Method for correcting a control of an optical scanner and the optical scanner

Abstract

In a method for correcting a control of an optical scanner ( 14 ) which has a beam deflecting element ( 31 ) for deflecting a beam of optical radiation and a drive unit ( 30, 30 ′) for moving the beam deflecting element ( 31 ), said drive unit deflecting a beam of optical radiation directed at the beam deflecting element ( 31 ) according to a predetermined setpoint movement using at least one parameter and/or a transfer function, preferably optical, said parameter or transfer function being used to control or regulate the system. In a determination step at least one instantaneous value of a drive unit transfer function that reproduces the response of the drive unit ( 30, 30 ′) to a predetermined setpoint movement or a change in a setpoint movement is ascertained for at least one frequency, and in a correction step at least one parameter and/or the transfer function is corrected as a function of the instantaneous value of the drive unit transfer function.

1 . Method for correcting a control of an optical scanner ( 14 ), having a beam deflecting element ( 31 ) for deflection of a beam of optical radiation and a drive unit ( 30 ,  30 ′,  35 ) for moving the beam deflecting element ( 31 ), said drive unit moving the beam deflecting element ( 31 ) according to trigger signals generated by using at least one parameter for control or regulation and/or using a transfer function, preferably optical, from a predetermined-setpoint movement, 
 wherein in a determination step at least one instantaneous value of a drive unit transfer function is determined for at least one predetermined frequency, said drive unit transfer function reflecting the response of the drive unit ( 30 ,  30 ′,  35 ) to trigger signals determined from a predetermined setpoint movement or a change in a setpoint movement and    in a correction step at least one parameter and/or the transfer function is corrected as a function of the instantaneous value of the drive unit transfer function.    
     
     
         2 . Method according to  claim 1 , wherein the instantaneous value of the drive unit transfer function is ascertained in the determination step in that an actual position of a drive ( 30 ) or a mechanical coupling element ( 30 ′) of the drive unit ( 30 ,  30 ′,  35 ) is ascertained as a function of the setpoint movement and/or the change in the setpoint movement or the trigger signals ascertained therefrom.  
     
     
         3 . Method according to  claim 1 , wherein the determination step and the correction step are repeated at predetermined intervals of time.  
     
     
         4 . Method according to  claim 1 , wherein the determination step and the correction step are performed with each activation of the scanner ( 14 ) or at a predetermined interval of time after each activation.  
     
     
         5 . Method according to  claim 1 , wherein the determination step and the correction step are repeated and the frequency used in these steps is change with each repetition.  
     
     
         6 . Method according to  claim 1 , wherein the determination step and the correction step are performed for several predetermined frequencies.  
     
     
         7 . Method according to  claim 1 , wherein a deviation in the instantaneous value of the drive unit transfer function from a corresponding value of the drive unit transfer function saved previously, said value having been ascertained within a predetermined interval of time before or after ascertaining the value of the optical transfer function currently being used at the frequency is determined in the correction step and the deviation is used for the correction.  
     
     
         8 . Method according to  claim 1 , wherein the correction for at least one frequency is performed in the correction step and a model for the frequency dependence of the parameter to be corrected and/or the transfer function to be corrected is determined for correction for other frequencies.  
     
     
         9 . Optical scanner having a beam deflecting element ( 31 ) for deflection of a beam of optical radiation and a drive unit ( 30 ,  30 ′,  35 ) for moving the beam deflecting element ( 31 ) which moves the beam deflecting element ( 31 ) according to trigger signals, and a scan control unit ( 35 ) that is connected to the drive unit ( 30 ,  30 ′) for transmitting trigger signals for control of the drive unit ( 30 ,  30 ′) by generating trigger signals which are designed so that, by using at least one parameter that is used for control or regulation and/or one transfer function, preferably optical, of a predetermined setpoint movement, corresponding trigger signals can be generated, and for correction of the control of the scanner ( 14 ) in a determination step at least one instantaneous value of a drive unit transfer function that reproduces the response of the drive unit ( 30 ,  30 ′) to trigger signals ascertained from a predetermined setpoint movement or a change in a setpoint movement, can be ascertained for at least one predetermined frequency, and in a correction step the at least one parameter and/or the transfer function can be corrected as a function of the instantaneous value of the drive unit transfer function.  
     
     
         10 . Optical scanner according to  claim 9 , wherein the drive unit ( 30 ,  30 ′) has a stepping motor for moving the beam deflecting element ( 31 ) and/or a position sensor ( 32 ) for acquiring the position of a motor or a mechanical coupling element of the drive unit ( 30 ,  30 ′) and the scan control unit ( 35 ) is further designed so that in the determination step the position of the stepping motor or a position signal of the position sensor ( 32 ) is used to ascertain the instantaneous value of the drive unit transfer function.  
     
     
         11 . Optical scanner according to  claim 9 , having a timer device which triggers the scan control unit ( 35 ) repeatedly at predetermined intervals of time so that it executes the determination step and the correction step.  
     
     
         12 . Optical scanner according to  claim 9 , wherein the scan control unit ( 35 ) is further designed so that the determination step and the correction step are performed with each activation of the scanner ( 14 ) or at a predetermined interval of time after each activation.  
     
     
         13 . Optical scanner according to  claim 9 , wherein the scan control unit ( 35 ) is further designed so that it repeatedly executes the determination step and the correction step and changes the frequency used in these steps with each repetition.  
     
     
         14 . Optical scanner according to  claim 9 , wherein the scan control unit ( 35 ) is further designed so that the determination step and the correction step are performed for several predetermined frequencies.  
     
     
         15 . Optical scanner according to  claim 9 , wherein the scan control unit ( 35 ) is further designed so that a deviation in the instantaneous value of the drive unit transfer function from a corresponding value of the drive unit transfer function saved previously is determined in the correction step, said previously saved drive unit transfer function having been ascertained within a predetermined interval of time before or after the determination of the value of the optical transfer function currently being used at the frequency, and this deviation is used for the correction.  
     
     
         16 . Optical scanner according to  claim 9 , wherein the scan control unit ( 35 ) is further designed so that in the correction step the correction for at least one frequency is performed and a model for the frequency dependence of the parameters to be corrected and/or the transfer function to be corrected is determined for other frequencies for the correction.  
     
     
         17 . Laser scanning microscope having an optical scanner according to  claim 9.