CFHT, Instruments, Spectroscopy, LAMA


These pages are now somewhat out of date. Please contact your support astronomer if you have questions. A Microsoft Word version of the current Lama II manual may be found here

Revision History:
6 March, 1991: T. Gregory
17 July, 1992: T. Gregory and D. Salmon
3 August, 1992: D. Salmon
11 June, 1996: J. Seerveld

Web Version by David Bohlender and Jon Seerveld: 9 October, 1996

For additional information about LAMA, contact Christian Veillet. For instructions regarding the design of slit masks please see the User's Manual for MOS: The CFHT Multi-Object Imaging Spectrograph@ or the User's Manual for OSIS: The CFHT Subarcsecond Imaging Spectrograph@.

    Room 412A - 4th floor - NESLAB COOLER CHECK-OUT

  1. Clearance of 2 ft on three sides of NESLAB cooler.
  2. Glycol level 1" below top of reservoir - covering coils. Look under metal plate located on the top left corner of the unit.
  3. Make sure the power switch of the cooler is on. NOTE: Unit will not turn on until power is applied in step #5.

    Room 412 - 4th floor - NESLAB COOLER POWER START UP

  4. Verify input power on wall panel to NESLAB and both lasers. (Green light indicator next to "emergency shut off" button is illuminated). This panel is located next to the lab entrance door.
  5. Push top green button of the power panel to turn the NESLAB cooler on. (Green light will illuminate).

    Room 412A - 4th floor - NESLAB GLYCOL CHECK-OUT

  6. Glycol flow at 4.2 gpm. It will be at >5 gpm at first. (Look at the float in the transparent column of the glycol flow-meter on right side in the lower right corner of the unit). NOTE: Flowtec switch on LAMA requires minimum 2 gpm.
  7. Glycol pressure - meter at 42 psi. (Pressure meter on right side in the lower right corner behind heat vent).
  8. Set point temperature = 15C (+/-2C). (Front panel of Neslab cooler). Press button to read.

    Room 412 - 4th floor - LASER START UP AND OPERATION

    Power Start Up Sequence

  9. Push the second button of the power panel to supply the electronics rack of LAMA I. (Green light will illuminate). This is needed for computer control of the laser gating signal.
  10. Push the third button of the power panel to supply the electronics rack of LAMA II. (Green light will illuminate).

    Electronics Rack Diagrams

    Below are two full diagrams of the electronics racks from which selected items will be referred to. These diagrams will allow you to find the specific electronic instrument panel within the entire electronics rack.

    Computer Interface (IP28) Start Up (Top unit of control rack)

    Refer to figure 1 below for steps 11 through 14 for locations of IP28 key switch and power button.

  11. Set IP28 computer interface to local mode ("L") with the 1/4 turn key switch located on the right side of the unit BEFORE applying power.
  12. Turn on IP28 power - "secteur" push-button switch located on the left side of the unit (button will illuminate).
  13. Set IP28 to distance mode ("D") using the same key switch on the right.

    NOTE : Do not apply power to any other component in the LAMA I rack.

    Figure 1.

    Laser Optical Pump Lamp Power Supply Start Up

    NOTE: Whenever the Yag laser is to be used for cutting, the laser safety shield must be closed or protective eye-wear - laser goggles - must be worn by all personnel in the room AT ALL TIMES.

    There are 2 lasers in the system. A red HeNe laser (wavelength 632.8 nm) - which should be visible as soon as the switch is turned on and the shutter is open - indicates the location of the cutting beam. The infrared YAG laser (wavelength 1.06 microns) - the high powered beam which does the cutting - is INVISIBLE. Its presence will generally be noted however by the white-hot spot it creates as it cuts the metal masks. The YAG beam should only be present when: i) the lamp power is turned up, and ii) when the cavity shutter is opened. But be careful. Don't assume that these conditions exist.

  14. Before applying any power to any component in LAMA II rack, turn the POWER CONTROL knob fully counterclockwise and the SHUTTER switch to the CLOSED position. See figure 2 below for power control knob and shutter switch location.

    Figure 2.

  15. Turn on the HeNe laser with the white power cord switch located on the left side of the X-Y stage. Note that the HeNe laser will not be seen until the electronics rack is turned on, the pumps are running and the shutter is open.
  16. Turn the main power key switch of the LAMA II top rack to the on position. The EMISSION INDICATOR and WATER FLOW interlock lights should be illuminated. The cooling pump should not be running at this time. Wait at least 10 seconds before proceeding to step 17. See figure 3 below for location of key switch.

    Figure 3.

    Before turning on the power supply to the lamps, check the operation of the safety shutter. Open the shutter by actuating the SHUTTER OPEN/CLOSE switch. Note that the HeNe laser now comes through the system and the red light on top of the laser unit is lit. Close the shutter and note that the HeNe laser is blocked off. IT IS IMPORTANT THAT THE SHUTTER REMAIN CLOSED DURING THE REST OF THE POWER UP SEQUENCE.
  17. Turn the main power key switch to the PUMP START position and hold it momentarily until the pump starts. Release the key and it will return to the ON position. The WATER FLOW indicator light should now be OFF.
  18. Push the POWER SUPPLY ON button to turn on the power supply. The POWER SUPPLY OFF indicator should go off, and the POWER SUPPLY ON indicator should light. Note: the power supply will be shut down if the RIC interlock circuit is opened while the power supply is running. (Interlock is currently not implemented and RIC is shorted at this time.) See figure 4 below for the location of the power supply on button and the lamp start switch indicator.
  19. The LAMP START indicator should gradually light in 30 seconds indicating that the capacitors are fully charged. You MUST wait these 30 seconds before firing the lamps.
  20. Press the LAMP START switch to fire the krypton arc lamp. The LAMP START indicator should go off, and the lamp power meter should come up to an idle power level of about 2.2 Kilowatts as read on the upper scale.

