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100 Great Kid's Games 2
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100gamesII.iso
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PROGRAMS
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SCI_PROJ
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LASER.TX_
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LASER.TX
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1998-06-28
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148 lines
CARBON DIOXIDE L A S E R
LASER, acronym for Light Amplification by Stimulated Emission of Radiation. The LASER is a device that amplifies light
and produces a coherent light beam which range from infrared to ultraviolet. The LASER utilizes the natural oscillations
of molecules or atoms between energy levels for generating coherent electromagnetic radiation. A light beam is coherent
when its waves, or photons, propagate in step with one another.
The following project discribes how to build a continuous beam Carbon Dioxide LASER. Its output power is in excess of
20 watts at 10.6 microns. This particular unit with proper colliminating optics can project an invisible beam of heat capable
of starting fires over considerable distances. It is extremely damaging to human tissue especially the eyes.
(THIS DEVICE IS NOT A TOY to be placed in the hands of an irresponsible or incompetent person. It can be a VERY
DANGEROUS device both to the operator and to the surroundings.)
CARBON DIOXIDE LASER PROJECT
Part 1: Material list and instructions
Part 2: Optical alignment and operation
PART: 1 (Fig. 1, 2, & 3)
PLASMA TUBE - Pyrex Borosilicate, length 28", outer diameter 35mm/1.378", wall thickness 2mm/.079" , and inner
diameter 31mm/1.220"
COOLING JACKET - 20" x 3" x .0625" Aluminum tubing. Drill holes as shown in Fig. 1 to install 1/4" tubing for inlet
and outlet of water. To install Plasma Tube in Cooling Jacket, build-up tube with layers of 1/2" glass tape. Seal tape
with RTV Silicon Sealant. The water inlet is on top and the outlet at the bottom. 1/4" Copper Tubing - 2" long and
used for the Cooling Jacket and the Cell Tubing.
MOUNTING BASE - 40" x 12" x 3/4" Plywood.
INSULATOR SUPPORTS - 7" x 6" x 1/4" lucite or equivalent. Cut half circle in Support, where Plasma Tube will rest.
Adjustable & Stationary Cell Plates - Fabricate as shown in Fig. 3, 7" x 7" x 1/4" steel plates. Center hole is equal
distance for outer diameter. Attach High Voltage wiring for Power Supply to Stationary Cell plate with Scews.
CELL TUBING LONG - 4" x 1" ID x 1/16" Copper Tubing. Drill holes as shown in Fig. 1 for 1/4" copper tubing. This
is for the Gas Inlet and Outlet. Solder tubing in place. Insert Tubing 2" in Plasma Tube, sealing with RTV Silicon
Sealant. If necessary shim between Plasma Tube with Glass Tape.
CELL TUBING SHORT - 1" x 1" ID x 1/6" Copper Tubing. Insert into Cell Plates and Solder in place. Tubing must be
flush with cell plate. ' 2 required '
NEOPRENE TUBING - or equivalent, 1" ID x 1 3/4" L x 3/32". This tubing is attached to Cell Tubing with hose clamps
and RTV Silicon Sealant. Leave 3/4" to 1" gap between Cell Tubings.
ADJUSTABLE CELL PLATE SCREWS - 3" long. Thread the Cell Plates or Solder nuts to Cell Plates to allow adjustment
of Screws.
MIRROR MOUNTS - 2 1/2" x 2 1/2" x 3/16" Metal square with circular groove cut in a 1" radius for a standard 2" 'O'
ring. Drill 4 holes to mount with with 10 - 32 Screws. It will be Mounted as shown in Fig. 2 & 3. ' 2 required'
RESONATOR - is a parabolic mirror ground from an optically flat circular 41 mm. in diameter and 8 mm. thick glass disc.
To build the Resonator you will need two glass disc, one for a tool used for grinding a abrasive against the other until
the desired curvature for the required focal length is obtained twice the distance between it and the flat output mirror.
The disc is ground with finer and finer abrasive, then polished. After the glass disc is polished it is coated with copper
by the " Sputtering Technique ". The amount of copper deposit should equal twice the amount to make the glass
opaque and letting the process continue a long again. " This is critical due to any absorbtion of infra-red can fracture
the mirror. The mirror is fastened to the mirror mount by RTV.
OUTPUT EXIT MIRROR - is a flat circular glass disc 41mm diameter and 8 mm thick with an exit hole drill in it. To drill
the hole in the glass disc follow these instructions. ..........(1) Coat glass disc with a film of pitch, tar, or some other similar
substance. (2) With modeling putty make a dam around the outer edge of the glass. (3) Put a 5/64 brass rod in a drill
press and clamp the glass in the center position of the drill press. (4) Fill the dam enclosure with a mixture of water and
220 grade Alundum grit ( mix to a slurry). (5) Carefully raise and lower the drill brass rod in one second intervals until a
hole is formed by the abrasive action of the slurry. (6) Completely clean the glass. ( 7) Coat one side of the glass disc
with a copper film using the Sputtering Technque.
