attoCFM IV

free-beam/fiber-based confocal microscope for transmission

combination of attoCFM I and attoCFM III

transmission via 1 free-beam & 1 fiber-based channel

unmatched long-term drift stability

measure single photon signals over extended periods

independent position both objectives in xyz

pump-probe @ large lateral separation (up to 3 mm)


Transmission experiments in confocal microscopy sometimes also require filtering and shaping of the optical beam, and hence free-beam access instead of purely fiber-based can have quite some advantages in terms of flexibility.

This instrument literally consists of a ‚conventional‘ attoCFM I, which has a free-beam based channel with any of our apochromatic objectives above the sample, and a fiber-based channel from below just like in the attoCFM III. So, despite fitting into any of our toploading cryostats, which usually features only 1 top and no side or bottom windows, this setup allows for at least either the excitation or the detection to be free-beam.

This provides the user with all the flexibility of the external optics head just like in case of the attoCFM I for one channel (plus potential reflection measurements).

At the same time, there are 3 degrees of freedom for the sample (xy translation under the fixed LT-APO objective as well as focussing), and another 3 degrees of freedom in xyz to position the fiber-based objective underneath the sample. All positioners are usually equipped with a /RES encoder for closed loop control, and there is an additional scanner for the sample in xy direction. For more info please refer to the fundamentals section.

Cryogenic Tablet


illumination port specificationFC/ APC-connector for single mode fibers or free-beam configuration
detection modee.g. transmission, reflection, luminescence, fluorescence, Raman (optional)
detection wavelength rangefree-beam channel 400 .. 1000 nm, default 650 nm (others on request), fiber channel limited to wavelength range of single mode fiber, default 650 nm (others on request)
detection port specificationfree-beam configuration or FC/ APC-connector for single mode fibers
Sample Positioning
total travel rangesample 3 x 3 x 2.5 mm³ (closed loop), fiber-based objective 5 x 5 x 5 mm³ (effective travel range limited by design of both positioner stacks)
step size0.05..3 µm @ 300 K, 10..500 nm @ 4 K
fine scan rangesample 30 x 30 µm² @ 300 K, 12 x 12 µm² @ 4 K (open loop)
sample holderTi plate with aperture of 8 mm in diameter with integrated heater and calibrated temperature sensor
Suitable Operating Conditions
temperature range1.5 K..300 K (dependent on cryostat); mK compatible setup available on request
magnetic field range0..14 T (dependent on magnet)(16 T compatible version available on request)
operating pressuredesigned for He exchange gas
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
General Specifications
type of instrumentconfocal microscope for transmission experiments with one free-beam and one fiber based channel
sensor head specificsone channel with unique LT compatible achromatic objectives with high numerical aperture, optimized for different wavelength ranges, and one channel with fiber-coupled LT compatible aspheric objective
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)
Confocal Unit
configurationcompact and modular design, two or more optical channels; standard configuration: one excitation and one detection channel
key benefitsquick and reliable alignment of each channel, steering mirror for combined beams long-term stability
quick-exchange of optical componentsbeamsplitters, filter mounts for up to 4 filters/polarizers, (1" diameter); optional piezoelectric rotator with filter mount
pinhole configurationtwo pinholes (fiber apertures), different illumination and collection wavelength possible
pinhole sizedependent on fibers, typically 3 .. 9 µm mode field diameter
compatible LT-objectiveLT-APO/VIS, LT-APO/VISIR, LT-APO/NIR (see accessory section for more information)
inspection unitsample imaging with large field of view: ~54 µm (attoDRY), ~40 µm (attoLIQUID)
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