Pulsed Lasers

Pulsed Lasers

Sirah’s pulsed dye laser are the standard for all applications in atomic and molecular spectroscopy.
Features are:

  • Precision Mechanics: Ultimate Wavelength Accuracy
  • Perfect Engineering: User Friendly, Reliable Operation
  • Maximum Performance: High Pulse Energies
  • Automatic Grating Exchange: No Gaps in Tuning-Range, Allways Optimal Efficiency
  • Handheld Remote Control
  • Operation from Both Sides
  • Tool-Free Exchange of Dye Cells
  • Integrated Autotracker

Resonator Design: Mechanics

Reliability is a key feature of our laser designs. All oscillator components are mounted on a solid block of low expansion stainless steel, mechanically and thermally isolated from the outer laser housing. This construction removes virtually all mechanical and thermal stress from the oscillator block. To achieve best results we have developed new linear guiding mechanics, mounted under the resonator base plate.

The use of Swiss made stainless steel guiding components result in ultimate wavelength accuracy (20 pm) and long term stability. Sirah’s own line of step motor drivers ensure easy and precise control of the laser wavelength.

Video: Dye Cell Mechanics

Resonator Design: Optics

At the heart of the laser system is a grazing incidence resonator designed to ultilize the grating’s dispersion twice per oscillator round-trip, ensuring narrow linewidths with low ASE levels and high efficiencies. An optional second grating can be added to the resonator for ultra narrow linewidths below 0.03 cm-1 at 570 nm. Therewith, narrow-line tuning over a broad tuning range without the need for intra-cavity etalon in possible, thus simplifiying measurement processes without a sacrifice in performance.

By using opto-mechanics optimized for easy and reproducible operation, the dye laser’s oscillator stage requires a minimum of user adjustment.

Grating Lift Option

The resonator allows the addition of an additional grating at the position of the grazing incidence grating. Two gratings, each with a different line density may be mounted to a single linear stage that can be activated by a button on the remote control. The grating lift option (patent pending) enables a single oscillator to cover the entire tuning range of a dye laser without any gap due to Wood’s anomaly. No recalibration is necessary after changing from one grating to the other.

By choosing a 1800 lines / mm grating and on the second position of the grating lift a 3000 lines / mm grating a tuning range from 370 .. 920 nm is achieved with a constantly good linewidth. This option eliminates all drawbacks of conventional grazing incidence resonator designs.

Video: Grating Lift

Quick Change Dye Cuvettes

The laser’s quartz dye cells are held in place by state-of-the-art mounts designed for stability and precision from high performance alloys and graphite-reinforced polymers. Hardened stainless steels sliding components force the cuvette into exactly the same position with high reproducibility even after years of operation. The design enables extreme ease of use the entire dye circulator can be removed in seconds and without interrupting the dye flow loop.

This design is ideal for applications that require more than one type of dye. Rapid changes from one dye to another are possible by swapping circulators.

Remote Control with Touch Screen

To allow operation from both sides of the housing all controls need to be flexible as well. Hence, lasers are eqipped with a handheld remote control. The control is connected by a 2 m cable to a connector panel at the pump laser entrance side. The remote control gives access to detailed information on the laser status and supports numerous commands.

Quick Change Pump Optics

Fast and reproducible change between 532 nm and 355 nm pump wavelength is achieved by using pre-aligned mechanics with two high power 180° steering mirror sets. These opto-mechanic assemblies fit exactly into holding fixtures inside of the dye laser. 532 nm and 355 nm mirror sets have dedicated mechanic assemblies. So, complete assemblies are swapped without the need to handle the delicate mirrors directly.

Video: Swapping Pump Optics

High Power Concept

The pre-amplification takes places in a separate capillary cell with 4 mm inner diameter followed by the main amplifier that uses a 6 mm capillary. The laser has a total of three circulation systems with three independent dye cells. This allows the use of an optimized dye concentration for each stage. At the same time the pump energy is distributed over three stages, keeping the power level at each stage well below damage threshold.

This scheme accomodates up to 1,500 mJ of 532 nm inside the dimensions of a PrecisionScan housing.

Furthermore, the use of two capillary cells in the amplifier stages support an excellent beam profile at high dye laser pulse energies.