Standard Operating Procedure
Control Laser CL-5 YAG Laser

 

YAG Laser

Introduction

This Standard Operating procedure applies to the modified Control Laser CL-5 YAG laser housed in Niagara College's High Power Laser Lab (V15). This highly modified class-IV laser is flashlamp-pumped and intended for research use.

Statistics

Manufacturer: Control Laser, Inc.
Type: YAG (Yttrium Aluminum Garnet)
Class: IV
Maximum Rated Energy: 1 Joule per Pulse
Wavelength: 1064nm
Cooling: Ambient Air, Convection cooled
Power Source: Two Sorenson DCR300-1.5B Power Supplies

Hazard Analysis

Report ID: 09072313811
Performed On: 2009/07/23
by Laser Safety Officer: D. Turnbull
Input Data: 1064nm, Single Pulse, 0.4J, 5E-05s pulse duration
Beam Diameter: 4mm
Small Source Ocular MPE: 5.4E-06J/cm2

Worst Case Optical Density: 5.29 OD
Intrabeam Eye NOHD: 4.4E+02m
Small Source Eye Diffused Reflection NHZ: 1.54m

Controls

YAG Laser
Primary controls of the CL-5 YAG Laser.

The control rack consists of three distinct units as shown. The bottom unit, a Sorenson power supply, is used to power the trigger circuit for the flashlamp. It is normally fixed at 250 VDC output (A separate trigger supply is used to ensure a powerful trigger voltage to fire the lamp regardless of the voltage on the main capacitor). The middle unit, another Sorenson power supply, provides a variable charging voltage for the main 1200mF main capacitor which stores energy for the lamp. At 300VDC, for example, the capacitor stores 54 Joules of energy.

The top unit is the firing controller. It provides the required class-IV safety startup delay as well as an interlock loop. To start the controller, the key is turned to the ON position. If the I/LOCK indicator is lit an interlock is open and must be closed before the laser can start. Assuming all interlocks are closed, the DELAY indicator will light during the initial, required, CDRH delay of 30 seconds. The FIRE indicator will then illuminate indicating the system is ready to fire. Press this button to fire the laser. The FIRE indicator will then extinguish and the DELAY indicator will again light. This 30 second delay prevents rapid-firing of the lamp which would lead to rapid thermal failure. After the delay, the FIRE indicator again illuminate and another firing will be allowed.

Each power supply can operate in constant-voltage or constant-current mode. For this capacitor-charging application little current is required so the COARSE CURRENT control is set only about one-tenth of a turn clockwise. Once charged, the VOLTAGE indicator will light on the supply indicating constant-voltage mode in which case the power supply is maintaining the capacitor voltage at a regulated value.


Operating Procedure

Revised 2005/10/12 by M. Csele

STARTING the laser

  1. Don safety glasses suitable for a YAG laser.
  2. Turn the targeting HeNe laser ON and align the output beam from the laser onto a suitable target such as an energy meter
  3. Turn the key on the controller ON.
  4. Verify that the I/LOCK indicator is not illuminated. If it is, locate the open interlock and correct the situation.
  5. Turn the bottom Sorenson power supply (the trigger supply) ON and adjust for an output of 250 VDC. The TRIG HV indicator will illuminate on the front of the laser.
  6. Turn the top Sorenson power supply (the main supply) ON and adjust for the desired charge. The MAIN HV indicator will illuminate on the front of the laser.
  7. When the DELAY indicator has extinguished and the FIRE indicator has lit, press the FIRE button to discharge the flashlamp and fire the laser.

SHUTDOWN

  1. Turn off the keyswitch on the control unit.
  2. Turn off the power switches for each Sorenson power supply.
  3. Turn off the targeting HeNe laser.

Copyright (C) Niagara College, Canada, 2005
This page is part of the SOP Repository Page