Guide Number Revision Effective Date Page C 04/13/2015 1 of 6 Subject Date of Issue Parent Command Media Optical Coating Laser Damage Resistance and Laser Damage Threshold Testing Plan 09/08/2014 P708 Definitions Document Details & Contact Information Supersedes, Revision B, Effective 09/08/2014 Definitions Failure Threshold Damage Threshold Testing Laser Damage Resistance Certification Testing Lot Effective Area Effective Beam Radius Effective Pulse Duration Safety Factor Any damage site which induces a change in the surface characteristics. Threshold refers to the energy density or power density of laser radiation impinging upon the optical surface above which the probability of damage is significant. Destructive testing performed by irradiating a number of sites of a coated optical surface at different energy or power densities. A fraction of sites (normally out of ten sites) which are damaged at the different energy or power densities is recorded. A plot is developed of damage frequency versus energy or power. The linear extrapolation of the damage frequency data to zero damage frequency yields the threshold energy or power. Non-destructive testing performed by irradiating a number of sites of a coated optical surface to the specification s designated limit, to ensure product compliance and to verify the supplier s coating process remains within control limits. All parts included in any single vapor deposited coating run. Note: A Lot may have more than one Part Number within it, hence Witness Samples may represent more than one Part Number. The ratio of total pulse energy to maximum energy density or the ration of power to maximum power density, respectively. The square root of the effective area divided by pi. The ratio of total pulse energy to maximum pulse power. The Safety Factor of a coated optical component is the ratio of the specified laser damage threshold to the laser intensity the optic is exposed to during normal operation in a production laser system.
Page: 2 of 6 Critical Performance Optics Overview Approach 1.0 A Critical Performance Optic is a coated optical component have a Damage Threshold Level of 1.0 GW/cm 2 or greater, per the part specification. Optics meeting this definition are listed on form P708- APK-F03. Optics having a lower damage threshold may also be included based on criticality of use as determined by LS. This test plan is intended to define test methods and parameters for the Laser Damage Resistance Certification Testing or Laser Damage Threshold Testing of LS laser optics when required of the Supplier. The testing requirement for Laser Damage Threshold Testing is modeled after ISO 11254, Laser And Laser-Related Equipment Determination Of Laser-Induced Damage Threshold Of Optical Surfaces. Laser Damage Resistance Certification or Laser Damage Threshold Testing shall be completed as part of the First Article Inspection Report, when Quality Assurance Provision (QAP) 21 or 22 are designated on the Purchase Order (PO). The witness sample or test piece and the parts submitted as FA must be from the same coating lot. 1.1 The supplier shall maintain a Process Control Plan, to ensure the optical coating process achieves and continues to meet or exceed the requirements of 1.2, below. LS may require additional testing if failures occur during the testing of optics at a higher level assembly. 1.2 Unless otherwise specified by LS, the following is the minimum frequency that Laser Damage Threshold and/or Resistance Testing shall be performed for each coating type, when QAP 36 or 36B (P703- APK-F02), is a contractual requirement of the PO, Statement of Work, and/or when required by the engineering drawing. The supplier is responsible for ensure that all testing requirements (i.e., this document) are passed down to lower-tier suppliers who may provide this service. 1.2.1 Single and Dual Wavelength AR Coatings: Shall have Laser Damage Resistance Testing at a minimum of once per year after First Article approval of the optic part/assembly. 1.2.2 Deleted 1.2.3 Complex Coatings (Dichroic, HRs, etc. ): Shall have Laser Damage Resistance Testing at a minimum of every calendar quarter or every four (4) lots, whichever occurs first, after First Article approval of the
Page: 3 of 6 optic part. 1.2.4 Critical Performance Optics: Shall have Laser Damage Testing performed on each coating run after First Article approval of the optic part. See P708-APK-F03 Listing considered Critical Performance Optics. 1.3 Test Sample: Shall be made from the same substrate material and have the same surface finish as the actual part and be coated in the same coating run as the production parts they represent. The Part Number, Coating Run Number, and Date shall be identified and documented for each test sample. If more than one part number was coated in the same coating run, Supplier shall provide a completed, fully traceable certification documentation package with each Part Number (including the sample), and reference the common sample number on each additional certification document (Sample XXX is with Part Number 12345). 1.4 Before Testing: A microscopic evaluation of surface quality and cleanliness shall be made using a Normaski/Darkfield microscope at 150x magnification or greater. If contaminants are observed, the test sample shall be wiped clean with spectroscopic grade acetone or methyl alcohol. The samples shall be handled with Nitrile gloves or finger costs (clean room grade), stored using desiccators, or stored at 50% +/- 10% relative humidity for 24 hours, prior to testing. 1.5 Testing Environment: Shall be in a clean area with clean filtered air at 50% +/- 10% relative humidity and shall be documented on the test report. 1.6 The diagnostic package shall be equipped with a calibrated detector to measure the pulse energy or beam power delivered to the target plan. The calibration shall be current, traceable to a national standard, and maintained in file with the testing authority. 1.7 The supplier is responsible to assure that Laser Damage Threshold Testing or Laser Damage Resistance Testing is performed in accordance with this guide and LS Form P708-APK-F02. Any deviations from the testing parameters provided must be submitted in writing for LS approval before testing occurs. 1.8 Initial Damage Detection: Shall be evaluated by using an in-line HeNe to check for scatter. When the initial inspection indicates damage, a microscope having a Nomarski-type differential interference contrast equipment set for maximum contrast will be used for further evaluation. A magnification from 100x to 150x in reflected light shall be used.
