scholarly journals Material Evaluation with Various Optical Measurement Systems: Focusing on Terahertz Spectroscopy

2010 ◽  
Vol 53 (5) ◽  
pp. 344-347
Keyword(s):  
Optical Measurement ◽  
Terahertz Spectroscopy ◽  
Measurement Systems ◽  
Material Evaluation

scholarly journals Nano-imprinted subwavelength gratings as polarizing beamsplitters

2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Julian Wüster ◽  
Yannick Bourgin ◽  
Patrick Feßer ◽  
Arne Behrens ◽  
Stefan Sinzinger
Keyword(s):  
Nanoimprint Lithography ◽  
Optical Measurement ◽  
Design Method ◽  
Optical Systems ◽  
Surface Metrology ◽  
Measurement Systems ◽  
Common Path ◽  
Dielectric Coatings ◽  
Subwavelength Gratings ◽  
Wide Range

AbstractPolarizing beamsplitters have numerous applications in optical systems, such as systems for freeform surface metrology. They are classically manufactured from birefringent materials or with stacks of dielectric coatings. We present a binary subwavelength-structured form-birefringent diffraction grating, which acts as a polarizing beamsplitter for a wide range of incidence angles −30∘…+30∘. We refine the general design method for such hybrid gratings. We furthermore demonstrate the manufacturing steps with Soft-UV-Nanoimprint-Lithography, as well as the experimental verification, that the structure reliably acts as a polarizing beamsplitter. The experimental results show a contrast in efficiency for TE- and TM-polarization of up to 1:18 in the first order, and 34:1 in the zeroth order. The grating potentially enables us to realize integrated compact optical measurement systems, such as common-path interferometers.

scholarly journals Detection of foot contact in treadmill running with inertial and optical measurement systems

2021 ◽  
pp. 110419
Author(s):  
Jasper Reenalda ◽  
Marit A. Zandbergen ◽  
Jelle D. Harbers ◽  
Max R. Paquette ◽  
Clare E. Milner
Keyword(s):  
Optical Measurement ◽  
Treadmill Running ◽  
Measurement Systems

Methods of temperature measurement in microwave heating technologies

2021 ◽  
pp. 20-28
Author(s):  
Boris A. Lapshinov
Keyword(s):  
Temperature Measurement ◽  
Microwave Heating ◽  
Microwave Radiation ◽  
Electromagnetic Fields ◽  
Optical Measurement ◽  
Measurement Methods ◽  
Heating Systems ◽  
Measurement Systems ◽  
Processed Material ◽  
Spectral Pyrometry

In industrial technological processes associated with the heating of the processed material by microwave radiation, it is necessary to measure the temperatures of objects. Methods for measuring temperatures in the fields of technology using microwave heating systems are considered. The main possibilities, disadvantages and limitations of the used contact and non-contact (optical) measurement methods are determined. The requirements for temperature measurement systems under conditions of exposure to strong electromagnetic fields are listed. The possibilities of the spectral pyrometry method are especially noted.

scholarly journals Multi-layered tissue head phantoms for noninvasive optical diagnostics

2015 ◽  
Vol 08 (03) ◽  
pp. 1541005 ◽  
Author(s):  
M. S. Wróbel ◽  
A. P. Popov ◽  
A. V. Bykov ◽  
M. Kinnunen ◽  
M. Jędrzejewska-Szczerska ◽  
...  
Keyword(s):  
Optical Properties ◽  
Near Infrared ◽  
Optical Measurement ◽  
Human Head ◽  
Medical Diagnostics ◽  
Optical Parameters ◽  
Measurement Systems ◽  
Tissue Phantoms ◽  
Optical And Mechanical Properties

Extensive research in the area of optical sensing for medical diagnostics requires development of tissue phantoms with optical properties similar to those of living human tissues. Development and improvement of in vivo optical measurement systems requires the use of stable tissue phantoms with known characteristics, which are mainly used for calibration of such systems and testing their performance over time. Optical and mechanical properties of phantoms depend on their purpose. Nevertheless, they must accurately simulate specific tissues they are supposed to mimic. Many tissues and organs including head possess a multi-layered structure, with specific optical properties of each layer. However, such a structure is not always addressed in the present-day phantoms. In this paper, we focus on the development of a plain-parallel multi-layered phantom with optical properties (reduced scattering coefficient [Formula: see text] and absorption coefficient μa) corresponding to the human head layers, such as skin, skull, and gray and white matter of the brain tissue. The phantom is intended for use in noninvasive diffuse near-infrared spectroscopy (NIRS) of human brain. Optical parameters of the fabricated phantoms are reconstructed using spectrophotometry and inverse adding-doubling calculation method. The results show that polyvinyl chloride-plastisol (PVCP) and zinc oxide ( ZnO ) nanoparticles are suitable materials for fabrication of tissue mimicking phantoms with controlled scattering properties. Good matching was found between optical properties of phantoms and the corresponding values found in the literature.

