Method and apparatus for laser safety

• US 5,999,549 A
• Filed: 02/09/1998
• Issued: 12/07/1999
• Est. Priority Date: 02/09/1998
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Freitag, Ladd W., Thatcher, Raymond Jonathan, Siljenberg, David Warren
• Primary Examiner(s): Healy, Brian
• Application Number:
  US09/020,553
• Time in Patent Office: 666 Days
• Field of Search: 372/9, 372/24, 372/25, 372/26, 372/29, 372/30, 372/33, 372/38
• US Class Current: 372/38.09
• CPC Class Codes: H01S 3/0014 Monitoring arrangements not otherwise provided for photometry G01J1/00, e.g. G01J1/4257; radiation pyrometry G01J5/00; measuring coherence of light G01J9/00; measuring wavelength of light G01J9/00, e.g. G01J9/0246; measuring optical pulses G01J11/00; calorimetrically measuring power of laser beams G01K17/003
• CPC Class Codes: H01S 5/06825 Protecting the laser, e.g. during switch-on/off, detection of malfunctioning or degradation

Abstract

A method and apparatus are provided for laser safety. A fault detector detects laser fault conditions and generates a laser fault control signal. A laser fault counter is coupled to the fault detector for counting laser fault conditions and for generating a disable laser control signal responsive to a predetermined fault count. A reset timer is coupled to the laser fault counter for identifying a predetermined reset time period responsive to the laser fault control signal and applying a reset signal to the laser fault counter. Features of laser safety method and apparatus of the invention are that the laser fault counter is reset if a second laser fault condition is not detected within the predetermined reset time period after the laser is turned on. The disable laser control signal is not generated when a safe laser optical power condition occurs between two laser fault conditions.

Claims

1. Apparatus for laser safety comprising:

fault detector means for detecting a laser fault condition and generating a laser fault control signal;

counter means coupled to said fault detector means for counting said laser fault conditions and for generating a disable laser control signal, said counter means comprising a pair of flip-flops arranged for counting two laser fault conditions and for generating said disable laser control signal, and

timer means coupled to said counter means for identifying a predetermined reset time period responsive to said laser fault control signal and for applying a reset signal to said counter means.

2. Apparatus for laser safety as recited in claim 1 wherein said timer means coupled to said counter means for identifying a predetermined reset time period responsive to said laser fault control signal and for applying said reset signal to said counter means comprises a single shot timer and a reset capacitor coupled to said single shot timer for defining said predetermined reset time period.

3. Apparatus for laser safety as recited in claim 1 wherein said timer means coupled to said counter means for identifying said predetermined reset time period responsive to said laser fault control signal and applying said reset signal to said counter means is responsive to a reset laser control signal for identifying said predetermined reset time period.

4. Apparatus for laser safety as recited in claim 1 further comprising power on reset (POR) initialization means for applying a reset signal to said counter means.

5. A method for providing laser safety comprising the steps of:

detecting a laser fault condition and generating a laser fault control signal;

utilizing a laser fault counter counting at least two successive laser fault conditions and responsive to a predetermined fault count, generating a disable laser control signal, and

utilizing a reset timer coupled to said laser fault counter identifying a predetermined reset time period responsive to said laser fault control signal and applying a reset signal to said laser fault counter, whereby said disable laser control signal is not generated when a safe laser optical power condition occurs between laser fault conditions.

6. A method for providing laser safety as recited in claim 5 further includes the step of utilizing said reset timer coupled to said laser fault counter, identifying said predetermined reset time period responsive to a laser reset control signal and applying a reset signal to said laser fault counter.

7. A method for providing laser safety as recited in claim 5 further includes the step of applying a reset signal to said laser fault counter from a power on reset (POR) initialization circuit.