Method and system for compensating intensity fluctuations of an illumination system in a confocal microscope

• US 6,444,971 B1
• Filed: 12/31/1999
• Issued: 09/03/2002
• Est. Priority Date: 12/31/1999
• Status: Expired due to Term

• Current Assignee: Leica Microsystems Gmbh (Danaher Corporation)
• Original Assignee: Leica Microsystems Gmbh (Danaher Corporation)
• Inventors: Engelhardt, Johann, Widzgowski, Bernd
• Primary Examiner(s): Pyo, Kevin
• Assistant Examiner(s): SOHN, SEUNG C
• Application Number:
  US09/476,649
• Time in Patent Office: 977 Days
• Field of Search: 250/201.3, 250/205, 250/216, 250/214.L, 250/214.DC, 250/234, 359/368, 359/385, 356/445, 356/448
• US Class Current: 250/214.0DC
• CPC Class Codes: G02B 21/008 Details of detection or image processing, including general computer control
• CPC Class Codes: G02B 21/0084 time-scale detection, e.g. strobed, ultra-fast, heterodyne detection
• CPC Class Codes: G02B 21/06 Means for illuminating specimens

Abstract

A method and system for compensating intensity fluctuations of an illumination system in a confocal microscope comprise a first and a second analog-to-digital converters for digitizing a first electrical signal corresponding to the light reflected from a specimen, and for digitizing a second electrical signal corresponding to an illumination reference, respectively. The digitized signals are sent to a first and a second look up tables carrying out a log conversion of the first and second electrical signals, respectively. Also provided is a calculator for correcting the first electrical signal for intensity fluctuations of the second electrical signal. The corrected electrical signal is sent to a third look up table for converting the corrected electric signal. The conversion is done by exponentiation of the corrected electrical signal.

Claims

1. A method for compensating intensity fluctuations of an illumination system in a confocal microscope having a scanning device and capable of generating a three-dimensional image of a specimen, the method comprising:

providing a first electrical signal corresponding to light reflected from the specimen, providing a second electrical signal corresponding to an illumination reference, and providing a third electrical signal corresponding to a position signal, the position signal being generated by the scanning device;

converting the first electrical signal into a first digitized signal, converting the second electrical signal into a second digitized signal, and converting the third electrical signal into a third digitized signal;

compensating intensity fluctuations by processing the first and the second digitized signals in a fluctuation compensation unit to obtain a quotient of the second digitized signal over the first digitized signal; and

sending the quotient and the third digitized signal to a computer capable of utilizing the quotient and the third digitized signal for displaying the three-dimensional image of the specimen.

2. The method of claim 1, wherein processing the first and the second digitized signals in a fluctuation compensation unit comprises feeding the first digitized signal to a first look-up table to carry out a conversion of the first digitized signal and feeding the second digitized signal to a second look-up table to carry out a conversion of the second digitized signal.

3. The method of claim 2, further comprising feeding results of the conversions of the first and the second digitized signals to a third look-up table to obtain a quotient of the second digitized signal over the first digitized signal.

4. The method of claim 2, wherein the first and the second look-up tables serve to perform a log conversion of the first and the second digitized signals, respectively.

5. The method of claim 3, wherein the third look-up table serves to perform exponentiation of the difference between a log of the second digitized signal and the first digitized signal.

6. The method of claim 1, further comprising amplifying the first, second and third electrical signals prior to converting them into the first, second and third digitized signals.

7. The method of claim 1, wherein the fluctuation compensation unit comprises field programmable gate arrays.

8. A system for compensating intensity fluctuations in a confocal microscope, the system comprising:

a first detector for detecting light reflected from a specimen and converting it into a first electrical signal;

a second detector for detecting light serving as an illumination reference and converting it into a second electrical signal;

a scanning device for scanning a specimen and generating a third electrical signal corresponding to a position signal of the specimen;

a control and processing unit for receiving and digitizing the first, the second and the third electrical signals and for outputting a quotient of the second digitized signal over the first digitized signal and the third digitized signal; and

a fluctuation compensation unit for processing the first and the second digitized signals to obtain the quotient of the second digitized signal over the first digitized signal.

9. The system of claim 8, wherein the fluctuation compensation unit comprises a first look-up table for performing a log conversion of the first digitized signal and a second look-up table for performing a log conversion of the second digitized signal.

10. The system of claim 8, wherein the fluctuation compensation unit comprises a third look-up table for performing exponentiation of the difference between a log of the second digitized signal and the first digitized signal.

11. The system of claim 8, further comprising a first amplifier and a second amplifier for digitizing the first and the second electrical signals before digitizing the first and the second electrical signals in the control and processing unit.

12. The system of claim 8, further comprising a computer capable of utilizing the quotient and the third digitized signal to display a three-dimensional image of the specimen.

13. The system of claim 8, further comprising an illumination system.

14. The system of claim 8, wherein the fluctuation compensation unit comprises field programmable gate arrays.