Information on the Sputtering Technque can be found at you local Library.
The Sputtering Technque is the process of coating one side of the lens with a Copper film.
Refer: to October 1967 issue of "Scientific American".
EXIT WINDOW - is a window is made of either rock salt or Barium Fluoride, just larger enough to cover the hole in the
Exit Mirror and sealed with RTV. Rock Salt is a much better Exit Window because it absorbs very little infra-red at 10.6
microns, but it is very hydroscopic and must be stored in dessicant. Barium Fluoride is less hydroscopic but could fracture
at 10.6 microns. Rock Salt must be ground and polished before installing on Exit Mirror.
(Fig. 4 )
VARIAC - 1.4 kva 0-120 volts AC at 12 Amps.
HIGH VOLTAGE TRANSFORMER - 10 kv Neon Sign Transformer or equivalent.
HIGH VOLTAGE RECTIFIERS - 10 kv piv, 100 ma DC, 2 in series per leg of bridge. These are the same kind of rectifiers
used on the High voltage Transformer of TV's. Use Automotive ingition wire to attach to Cell Plates.
VACUUM PUMP - a small Refrigeration compressor makes a good vacuum pump.
VACUUM FILTER JAR - Standard 1 gallon jar enclosed in a wooden or cardboard box in case of implosion. Fill jug with
Fiber Glass. Make 2 holes in the lid of the Jar and install in on a 1/4 tubing to the bottom of the Jar. In the other install a
1/4" tube at the top of the lid. This is to prevent oil from back flowing to the Plasma Tube
CARBON DIOXIDE GAS - can be aquired from either Dry Ice in a container sealed with a rubber stopper with two holes
and the appropriate connections. Carbon Dioxide can also be produced in a Carbon Dioxide Generator, using baking
power, water and a drier to dry gas.
NITROGEN GAS - can be aquired by using a flask or other container with two holes in a rubber stopper, one hole for
draw in air though water and the other with a cotton filled filter tube to dry gas.
HELIUM GAS - can be purchased from Edmund Scientific in small containers or at some Wal Marts as party Helium.
MANOMETER - Use a standard 8 mm glass tubing to form an 18" 'U' tube. Close one end off on the tube. The scale
divisions are proportional to the density of mercury (13.55) divided by the density of the vacuum oil used in the
manometer. Use your own ingenuity for loading the 'U' tube with oil. The oil should be kept in a vacuum for several hours
to degas.
The Glass tubing for Plasma Tube can be purchused at VWR Scientific Products under G for Glass. If you are unable to
fine the glass disc you may be able to substatute. Use your own ingenuity on the use of other items.
Part 2:
OPTICAL ALIGNMENT - is to adjust the mirrors so they are parallel to each other and perpendicular to the axis of the
Plasma Tube. Take two cardboard discs with a 1/8" hole in the center, and install them in place of the mirror plates.
Take a third cardboard disc and place it about 5 fee t from the Plasma tube. Take a high intensity light source such
as a projector with a pin hole of light being projected using a telescope or other such device. Place the high intensity
light source about 10 to 15 feet from the laser and ajust so the light beam just grazes the edges of the holes in the
cardboard discs. Remove the cardboard discs for the Plasma tube and leave the one between the laser and light
source. Mount the resonator mirror and adjust screw until the reflection is on the center of the third cardboard disc.
The Resonator mirror is now aligned. Mount the exit mirror and adjust in a similar manner. Leaving the light source on,
apply vacuum and check the alignment. If alignment change, place a plain glass plate in place of the exit mirror. Apply
vacuum and realign resonator mirror, then exit mirror.
FIRING-UP LASER - Once the Optics are aligned we can begin firing up the laser. The first thing to do is to check for
leaks. Admit 15 torrs of Helium into tube and ajust the variac to 100 MA. The color of Plasma in the tube should turn
from purple to pinkish orange glow. Any trace of purple indicates a leak in the Plasma Tube. If there is an indication of
purple, pump down unit to 1 torr and note a whitish gray discharge. If there is still a purplish glow, power down system
a check entire system for leaks. Once everything checks-out pump plasma tube down to limit of vacuum pump. Adjust
Carbon Dioxide (CO2) for .5 torr, adjust Nitrogen (N2) to 1 torr, and adjust Helium (He) to 4 torr. Slowly adjust variac to
50 MA. If eveything is functioning properly an invisible beam should be coming out of the exit end. Place a block of
wood in front of the exit end and adjust mirror position screws for charring effect. Optimum output can be fine tuned not
only by optic mirror alignment, but by adustments in gas mixtures and current settings.
USE EXTREME CARE WHEN USING TO PROTECT YOUR EYES AND SKIN.