Contactless 3D Inspection of Surfaces Using a White Light Interferomter
Surface inspection is important for many manufacturing processes in countless industrial and research fields. Today optical measuring methods provide resolutions down to single-digit nanometers. Such depths of field require the use of high resolution nanopositioners.
piezosystem jena’s MIPOS 500 SG is one of the main components of the white light interferometer smartWLI. The MIPOS 500 SG provides a motion range of up to 500 µm and is capable of moving objectives up to 500 grams at a high resonant frequency.
The modells of the white light interferometer smartWLI is an upgrade for optical microscopes. This system is developed and manufactured by GBS mbH, Ilmenau and can fit on all well-known microscope manufacturers, e. g. ZEISS, LEICA, NIKON, OLYMPUS, MT RATHENOW. By using the smartWLI-system, the user can upgrade a common 2D optical microscope to a 3D surface measurement system.
From a Microscope to a Nanoscope - Piezoelectric Solutions
In conventional confocal microscopy the limit of the resolution is half of the wavelength of light. For blue light this is 200 nm. This resolution limit was postulated by Ernst Abbe 1873 and for decades it was considered, that this limit could not be overcome. The reason is based on the diffraction, which occurs at two clearly differentiated objects and makes both objects appear blurred together as one. Using the Stimulated Emission Depletion Method (STED) developed by Prof. Dr. Stefan W. Hell, a higher resolution could be achieved, which was far below the previously mentioned limit. The microscope became a nanoscope and alters long-standing conceptions about the resolving powers in light microscopy.
In the STED method, a specimen is excited by a diffraction-limited pulsed ultra fast laser source (10 to 300 pico seconds) reaching a fluorescent state. The specimen is phase delayed being overlaid by a depleting laser source. This second laser pulse (STED-beam), takes advantage of the subsequently molecular relaxation and of the interferences of coherent light. This produces radial depletion zones and gives the beam a doughnut-shape. The result is a prevention of the effective excitation of the specimen, except in the focal spot, which is in the central area of the doughnut-shaped beam. The remaining spot can be reduced in circumferences to achieve a higher resolution. The remaining fluorizing spot is beeing scanned over the complete sample to obtain the final image. Molecular processes can be inspected in vivo and can also be investigated and tracked in real time. In contrary to other microscopy methods, the specimen is not being destroyed, its molecular constitution remains preserved because the microscope uses harmless visible light. Studying living cells is not just one of the more interesting but also demanding subjects in the nanoscopy. The noninvasive method constitutes one of the biggest advantages of the the STED microscopy. 3D-images can be obtained of samples like proteins down to a resolution of nanometers, almost the real size of the proteins theirselves. Another big advantage that contributes to the increasing popularity of the STED method is the speed. With 80 fps for a range of 60 to 80 nm is STED the fastest one of the microscopy methods. The method works with every fluorecent molecule, the image processing is not complicated.
The scanning processes in STED microscopy setups have to be very fast to meet those special requirements. Piezoelectric stages, tilting systems and objective positioners from Piezosystem Jena are suitable instruments, which are indispensable in these STED setups. The functionality of these systems are based on the inverse piezoelectric effect, discovered first by the Curie brothers in 1880. The inverse piezoelectric effect states, that an applied voltage to a piezoelectrical material causes a change in the dimensions of the material. With this change in dimension a motion is generated. Actuators from Piezosystem Jena use a special PZT (lead-zirconium-titanate) ceramic to generate a motion down to nanometer range. Piezosystem Jena also offers a variaty of actuators for applications such as laser technologies, semiconductor industry, life science among others.
The objective positioners of the series MIPOS, the mirror tilting system series PSH and the z-axis scanner PZ300AP CAP AP are great examples of products, that can be used for STED microscopy. These elements can move to pre-defined positions very fast with a high precision in nanometers.
The series MIPOS offers microscope objective positioners for standard and special objectives for all major microscope brands, Carl Zeiss, Nikon, Leica, Mitutoyo, just to mention a few. They can be used for single objectives or to move the complete objective revolver. The series PSH includes large tilting stages for mirrors and other optics, that can be tilted and positioned with frequencies up into the kilohertz range.
