System and method of measuring and controlling temperature of optical fiber tip in a laser system

• US 7,144,154 B2
• Filed: 08/28/2003
• Issued: 12/05/2006
• Est. Priority Date: 06/08/2001
• Status: Expired due to Term

• Current Assignee: Ethicon Endo-Surgery, Inc. (Johnson & Johnson)
• Original Assignee: Ethicon Endo-Surgery, Inc. (Johnson & Johnson)
• Inventors: Yates, David C., Trusty, Robert M., Nield, Scott Allen, Pollack, William A.
• Primary Examiner(s): Gutierrez, Diego
• Assistant Examiner(s): Jagan, Mirellys
• Application Number:
  US10/650,535
• Publication Number:
  US 20040073133A1
• Time in Patent Office: 1,195 Days
• Field of Search: 606/10, 606/11, 606/12, 606/15, 606/16, 374/161, 372/38.01, 372/38.02, 372/38.07, 372/29.02, 372/29.021, 372/32
• US Class Current: 374/161
• CPC Class Codes: G01K 11/3213 using changes in luminescence, e.g. at the distal end of the fibres
• CPC Class Codes: H01S 3/005 Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping shaping laser beam for working metal or other materials B23K26/06; optical elements, systems or apparatus in general G02B

Abstract

A system and method of sensing temperature at an optical fiber tip, including the steps of positioning a slug of fluorescent material adjacent the optical fiber tip, providing an optical stimulus having a wavelength within a first predetermined range through at least one fiber optically linked to the optical fiber tip, wherein a desired optical fluorescent response having a wavelength within a second predetermined range from the fluorescent slug is generated, detecting a signal representative of the optical stimulus, detecting a signal representative of the optical fluorescent response, digitally processing the optical stimulus signal and the optical fluorescent response signal to determine a phase difference therebetween, and calculating a temperature for the optical fiber tip as a function of the phase difference. The phase difference between the optical stimulus signal and the optical fluorescent response signal may be determined directly or indirectly as a function of the phase difference between a reference signal and the optical stimulus signal and the phase difference between the reference signal and the optical fluorescent response signal.

Claims

1. A method of maintaining temperature of an optical fiber tip in a laser system at a desired temperature, comprising the following steps:

(a) processing an optical stimulus and an optical response to determine a temperature for said optical fiber tip as a function thereof;

(b) comparing said determined temperature for said optical fiber tip to said desired temperature;

(c) generating an error signal as a function of any difference between said determined temperature and said desired temperature; and

(d) controlling power output to a laserdiode of said laser system in accordance with said error signal;

wherein the method further comprises the step of determining whether said determined temperature is within a defined control band having an upper and lower limit; and

wherein a maximum power output is provided to said laserdiode when said determined temperature is less than said lower limit.

2. The method of claim 1, wherein a minimum power output is provided to said laserdiode when said determined temperature is greater than said upper limit for said control band.

3. The method of claim 1, wherein said power output to said laserdiode is a function of a proportional component and an integrator component when said determined temperature is within said control band.

4. The method of claim 3, said proportional component of said power output being the product of said error signal and a proportional scaling factor.

5. The method of claim 3, said integrator component of said power output being the product of an integrator scaling factor and each said error signal integrated over time.

6. The method of claim 5, wherein said integrator component is only utilized upon said determined temperature transitioning into said control band so that said power output to said laserdiode remains continuous during said transition.

7. A system for maintaining temperature of an optical fiber tip in a laser system at a desired temperature, said laser system including a laser diode for providing a laser beam to said optical fiber tip, comprising:

(a) a processor for determining a temperature by processing an optical stimulus and an optical response;

(b) a power amplifier for supplying power to said laser diode; and

(c) a controller for providing a power output signal to said power amplifier, said controller containing an algorithm for calculating said power output signal which is a function of an error signal generated by a comparison of said determined temperature and said desired temperature;

wherein said controller provides a power output signal so that a maximum power is supplied to said laser diode by said power amplifier when said determined temperature is less than a lower limit of a defined control band for said desired temperature.

8. The system of claim 7, wherein said controller provides a power output signal so that a minimum power is supplied to said laser diode by said power amplifier when said determined temperature is greater than an upper limit of a defined control band for said desired temperature.

9. The system of claim 7, wherein said algorithm is a function of a proportional component and an integrator component when said determined temperature is within a defined control band for said desired temperature.

10. The system of claim 9, said proportional component of said algorithm being a product of said error signal and a proportional scaling factor.

11. The system of claim 9, said integrator component of said algorithm being a product of an integrator scaling factor and each said error signal integrated over time.

12. The system of claim 11, wherein said integrator component is only utilized upon said determined temperature transitioning into said control band so that power supplied to said laser diode remains continuous during said transition.