Surelite Laser Training - aita-martin.comaita-martin.com/training.pdf · Beam Profile Make sure that the beam profile is round and uniform If it isn’t adjust the Rear Mirror one

Surelite Laser TrainingSurelite Laser Training

VashayVashay VitramonVitramonJune 3, 2004June 3, 2004

AgendaAgenda

IntroductionIntroductionLaser TheoryLaser TheorySafetySafetySurelite ElectronicsSurelite ElectronicsSurelite Optics and Hands On ExperienceSurelite Optics and Hands On ExperienceQuestionsQuestions

IntroductionIntroductionWho am I and why am I here?Who am I and why am I here?

Scott Cannon, Technical Service Engineer, Continuum/Excel Corp.Scott Cannon, Technical Service Engineer, Continuum/Excel Corp.Give InGive In--depth training on your Surelite laserdepth training on your Surelite laserGive an overview of what we do and what we buildGive an overview of what we do and what we buildAnswer all your questions?Answer all your questions?

–– Who is Continuum/Excel?Who is Continuum/Excel?WorldWorld’’s Leading manufacturer of High Energy Pulsed Laser s Leading manufacturer of High Energy Pulsed Laser systemssystemsAbout 25 years oldAbout 25 years oldAcquired by Excel Corporation one year agoAcquired by Excel Corporation one year agoA bunch of really smart, really great peopleA bunch of really smart, really great people

What is a LASER?What is a LASER?In theory, the idea behind the laser is very simple. Think of a In theory, the idea behind the laser is very simple. Think of a crowd of crowd of people doing the wave at a baseball stadium. Here people stand upeople doing the wave at a baseball stadium. Here people stand up for a p for a brief moment and wave their hands up and down in unison. The effbrief moment and wave their hands up and down in unison. The effect is the ect is the appearance of a wave of wiggling people traveling from one end oappearance of a wave of wiggling people traveling from one end of the f the stadium to another and back. To start the wave, just one or two stadium to another and back. To start the wave, just one or two people people stand up. At this point, the wave is little more than a ripple astand up. At this point, the wave is little more than a ripple as few people s few people realize its even passing. But each time the ripple travels back realize its even passing. But each time the ripple travels back and forth and forth across the stadium, a few more people stop eating their hot dogsacross the stadium, a few more people stop eating their hot dogs and are and are stimulated by the excitement to join the crowd. The wave grows astimulated by the excitement to join the crowd. The wave grows as more s more peolepeole join in. Eventually the crowd is a sea of people swaying and jujoin in. Eventually the crowd is a sea of people swaying and jumping mping in unison. What started out as a single, lonely person waving hain unison. What started out as a single, lonely person waving has, after s, after many repetitions of the wave, turned into a powerful force follomany repetitions of the wave, turned into a powerful force following in one wing in one direction.Thisdirection.This is exactly what happens in a laser.is exactly what happens in a laser.More SimplyMore Simply……

What is a Laser ? Cont.What is a Laser ? Cont.





Light: Light: All light is a form of electromagnetic radiation that All light is a form of electromagnetic radiation that is visible to the human eye.is visible to the human eye.


Incoherent Light Rays

Light emitted by common sources is incoherent


Excited Atoms release photons when the energy is released The released photons have specific

wavelengths dependent on the atom


Amplification:Amplification:


Stimulated Emission:Stimulated Emission:To stimulate means to stir to action. Laser To stimulate means to stir to action. Laser light is created when a burst of light light is created when a burst of light (electricity) excites the atoms in the laser to (electricity) excites the atoms in the laser to emit photons. These photons then stimulate emit photons. These photons then stimulate the creation of additional identical photons to the creation of additional identical photons to produce the bright laser light.produce the bright laser light.


RRadiation:adiation: The laser light is a form of energy that radiates, or moves The laser light is a form of energy that radiates, or moves out, from the laser sourceout, from the laser source


Parts of a LASER:Parts of a LASER:

Gas LaserUsually Continuous-Wave (CW) Output

Solid State LaserCan be CW or Pulsed

Why do we care?Why do we care?

