably a - 0.5.

When the focus offset adjustment unit 190 is operated in the second operating state, it outputs an actuating signal to the control unit 164 for the main objective system 101 in order to control the Focus F of the main lens system 101 by a selectable amount F ₂ = ax ST ₂₈₁₂₆ or Yi = ax ST _ZBni or F ₂ = O x ST _κm or F ₂ = ax ST _{Kl] 5} in the direction of arrow 199 from the object area 108 out too shift, where 0 <a <1 and preferably a = 0.5.

FIG. 2 shows the main objective system 101 of the microscope arrangement 100 from FIG. 1 with the observation beam paths 102 and 103 in a first focusing state with a setting without focus offset.

FIG. 3 shows the main objective system 101 of the microscope arrangement in a second focusing state with a corresponding focus offset Fi in the direction of the main objective system 101. This adjustment of the focus offset is favorable for operating in a deep and narrow operation channel as shown at reference numeral 301 in FIG. Thus, on the one hand, it can be ensured that with the microscope arrangement the bottom section 302 of the surgical channel 301 can be seen sharply, and, on the other hand, that not only the front section 303 of a surgical instrument

304, which is guided in the operation channel 301, but also its center portion

305, which allows a particularly precise working with the instrument 304 for the surgeon.

FIG. 4 shows the main objective system 101 of the microscope arrangement with a focus offset F _{2 of} the main objective system 101 in the direction of the object plane 200. This setting may prove to be favorable in particular for the visualization of structures in the transparent object area.

The illustrated microscope arrangement is advantageously equipped with an autofocus system, which enables an automated focusing of the system on an object area. However, the microscope assembly may as well be designed as a system for manual focusing on an object plane.

The microscope assembly may also include a head mounted display (HMD). It is not necessary that in the microscope assembly optical Observation beam paths are led to an observer eye. The image of the object area with increased depth of field can also be displayed on an external monitor, for example.

Claims

claims:

A microscopy arrangement (100) for viewing an object (108) or an intermediate image (126, 127) generated by an object, in particular in microsurgery, comprising:

an objective arrangement (101) having an object plane (200) for arranging the object or intermediate image to be viewed;

a focus offset adjusting unit (190) which outputs a focus offset signal to an objective lens unit (101) adjusting unit for defocusing the lens assembly (101) in a defined manner relative to a focusing condition;

characterized in that

a depth-of-field calculation unit (160) is provided which is connected to the focus offset adjustment unit (190) and which, when activated from adjustment parameters of the microscope assembly (100), calculates a depth-of-field value (ST); in which

the focus offset setting unit (160) generates a focus offset signal that corresponds to a focus offset (F ₁ , F ₂ ) for the objective arrangement (102) by a fraction of the calculated depth of field (ST) in the direction (198) of the object array (101) or in the direction ( 199) corresponds to the object plane (200).

2. Microcopy arrangement according to claim 1, characterized in that the adjustment parameters include the numerical aperture (NAiO ₂ , NA ₁ 03, NA133, NA134) of an imaging beam path (102, 103, 133, 134) of the microscope device (100).

3. Microscopy arrangement according to claim 2, characterized in that the imaging beam path is a visual imaging beam path (102, 103).

4. Microscope arrangement according to claim 2, characterized in that the imaging beam path is a camera imaging beam path (133, 134).

5. Microscopy arrangement according to one of the preceding claims, characterized in that the adjustment parameters include the enlargement (ß) of an imaging beam path (102, 103, 133, 134) of the microscope assembly (100).

6. Microscopy arrangement according to one of the preceding claims, characterized in that the adjustment parameters comprise a wavelength (λ) for observation light.

7. microscopy arrangement according to claim 6, characterized in that the wavelength is in the range 490 nm to 510 nm and that it is preferably 500 nm.

8. Microscopy arrangement according to claim 6, characterized in that the wavelength in the range 820 nm to 900 nm and that it is preferably 840 nm.

9. Microscopy arrangement according to claim 6, characterized in that the wavelength is in the range 620 nm to 740 nm and that it is preferably 630 nm or 704 nm.

10. Microscope arrangement according to claim 6, characterized in that the wavelength is in the range 520 nm to 530 nm

11. Microscopy arrangement according to claim 6, characterized in that the wavelength in the range 540 nm to 560 nm and that it is preferably 550 nm.

12. Microscopy arrangement according to claim 6, characterized in that the wavelength is 509 nm or 461 nm or 556 nm or 480 nm or 510 nm or 528 nm or 565 nm.

13. Microscopy arrangement according to one of claims 1 to 12, characterized in that the focus offset Fi, F ₂ for the objective arrangement (101) corresponds to the fraction 0.5 of the calculated depth of field depth (ST).

14. A method for adjusting a microscope assembly (100) having the features of claims 1 to 13, characterized in that

a depth of field value (ST) is calculated from adjustment parameters of the microscope assembly (100); and

a focus offset (Fi) is set which corresponds to a fraction of the calculated depth of field value (ST) in the direction (198) of the objective arrangement (101); or

a focus offset F _{2 is} set, which corresponds to a fraction of the calculated depth of field value (ST) in the direction (199) of the object plane (200).