Development of Laser-Induced Capillary Wave Method for Viscosity Measurement Using Pulsed Carbon Dioxide Laser

Abstract

A new experimental apparatus, based on the laser-induced capillary wave method involving the use of a pulsed carbon dioxide laser (wavelength 10.6 µm, pulse width 50 ns, power 65 mJ) as a heating source has been developed. Since the present technique is applicable to a wide range of viscosity, this method is applicable to the process in which the viscosity drastically changes within a short period of time. In this method, interfering laser beams heat a liquid surface and generate a capillary wave (the wavelength can be adjusted from 20 to 200 µm) caused by a spatially sinusoidal temperature distribution. The temporal behavior of the capillary wave is detected by a diffracted probe beam (He-Ne laser, 15 mW) at the heated area. The dynamics of the capillary wave provide information regarding thermophysical properties such as viscosity and surface tension. In the present study, several liquid samples spanning the viscosity range from 0.33 to 7080 MPa · s (e.g., acetone, toluene, 1-hexanol, ethylene glycol, JS1000, and JS14000) were investigated at room temperature. The detected signals for several liquid samples exhibiting a wide range of viscosity agree well with theoretical calculations, taking into account the influence of the distribution of surface tension.

Micro Optical Viscosity Sensor for in situ Measurement Based on a Laser-Induced Capillary Wave

“…The laser-induced capillary wave method was utilized for the optical viscometry. Terazima et al (14) first demonstrated the laser-induced capillary wave method for the investigation of surface interactions of a gas/liquid interface, and Nagasaka et al (15) have developed a bench-top-type in situ viscometer using a nano-second pulsed carbon dioxide laser for the control of industrial materials such as food. The sample surface is heated by two pulsed laser beams, which intersect and generate an optical interference fringe pattern on the surface.…”

High-speed sensing of microliter-order whole-blood viscosity using laser-induced capillary wave

“…The temporal behavior of the laser-induced surface displacement of a Newtonian liquid can be expressed by Eqs. 5-15 [21], which are inevitably not straightforward because of the complexity of the phenomena involved, and it is possible to simultaneously determine the viscosity and surface tension by detecting the time dependence of the first-order diffracted beam I 1 ðtÞ and the grating period K [22][23][24][25][26]. This method enables us to determine the viscosity and surface tension simultaneously in a contact-free manner with (1) a very short time (microseconds to milliseconds), (2) high spatial resolution (10-100 lm), (3) small sample volume (ll-ml), and (4) a wide range of viscosity (10 -1 -10 6 mPa s).…”

P2EM.1 - Laser-induced surface displacement detection instrument with Doppler shift composed of optical fiber

“…Recently, several laser-applied techniques have been proposed for measuring liquid viscosity [1], [2]. These techniques include non-contact with samples and micro-liter sample volume, both of which provide significant advantages in terms of actual applications.…”