With the PZ300 AP Piezosystem Jena developed a special product for microscopy applications. With a very small overall height, and a very big aperture, the PZ300 AP accommodates standard microscopy accessories like incubators and multiwells sample holders. The stage has been designed to fit into Märzhauser and Prior XY-microscope standard stages.
All the systems can be controlled with Piezosystem Jena amplifiers. You can easily find one, that meets your requirements, within a wide range of products and a long variety of features. Such as: high current, integrated function generators with storage function, filters (notch, low pass), triggering and interfaces (USB, RS232, Ethernet).
Piezosystem Jena elements used in the super-resolution imaging of a neuronal cell in a living mouse brain.
Products in the above set up: Microscope Positioner Mipos 100 CAP and Piezo Amplifier NV120CLE.
Images courtesy of Dr. Katrin Willig, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Göttingen; As well as Prof. Dr. Stefan W. Hell, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
Nanolife AFM System based on Piezosystem Scanners
The company Nanotec Eléctronica S.L. from Spain has developed an innovative concept for the AFM microscopy. By using this platform, conventional optical microscopes (fluorescence microscopes, up-side down) or Raman microscopes can produce simultaneously an AFM image in addition to the optical images. These generated images can be viewed at the same time. In order to meet the high speed and resolution requirements, the SPM system "Nanolife“ contains piezoelectric elements (PXY 80 D12) of piezosystem jena.
The following pictures were generated by Dr. Elena López-Elvira by using the innovative AFM platform in the ICMM-CSIC (Madrid, Spain).
More information can be requested from Nanotec Eléctronica (www.nanotec.es).
AFM Images of Fibroblast in air
Topography AFM images of 60x60µm and Z scale 1.8µm
AFM Images of P3OT polymer in air (non-contact Mode)
Topography AFM (left) and Frequency Shift (right) images of 3.75x3.75 µm and Z scale 32 nm
AFM Images of DNA in buffer (non-contact mode)
Amplitude Modulation –Dynamic Scanning Force Microscopy (+ PLL)
Topography AFM (left) and Frequency Shift (right) images of 1x1 µm and Z scale 3nm
Frequency Modulation –Dynamic Scanning Force Modulation
Topography AFM (left) and Dissipation (right) images of 1x1µm and Z scale 3nm
Optical and AFM images of single cells in buffer (non-contact mode)
AFM Topography (right) image of 35x35µm and Z scale 360nm
Scanning Near-Field Optical Microscopy at Infrared Wavelengths
In optical imaging, a well-known limit to the resolution is due to the diffraction limit. The maximum spatial resolution achievable by a classical optical instrument such a microscope lambda/2, where lambda is the wavelength used for the observation. The Fourier amplitudes of the electromagnetic field corresponding to high spatial frequencies, which are necessary to resolve details much smaller than lambda, are contained in electromagnetic waves confined near the sample surface, in a region called the near-field, as they decay exponentially in the direction perpendicular to the surface. These evanescent waves can in principle not be detected far from the sample. This constitutes a severe limitation to the resolution in classical optical imaging, especially in the infrared where the wavelength is typically of the order of 10 µm.
Scanning near-field optical microscopy (SNOM) allows one to detect the evanescent waves in the near-field in order to produce optical images at nanometer resolution. This instrument is based on an atomic force microscope (AFM), which uses piezoelectric translations in order to image the topography of the scanned area of a sample by raster scanning a nanosized tip on it. The principle of a SNOM with a scattering tip (s-SNOM) is illustrated in figure 1, for the case of near-field imaging the surface of semi-conductor laser devices, as discussed below. While in a basic AFM experiment, only the feedback signal which controls the Z position of the tip is recorded as a function of its XY position to image the topography of the sample, in a s-SNOM experiment, the tip also serves to scatter the electromagnetic near-field. As its apex constitutes a subwavelength scatterer, the intensity of the scattered field measured as a function of the XY tip position by means of a single channel photodetector combined with collection optics (parabolic mirrors, lenses, …) produces a super-resolved optical image of the scanned area of the sample surface, with the same resolution as that of the simultaneously recorded AFM topography. Resolutions as good as a few tens of nanometers can be achieved using s-SNOM in optical images, even at infrared wavelengths.
