attoCFM II

fiber-based confocal microscope

miniaturized fiber-based confocal microscope head

ultimate drift stability at low temperatures

1 single mode fiber for excitation and detection

fast turnaround without optical alignment

closed loop scanning (optional)

easy retrieval of regions-of-interest


The attoCFM II is an ultra-stable fiber-based confocal microscope for use at low temperature and in high magnetic fields in reflection mode. Based on a single mode fiber and a fiber-based objective, it was designed for ultimate long-term stability: without free-beam optics entering the cryostat, and all optical elements well thermalized inside the cryostat and cold, there is basically no observable drift at all, and hence extended measurement periods even of several weeks are feasible. The wavelength range is obviously limited by the range of the single mode fiber used, but can be adapted by using different fibers for different ranges. Splitting of the excitation and detection signals is usually performed outside of the cryostat either with a fiber coupler or an optical splitter box. The easy handling and the outstanding longterm stability open up new possibilities in all quantum optics and spectroscopy applications in the sub-micron range.

The microscope uses a set of xyz-positioners for coarse positioning of the sample over a range of several mm, and a dedicated mechanically amplified piezo based xy scanner with a very large scan range even at cryogenic temperatures.

Optionally, the attoCFM II can be equipped with interferometric encoders for closed loop xy scanning with 1 nm resolution, and an ultra large range scanner with 125 μm scan range at 4 K. Being made from non-magnetic materials, the microscope is ideally suited for photoluminescence spectroscopy and other quantum optics applications in combination with high magnetic fields.

For data acquisition during scanning, our powerful and flexible ASC500 SPM controller with its open signal architecture can be used. It addresses the needs of experts to have control over all signals, while maintaining a very user-friendly software interface that also supports measurement routines based on LabVIEW scripts. All in- and output signals are accessible via front panel BNCs, and can hence easily be monitored, stored and used for additional control loops or spectroscopies. Finally, our unique closed loop scan option allows for global sample navigation over the complete range of the microscope at cryogenic temperatures, and hence enables the retrieval of regions of interest very precisely. For more info please refer to the fundamentals section.

Cryogenic Tablet


General Specifications
type of instrumentfiber optics based confocal microscope for maximum stability
sensor head specificsfiber-coupled low temperature compatible aspheric objectives for ultimate stability
Confocal Unit
configuration50/50 fiber coupler integrated into laser/detector module LDM600 (see SPM and electronics section)
key benefitsultimate longterm stability & ease-of-use
pinhole configurationpinhole provided by single mode fiber core
pinhole sizedependent on fibers, typically 3 .. 9 µm mode field diameter
compatible LT-objectiveLT-IWDO, LT-LWDO (see accessory section for more information)
excitation wavelength rangelimited to wavelength range of single mode fiber, default 650 nm (others on request)
detection modee.g. reflection, luminescence, fluorescence
detection wavelength rangelimited to wavelength range of single mode fiber, default: 650 nm (others on request)
Sample Positioning
total travel range5 x 5 x 4.8 mm³ (open loop)
step size0.05..3 µm @ 300 K, 10..500 nm @ 4 K
fine scan range50 x 50 µm² @ 300 K, 30 x 30 µm² @ 4 K (optional, open loop)
sample holderASH/QE/0 quick exchange sample holder and integrated heater with calibrated temperature sensor
Suitable Operating Conditions
temperature range1.5 K..300 K (dependent on cryostat); mK compatible setup available on request
magnetic field range0..15 T+ (dependent on magnet)
operating pressuredesigned for He exchange gas (vacuum compatible version down to 1E-6 mbar on request)
Suitable Cooling Systems
titanium housing diameter48 mm
bore size requirementdesigned for a 2" (50.8 mm) cryostat/magnet bore
compatible cryostatsattoDRY1000/1100/2100, attoLIQUID1000/2000 (attoLIQUID3000/5000 on request)
Compatibility with Electronics
scan controller and softwareASC500 basic (optional; for detailed specifications please see attoCONTROL section)
laserLDM600 laser/detector module (for detailed specifications please see attoCONTROL section)
Options and Upgrades
closed loop scanning & global sample coordinatesinterferometric encoders for scan linearization and closed loop sample navigation
ultra-large scan range upgrade80 x 80 µm² @ 300 K, 125 x 125 µm² @ 4 K
closed loop upgrade for coarse positionersresistive encoder, range 5 mm, sensor resolution approx. 200 nm, repeatability 1-2 µm
sample holder upgradeASH/QE/4CX quick-exchange sample holder (8 electrical contacts, integrated heater & T-sensor)
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