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Probe calibration

a calibration and probe technology, applied in the direction of scanning probe techniques, instruments, etc., can solve the problems of uncertainty in the spring constant of the cantilever, and the limited range in which the spring constant can be reliably measured, and achieve the effects of large sensitivity range, different resonance frequency, and fast and simpl

Inactive Publication Date: 2015-01-08
NEDERLANDSE ORG VOOR TOEGEPAST NATUURWETENSCHAPPELIJK ONDERZOEK TNO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This method provides high linearity and sensitivity over a large dynamic range, enabling reliable and efficient calibration of AFM probes with varying spring constants, suitable for both single and batch calibrations, and is compatible with small-sized calibration levers.

Problems solved by technology

Process non-uniformities and variations during fabrication of the cantilever, contaminations and imperfections lead to uncertainties in cantilever's spring constant.
However, due to the large scale of the calibration lever the range in which the spring constant can be reliably measured is limited.

Method used

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Experimental program
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first embodiment

[0055]FIG. 1 schematically shows an arrangement 1 according to the invention for calibrating probes 2. The arrangement comprises a source 10 of coherent photon radiation with wavelength δS, such as a lensed fiber laser diode, a grating coupled laser diode or an invert tapered laser diode. The arrangement further comprises a sense unit 12 including an optically based strain sensor 12a for measuring an amount of strains. The optically based strain sensor has an optical property dependent on an amount of strain. The sense unit 12 further has a read-out unit (also denoted as interrogator) 12b for generating an electric signal indicative of said dependent optical property. The sense unit 12 is coupled to the source of coherent photon radiation.

[0056]The arrangement further comprises a calibration lever 14 having a surface 15 for placement of a tip 21 of a probe 2 to be calibrated. The calibration lever 14 is mechanically coupled to the sense unit 12 for converting a force exerted by said...

second embodiment

[0061]FIG. 3 schematically shows an arrangement according to the invention. In this embodiment the source of coherent photon radiation has a tunable wavelength and the source 10 is controlled by a wavelength control facility 11 for varying said wavelength over a wavelength range by a control signal SC. The wavelength control facility 11 also provides an output signal Sλ indicative for the wavelength to which the source is tuned. This embodiment is preferred as the resonation wavelength is linearly dependent of the strain in the sensor and therewith also linear dependent with the force exerted by the probe to be calibrated.

[0062]In an embodiment the wavelength control facility 11 causes the source of coherent photon radiation to vary the wavelength λS over a wavelength range and the read-out 12b is arranged to determine the wavelength λS for which the measured intensity I is optimal, i.e. the resonation wavelength λres being indicative for the amount of strain sensed in the optically...

fourth embodiment

[0064]FIG. 4 schematically shows a The arrangement in this embodiment further comprises a wavelength tracking unit 12c having an input coupled to the source of coherent photon radiation 10. The wavelength tracking unit 12c is arranged for generating an output signal Sλ indicative for the sensed wavelength λS. In this case the wavelength tracking unit 12c and the optically based strain sensor 12a of the sense unit are coupled to the source 10 via a splitter 16.

[0065]FIG. 5 shows part of a particular arrangement according to the present invention in more detail. FIG. 5A provides a further detailed view according to VA in FIG. 5. FIG. 5B is a top-view according to VB in FIG. 5A. Hidden surfaces are shown therein as dashed lines. In the embodiment shown in FIGS. 5, 5A and 5B the optically based strain sensor 12a is an integrated nanophotonic sensor, comprising a ring resonator or other sensitive device mounted on a substrate 30. The optically based strain sensor 12a receives an input b...

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Abstract

The arrangement for calibrating probes comprises a source (10) of coherent photon radiation and at least one optically based strain sensor (12a) for measuring an amount of strain (ε). The at least one optically based strain sensor is optically coupled to said source of coherent photon radiation. The arrangement further comprises at least one calibration lever (14) having a surface for placement of a tip (21) of a probe (2) to be calibrated, and that is mechanically coupled to the at least one optically based strain sensor for converting a force (F) exerted by said tip at said surface into an amount of strain in the optically based strain sensor. The arrangement further comprises at least one probe holder (24) for holding the probe (2) to be calibrated, the at least one probe holder having a controllable position in at least a direction (y) transverse to the surface of the calibration lever (14). The arrangement further comprises a calibration control facility (46) for controlling said controllable position within a range of position values, and for determining a mechanical property of said probe from the measured amount of strain (ε) and a deflection (δC) of the tip (21) of the probe relative to the probe holder as a function of said position. The arrangement may be used as a stand-alone device or may be integrated in a device, such as an AFM-device. The arrangement may also be carried out as a batch-calibration device.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the invention[0002]The present invention relates to an arrangement for calibrating probes such as AFM probes.[0003]The present invention further relates to an atomic force microscope including such an arrangement.[0004]The present invention further relates to a batch calibration device for calibrating a batch of probes, such as a batch of AFM-probes.[0005]The present invention further relates to a method for calibrating AFM probes.[0006]2. Related Art[0007]Atomic force microscopes AFMs are widely used for the physical characterization of materials and devices when high spatial resolution and small feature sizes are of interest. AFMs are primarily used in imaging modes to provide topographic information, but they can also record the force interaction between the cantilever sensor tip and a sample.[0008]Measuring the force interaction between the tip and surface involves measuring the deflection of a spring suspension. In the case of an AFM...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G01Q40/00
CPCG01Q40/00
Inventor SADEGHIAN MARNANI, HAMED
Owner NEDERLANDSE ORG VOOR TOEGEPAST NATUURWETENSCHAPPELIJK ONDERZOEK TNO