Academic literature on the topic 'Thermischer Drift'

ZusammenfassungIn diesem Artikel wird die Messpräzision eines hochfrequent fokusabstandsmodulierten, fasergekoppelten Konfokalsensors unter temperaturstabilen Bedingungen bestimmt. Insbesondere in der Mikro- und Nanomesstechnik verursachen thermische Driften signifikante Messabweichungen. Diese lassen sich bei wiederholten Messungen zwar zu einem großen Teil korrigieren, innerhalb einer Messung ist dies bisher jedoch nicht möglich. Das verwendete Nanokoordinatenmesssystem (NMM-1) wurde daher um eine Temperierhaube erweitert, um thermische Driften zu minimieren. Weiterhin wird die Temperatur mittels kalibrierter Pt100-Temperatursensoren während der Messungen erfasst, um die Korrelation des Messergebnisses und der Temperatur quantitativ zu bestimmen. Inwiefern die Korrektur des Messergebnisses anhand der aufgenommenen Temperatur möglich ist, wird in diesem Artikel evaluiert.

Aufgrund ihrer Kinematik und ihrer Beweglichkeit bieten Industrieroboter (IR) eine flexible, anpassungsfähige Basis. Ein Hauptnachteil der Verwendung von IR zur Bearbeitung ist die geringe strukturelle Steifigkeit sowie fehlende Genauigkeit der seriellen Kinematik. Eine Einflussgröße, die insbesondere für Prozesse mit langen Prozesszeiten relevant ist, ist die Erwärmung der Roboterstruktur und die damit verbundene thermische Drift des Tool Center Point (TCP). Die maximale Abweichung von der tatsächlichen Sollposition kann bis zu 1,5 mm betragen.   Due to their kinematics and their mobility, industrial robot (IR) systems offer a flexible, adaptable basis. A major disadvantage of the use of IR for machining is the structural low stiffness and low accuracy of serial kinematics. An influencing variable, which is particularly relevant for processes with long process times, is the thermal heating and the associated thermal drift of the tool center point (TCP). The maximum deviation from the actual nominal position can reach up to 1.5 mm.

Crystal structure, DRIFT, infrared and Raman spectra, and the results of thermal analyses of the hitherto wrongly as Mg(H4IO6)2 · 4H20 and Mg(IO4) · 8H2O described dimesoperiodate MgH4I2O10 · 6H2O and of the isostructural zinc compound are presented. The compounds crystallize in the monoclinic space group P21 (Z = 2) with a = 1071.0(2), b = 547.0(1), c = 1194.9(2) pm, and β = 112.58(3)° and a = 1073.3(3), b = 545.3(2), c = 1188.3(5) pm, and β = 112.52(3)°, respectively. The structure, which was refined from X-ray single crystal data of the magnesium compound (R1 = 2.72%, 3824 independet reflections), is built up from isolated distorted M(H2O)62+ octahedra and dimesoperiodate ions H4I2O102- connected by a network of hydrogen bonds formed by the H4I2O102- ions and six crystallographically different hydrate H2O molecules. The strength of the hydrogen bonds ranges from unusually weak bonds corresponding to uncoupled (isotopically dilute samples) OD stretching modes of > 2600cm-1 and very strong ones (νOD: < 2200 cm-1). The IO stretching modes of the transconfigurated H4I2O102- ions are assigned to terminal I-O groups (816 cm-1), I-OH groups (746 and 762cm-1) and bridging I-O groups (618 and 647cm-1). On heating, MgH4I2O10 · 6H2O undergoes dehydration in the range of 373 - 485 K (Differential Scanning Calorimetry) to two different polymorphs of magnesium metaperiodate (H4I2O102-→2IO4- + 2H2O). Anhydrous Mg(IO4)2 is instable. Above 423 K (high-temperature Raman data), it decomposes to magnesium iodates.

