Microscopy method and microscope for imaging an object

Abstract

A microscope and a microscopy method for imaging an object, wherein use is made of a microscope comprising an objective which defines an optical axis and a focal plane perpendicular thereto, and an adjustable correction optical unit which, at the objective, corrects a spherical aberration occurring when imaging the object with a certain depth position of the focal plane. The method comprises the following steps: determining an actual type of object; reading a database in which refractive indices of different types of objects are stored in order to determine the refractive index of the object; using a relationship between the refractive index and the spherical aberration caused by the object in order to ascertain an adjustment value of the correction optical unit such that there is a reduction in the spherical aberration in the focal plane; adjusting the correction optical unit to the adjustment value; and imaging the object.

What is claimed is: 
     
         1 . A method for imaging an object, the method comprising:
 providing an imaging beam path to image the object, the imaging beam path comprising a magnifying objective introducing a first spherical aberration influenced by optical properties of the object and a correction optical unit introducing a second spherical aberration, wherein the correction optical unit is adjustable with respect to the second spherical aberration introduced,   providing a relationship assigning set values of the correction optical unit to types of objects wherein at each set value, the correction optical unit introduces the second spherical aberration such that the second spherical aberration at least partly compensates the first spherical aberration occurring with the type of object assigned to that set value and, thus, reduces an overall spherical aberration occurring when imaging the assigned type of object,   determining an actual type of object,   retrieving from the relationship, the set value assigned to the actual type of object,   using the retrieved set value to adjust the correction optical unit and imaging the object through the imaging beam path with reduced overall spherical aberration.   
     
     
         2 . The method as claimed in  claim 1 , wherein the relationship assigns the set value in two stages, the two stages including a first stage being a database holding refractive indices as a function of type of object and a second stage being an interrelation between refractive index and the set value. 
     
     
         3 . The method as claimed in  claim 1 , wherein in the relationship, the set value also depends on at least one further parameter that influences first spherical aberration. 
     
     
         4 . The method as claimed in  claim 1 , wherein in the relationship, the set also depends on a depth position of a focal plane in the object. 
     
     
         5 . The method as claimed in  claim 4 , wherein
 the object is carried by an object carrier, and   the depth position is measured by detecting an interface between the object carrier and the object and by measuring a distance between the interface and the focal plane in the object.   
     
     
         6 . The method as claimed in  claim 4 , wherein several depth position regions are defined, and wherein a dependency of the set value from the depth position is constant within each region. 
     
     
         7 . The method as claimed in  claim 6 , wherein sizes of the regions depend on a numerical aperture of the objective. 
     
     
         8 . The method as claimed in  claim 3 , wherein the at least one further parameter comprises at least one of:
 temperature of the object,   material of an object carrier,   object carrier thickness,   immersion medium, and   wavelength of imaging, and   a depth position of a focal plane in the object.   
     
     
         9 . The method as claimed in  claim 3 , wherein
 the object is carried by an object carrier, and   the carrier comprises a storage medium storing data comprising at least one of the type of object and the further parameter and wherein the storage medium is read.   
     
     
         10 . The method as claimed  claim 1 , wherein
 the object is illuminated by illumination radiation and   a temperature the object has during imaging is determined by detecting or measuring an energy parameter of the illumination radiation and by deriving the temperature of the object from the energy parameter.   
     
     
         11 . A microscope for imaging an object, the microscope comprising
 an imaging beam path to image the object, the imaging beam path comprising a magnifying objective introducing a first spherical aberration influenced by optical properties of the object and a correction optical unit introducing a second spherical aberration, wherein the correction optical unit is adjustable with regard to second spherical aberration introduced,   a drive for adjusting the correction optical unit with regard to second spherical aberration introduced,   a control device for controlling the drive, and   a storage device accessible by the control device, in which storage device a relationship assigning set values of the correction optical unit to types of object is stored, wherein at each set value the correction optical unit introduces the second spherical aberration such that this second spherical aberration at least partly compensates the first spherical aberration occurring with the type of object assigned to that set value and, thus, reduces an overall spherical aberration occurring when imaging the assigned type of object,   wherein the control device is adapted to determine an actual type of the object, to retrieve from the relationship the set value assigned to the actual type of object, and to control the drive on the basis of the set value to reduce the overall spherical aberration.   
     
     
         12 . The microscope as claimed in  claim 11 , wherein the relationship stored in the storage device provides assignment of the set value in two stages, the two stages including a first stage being a database holding refractive indices as a function of type of object and a second stage being an interrelation between refractive index and the set value. 
     
     
         13 . The microscope as claimed in  claim 11 , wherein in the relationship hold in the storage device the set value is also dependent on at least one further parameter that influences the first spherical aberration. 
     
     
         14 . The microscope as claimed in  claim 11 , wherein in the relationship stored in the storage device the set value is also dependent on a depth position of the focal plane in the object. 
     
     
         15 . The microscope as claimed in  claim 14 , wherein
 the objective is adjustable regarding the depth position of the focal plane,   the control device is adapted for controlling the objective regarding the depth position,   the microscope further comprises an object carrier for the object, and   the control device is adapted to measure the depth position by detecting an interface between the object carrier and the object and by measuring a distance between the interface and the focal plane in the object.   
     
     
         16 . The microscope as claimed in  claim 14 , wherein several depth position regions are defined, and wherein a dependency of the set value from the depth position is constant within each region. 
     
     
         17 . The microscope as claimed in  claim 16 , wherein the microscope further comprises an objective change device for selecting a utilized one of several different objectives and wherein sizes of the regions depend on a numerical aperture of the objective utilized. 
     
     
         18 . The microscope as claimed in  claim 13 , wherein the at least one further parameter comprises at least one of:
 temperature of the object,   material of an object carrier,   object carrier thickness,   immersion medium,   wavelength of imaging, and   a depth position of the focal plane.   
     
     
         19 . The microscope as claimed in  claim 13 , further comprising
 an object carrier, wherein the carrier comprises a storage medium storing data indicating at least one of the type of object and the further parameter, and   a storage medium reading device for inputting the read data to the control device.   
     
     
         20 . The microscope as claimed  claim 11 , further comprising:
 an illumination beam path to illuminate the object by illumination radiation and   a detecting or measuring device for detecting or measuring an energy parameter of the illumination radiation,   wherein the control device is adapted to determine a temperature the object has during imaging by deriving the temperature of the object from the energy parameter.   
     
     
         21 . The microscope as claimed  claim 11 , wherein the control device is adapted to perform the microscopy method according to  claim 1 .