LASER REGISTRATION FORM (LS-1)

Transcription

1 Appendix 1 LASER REGISTRATION FORM (LS-1) LASER REGISTRATION FORM (LS-1) Laser Ref. No: Supervisor Training Example Policy Note: This form is to be completed and a copy sent to the Departmental Laser Supervisor, for all lasers except inherently safe Class 1 lasers (e.g. laser printers, CD players etc) and laser pointers below Class Department Department: Safety Office Room Number/ Name of Research Professor Smith Supervisor: 2. Laser Safety Process Process Date Completed / Not Required LS1 Registration 01/10/11 LS2 Risk Assessment LS3 Local Rules Location: Name of Departmental Laser Supervisor: Research Supervisor Signature Brian Jenkins Departmental Laser Supervisor Signature 3. Overview of project, the laser and environment ULTRAFAST LOGIC ANALYSER (ULA) The ULA works by exploiting the rapid response of certain materials to an exciting optical pulse to both generate test data streams and to probe the outputs from those streams when applied to the device under test. The ultrafast laser system forms the clock and sampling source for an ultrafast logic analyser used to evaluate gigahertz and terahertz digital logic devices. The laser produces a continuous stream of sub 100fs pulses at a repetition rate of 100MHz. These pulses are split into two, one of which is used to optically gate an ultrafast superconducting sampling junction (used as a probe) and the other is processed to construct a simple ultrafast digital drive pulse sequence with which to drive the device under test. The probe pulse is passed, via an optical delay line, to the probe junction whilst the drive pulse sequence is applied to the input stage of the logic element being evaluated. Processing of the drive pulse is generally by time division using variable thicknesses of glass for very fast sequences and via an active pulse shaping filter for longer, slower sequences. The optical configuration is outlined below: The Laser: The Millenia VIs pumps the Ti:Sapphire Tsunami A separate power supply operates the Millenia VIs, which is itself controlled by a key switch. The Tsunami can only produce a beam when the Millenia VIs is operational and so again is controlled by the key access and door entry system. The Tsunami output is controlled by the controlling the Millenia VIs. The beam path can be manipulated by external controls on top of the laser head. On the output aperture of the Tsunami there is a Lasermet shutter which is linked to room doors through an ICS-1 panel. The Tsunami is a tunable laser, which can be operated between nm (near-infrared). However, it is usually operated at 810nm. Both lasers are water cooled from the same closed loop system. The lasers are sat upon an air table, with the accompanying controls/power supply and cooling system positioned below. The power supply is on a trolley stored off the ground. The power supply connects into a 13Amp standard plug and was electrically tested on 14/05/11. Beam Delivery: The beam delivery is outlined in the diagram in Appendix A.

2 LASER REGISTRATION FORM (LS-1) Laser Ref. No: Supervisor Training Example In summary, although around 800mW can be produced from the Tsunami, a neutral density filter is positioned directly next to the aperture shutter that cuts the power to 50mW. The filter is a Dark Shot Glass which can be lifted in and out of position. The beam is then passed through a manual neutral density filter wheel where the power is controlled to around 20-30mW. The beam is then split using a thin beam splitter (fixed mirror). Half the beam is propagated towards the cryostat and the other is passed through a retroreflector in order to produce a time delay. The delay between the two beams can be altered by modifying the position of the retroreflector which is mounted on a sliding rail. The two separated beams are then combined and passed through a double chopper to control the frequency. Finally, they are directed through a 3-axes manipulation lens into the cryostat and towards the specimen. In addition to the general process described above, routine alignment takes place at the beginning of the week, where a 100fs mode-locked beam is targeted towards the diffraction grating by moving the optic on the flipper mirror. If the beam is mode locked, this will appear as a smear on the grating. Process: Laser power at the output is 800mW and powers as high as 30mW are applied to the sampling junction and device inputs. Devices under test have ranged from superconducting SQUID logic running at 400GHz to nanostructured semicondutor gates with slower responses. About 3L of Liquid nitrogen is used in the cryostat. A speedvac diffusion pump, cooled by a closed loop system, is used to create a vacuum in the cryostat. The vacuum exhaust is piped out of the room. Environment: The laser is fitted with an interlock system which links to the door entry, which when open will restrict emission of the beam from the Tsunami. The control box also enables override of this interlock by someone inside the room to permit entry to someone outside. It also has an emergency stop button, which when operated automatically shuts the power to the laser. The door is fitted with a keycode system which restricts entry to authorised personnel only. When the code is entered, there is a time-delay on the laser control system which provides 15 seconds for a person to enter, without closing the laser shutter. Inside the room, the walls are mat white. There are windows, but these are fitted with laser curtains. Cupboards are fixed to the wall to the side of the laser table and these are glass-fronted. The room is fitted with an interlocked laser curtain, so it can be operated as a single room or two separate rooms. Generally the room is operated as a single room. The room can be separated by a curtain, but the other side of the room is used by a 4th year project student. No chairs are present.

3 4. Detail the specifications of all Laser(s) involved in the system: Make: Spectra-Physics Spectra-Physics Model: Millennia VIs Tsunami Serial no: Wavelengths/ Bands: 532nm nm (operated at 810nm) Maximum output 6W 800mW, 8nJ / pulse power: Beam diameter: 2.3mm (1/e 2 ) 2mm (1/e 2 ) Beam divergence: 0.5mrad 1mrad CW or Pulse CW 100MHz repetition rate: CW or Pulse length: CW 100fs Classification: 4 4 MPE Eye (If known): MPE Skin (If known): Nominal Ocular Hazard Distance (If known): 6.36 J/m nj/m 2 Unknown Exceeds room dimensions (1.094Km) Unknown Exceeds room dimensions (251m)

4 Appendix A Layout of laser experimental table

5 Appendix B Photograph of existing laser experimental table

6 Tsunami Appendix C Schematic floor layout of Room (not to scale) Laser Curtains Millennia Optical Tables