Properties of LASER light:Properties of LASER light:–– Laser Light is CoherentLaser Light is Coherent–– Laser Light is MonochromaticLaser Light is Monochromatic–– Laser Light is DirectionalLaser Light is Directional


Coherent Light has waves that are in phase in time and space


Monochromatic Light has a very Monochromatic Light has a very narrow band of wavelengthsnarrow band of wavelengths

Why do we care?Why do we care?Lasers are highly directional or collimated, meaning they can trLasers are highly directional or collimated, meaning they can travel long avel long distances without spreading out. All light beams spread, or divdistances without spreading out. All light beams spread, or diverge, as they erge, as they propagate. Lasers have very low divergence, and can travel to tpropagate. Lasers have very low divergence, and can travel to the moon he moon while spreading to only onewhile spreading to only one--half mile in diameter.half mile in diameter.


Uses of LasersUses of Lasers–– Physics Physics (High Energy plasmas, X(High Energy plasmas, X--Ray generation)Ray generation)

–– Chemistry Chemistry (Spectroscopy, etc. )(Spectroscopy, etc. )

–– Engineering Engineering ( Communications, materials, etc.)( Communications, materials, etc.)

–– EntertainmentEntertainment (Light Shows, etc.)(Light Shows, etc.)

–– MetrologyMetrology (Distance (Distance measurmentsmeasurments, precision motion, etc), precision motion, etc)

–– Calibration (Calibration (Streak Cameras, DetectorsStreak Cameras, Detectors))

Laser SafetyLaser Safety

SkinSkinEyeEyeExposure LimitsExposure LimitsProtectionProtection

SkinSkin

Skin is the largest organ of your body, and Skin is the largest organ of your body, and the bodies first defense.the bodies first defense.The skins absorptive and reflective The skins absorptive and reflective properties are dictated by the skins properties are dictated by the skins smoothness, density differences, smoothness, density differences, circulation, pigments (i.e. melanin), and circulation, pigments (i.e. melanin), and hemoglobin.hemoglobin.

Skin (cont.)Skin (cont.)

Damage caused from 1064nm light:Damage caused from 1064nm light:–– Thermal burns from increased skin Thermal burns from increased skin

temperaturetemperature–– Acoustic Shock caused by short pulse Acoustic Shock caused by short pulse

generally from Qgenerally from Q--switched lasers.switched lasers.99% of radiation penetrating the skin is 99% of radiation penetrating the skin is

absorbed in the first 4mmabsorbed in the first 4mmUVUV--B (200B (200--320nm) is the most dangerous form 320nm) is the most dangerous form

of radiation, it causes sunburn, skin aging and of radiation, it causes sunburn, skin aging and cancer, and is harmful to DNA.cancer, and is harmful to DNA.

EyeEye

The eye is one of the most sensitive The eye is one of the most sensitive detector, but it is very spectraldetector, but it is very spectralIt responds best to wavelengths near It responds best to wavelengths near 550nm.550nm.Easily damaged because blink response Easily damaged because blink response only occurs in the visible.only occurs in the visible.Different wavelengths damage different Different wavelengths damage different areaarea’’s of the eye.s of the eye.

Eye (cont)Eye (cont)

Eye (cont)Eye (cont)

Maximum Permissible Exposure (MPE)Maximum Permissible Exposure (MPE)-- WavelengthWavelength-- ExposureExposure-- CW or PulsedCW or Pulsed-- And ANSI StandardsAnd ANSI StandardsAccessible Emission Limits (AEL)Accessible Emission Limits (AEL)–– Area of limiting apertureArea of limiting aperture–– MPEMPE

For wavelengths of 400For wavelengths of 400--700nm exposure duration is taken to be 0.25s or the aversion res700nm exposure duration is taken to be 0.25s or the aversion response of the eye.ponse of the eye.

Determine MPE for 1064nmDetermine MPE for 1064nm

1.1. Since 1064nm does not provide a natural aversion response Since 1064nm does not provide a natural aversion response assume a 10s exposure duration assume a 10s exposure duration –– T = 10sT = 10s t = 5nst = 5ns

2.2. Determine total number of pulses in 10s (assuming 20Hz)Determine total number of pulses in 10s (assuming 20Hz)n = F x Tn = F x T (20Hz) x (10s) = 200 (20Hz) x (10s) = 200

3.3. From the MPE table from ANSI for a 10s exposure we use the From the MPE table from ANSI for a 10s exposure we use the equation:equation:

H = n x (9.0 CH = n x (9.0 CCC tt3/43/4) mJ/cm) mJ/cm22 H = 1.1 mJ/cmH = 1.1 mJ/cm22