The s-SNOM developed by the group of Dr. Yannick De Wilde at Institut Langevin, ESPCI ParisTech – CNRS in Paris, is based on piezosystem jena nanopositioning systems (figure 1). The sample is mounted on a XY piezoelectric translation PXY 100SG, which achieves displacements with a resolution of the positioning better than 2 nm over a total range of 80 µm x 80 µm in closed loop. It uses an electrochemically etched tungsten tip which is glued on a quartz tuning fork (QTF). During the measurements, the latter is excited near its mechanical resonance by means of a small piezoelectric plate. The resulting oscillations produce intermittent contacts of the tip with the sample surface at a frequency of approximately 30 KHz. The amplitude of the QTF electrical signal is used in a feedback loop which controls the tip height by means of a N-series stack actuator with a full range of 16 µm. The scanning head is placed under a high numerical aperture reflective objective aimed at collecting the infrared light scattered by the tip apex, which is then focused on a nitrogen cooled mercury cadmium telluride (MCT) detector. The output signal from the detector is measured with a lock-in amplifier using the tip oscillation frequency as a reference, in order to extract the near-field signal due to tip scattering from parasitic background contributions.
This s-SNOM is capable to image the near-field at infrared wavelengths on semiconductor devices in operation, or even to image the sole infrared thermal emission from a heated sample. As a first illustrative example, figure 2 shows images of the surface topography and the near-field which have been simultaneously recorded at the surface of a mid-infrared quantum cascade laser emitting at lambda=7.5 µm. The latter was developed by the group of Dr. Raffaele Colombelli at the Institut d’Electronique Fondamentale, Univ. Paris Sud and CNRS, in Orsay. The region of the device which has been scanned is the upper metal electrode structured in a 1.2 µm-pitch grating, whose role is to generate surface waves called surface plasmons when the laser is electrically pumped [1,2]. While the topography image reveals the grating structure, the infrared near-field image shows the spatial distribution of the electromagnetic mode on the laser cavity. These type of s-SNOM observations performed at Institut Langevin, have played a key role in the development of novel devices by the team at the Institut d’Electronique Fondamentale. Among the recent demonstrations, we can cite the generation of hybrid surface plasmons by electrical pumping , the coupling of surface plasmons into passive waveguides , and the enhancement of their confinement properties .
Another example of application of the s-SNOM set-up at Institut Langevin is its use for probing the infrared thermal emission in the near-field . This novel mode of operation of a s-SNOM, called thermal radiation scanning tunnelling microscopy (TRSTM), can be considered as the near-field equivalent of infrared night-vision camera. The set-up allows one to measure the infrared thermal emission at the surface of a sample which is mounted on a hot plate to raise its temperature up to 200 °C. New physical phenomena such as the standing mode pattern formed by thermally excited surface plasmons, have been demonstrated in TRSTM mode. Remarkably, the instrument allows one to probe the electromagnetic local density of states, which is a quantity of fundamental interest . Figure 3a, gives an example illustrating the spatial resolution of the instrument for imaging the near-field thermal emission of two materials at lambda=10 µm.
Besides near-field imaging, the group has recently combined the scanning probe with a Fourier transform infrared spectrometer, in order to develop a new type of FTIR spectroscopy capable to measure an infrared spectrum with a spatial resolution of approximately 100 nm . As an example, figure 3b shows the near-field spectrum measured at the surface of a silicon carbide sample by Florian Peragut who is PhD student in the Institut Langevin group. Now that near-field spectroscopy has been demonstrated, his goal is to tweak the instrument to achieve hyperspectral imaging in the infrared. The principle will then be to acquire spectra not only at one fixed location, but at every points of an image in order to map the spectral properties of the studied sample with a sub-wavelength spatial resolution .
This work was supported by LABEX WIFI (Laboratory of Excellence ANR-10-LABX-24) within the French Program “Investments for the Future” under reference ANR-10- IDEX-0001-02 PSL*.
