Microscope system and microscope focus maintaining device for the same

Abstract

A microscope system has a stage on which an observation sample, including an observation object and a transparent member, is to be placed. An objective lens is placed to face the observation sample placed on the stage, and a focusing unit moves at least one of the stage and the objective lens to perform a focusing operation. An autofocus unit controls a focusing driving unit by a so-called Through-the-Lens: TTL system. After autofocus is performed for the transparent member by the autofocus unit, the focusing driving unit makes at least one of the stage and the objective lens move by a predetermined constant amount.

1 - 4 . (canceled) 
   
   
       5 . A microscope focus maintaining device for a microscope including a stage on which an observation sample is to be placed, an objective lens which is placed to face the observation sample placed on the stage, an observation optical system which includes an objective lens for observation of the observation sample, and a focusing unit which moves at least one of the stage and the objective lens to perform focusing operation, comprising:
 a focus detection optical system which includes the objective lens for in-focus detection; and   a control unit which controls a focusing driving unit on the basis of information obtained by the focus detection optical system,   wherein the focus detection optical system has the same focus drift as that of the observation optical system due to a temperature change.   
   
   
       6 . A device according to  claim 5 , wherein the focus detection optical system and the observation optical system comprise identical members in terms of optical characteristics. 
   
   
       7 . A device according to  claim 6 , wherein the focus detection optical system includes an imaging lens, and the observation optical system includes another imaging lens, the two imaging lenses having the same optical characteristics. 
   
   
       8 . A device according to  claim 6 , wherein both the focus detection optical system and the observation optical system comprise imaging optical systems for objective lens primary images. 
   
   
       9 . A device according to  claim 5 , wherein magnifications of the focus detection optical system and the observation optical system can be changed to the same magnification. 
   
   
       10 . A device according to  claim 9 , wherein the focus detection optical system and the observation optical system include variable power lenses which can be inserted/withdrawn on/from an optical path, the variable power lenses having the same magnification. 
   
   
       11 . A device according to  claim 9 , wherein the control unit changes focus detection parameters in accordance with a change in magnification of the focus detection optical system and the observation optical system. 
   
   
       12 . A microscope focus maintaining device for a microscope including a stage on which an observation sample is to be placed, an objective lens which is placed to face the observation sample placed on the stage, an observation optical system which includes an objective lens for observation of the observation sample, and a focusing unit which moves at least one of the stage and the objective lens to perform focusing operation, comprising:
 a focus detection optical system which includes the objective lens for in-focus detection; and   a control unit which controls a focusing driving unit on the basis of information obtained by the focus detection optical system,   the focus detection optical system including a laser light source which emits a laser light beam, a beam diameter changing unit which changes a diameter of a laser light beam, and a power changing unit which changes power of the laser light source.   
   
   
       13 . A device according to  claim 12 , wherein the beam diameter changing unit includes beam diameter restriction stops, and a stop control unit which selectively places one of the beam diameter restriction stops on an optical path of a laser light beam, the objective lens is selected from objective lenses prepared in advance, and each of the beam diameter restriction stops has an opening with a diameter coinciding with a pupil of a corresponding one of the objective lenses. 
   
   
       14 . A device according to  claim 12 , wherein the beam changing unit changes a laser light beam diameter so as to make the laser light beam diameter equal to a pupil diameter of the objective lens. 
   
   
       15 . A device according to  claim 12 , wherein the power changing unit changes the power of the laser light source so as to keep power of a laser light beam striking the objective lens constant regardless of a change in laser light beam diameter. 
   
   
       16 . A device according to  claim 14 , wherein the power changing unit changes the power of the laser light source so as to keep power of a laser light beam striking the objective lens constant regardless of a change in laser light beam diameter. 
   
   
       17 . A microscope focus maintaining device for a microscope including a stage on which an observation sample is to be placed, an objective lens which is placed to face the observation sample placed on the stage, an observation optical system which includes an objective lens for observation of the observation sample, and a focusing unit which moves at least one of the stage and the objective lens to perform focusing operation, the objective lens being selected from objective lenses prepared in advance, comprising:
 a focus detection optical system which includes the objective lens for in-focus detection; and   a control unit which controls a focusing driving unit on the basis of information obtained by the focus detection optical system,   the focus detection optical system including a laser light source which emits a laser light beam, the laser light beam having a diameter equal to a smallest pupil diameter of the objective lenses.   
   
   
       18 . A microscope focus maintaining device for a microscope including a stage on which an observation sample is to be placed, an objective lens which is placed to face the observation sample placed on the stage, an observation optical system which includes an objective lens for observation of the observation sample, and a focusing unit which moves at least one of the stage and the objective lens to perform focusing operation, the observation sample including an observation object and a transparent member which holds the observation object, comprising:
 a focus detection optical system which includes the objective lens for in-focus detection; and   a control unit which controls a focusing driving unit on the basis of information obtained by the focus detection optical system,   wherein the focus detection optical system applies a laser light beam to the observation sample to detect an in-focus state on the basis of light reflected by a boundary surface between the observation object and the transparent member, and the laser light beam has a diameter corresponding to an NA smaller than a refractive index of the observation object.   
   