AEL and Proper OD GogglesAEL and Proper OD Goggles

To calculate the proper OD Goggles the AEL To calculate the proper OD Goggles the AEL needs to be calculated needs to be calculated –– AEL = MPE x (area of limiting aperture)AEL = MPE x (area of limiting aperture)–– The limiting aperture is the iris of the eye (7mm)The limiting aperture is the iris of the eye (7mm)–– AEL = 1.1mJ/cmAEL = 1.1mJ/cm22 x (0.4 cmx (0.4 cm22))–– AEL = 0.44mJAEL = 0.44mJ

Proper OD Goggles would be:Proper OD Goggles would be:–– OD = log (power of beam/AEL)OD = log (power of beam/AEL)–– OD = log (450mJ/0.44mJ)OD = log (450mJ/0.44mJ)–– OD = OD = 3.03.0

Eye SafetyEye Safety

Electrical SafetyElectrical Safety

1. Resonator Frame

2. Rear Mirror

3. Pockels Cell

4. Plate Polarizer

5. YAG Rod, Flashlamp, and Pump Chamber

9. Cavity Shutter

10. Gaussian Output Mirror

11. Compensating Wedge

12. Cleaning Quarter Waveplates

13. Cleaning Polarizer

14. Shaping Lenses

15. Marx Bank PCB

16. 750V Power Supply

Laser Bench Components

750V PCB750V PCB

1. Supplied by 24V, and supplies 750V to the Marx Bank

Good/Bad

- Measure 24VDC at input of board, and ~750VDC out output going to Marx Bank

Marx Bank PCBMarx Bank PCB1. Takes voltage from 750V PCB and supplies

high voltage to pockel cell for Q-switching

Good/Bad

- Measure voltage drop across R22 with Q-switch off, it should be between 1V and 8V drop.

- Check trigger input to Marx board, use O-scope to measure pulse on J1-1. It should be a +12V pulse about 20µs wide every time the Q-switch fires.

- Check Marx board output by laying a normal scope probe between the two HV wires that plug into the Pockel cell. Do not physically attach the probe. Trigger from the flashlamp sync out. The output should be negative going spike when Q-switching. Test Points

Power Supply ComponentsPower Supply Components

Front Panel PCBFront Panel PCB1. Checks securities before startup

2. Powers up water pump and main power PCB

3. Sends out charge command to SL power control PCB

4. Monitors EOC from SL power control PCB

5. Clocks FIRE command to SL power control PCB

6. Monitors Simmer status of flashlamp

7. Sends “Q-switch” command pulse to Marx PCB

8. Gives Lamp Fire command to SCR PCB

Power Control (Logic) PCBPower Control (Logic) PCB

1. Monitors Line Voltage and frequency

2. Drives switching FET’s

3. Sends EOC to Front Panel PCB

4. Passes Lamp Start command to Power PCB

5. Gives a Lamp Fire command to Power PCB

Power PCBPower PCB

1. Charges main Storage cap (30µm)

2. Provides trigger spike (~700V) to trigger transformer to start lamp

3. Passes lamp fire command to SCR PCB

4. Laser plug security circuit for quick discharge of storage cap

Good/Bad

- Determine if SCR PCB is functioning properly

Current Source PCBCurrent Source PCB

1. Provides dc current to simmer flashlamp

2. Provides ~700V dc to Power PCB for the start lamp circuit

Good/Bad- Determine if SCR PCB is

functioning properly

SCR PCBSCR PCB1. Dumps HV stored in 30µF

cap through flashlamp

Good/Bad- Measure flashlamp

charging voltage to main capacitor. Use a high voltage probe and O-scope, it should be the same as displayed on front panel board.

- Measure simmer voltage with multi-meter. Before lamp simmers or flashes should be ~700V. After simmering should be ~-150 to -225V

Simmer Voltage

Flashlamp Voltage

Temp Control PCBTemp Control PCB

1. Controls speed of water side ac cooling fans to regulate laser water temperature

Good/Bad

- If cooling fans are not turning when laser is fully warmed up, unplug connector J2. Fans should turn on if they don’t, board is bad.

Trigger TransformerTrigger Transformer

1. Steps up the voltage to the flashlamp

Good/Bad

- With leads disconnected, ohm terminals 3 to 4 and 1 to 2 together, they should read very low ohms. If either reads a OPEN replace the transformer.