Optical measurement systems

Mechatronics ◽  
1991 ◽  
pp. 49-74
Author(s):  
D. A. Bradley ◽  
D. Dawson ◽  
N. C. Burd ◽  
A. J. Loader
Keyword(s):  
Optical Measurement ◽  
Measurement Systems

Centering of Camera Principal Point and Turntable Axis in Optical Measurement Systems

2019 ◽  
Vol 46 (11) ◽  
pp. 1104002
Author(s):  
侯艳丽 Hou Yanli ◽  
苏显渝 Su Xianyu ◽  
陈文静 Chen Wenjing
Keyword(s):  
Optical Measurement ◽  
Principal Point ◽  
Measurement Systems

High-speed laser interferometric distance sensor with reference mirror oscillating at ultrasonic frequencies

2019 ◽  
Vol 86 (3) ◽  
pp. 164-174 ◽  
Author(s):  
Sebastian Hagemeier ◽  
Stanislav Tereschenko ◽  
Peter Lehmann
Keyword(s):  
High Speed ◽  
Optical Measurement ◽  
Limited Range ◽  
Distance Measurement ◽  
Reference Mirror ◽  
Acquisition Rate ◽  
Measurement Systems ◽  
3D Topography ◽  
Distance Sensor ◽  
Laser Interferometric

AbstractOptical measurement systems are an important part of the portfolio of 3D topography sensors. By precise, contactless and rapid measurements these sensors constitute an alternative to tactile instruments. In this contribution the principle of a laser interferometric distance sensor is presented, which in combination with lateral scan axes acts as a topography sensor and also as distance sensor for the compensation of vibrations in a coherence scanning Linnik interferometer. An advantage of this distance sensor is its high acquisition rate of height values, which in case of working as a topography sensor enables high scan velocities as it is demonstrated at a chirp standard measured with a scan velocity of 80 mm/s. This is much higher than the scan velocity of tactile instruments, which are typically limited up to 1 mm/s. In addition, the compensation of vibration disturbances demonstrates the capability of the fast distance measurement.In contrast to other existing high-speed point sensors the relevant components are mass products. This keeps the costs of the sensor setup in a limited range. Furthermore, the sensor shows potential of much higher measurement rates than 116 kHz provided by the sensor used here.

scholarly journals Analysis of Modern Optical Inspection Systems for Parts Manufactured by Selective Laser Melting

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3202
Author(s):  
Sara Giganto ◽  
Susana Martínez-Pellitero ◽  
Eduardo Cuesta ◽  
Víctor M. Meana ◽  
Joaquín Barreiro
Keyword(s):  
Selective Laser Melting ◽  
Optical Measurement ◽  
Point Of View ◽  
Laser Triangulation ◽  
Laser Melting ◽  
Measurement Systems ◽  
Geometric Dimensioning And Tolerancing ◽  
Inspection Systems ◽  
Conoscopic Holography ◽  
T Values

Metal additive manufacturing (AM) allows obtaining functional parts with the possibility of optimizing them topologically without affecting system performance. This is of great interest for sectors such as aerospace, automotive, and medical–surgical. However, from a metrological point of view, the high requirements applied in these sectors constitute a challenge for inspecting these types of parts. Non-contact inspection has gained great relevance due to the rapid verification of AM parts. Optical measurement systems (OMSs) are being increasingly adopted for geometric dimensioning and tolerancing (GD&T) verification within the context of Industry 4.0. In this paper, the suitability (advantages and limitations) of five different OMSs (based on laser triangulation, conoscopic holography, and structured light techniques) for GD&T verification of parts manufactured by selective laser melting (SLM) is analyzed. For this purpose, a specific testing part was designed and SLM-manufactured in 17-4PH stainless steel. Once the part was measured by contact (obtaining the reference GD&T values), it was optically measured. The scanning results allow comparing the OMSs in terms of their inspection speed as well as dimensional and geometrical accuracy. As a result, two portable systems (handheld laser triangulation and structured blue-light scanners) were identified as the most accurate optical techniques for scanning SLM parts.

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