This work has been supported by the Region Ile-de-France in the framework of C’Nano IdF, the nanoscience competence center of Paris Region.
The authors are grateful to their fruitful collaborators at the Institut d’Electronique Fondamentale (R. Colombelli and A. Bousseksou), Institut P Prime (K. Joulain), Centre de Thermique de Lyon (P.-O. Chapuis), and Laboratoire Charles Fabry, Institut d’Optique (J.-J. Greffet).
Florian Peragut and Yannick De Wilde
Institut Langevin, ESPCI ParisTech, CNRS, 75238 Paris Cedex 05, France
Figure 1: Schematic view illustrating the principle of operation the s-SNOM developed at Institut Langevin for imaging the near-field on semiconductor laser devices
Figure 2: Images measured simultaneously with a s-SNOM showing (a) the topography, and (b) the near-field at the surface of a 1.2 µm-pitch metal grating patterned on the cavity of a quantum cascade laser emitting at =7.5 µm. The near-field image shows that surface plasmons are generated at the surface of the grating [1,2].
Figure 3a: Thermal radiation scanning tunnelling microscope image of a silicon carbide (left side) substrate partially covered by 100 nm thick gold layer (right side) illustrating the spatial resolution of the instrument
Figure 3b: Near-field thermal emission spectrum obtained on SiC with a thermal radiation scanning tunnelling microscope combined with a Fourier transform infrared spectrometer .
 A. Bousseksou, R. Colombelli, A. Babuty, Y. De Wilde, Y. Chassagneux, C. Sirtori, G. Patriarche, G. Beaudoin, I. Sagnes, A semiconductor laser device for the generation of surface-plasmons upon electrical injection, Opt. Express 17, 9391-9400 (2009)
 A. Babuty, A. Bousseksou, J.-P. Tetienne, I. Moldovan Doyen, C. Sirtori, G. Beaudoin, I. Sagnes, Y. De Wilde, R. Colombelli, Semiconductor Surface Plasmon Sources, Phys. Rev. Lett. 104, 226806 (2010)
 A. Bousseksou, A. Babuty, J.-P. Tetienne, R. Braive, G. Beaudoin, I. Sagnes, Y. De Wilde, R. Colombelli, Sub-Wavelength Energy Concentration with Electrically Generated Mid-Infrared Surface Plasmons, Opt. Express 20, 13738 (2012).
 Y. De Wilde, F. Formanek, R. Carminati, B. Gralak, P.-A. Lemoine, K. Joulain, J.-P. Mulet, Y. Chen, J.-J. Greffet, Thermal Radiation Scanning Tunnelling Microscopy, Nature 444, 740-743 (2006).
 A. Babuty, K. Joulain, P.-O. Chapuis, J.-J. Greffet, Y. De Wilde, Blackbody Spectrum Revisited in the Near Field, Phys. Rev. Lett. 110, 146103 (2013).
 F. Peragut, J.B. Brubach, P. Roy, Y. De Wilde, Near-field imaging and spectroscopy with broadband sources, submitted (2014)
Products for Microscopy Application
New super-resolution techniques, such as stimulated emission depletion microscopy, photo-activated localization microscopy and stochastic optical reconstruction microscopy, have reduced resolution from 100 – 200 nm down to 2.4 nm. Piezo positioning stages are perfectly suitable for these and higher resolutions.
The alignment of microscopes and sample holders demands precise, rapid movements. Based on the piezoelectric effect, products by piezosystem jena offer unique technical characteristics, compared to other solutions on the market.
They are characterized by almost unlimited refinement of motion, while avoiding any sort of mechanical play. Thus, they are completely resistant to internal friction. Piezo positioning stages’ high stiffness results in very short response and settling times.
In combination with the flexure hinges design, piezoelectric actuators can generate high accuracy and high speed, perfect for sample adjustment, beam alignment and beam tracking.
piezosystem jena can rely on more than 20 years ofexperience in the research and development of piezoelectrical elements and translation stages for microscopy applications.
TRITOR 102 CAP designed for probe alignment (microscopy)
The TRITOR 102 CAP perfectly meets the requirements for probe alignment applications. The large central opening of 40mm allows the placement of the objective lens directly underneath the sample. Integrated closed loop feedback sensors guarantee long term high precision sample adjustment with nanometer accuracy.