Cooling Group ChassisCooling Group Chassis

1. Pump

2. Heat Exchanger

3. Fans

4. DI Filters

5. Reservoir

6. Pressure Sensor

7. Temperature Sensor

8. Temp Switch

Maintenance of Surelite LaserMaintenance of Surelite Laser

System AlignmentSystem Alignment

Check the Free Running BufferCheck the Free Running BufferOperating voltage must be 100V under Operating voltage must be 100V under Free RunningFree Running

Beam ProfileBeam ProfileMake sure that the beam profile is round and uniformMake sure that the beam profile is round and uniform

If it isnIf it isn’’t adjust the Rear Mirror one axis at a timet adjust the Rear Mirror one axis at a timeNever adjust the Output CouplerNever adjust the Output Coupler

Inspect Optics and CleanInspect Optics and Clean

Use a inspection mirror and a small Use a inspection mirror and a small flashlight.flashlight.Look for any damage, if any is found Look for any damage, if any is found contact Continuumcontact ContinuumUse compressed air to clean optical Use compressed air to clean optical surfaces, or if need be use alcohol and surfaces, or if need be use alcohol and optical tissues.optical tissues.

Replacing the Replacing the FlashlampFlashlamp

FlashlampsFlashlamps are replaced every 15are replaced every 15--20 20 million shots, or if the power is noticed to million shots, or if the power is noticed to decrease over time.decrease over time.

Error CodesError Codes

The Front Panel board display gives first The Front Panel board display gives first indication of Laser Electrical problemsindication of Laser Electrical problems

If the display does not come on check all If the display does not come on check all power connections, and reset the ac power connections, and reset the ac breakerbreaker

Error Codes (cont)Error Codes (cont)

E01 E01 –– Serial Port OffSerial Port Off-- Using Arrow Buttons turn Using Arrow Buttons turn SoFSoF to to SoNSoN

E02 E02 –– Water flow interruptWater flow interrupt-- Check the reservoir levelCheck the reservoir level-- Check for Kinks in water linesCheck for Kinks in water lines-- Verify that the pump is runningVerify that the pump is running


E03 E03 –– Cooling Water Temp too HighCooling Water Temp too High-- Verify cooling fans are operatingVerify cooling fans are operating-- Clean the heat exchanger grillClean the heat exchanger grill-- Lab temperature is less the 85Lab temperature is less the 85ooFF-- Check reservoir levelCheck reservoir level


E04 E04 –– Not UsedNot UsedE05 E05 –– Laser Bench InterlockLaser Bench Interlock

-- Check oscillator housing cherry switch, Check oscillator housing cherry switch, making sure that the lid is pushing the making sure that the lid is pushing the switch down.switch down.

-- Check continuity between the two poles of Check continuity between the two poles of the thermal switch located on the top of the thermal switch located on the top of the laser head.the laser head.


E06 E06 –– External interlock has openedExternal interlock has opened-- Check Customer installed lab interlock Check Customer installed lab interlock loop.loop.-- Locate the EXTERNAL 9 pin D connector Locate the EXTERNAL 9 pin D connector on front panel and jumper pin 9 to pin 1.on front panel and jumper pin 9 to pin 1.-- Reset the system logic by turning the key Reset the system logic by turning the key switch OFF and then ON.switch OFF and then ON.


E07 E07 –– No End of ChargeNo End of Charge-- Check the head plug cable at the rear of Check the head plug cable at the rear of the laser bench.the laser bench.-- Check the Check the flashlampflashlamp, it may need , it may need replacedreplaced-- Power down system and restartPower down system and restart


E08 E08 –– Simmer not detectedSimmer not detected-- Check fuses at rear of power supplyCheck fuses at rear of power supply-- Remove laser bench housing and defeat Remove laser bench housing and defeat interlock, restart systeminterlock, restart system-- Observe end of laser head and see if Observe end of laser head and see if glow is detected, if not replace glow is detected, if not replace flashlampflashlamp..


E09 E09 –– Flow Switch StuckFlow Switch Stuck-- Locate pressure/flow switch and make Locate pressure/flow switch and make sure there are no obstructions to the sure there are no obstructions to the switchswitch-- If pump is running and no obstructions If pump is running and no obstructions replace the pressure/flow switchreplace the pressure/flow switch

Thank you for your time and attentionThank you for your time and attention

Questions?Questions?

Documents

Surelite Laser Training - aita-martin.comaita-martin.com/training.pdf · Beam Profile Make sure that the beam profile is round and uniform If it isn’t adjust the Rear Mirror one