    Figure 4.

  21. Set the power level to 3.0 Kilowatts by rotating the POWER CONTROL knob clockwise while observing the power meter reading the upper scale. See figure 5 below for power control and power meter locations.

    Figure 5.

    NOTE: Laser output is not optimized at this time; it may take at least 20 minutes of system warm-up time, but you may begin cutting immediately after turning on the Q-switch in the next section. The emission indicators should be on. There is one on the rack and one on top of the laser unit (a yellow light).

    Q-Switch Driver Start Up

  22. Press the ON/OFF push-button switch; the ON indicator in the switch should light. The LOW POWER fault indicator light may come on for about 15 seconds while the system is charging up the capacitors.
  23. Make sure that all FAULT INDICATOR lights are off before proceeding. See figure 6 below for ON/OFF switch and fault indicator light locations.

    Figure 6.


  24. Set the MODULATION CONTROL KNOB to the INTERNAL position and the TOGGLE SWITCH to the FREE RUNNING position.
  25. Adjust the modulation frequency, if needed, to 2.0 Kilohertz by turning the INTERNAL FREQUENCY ADJUST KNOB while watching the meter scale.

    Note: the frequency meter scale will read 0 KHz until the computer program turns the modulator on as needed.

    Figure 7.

    Computer Initialization

    Refer to the LAMA software control document for a more explicit description of the following steps.

  27. Turn on the Gateway 2000 computer if it has been turned off and allow it to boot up until you have a desktop with various icons displayed.
  28. Double click the Netscape icon and let the LAMA Conversion Utility program start up.
  29. In the text window, type over the example the name of the file you want to convert.
  30. Click the CONVERT button and check to see that there are no errors. Iconize Netscape for later use with the "-" button in the upper right hand of the Netscape window. The program is now immediately available on the "task bar" at the bottom of the screen. Clicking this will bring up the conversion program.
  31. Double click the CUT MASK ICON and find the converted file as a "filename.dmc" NOTE: the truncation in the filename is normal. This window also can be iconized for later immediate use.

    You can Click here for a demonstration of the LAMA Conversion Utility program.

    Focussing TV Camera Set-Up

  32. Turn on the Video X-Y Cross Hair generator and the video monitor located above the LAMA II electronics rack. Turn on the high intensity lamp located near the X-Y stages. With the light directed at the laser cutting point from the front, and the main focus control properly set, a magnified image of the foil should appear on the monitor with the aligned cross hair target when the stages move the foil under the laser focal point.

    If no image appears then check power cords from both the camera power supply and the monitor. Also check that the BNC signal cable from the camera goes to the Colorado Video cross hair generator input on the back and that a BNC goes between the Colorado Video cross hair generator output to the monitor input.

    When Ready To Cut Masks

  33. Set mask holder securely into X-Y stage. Note: the mask frames must be mounted with the registration pin cutout to the back right corner of the vise.
  34. Check the laser lens focus. Focus is adjusted with the large micrometer head visible at the front of the YAG laser. Focus values for mask cutting are as follows:
                        MOS       50.95 
                        OSIS      43.60
    Focus values for cutting mask blanks using the `platform' are:
                        MOS or OSIS    37.00 
  36. Open SHUTTER SWITCH to the OPEN position. Red light on top of laser indicates that shutter is open.
  37. Turn on the vacuum switch if desired. The switch is located to the left of the focussing monitor above the electronics rack.

    To Cut Masks

  38. Double click the "filename.dmc" icon in the cut mask window. The stages will initialize themselves and then cut the requested mask. Look at the Gateway computer for feedback.

    When Mask Cutting Is Completed

    1. close cavity shutter by turning the shutter switch to the CLOSE position.
    2. turn lamp power down to 2.2 Kilowatts.
    3. turn off vacuum switch.

    Mask Cutting Trouble-Shooting

    The most common problem in cutting masks is that some or all of the apertures are not cut cleanly. If all the apertures are not cut properly, it is most likely that the focus control knob is off by +/-1 rotation from the nominal focus position. Rotate the knob a long ways off until you are sure where you are and then go back to the focus position and try again.

    If only some of the apertures are not cut cleanly, examine the density of the apertures within the mask. If too many apertures are cut close together, local heating from the cutting process may warp the mask material enough to take it out of focus. In this case, reduce the power to 2.6 or 2.5 Kilowatts and increase the number of passes taken around each aperture.

    Shutdown Procedure

  39. Follow these steps to shutdown the LAMA system:
    1. Turn off the Q-SWITCH DRIVER by pushing the POWER ON/OFF switch noting that the light goes out.
    2. Set the POWER CONTROL knob back to minimum power.
    3. Press the POWER SUPPLY OFF button to turn off the power supply.
    4. Allow the water pump to run for 2-3 minutes, before turning the main power key switch off, to prevent thermal shock damage to the laser crystal.
    5. Turn power off on the IP28 module.
    6. Turn off NESLAB cooler power and LAMA I & II power in room 412 by pushing the emergency shut off button on the bottom of the power panel.
    7. Turn off the HeNe laser switch located on the left side of the system.
    8. Turn off both the Colorado Video cross hair generator and the associated monitor.
    9. Turn off vacuum switch if necessary.

Page maintained by: Christian Veillet