Laser safety instruction For 99/ E1-A-09 & E1-A-10

by Juliane Rönsch-Schulenburg

Version March 2014

This slides • https://beschleunigerphysik.desy.de/e172292/index_ger.html

Logbook • http://ttfinfo.desy.de/CFELHHGelog/index.jsp

Overview • Laser safety in general – Accidents, hazards – General Rules

• The interlock system • Most important stuff again

Laser-eye interaction Damages: • Thermal • Photo chemical • short pulse effects (“explosions”, shockwaves … )

• • •

•

•

If accident occurred immediately call “Notdienst” to be brought to the next eye clinic. Most blinding effects vanish after hours or days Really damaged parts can not be recovered, BUT certain medication can prevent the damage from growing ( because of toxic degradation products) Medical certificate of new damage is needed for insurance benefit from “Berufsgenossenschaft” Class 4 is also dangerous for your skin !!!

Example of eye injury

Experience has demonstrated that most laser injuries go unreported for 24–48 hours by the injured person. This is a critical time for treatment of the injury. 6

Retinal Burn

A range of injuries induced with a Nd:YAG laser on a retina. The white spots in the center are thermal burns, i.e. coagulation of retinal layers. With larger energies, holes in the retina are produced which result either in bleeding into the vitreous (the gel-like substance which fills the center of the eye ball), or the bleeding is contained in the layers of the retina, which results in functional loss in the affected area. Photograph courtesy of J. Zuclich, TASC Litton, TX, USA. 7

Eye Damage: Focusing Remember: Your Eyes Are Designed to Focus

With safety rule

Cornea Damage BAD

Retina Damage WORSE

8

9

Spectral region Ultra-violet C (180 nm to 280 nm) Ultra-violet B (280 nm to 315 nm) Ultra-violet A (315 nm to 400 nm) Visible (400 nm to 780 nm) Infra-red A (780 nm to 1400 nm)

Eye

Photokeratitis

Skin Erythema (sunburn) Accelerated skin ageing

Photochemical cataract Pigment darkening Photosensitive Photochemical & reactions thermal retinal injury Cataract, retinal burn

Infra-red B (1,4 µm to 3,0 µm)

Aqueous flare, cataract, corneal burn

Infra-red C (3,0 µm to 1 mm)

Corneal burn only

Skin burn

Where are we with our lasers ?

Conjunktivitis simplex acuta (einfache akute Bindehautentzündung)

Numbers for Laser classes Maximum “permitted radiation” Factor 5 below damage !

Laser class 2

max. power in optical range in mW 1 mW

3R

5 mW

3B

500 mW

4

Above 500 mW

Class 4:

Max. Pulse energy

•

Power output >500 milliwatts (vis +cw). These CAN and WILL cause eye damage.

•

The reflected/scattered beam should be considered as dangerous as the primary beam.

•

Dangerous for skin. May cause burn and CANCER

•

These laser systems MUST have Interlocks to prevent the system from being used by non instructed people

at 800 nm and fs/ps

0.5 nJ/mm2

30 nJ

Highest number (power or pulse energy) defines the class

(simplified !!)

general rules

Rules for working with the laser beam • •

• • • • • •

The standard DESY laser safety regulations apply Always wear eye protection glasses, if there is indication of laser radiation (warning sign “laser on ” in the gate area is illuminated). Ask personnel working in the hutch which lasers are on –> choice of the right goggle All alignment has to be done WITH laser goggles using fluorescence cards / IR Viewer Never look directly into a laser beam, even not with laser safety eyewear. Even reflected and scattered light can be hazardous Class 4 laser radiation is dangerous for your skin – mindful and responsible alignment required ! Manipulation on the safety installation (e.g. safety shutter / shielding) is forbidden. Dangerous alignment shall be carried out by at least 2 persons. Persons which are not involved in the alignment shall exit the laser room Special care if cover of laser is opened. (a broader wavelength spectrum is present than when working with the amplified pulses only. The powerful pump radiation is not shielded!)

• •

Block the beam before unscrewing optics, inserting flip mirrors or visual inspection of optical components Remove all reflective parts from your hands (watches, rings, bracelets, … ) before starting to work in the laser setup.

