Time resolved optically pumped scanning optical microscope (TROPSOM)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Pump-probe setup with fs-time and sub-micron spatial resolution for direct spin-waves mapping. The key knots of TROPSOM setup are:

Femtosecond Laser System with tunable wavelength

TEMA + TOPOL (OPO) laser system (Avesta LTD)

Pulse duration <120 fs

Three outputs: 730-1080, 1050, 525 nm

Pulse repetition rate 70 MHz

Average power up to 800 mW

High-clearence micro-objectivies
Olympus and Mitutoyo

Magnification x20 and x50, NA 0.4 and 0.42 allow to get spot diameters ~1.5 μm. Working distancies 12 and 17 mm 

Three-coordiante piezo-translator
Piezosystem Jena

The translator is used to shift pump and probe spots on the sample. Motion 0-80 μm with Resolution 10 nm.

Water-cooling electromagnet

The magnet is specially designed by AMT&C Group to get fields up to 2 T with poles distance up to 40 mm.

Time-resolution and Detection system

The probe beam is analyzed by an optical bridge detector composed of a Wollaston prism and balanced detector. Lock-in amplifier is turn on the pump  modulation frequency 84 kHz; Pump is modulated by the photoelastic modulator (PEM, HINDS instruments). The temporal resolution is obtained by using a retroreflector mounted on a linear translation stage (Thorlabs) 600mm-long (time window 4 ns).

 

Time resolved magnetooptic Kerr effect measurement with micron spatial resolution

Pump-probe setup with subpicosecond-time and micron spatial consists of several important parts:

Laser system
Regenerative Amplifier PHAROS + Optical Parametric Amplifier ORPHEUS (RA + OPA)

There is an opportunity to perform two-color pump-probe experiment

PHAROS SP-06-200-PP (Light Conversion)

Output pulse duration 190 fs

Output average power 5 W

Central wavelength 1028 nm ± 5 nm

Pulse repetition rate 1 kHz – 1MHz

Max. pulse energy 1mJ

Oscillator output is optional

ORPHEUS PO15F1H (Light Conversion)

Tuning range 630 – 1030 nm (Signal), 1030 – 2600 nm (Idler)

Output pulse duration 120 – 190 fs

Average power 500 mW

Pulse repetition rate 5 kHz

 

High-clearance reflective microobjective Newport

Magnification x15, NA 0.4 allows to get spot diameters ~5 μm. Working distance 13 mm. No dispersion in wavelength range 200-20000 nm

One-coordinate translator with DC-motor Standa

The translator moves sample relatively to the pump and probe spots

Motion 0-30 mm with resolution 1 um.

Electromagnet

provides fields up to 1 T with poles distance up to 40 mm 

Time-resolution and Detection system

The probe polarization change is measured by the detection scheme including optical balanced detector and Wollaston prism. Lock-in amplifier reference channel is on the pump modulation frequency up to 2 kHz; Pump is modulated by the optomechanic modulator (Chopper Thorlabs). The temporal resolution is provided by a linear translation stage (Newport) 600mm-long (time window 4 ns).

 Cryostat Oxford

allows to perform pump-probe experiments with temperature degree of freedom (5-350 K)

 

 

 

 

Whiteboard


 

Equipment we tested in FerroLab

 

Optomechanics ST1 ENGINEERING KOREA

 

Today we got into the hands of the optomechanics of fabrication of the St1 Engineering, Korea. The trial set courtesy of our partners, In-Science company. A few different products are in the set:

  • X- and z-translation stages
  • Post holder
  • Tilt platform
  • Optics holder

All items are made of anodized aluminum, but x-stage is made of steel.

Post holder is 1/2 inch. size and is well match the Thorlabs post. It has spring-loaded thumbscrew, like Thorlabs. It is more convenient than simple thumbscrew. But manufactures did not make the hex hollow for locking. There is some sticker on this place, but there is no wonted hollow under that. The thumbscrew is sitting nice in the thread. Standard M6 tapped hole on bottom.

Optics holder is assembled from well-matched details, no noticeable slackness. The fine clamp is very smooth to the touch. There is M6 tapped hole on bottom.

Linear stages are smooth in movement. They are fully lockable. The z-stage has side lead screw. That may be more convenient than Standa solution at vertical stages. The stages could be attached to each other directly, but not to the optical table –some base is needed. Vertical stage has M6 and M3 holes, x-stage – M3 holes only. This solution is not convenient as M6 and M4 are used usually. Standa has the same issue.

Tilt platform could be mounted in horizontal or vertical positions both with M4 holes. The adjustment knobs are made of plastic suddenly, not of aluminum. The solution is looking untrustworthy, fragile. And with stickers again. Four M4 holes on the surface are convenient and give the freedom to install some elements like prisms.

 

In conclusion, the quality of the items is at the level of Thorlabs and Standa companies, some aspects are more convenient, but some (stickers, plastic parts) are unconventional and may be the issues of the products. Generally, the products may be used with optomechanics of famous brands (Thorlabs, Standa, others) together as they are compatible and with the nice quality.