- 3D piezo based sample positioner
- Free central hole (40 mm)
- Sample positioning without mechanical play
- Motion range up to 100µm
- Lowest settling time for fastest scan behavior
PZ 300 AP – Z-axis microscope stage for confocal, fluorescence & laser scanning applications (microscopy)
The PZ 300 AP from piezosystem jena is an Z-axis elevator stage with a motion range of 300µm. The stage fits into microscope stage openings by the dimensions of 160x110mm. As a result this the stage fits to nearly all standard microscopes of the major brands. The PZ 300 is set up for the smooth integration into most of the popular commercial motorized stages (to install in upright and inverse microscopy assemblies).
- Low profile piezoelectrical microscope Z-stage
- Travel range of 300 microns
- Typical working frequency 50Hz
- Settling time in millisecond range
- Inside frame supports standard multi-well size
- Additional probe adapter available
|Märzhäuser SCAN IM||Prior ProScan H117||Prior ProScan H101a|
|Leica DMI3000–5000||Leica DMI4000/5000/6000||Leica DM - range|
|Leica DMI5000M||Leica DMIRB||Nikon Eclipse - range|
|Nikon Eclipse MA100||Nikon TE2000/TI||Olympus BX - range|
|Nikon Eclipse MA200||Olympus IX51/71/81||Olympus IX51/71/81|
|Olympus BX45/BX51/BX61||Zeiss AxioObserver||Zeiss AxioImager|
|Olympus WI/GX51/GX71||Zeiss AxioVert 200||Zeiss Axioplan|
|Olympus IX51/IX71/IX81||Zeiss AxioSkop|
|Zeiss AxioVert 200|
Lens focusing devices series MIPOS
The series MIPOS actuators were developed for the fine adjustment of micro objective lenses and for the adjustment of the whole nosepieces (MIPOS N90). They provide a motion range from 20µm up to 500µm. Position accuracy and resolution are extraordinary high. Therefore, the MIPOS series is the perfect upgrade for modern microscopes.
• Focus range up to 500µm
• Threading size available for all standard microscopes
• Easy assembling and disassembling by Flex-Adapter mechansim
• Spacer rings prafocal for tube extension
• Compatible to standard and inverted microscopes
Thread size available: MIPOS systems can be equipped with available standard micro objective thread sizes from Zeiss, Leica, Nikon, Olympus. Exchangeable thread adapter makes the adjustment of the MIPOS easy to use with every single thread size from W0.8x1/3” up to M32x0.75.
MICI-KMI53 - Semprex Kit (microscopy)
The KMI53 is a result of the cooperation between piezosystem jena and Semprex. By combining the advantages of manual and automated positioning the microscope stage the KMI53 enables a highly flexible alignment. The digital Vernier Micrometer from Semprex provides a travel range of 25 mm. In addition the special piezo-driven micrometer holder MICI guarantees precise automated motion up to 200 µm.
Equipment for piezosystem jena nano-positionig stages (microscopy)
Together with our partner Bioptechs, piezosystem jena has developed specially adapted tables for sample adjustment. This combination enables sample heading, thermal insulation and an effective CO2 control mechanism under the scope. Live cell microscopy is just one out of many applications, where these characteristic represent an exceptional advancement.
- Plate, incubate, and observe without the need to transfer your cells
- Ambient to 50°C temperature range
- Perfusion available
- Heat specimens in standard plasticware
- For use on the microscope stage
- Reduce Z-axis drift
- Live cell microscopy
- Z-axis stable
- Plate, incubate, and observe without the need to transfer your cells
- Ambient to 50°C temperature range
- Perfusion available
Ask us about other environmental control solutions such as:
- CO2 control
- objective cooling collars
- objective thermal isolators
- specimen cooling rings
piezosystem jena positioning stage can be equipped with sample holders and accessories from BIOPTECH®, PECON®, LABTEC®, TOKAI HIT®
Thermal Isolation for Objective Lenses
Demonstration Adapters for MIPOS Objective Positioner