Responsibilities • Avoid safety hazards for non-involved people • Every body working in 99/ E1-A-09 has to make sure that all other people working there as well obey the rules stated in the instruction • In case somebody acts against the instruction you have to immediately remind the person and inform the safety officer • In case someone feels sick and dizzy – stop dangerous alignment to avoid accidents • Keep the space at the emergency exit door and behind it clear • wear clean room coat • cover shoes with plastic “over-shoes” • Wear hair net if working “in” the laser

Access to the laser hutch for not-instructed people (“guests”) •

Access with KEY for instructed people –

Only people with this Safety instruction get permission to access •

–

•

Never give your KEY to another person

Guests who do not need to work on the laser – – – –

•

It is also expected that you attended: „General Safety instruction“

Guests are only allowed to enter if they are accompanied by instructed personnel (guide) – even if the laser warning lights are off ( no laser operation ) If the (jellow “laser on”) warning lights are on get the appropriate goggles for the guests. Instruct them to always wear their laser safety glasses. They shall not to look into the beam. No guests in E1-A-9 when OPCPA is in operation No guests in the LAB if the OPA is used in “special alignment mode”

Guests who need to work with the laser – – – –

have to be > 18 years Need a laser safety instruction before entering the lab Typically this will be done by the responsible person for the lab. If the responsible person for the lab is not available the instruction text (these transparencies) can be found under http://beschleunigerphysik.desy.de/e172292/index_ger.html and the instruction can be performed by Mark Prandolini. The guests have to sign in the instruction list The person giving the instruction has to inform the responsible person for the lab

Shutter key

Lab - layout

Laser indication light

Gate area with gogles and clean room coats

09

Interlock key

11

Interlock key & shutter control

09

11

Laser Lab of group of Prof. Dr. 1,25Grüner 3,6

3,6

3,6

1,5

2,4

1,5

1,5 1,5

1,5

E1-A-09

1,5

1,5

E1-A-11

1,7 1,4 3,6

1,5

2,0 1,5

E1-A-10

2,4

3,6

Emergency exit

1,13

measurement Lab of group of Prof. Dr. Grüner

E1-A-12

1,62

The interlock system

The interlock system - general • General idea: Prevent that the laser beam gets uncontrolled out of the lab • Gate area – only one door open at a time • Back door – can be opened for transport but will cause interlock break in E1-A-10 • Reset interlock: Push the reset button at the SPS- located in the technical room – note you have to leave the lab and to reenter the lab after resetting the interlock.

Shutter key

Lab - layout

Laser indication light

Gate area with gogles

09

11

Interlock key & shutter control

and clearn room coats

Interlock key

09

11

1,25

3,6

3,6

1,5

2,4

1,5

1,5

E1-A-11

1,7 1,4 1,5

2,0

1,13

1,5

E1-A-10

Emergency exit

3,6

1,5 1,5

E1-A-09

3,6

3,6

E1-A-12

2,4

1,5

1,5

1,62

The interlock system – gate area • „regular entrance“ procedure: unlock door with your key and additionally press open button to release the door holding magnet for 20 seconds • „Tür-Notauf“ releases door but does not cause break of the interlock.

“Tür-Notauf”

The interlock system how to start the laser • enabling the laser via switch has to be communicated to all people working in the laser hutch • Leaving the lab (without further usage of the laser for experiments) the key-switches shall be deactivated and shutters closed.

The interlock Labsystem - layout 09

Interlock key

11

Interlock key & shutter control

09

11

1,25

3,6

3,6

1,5

2,4

1,5

3,6

3,6

1,5 1,5

1,5

E1-A-09

2,4

1,5

1,62

1,5

E1-A-11

1,7 1,4 3,6

1,5

2,0

1,13

Indicates status of both labs, it is on: as long as interlock is set in one of the two labs

1,5

E1-A-10

Emergency exit

Danger! Alkali-oven !! Vapors of Alkali up to 700°C !!

E1-A-12

The interlock Labsystem - layout 09

Interlock key

11

Interlock key & shutter control

09

11

1,25

3,6

3,6

1,5

2,4

1,5

3,6

3,6

1,5 1,5

1,5

E1-A-09

2,4

1,5

1,62

1,5

E1-A-11

1,7 1,4 3,6

1,5

2,0

1,13

Shutter to be opened with key on both sides

1,5

E1-A-10

Emergency exit

Danger! Alkali-oven !! Vapors of Alkali up to 700°C !!