Page: 4 of 6 1.9 When performing a Laser Damage Threshold Test, a minimum of 10 sites shall be tested for each energy density or power density increment. The range of pulse energies or beam powers utilized must be sufficiently broad to include points of zero damage frequency, as well as points of 100% damage frequency. The data of damage frequency verses energy or power, shall be plotted and the threshold value determined by the testing facility and converted to an appropriate unit(s). The supplier shall submit the data package with the LS Form P708-APK-F02 to LS for final evaluation/approval of the threshold value. The supplier shall maintain this data in a part number reference folder or electronic file with the rest of the quality documentation package. 1.10 Each sample tested shall be traceable (assigned a unique run/lot number), which shall accompany it through the test process from initial receipt to submission of the final report. Information pertaining to test station configurations, source calibration, cleaning, microscope inspections, exposure parameters, raw data, and test results produced, shall be traceable to this run/lot number. This data, except for the following information required, shall be retained by the testing laboratory and available for request by LS or their customers. 1.10.1 LS Form, P708-APK-F02, Test Report (or an equivalent supplier format) shall be used to document all test results. The report must contain the information below at a minimum: a. The name, address, phone number of the supplier performing Testing. b. LS Part Number (provided on manufacturer s PO), Part name. Test Certificate must trace directly back to LS CPO Number. c. Sample/Part material type, coating type. d. Manufacturer of the Sample and their PO number (Must trace back to original LS PO Number). e. Also, part traceability to coating lot identification. f. Testing Type required and the testing date. g. Reference to the International Standards or Supplier standards used as a basis for the test (ISO 11254 or approved equivalent). h. Testing parameters or certification to the requirements of 1.7 (LS Form, P708-APK-F02), above. i. Actual test results and/or pass/fail noted in accordance with the engineering requirements. j. The linear plot of damage frequency verses energy or power for damage threshold test. k. Manufacturer s specification for storage, cleaning, or pre-
Page: 5 of 6 conditioning if is different than the requirements of this procedure. 1.11 1.12 l. An authorized signature of the person responsible for performing and/or verifying the test and the results. The supplier shall notify LS, within 24 hours, if a lot fails laser damage resistance or damage threshold with a get well plan. --------------------------------------------------------------------------------------------- Similar parts can utilize the same annual resistance certification under the following conditions: (1) Drawing specifications for coatings are identical in regard to material, coating type, wavelength, polarization, incidence angle, pulse width and resistance value (equal to or less than certification value). (2) The coating facility, equipment and process must be the same. Only applicable for parts which fall under the annual re-certification matrix. Not applicable for FAI, CPO or parts with complex coatings (High reflector, Partial reflector, Beam splitter, Multi-spectral AR coating specified at three or more wavelengths). Additional certification testing as needed when prescribed by LS to ensure the Supplier s process remains in control, shall be performed in accordance with LS s Test Plan P708-APK-GO047 and results submitted to LS. 1.13 When the Testing demonstrates the requirements to be conforming, the coating process is qualified per this procedure. Any changes made to the optical coating process after qualification may require additional Laser Damage Threshold qualification testing. The supplier shall notify LS before changes to the process are implemented. Responsibilities LS Supplier References Definition of Laser Damage Threshold and Laser Damage Resistance Testing parameters Performance of testing in accordance with the requirements defined within this Guide. Forms DSD_LaserSystems-QA-Provision, Quality Assurance Provisions
Page: 6 of 6 Other P708-APK-F02, Laser Damage Testing Request/Report Form P708- F03-APK, Critical Performance Optics Listing ISO 11254 Optical and Optical Instruments Laser and laser related equipment Test methods for Laser Induced Damage Threshold of Optical Surfaces