In the past decades, numerous single-molecule techniques have been developed to investigate individual bio-molecules and cellular machines. While a lot is known about the structure, localization, and interaction partners of such molecules, much less is known about their mechanical properties. To investigate the weak, non-covalent interactions that give rise to the mechanics of and between proteins, an instrument capable of resolving sub-nanometer displacements and piconewton forces is necessary. One of the most prominent biophysical tool with such capabilities is an optical tweezers. Optical tweezers is a non-invasive all-optical technique in which typically a dielectric microsphere is held by a tightly focused laser beam. This microsphere acts like a microscopic, three-dimensional spring and is used as a handle to study the biological molecule of interest. By interferometric detection methods, the resolution of optical tweezers can be in the picometer range on millisecond time scales. However, on a time scale of seconds—at which many biological reactions take place—instrumental noise such as thermal drift often limits the resolution to a few nanometers. Such a resolution is insufficient to resolve, for example, the ångstrom-level, stepwise translocation of DNA-binding enzymes corresponding to distances between single basepairs of their substrate. To reduce drift and noise, differential measurements, feedback-based drift stabilization techniques, and ‘levitated’ experiments have been developed. Such methods have the drawback of complicated and expensive experimental equipment often coupled to a reduced throughput of experiments due to a complex and serial assembly of the molecular components of the experiments. We developed a high-resolution optical tweezers apparatus capable of resolving distances on the ångstrom-level over a time range of milliseconds to 10s of seconds in surface-coupled assays. Surface-coupled assays allow for a higher throughput because the molecular components are assembled in a parallel fashion on many probes. The high resolution was a collective result of a number of simple, easy-to-implement, and cost-efficient noise reduction solutions. In particular, we reduced thermal drift by implementing a temperature feedback system with millikelvin precision—a convenient solution for biological experiments since it minimizes drift in addition to enabling the control and stabilization of the experiment’s temperature. Furthermore, we found that expanding the laser beam to a size smaller than the objective’s exit pupil optimized the amount of laser power utilized in generating the trapping forces. With lower powers, biological samples are less susceptible to photo-damage or, vice versa, with the same laser power, higher trapping forces can be achieved. With motorized and automated procedures, our instrument is optimized for high-resolution, high-throughput surface-coupled experiments probing the mechanics of individual biomolecules. In the future, the combination of this setup with single-molecule fluorescence, super-resolution microscopy or torque detection will open up new possibilities for investigating the nanomechanics of biomolecules.

Shutter-less infrared cameras based on microbolometer focal plane arrays (FPAs) are the most widely used cameras in thermography, in particular in the fields of handheld devices and small distributed sensors. For acceptable measurement uncertainty values the disturbing influences of changing thermal ambient conditions have to be treated corresponding to temperature measurements of the thermal conditions inside the camera. We propose a compensation approach based on calibration measurements where changing external conditions are simulated and all correction parameters are determined. This allows to process the raw infrared data and to consider all disturbing influences. The effects on the pixel responsivity and offset voltage are considered separately. The responsivity correction requires two different, alternating radiation sources. This paper presents the details of the compensation procedure and discusses relevant aspects to gain low temperature measurement uncertainty.

In the past decades, numerous single-molecule techniques have been developed to investigate individual bio-molecules and cellular machines. While a lot is known about the structure, localization, and interaction partners of such molecules, much less is known about their mechanical properties. To investigate the weak, non-covalent interactions that give rise to the mechanics of and between proteins, an instrument capable of resolving sub-nanometer displacements and piconewton forces is necessary. One of the most prominent biophysical tool with such capabilities is an optical tweezers. Optical tweezers is a non-invasive all-optical technique in which typically a dielectric microsphere is held by a tightly focused laser beam. This microsphere acts like a microscopic, three-dimensional spring and is used as a handle to study the biological molecule of interest. By interferometric detection methods, the resolution of optical tweezers can be in the picometer range on millisecond time scales. However, on a time scale of seconds—at which many biological reactions take place—instrumental noise such as thermal drift often limits the resolution to a few nanometers. Such a resolution is insufficient to resolve, for example, the ångstrom-level, stepwise translocation of DNA-binding enzymes corresponding to distances between single basepairs of their substrate. To reduce drift and noise, differential measurements, feedback-based drift stabilization techniques, and ‘levitated’ experiments have been developed. Such methods have the drawback of complicated and expensive experimental equipment often coupled to a reduced throughput of experiments due to a complex and serial assembly of the molecular components of the experiments. We developed a high-resolution optical tweezers apparatus capable of resolving distances on the ångstrom-level over a time range of milliseconds to 10s of seconds in surface-coupled assays. Surface-coupled assays allow for a higher throughput because the molecular components are assembled in a parallel fashion on many probes. The high resolution was a collective result of a number of simple, easy-to-implement, and cost-efficient noise reduction solutions. In particular, we reduced thermal drift by implementing a temperature feedback system with millikelvin precision—a convenient solution for biological experiments since it minimizes drift in addition to enabling the control and stabilization of the experiment’s temperature. Furthermore, we found that expanding the laser beam to a size smaller than the objective’s exit pupil optimized the amount of laser power utilized in generating the trapping forces. With lower powers, biological samples are less susceptible to photo-damage or, vice versa, with the same laser power, higher trapping forces can be achieved. With motorized and automated procedures, our instrument is optimized for high-resolution, high-throughput surface-coupled experiments probing the mechanics of individual biomolecules. In the future, the combination of this setup with single-molecule fluorescence, super-resolution microscopy or torque detection will open up new possibilities for investigating the nanomechanics of biomolecules.