   
       19 . A device according to  claim 18 , wherein the focus detection optical system includes a laser light source which emits a laser light beam, and a beam diameter changing unit which changes a diameter of a laser light beam, and when an NA of the objective lens is larger than the refractive index of the observation object, the beam diameter changing unit reduces a diameter of a laser light beam to a diameter smaller than the refractive index of the observation object. 
   
   
       20 . A device according to  claim 19 , wherein the beam diameter changing unit includes a beam diameter restriction stop which reduces a diameter of a laser light beam, and a stop control unit which properly places the beam diameter restriction stop on an optical path of a laser light beam. 
   
   
       21 . A microscope focus maintaining device for a microscope including a stage on which an observation sample is to be placed, an objective lens which is placed to face the observation sample placed on the stage, an observation optical system which includes an objective lens for observation of the observation sample, a focusing unit which moves at least one of the stage and the objective lens to perform focusing operation, and an epi-fluorescence illumination system for fluorescence observation, comprising:
 a focus detection optical system which includes the objective lens for in-focus detection; and   a control unit which controls a focusing driving unit on the basis of information obtained by the focus detection optical system,   wherein light used for focus detection is guided from a side closer to the objective lens than the epi-fluorescence illumination system.   
   
   
       22 . A device according to  claim 21 , wherein a wavelength of light used for focus detection differs from a wavelength of light used for fluorescence observation. 
   
   
       23 . A device according to  claim 22 , wherein the epi-fluorescence illumination system includes a fluorescence filter cassette, and the focus detection optical system includes a light guide element which guides light used for focus detection to the objective lens, the light guide element being located between the objective lens and the fluorescence filter cassette. 
   
   
       24 . A device according to  claim 23 , wherein the light guide element comprises a dichroic mirror which reflects one of light used for focus detection and light used for observation and transmits the other. 
   
   
       25 . A microscope focus maintaining device for a microscope including a stage on which an observation sample is to be placed, an objective lens which is placed to face the observation sample placed on the stage, an observation optical system which includes an objective lens for observation of the observation sample, and a focusing unit which moves at least one of the stage and the objective lens to perform focusing operation, the objective lens comprising an infinity objective lens, and the observation optical system including an imaging lens which forms an image of the infinity objective lens, comprising:
 a focus detection optical system which includes the objective lens for in-focus detection; and   a control unit which controls a focusing driving unit on the basis of information obtained by the focus detection optical system,   wherein light used for focus detection is guided from between the infinity objective lens and the imaging lens.   
   
   
       26 . A device according to  claim 25 , wherein a wavelength of light used for focus detection differs from a wavelength of light used fluorescence observation. 
   
   
       27 . A device according to  claim 26 , wherein the focus detection optical system includes a light guide element which guides light used for focus detection to the infinity objective lens, the light guide element being located between the infinity objective lens and the imaging lens. 
   
   
       28 . A device according to  claim 27 , wherein the light guide element comprises a dichroic mirror which reflects one of light used for focus detection and light used for observation and transmits the other. 
   
   
       29 . A microscope focus maintaining device for a microscope including a stage on which an observation sample is to be placed, an objective lens which is placed to face the observation sample placed on the stage, an observation optical system which includes an objective lens for observation of the observation sample, and a focusing unit which moves at least one of the stage and the objective lens to perform focusing operation, comprising:
 a focus detection optical system which includes the objective lens for in-focus detection; and   a control unit which controls a focusing driving unit on the basis of information obtained by the focus detection optical system,   the focus detection optical system including a light guide element which guides light used for focus detection to the objective lens, and the light guide element being located on an optical path only at the time of focus detection.   
   
   
       30 . A device according to  claim 29 , wherein whether to enable or disable operation of placing the light guide element on the optical path only at the time of focus detection can be selected. 
   
   
       31 . A device according to  claim 30 , wherein whether to enable or disable operation of placing the light guide element on the optical path only at the time of focus detection is automatically determined upon switching of objective lenses and microscopic examination methods on the basis of types of objective lens and microscopic examination method. 
   
   
       32 . A microscope focus maintaining device for a microscope including a stage on which an observation sample is to be placed, an objective lens which is placed to face the observation sample placed on the stage, an observation optical system which includes an objective lens for observation of the observation sample, and a focusing unit which moves at least one of the stage and the objective lens to perform focusing operation, the observation optical system including a retardation changing element for differential interference observation, comprising:
 a focus detection optical system which includes the objective lens for in-focus detection; and   a control unit which controls a focusing driving unit on the basis of information obtained by the focus detection optical system,   the focus detection optical system comprising   a laser light source which emits linearly polarized light for focus detection,   a photodetector which detects reflected light from the observation sample,   a polarizing beam splitter which splits reflected light from the observation sample from linearly polarized light from the laser light source,   a λ/4 plate which is placed between the polarizing beam splitter and the retardation changing element, and   a retardation correction device which generates a retardation which cancels out a retardation generated by the retardation changing element.   
   
   
       33 . A device according to  claim 32 , wherein the retardation correction device includes a motor which rotates the λ/4 plate around an optical axis. 
   
   
       34 . A device according to  claim 33 , wherein the retardation correction device further includes a retardation sensor which detects a retardation generated by the retardation changing element, and a control unit which automatically corrects a retardation on the basis of the retardation detected by the retardation sensor.