NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual
Basic parts of the measuring head are shown in Fig. 1-5.
1, 2 – screws for XY probe adjusting; 3, 4 – photodiode mirror adjusting screws;
5 –screw for fine focusing of the lens; 6, 7 –screws for XY lens adjusting;
8 – lens positioning device spring stop; 9 – entrance aperture; 10, 11, 12 – screw legs;
13 – lens; 14 – probe holder; 15 –spring stop of the probe holder positioning device
The main functional component of the measuring head is the Mitutoyo M Plan Apo 100
lens (pos. 13). The numerical aperture of the lens is 0.7 and the focal length is 2 mm
while the working distance is 6 mm. The lens provides the following options along with
conventional AFM techniques:
− Viewing the sample with resolution limited by 0.4 μm (at wavelength 550 nm);
− Delivery and focusing the exciting laser radiation;
− Aiming the laser beam at the probe aperture;
− Detecting the probe deflection (needs an additional semiconductor laser diode to
generate radiation of 650 nm or 830 nm wavelength).
The screw for fine focusing of the lens 5 is located in front of the lens. The
microscrews 1 and 2 move the probe holder relative to the lens. Moving the probe holder
provides directing the laser beam of the optical cantilever deflection detection system
(hereinafter referred to as detection system) to the cantilever reflective surface. The
photodiode mirror is adjusted with the screws 3 and 4 so that the beam reflected from the
probe could come directly to the centre of the photodiode. For adjusting the measuring
head in angle and height, three screw legs 10, 11, and 12 are used. The microscrews 6 and
7 provide positioning of the lens against the probe and external optical devices.
ATTENTION! Height adjustment of the legs 10, 11, and 12 is not
recommended as this can misalign the optical system.
Cantilever deflection in AFM modes is detected with the detection system operating a
semiconductor laser (with λ =830 nm or 650 nm) that supplies radiation through the lens.
The system dichroic mirror selectively reflects the radiation of the semiconductor laser. It
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