Mechanical and dimensional measurements

The latest publications in this offer are:

• July 8, 2026

  R1815 Reviewed

  Activity Recognition from Accelerometer Data

  Data based activity recognition has many applications such as postoperative monitoring of ambulatory medicine patients or monitoring of the daily physical activities of elderly people. In this paper it is chosen to consider only the data supplied by an accelerometer. Indeed the accelerometer is a sensor allowing an easy data collection without being dependent on the user’s environment, this due to its availability on smartphones or dedicated devices. The aim of this paper is to review the solutions proposed in the literature for the activity recognition on the basis of accelerometric data.

• July 8, 2026

  R1812 Reviewed

  Acceleration measurements

  Applications for accelerometers have grown steadily. We encounter them everywhere in our day-to-day lives, and they are mass produced. Among the applications for the general public are car airbags, computerized automobile handling systems (such as ABS and ESP) and even washing machines (for keeping the load balanced in the drum). In this article, definitions and some elements of physics are first proposed, followed by an explanation of the different measurement principles. Finally, the gyrometer (a vibrating and acoustic structure) is examined in more detail.

• May 12, 2026

  R1394 Reviewed

  Atomic force microscopy (AFM)

  Atomic force microscopy (AFM) was introduced in 1986 by G. Binnig, C.F. Quate and C. Gerber. Gerber as an application of the scanning tunneling microscope (STM) concept. to study the surfaces of insulating materials on an atomic scale. By combining the principles of the scanning tunnelling microscope and the profilometric stylus, the authors demonstrated the possibility of imaging, in open air, the surface of conductive or non-conductive samples, with a lateral resolution of 30 Å and a vertical resolution of less than 1 Å. Since then, the technique has been adapted to a variety of environments, including vacuum, liquids, low temperatures and magnetic fields, as well as for applications in chemistry and biology.

• March 10, 2026

  R6714 Reviewed

  Scanning optical microscopy

  For a long time, observation through the microscope was carried out solely with the human eye. Photography was soon applied to the microscope, enabling documents to be preserved in memory, and cinematography gave access to the study of temporally variable phenomena. Other information has also been acquired thanks to the spectroscopic or spectrophotometric study of objects which, combined with photographic techniques, makes it possible to obtain images in a given "color", which is a means of analyzing the properties of a preparation or recognizing some of its elements. It should therefore be noted that microscopy is a technique that users are always ready to develop in line with advances in information acquisition.

• March 10, 2026

  R6712 Reviewed

  Light microscopy

  The optical microscope is essentially made up of two optical components: the objective and the eyepiece (figure ). This assembly, attached to a tube, is pointed at the object or preparation placed on a table or stage equipped with devices for positioning the object in its plane, generally by two translational movements and/or one rotational movement. Focusing is ensured by two translation stages parallel to the optical axis: fast and slow movements (highly sophisticated instruments used in research laboratories may have an ultra-slow movement, while some teaching microscopes may only have a single movement with an amplitude and speed intermediate to the usual values).

• March 10, 2026

  R6710 Reviewed

  Microscopy

  Microscopy makes it possible to examine (σκοπειν) objects or their details that are too small (µικροσ) to be seen with the naked eye, by providing enlarged images of them, i.e. to see them from apparent larger angles, to magnify them. Microscopes bring within human reach the infinitely small that escape ordinary vision. Recently, these instruments have been divided into two main classes, depending on whether they use electromagnetic radiation beams to form images - to which we associate the notion of photon, which practically extends in this spectrum from the near infrared to X-rays - or corpuscular radiation beams: electrons or heavier particles such as protons or certain ions, to which modern physics knows how to associate a wave, even if it is not electromagnetic.

• March 10, 2026

  R6470 Reviewed

  Optical activity: optical dichroism

  The use of optical activity, and in particular via circular dichroism, belongs to the most widely used physico-chemical approaches in chemistry and above all life science laboratories, to date. The knowledge of this parameter allows for a better understanding of the fundamental phenomena of living organisms. After introducing the various forms of light polarization, this article presents the main characteristics of optical activity. It then proceeds to describing two essential and strongly linked phenomena, namely the optical rotation and especially the circular dichroism. Various applications of the circular dichroism are presented for the study of small molecules and biomolecules.

• March 9, 2026

  R6733 Reviewed

  Ultra High Speed Digital Imaging

  High-speed imaging records images at much higher rates than the human eye. This allows the prompt analysis of phenomena in the laboratory or the industrial plant. Since the advent of digital onboard memory cameras (CCD and CMOS), recording rates of up to 75 000 FPS have been reached for megapixel format. Decimating* resolution allows one million frames per second. These stupendous rates are permitted at full resolution using storage sites close to the active image, but only for a few hundred images. The response of the sensors to light must be very high, and thus permits very short shutter time.

• March 9, 2026

  R6732 Reviewed

  Ultra-fast cinematography

  In order to break down movements of objects that are too fast to be captured by the eye, optical cinematography has, since its inception , made use of the three dimensions contained in each image (two spatial dimensions and one intensity dimension). The "time base," which provides a regular succession of images, makes it possible to locate the evolution of an object at different moments and to measure its speed and even its acceleration; if the object is deformed, the speed of deformation can also be measured. Transposed to an industrial or laboratory environment, this technique also allows for the measurement of timing and synchronization of events.

• March 9, 2026

  R6410 Reviewed

  Radiometry. Photometry

  This article deals only with the metrological aspects of characterizing optical radiation, sources, propagation in media, properties of samples and passive objects, and detectors. For a description of the structure and properties of sources, media and detectors, the reader will find several references in the bibliography of the fact sheet. . As we shall see, photometry, taken in its broadest sense, is a difficult art, due to the complexity of the spatial and spectral distribution of radiation. For this reason, metrologists have been led to define a relatively large number of quantities that can be measured without too much difficulty, as we shall see.

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