Temperature measurements using YAG : Dy and YAG : Sm under diode laser excitation (405 nm)

Abstract

Temperature-sensitive phosphors offer an option of accurate contactless temperature measurement. The method can be applied to a wide temperature range and up to more than 1500 K. In the current paper, phosphor thermometry based on four rare earths doped in YAG was studied. The standard excitation of thermographic phosphors is carried out with a Nd : YAG laser often at 355 or 266 nm. We examined the temperature dependent luminescence at an excitation wavelength of 405 nm. The excitation with visible blue light offers two main advantages: the excitation sources are rather cheap and they involve less safety issues. Accordingly, a variety of new application of such remote-thermometry would be possible. The results show that YAG : Dy and YAG : Sm may be well utilized for phosphor thermometry excited by a 405 nm diode laser.

Afterglow-intensity-ratio-based temperature sensing using a persistent phosphor

“…[10][11][12] Optical thermometry uses phosphor as the sensing material to achieve changes in various optical parameters, such as the fluorescence intensity ratio (FIR), 13 fluorescence lifetime, 14 peak position, 3 bandwidth, 9 polarization anisotropy, 11 and emission intensity 15 in a real-time photo-excitation process at different temperatures. However, stray light in real-time photo-excitation is inevitable, and ultraviolet excitation light 16,17 can simultaneously produce background fluorescence for some substances being measured (e.g., chemical fibers, 18 proteins, 19 and organic matter 20 ). An upconverting phosphor can avoid background fluorescence; however, it does produce a lot of heat to increase the temperature due to its low up-conversion efficiency.…”

Development of a spatially resolved optical technique for measuring heat flux and thermal footprint of firebrand piles

“…Increasing temperature increases emission originating from the higher energy level 4 I15/2 with respect to the lower energy level 4 F9/2, in a manner captured well by a Boltzmann distribution. Consequently, the intensity ratio I458 nm/I497 nm can be used for high-sensitivity temperature measurements [22] [23]. Normalization of the integrated luminescence of one emission band with another eliminates several experimental uncertainties, since the detected intensities of different wavelengths are influenced in a similar manner.…”

“…[7]. The steady state response time can be approximated by = 0.54 2 (23) for a perfectly insulated backside surface which is an acceptable assumption in this case since radiative and free-convective losses on the bottom sides of the substrate can be shown to be relatively small. Figure 14 shows the steady state response time of fused quartz for two thicknesses as a function of material temperature.…”

Flexural-torsional-coupled vibration analysis of Euler-Bernoulli beam by using the differential transform method

“…Eslimy-Isfahany, Banerjee and Sobey [3] analysed free and forced vibration of bending-torsion coupled beam with Euler-Bernoulli beam theory for deterministic and random loads using modal analysis. Hashemi and Richard [4] worked on the study of the bending and torsion vibration response of the axially loaded beam by using dynamic finite element method in order to obtain natural frequencies and related mode shapes for uncoupled and coupled beam, separately. Surace [5] used a new approximate method, based on the use of Green functions, for the analysis of the modal characteristics of non-uniform blades corresponding to the coupled flapwise bending, chordwise bending and torsion of both rotating and non-rotating blades.…”

“…Oh and Yoo [7] examined the coupling effects between stretching, bending, and torsion of a rotating pre-twisted blade using a complex modal analysis method. These studies have shown [3][4][5][6][7] that compared with numerical methods, analytical methods are more preferred to solve vibration problem in order to obtain the behavior of coupled bending-torsion beams.…”