E1-A-12

The current lasers in the lab: Yb fiber laser: mean power : 15W, 1,5 kW during the burst, 1030 nm, 1 ps< pulse duration >1nm. Different rep. rates, 100 kHz during burst 2 Harmonic (515nm) – 50% conversions efficency -> class4 Ti:Sa oscillator: mean power : 0.26 W, 800 nm (+/-150nm), ~ 10 fs, 2.4 nJ pulses, 108 MHz -> class 4 Fiber pump:

output power: 20W, 1030 nm, < 1ps (~2ns) , ~ 0.2 mJ, 100 kHz (burst)

-> class 4 Inno-Slab pumps: > 1 kW, 1030 nm (515 nm), < 1ps (~2ns) , > 20 mJ, 100 kHz (burst) -> class 4 Thindisk pump: 1030 nm (515), < 1ps (~1ns) , > 100 mJ, 100 kHz (burst) 140 W im burst -> class 4 OPA: 1 W, 680 -1000 nm, < 30fs > 1 mJ per pulse, 100 kHz (burst) -> class 4

In the measurement lab: Laser diode: 50 mW,, CW, 420 nm, -> class3B (until may 2014) Ti:Sa oscillator: mean power : 0.26 W, 800 nm (+/-150nm), ~ 10 fs, 2.4 nJ pulses, 108 MHz -> class 4

The usage of any other laser or the manipulation / changes of the current laser system properties have to be agreed with the laser safety officer and the responsible person for lab!

modes • Oscillator mode – Only the 800 nm (700 nm - 900 nm ) oscillator is on – the side panels may be open or closed
As long as the door and the shutter is closed there is no danger in E1-A-10 but access through E1-A-9

• the “standard mode” – Oscillator (800 nm) and pump lasers (1030 nm and 515 nm ) are on – the side panels may be open or closed
As long as the door and shutter is closed there is no danger in E1-A-10 but access through E1-A-9

modes • special (potentially dangerous) alignment mode  Oscillator (800 nm) and pump lasers (1030 nm and 515 nm ) are on

 side panels are open

In this case there is NO other work in the lab allowed. !! Only people involved in the OPCPA operation are allowed in the lab. The operation mode has to be indicated at the entrance door by an appropriate sign.

Attention, dangerous Laser alignment work Don‘t enter! Please, ring the bell for urgent requests! Achtung, gefährliche LaserJustagearbeiten Zutritt verboten! Bei dringenden Fragen bitte klingeln!

Eye protection: What goggle to use 3 different laser safety goggles are available in the gate area. They are labeled: 1. 690nm - 1320nm (R14.T1Q01.1001) 2. 180nm -532 nm + 750nm - 1100 nm (R14.T1P01.1001) 3. 180nm -532 nm + 1030nm - 1100 nm (R14.T1L02.1001)

Eye protection: What goggle to use 2 different laser safety goggles + in future a laser safety helmet are available • For Oscillator alignment : – 800 nm goggle (700nm-1100nm) – Close shutter for pump-amplifier to prevent 1030/515 nm

• For work at the pump laser work: – 515 nm +1030 nm goggle – close shutter of oscillator to prevent 800 nm

OPCPA alignment / goggles part II • For OPCPA amplification. All alignment with attenuated amplifier pulses. • • • •

Install diagnostics close cover turn up laser power with closed covers turn down power before reopening the covers

• In the case it is unavoidable to align with open covers: Use the night vision head in combination with the appropriate laser safety goggle. However one has to be aware that the combination goggle + night vision still has a minimum residual risk !!! • In future laser safety helmet.

gas

Interlock key

• Gas bottles have to be stored only in apporiate board – contact responsible person for the lab

Most important again • Wear eye protection / Never look in the laser beam • No major alignment with “full” laser beam – always attenuate • Witnessing dangerous laser usage -> tell them AND the safety people • If indication for laser accident (partial blinding) -> tell “Notdienst” (and laser safety people) • Be aware: lasers are dangerous!! There is always a residual risk Only working carefully can prevent accidents ! • Deactivate the key-switches when leaving the lab ongoing)

(and the experiment is not

People to ask Notdienst:

2500

laser safety officers (Laserschutzbeauftragte) Juliane Rönsch-Schulenburg 6686 Responsible person for lab (Laborverantwortliche) Juliane Rönsch-Schulenburg 6686 Safety intructions can be given by (Unterweisungsbefugte) Mark Prandolini 1954