System for optimizing alignment of laser beam with selected points on samples in maldi mass spectrometer

• US 7,359,574 B2
• Filed: 07/27/2004
• Issued: 04/15/2008
• Est. Priority Date: 04/17/2001
• Status: Expired due to Term

• Current Assignee: Thermo Finnigan LLC (Thermo Fisher Scientific Incorporated)
• Original Assignee: Thermo Finnigan LLC (Thermo Fisher Scientific Incorporated)
• Inventors: Michael, Samuel G., Makusky, Anthony J., Lennon, John J.
• Primary Examiner(s): PATEL, KANJIBHAI B
• Application Number:
  US10/901,254
• Publication Number:
  US 20040262514A1
• Time in Patent Office: 1,358 Days
• Field of Search: 382/274, 382/275, 382/308, 382/312, 382/128, 382/151, 382/291, 250/281, 250/287, 250/288, 250/311, 436/47, 436/173, 436/174, 356/300, 356/303, 356/326, 356/451
• US Class Current: 382/274
• CPC Class Codes: G06T 7/70 Determining position or orientation of objects or cameras camera calibration G06T7/80
• CPC Class Codes: H01J 49/0418 for laser desorption, e.g. matrix-assisted laser desorption/ionisation [MALDI] plates or surface enhanced laser desorption/ionisation [SELDI] plates
• CPC Class Codes: Y10T 436/24 Nuclear magnetic resonance, electron spin resonance or other spin effects or mass spectrometry

Abstract

A mass spectrometry apparatus uses image processing of output signals of a camera in a mass spectrometer to provide feedback for directing the laser. The present invention provides for the determination of where samples have actually been deposited on a plate, and for the selection of different points for each sample, based on its structure, at which to aim a laser, during the cycle period of the mass spectrometer. Such feedback information increases the likelihood that the laser impinges samples and provides useful data.

Claims

1. A mass spectrometry apparatus comprising:

a laser for emitting a laser beam;

a controller for aiming said laser beam at a sample on a sample plate for mass spectrometry analysis;

a camera having a field of view comprising the sample on the sample plate, said laser targeting a portion of the sample for laser impingement;

a processing device configured to;

receive an image of the sample from said camera;

analyze the image of the sample to generate control signals for use by said controller to direct the manner in which said laser beam impinges said sample plate and the sample;

said processing device being operable to;

identify locations on the sample based on an evaluation of characteristics of the sample; and

provide position data in said control signals that correspond to said locations; and

wherein said position data is for said controller to aim said laser at said locations for laser impingement.

2. A mass spectrometry apparatus as set forth in claim 1, wherein said processing device is operable to identify locations corresponding to a crystalline structure within the sample on said sample plate, said crystalline structure selected from the group consisting of a thin crystal, a hair-like crystal, and a crystal having at least one finger-like appendage.

3. A mass spectrometry apparatus as set forth in claim 2, wherein said processing device automatically evaluates the image of the sample on said sample plate and automatically provides signals to said controller for aiming and firing said laser.

4. A mass spectrometry apparatus as set forth in claim 1, wherein said image comprises pixels, said pixels being characterized by respective values corresponding to different levels of brightness, said processing device operable to:

select a minimum brightness level such that said pixels having a value less than said minimum brightness level are determined to not belong to one of said samples; and

analyze groups of said pixels having values above said minimum brightness level to locate clusters of said pixels that correspond to one of said samples.

5. A mass spectrometry apparatus as set forth in claim 4, wherein said processing device is further operable to generate said position data by determining an approximate centroid for at least one of said clusters.

6. A mass spectrometry apparatus as claimed in claim 5, further comprising a monitor for displaying the image of the sample and an output device for providing said position data to said controller.

7. A mass spectrometry apparatus as claimed in claim 1, wherein said samples are characterized by crystal structures, said processing device being operable to identify points on the samples at which to direct said laser, said points varying among the samples depending on their respective structures, said processing device providing data relating to said points in said control signals.

8. A mass spectrometry apparatus as claimed in claim 7, further comprising an input device for providing said position data relating to said points to said controller.

9. A mass spectrometry apparatus as claimed in claim 8, wherein said controller is operable to use said control signals to move said sample plate relative to said laser.

10. A mass spectrometry apparatus as claimed in claim 1, wherein said mass spectrometry apparatus is operated in conjunction with a frame grabber and has a monitor for displaying an output signal generated by said camera, said mass spectrometry device providing an output from said monitor to said frame grabber to facilitate generating said image.

11. A mass spectrometry apparatus as claimed in claim 1, wherein said position data is defined as coordinates, said processing device being operable to store said coordinates in a file having a file format that is compatible with said mass spectrometry apparatus, said controller being operable to move at least one of said sample plate and said laser to impinge said sample plate at locations corresponding to said coordinates provided in said file.

12. A mass spectrometry apparatus as claimed in claim 11, further comprising a monitor operable to receive an output signal from said camera, and a frame grabber connected to said monitor to generate said image and provide said image to said processing device.