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             - Lasers 85/95 Specifications Charts


Features of LEXEL™ Lasers

          Laser head
          Plasma tube
          Optical resonator
          Power supply
              - Power supply interior
          Single-frequency operation
              - Model 503 Etalon
              - Typical frequency stability

FEATURES OF LEXEL™ LASERS:
OPTICAL RESONATOR

Optical resonator, alone and installed in laser head - click for enlarged viewThe optical resonator is the most important structure affecting the overall power, frequency and beam-pointing stability of the laser. The resonator must hold the plasma tube, the laser mirrors and all other optical components in precise alignment.

The LEXEL™ Solid Invar® Rod Resonator Structure with its patented mirror mounts is the ultimate laser resonator design for all ion laser applications. It is a rugged lightweight structure with all the precision and stability of the finest Fabry-Perot Interferometer.

Ultra-low thermal expansion Invar®

The LEXEL™ Resonator uses Invar with a thermal expansion of less than 0.9 x 10-6/ °C which results in a basic resonator frequency stability of better than 0.5 GHz/°C. This stability is comparable to quartz tube resonator systems and is more than 25 times better than the best aluminum resonator.

Solid rod construction

LEXEL™'s straightforward design utilizes solid one-piece rods that run the full length of the resonator, to provide unmatched mechanical rigidity.

Other low expansion resonator designs are complex structures which must combine quartz rods or tubes inside of an aluminum tubing structure. Transverse movement or vibration between the quartz and aluminum can cause undesired frequency jitter.

Only LEXEL™'s solid rod construction provides the excellent transverse rigidity required to reduce frequency jitter to its very minimum.

Stress-isolated resonator mounting

Stress-isolated resonator mountingThe LEXEL™ optical resonator is mounted to the base of the laser head with an advanced kinematic mounting system that prevents thermal or mechanical stresses from detuning the mirrors or plasma tube alignment. The mounting system consists of a transverse flex plate, a spherical bearing, and an axial sliding pin to provide positive kinematic positioning with complete stress isolation between the case and the resonator.

Kinematic mirror suspension system

LEXEL™'s patented mirror suspension system permits stable and repeatable mountings of the laser mirrors to the resonator structure. Three reentrant-type springs provide the strong compressive force between the three pivot points and the ends of the resonator rods. Kinematic mirror suspension systemThe reentrant springs also complete the kinematic mounting by preventing lateral or rotary movement of the tuning plate. Positive orthogonal tuning with outstanding repeatability is always assured.

The reentrant compression springs do not rub or move in contact with the optical resonator, thus the optical tuning "noise" associated with coil springs is not present in LEXEL™ lasers. Micrometer pitch tuning screws are used to provide smooth precise mirror tuning.

The LEXEL™ resonator and mirror mount system will withstand shock and vibration that would misalign other laser designs. LEXEL™ lasers are shipped all over the world and in virtually every case, they arrive in precise alignment.

Unmatched beam-pointing stability

Most ion lasers exhibit angular beam drift caused by thermal mismatches in resonator or optical elements. The combination of LEXEL™'s low temperature conduction­cooled plasma tube, the thermally-matched Invar resonator system and the Temperature Compensated Prism Wavelength Selector results in beam-pointing stability from LEXEL™ lasers of better than ±1.5 arc sec/ °C (± 7.25 µ rad/°C). This performance is repeatedly verified by scanning and film recording users in critical alignment systems and is reportedly the best available from commercial ion lasers.

Long-term power stability

The ultimate test of a resonator's stability is the extent of long-term power drift when the laser is operating at a constant current level. LEXEL™ lasers have the best power stability available in commercial ion lasers. They are capable of maintaining a given power level within 2% for 10 or more hours. In long-term industrial applications LEXEL™ lasers frequently operate for months without requiring any retuning.

Sealed contamination-free cavity space

Sealed optical cavity spaceThe most common and troublesome cause of power fall-off and mode distortion in ion lasers comes from contamination of the optical surfaces and air space making up the optical cavity. We have completely eliminated this problem by the use of its patented dust cover assembly which seals and protects the optical components and cavity space between the mirrors and the Brewster windows of the plasma tube.

The LEXEL™ dust cover assembly uses O-rings and Teflon® seals to provide a completely sealed intracavity space. All of the dust cover parts are made of materials carefully selected for compatibility with the UV radiation and resulting ozone atmosphere existing in the optical cavity. Each part is thoroughly cleaned, chemically-treated and air-baked just before being assembled into the resonator.

Periodic optical cleaning eliminated

The LEXEL™ Optical Cavity dust cover has proven so effective that, if left sealed, the mirrors and windows rarely have to be cleaned. LEXEL™ lasers commonly operate for one to two years even in dirty industrial environments without needing cleaning.

To our knowledge no other ion laser manufacturer has even come close to this performance, since weekly or monthly cleaning of optics is a standard procedure required to keep most other lasers operating correctly.

Sealed light sampler assemblySealed light sampler and photocell

The beam splitter and photocell which sample a portion of the laser output are also sealed to prevent dust, dirt and even stray room light from disturbing the performance or accuracy of the Light Regulator and Power Meter.

Efficient optical design eliminates aperture

The LEXEL™ optical design uses the full plasma tube bore as the limiting aperture of the optical system. The mirror radius is chosen to provide optimal TEM00 operation in conjunction with the bore aperture. When other mode configurations are required they can be obtained simply by changing the mirror. Thus maximum optical efficiency is always obtained since the full bore diameter is always used. The problems associated with an extra intracavity aperture, such as misalignment and optical contamination, are totally eliminated with LEXEL™'s superior optical design.

Easy mirror changing

The mirrors in LEXEL™ lasers are easily and quickly removed and reinstalled. Since the front surfaces of the mirrors are aligned by three precision balls, both repeatability and correct orientation are always assured.

Magnetically-coupled Shutter AssemblyMagnetically-coupled shutter assembly

The LEXEL™ beam attenuator consists of a counter-balanced shutter located inside the optical cavity near the output mirror. A magnet attached to the operating lever holds the intracavity shutter either fully open or completely closed.

The magnet coupling provides positive operation of the shutter without breaking the dust cover seal. The intracavity shutter design eliminates the cumbersome heat dissipating structures needed for external-type beam terminators.

Threaded output aperture

The output mirror retainer contains a ¾"-32 thread for mounting accessories to the output aperture. This thread will accept standard optical accessories such as polarization rotators, beam expanders or dye laser coupling tubes.
 
 


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