Making an efficient but cost-effective automated goniometric device for a light-scattering study

Abstract

A goniometer is an instrument which is frequently used in optics and other branches of physics. It enables the study of light scattered in various directions from a solid, liquid or powdered sample. The goniometric instruments that are already available on the market are designed for a specific purpose and are quite costly. Fully-computerized devices—which automatically acquire data and control the positions of the light source and detector—are even more expensive. In this work, the instrumentation of a self-fabricated, low cost, but fully computerized goniometric instrument designed for studying a light-scattering problem in planetary science is described in detail. This device uses Arduino microcontroller boards for acquiring data, and stepper motors are employed for automated control of the positions of the light source and detector. A low-cost but high-intensity laser diode was used as the light source, and a very sensitive photodiode integrated circuit was used as the light detector. This work has a pedagogical value in the sense that the reader will benefit from learning about the techniques used, the components and their calibration, the software, etc. More importantly, the cost-effectiveness of this work may be beneficial to many experimentalists and instrument designers working in this field, to control their project budgets.

A Photometric Study of Regolith Intimate Mixing with Ice-Like Impurity

“…5). The re ectance of the combined sample can be calculated from their end members with the following relationship r calculated = r SS1 ×(Mass fraction of SS1) + r Q1 ×(Mass fraction of Q1)……….. (5) Here r SS1 and r Q1 are re ectances of SS1 and Q1 respectively, and r calculated is the theoretically calculated re ectance assuming linear combination for the intermediate sample with mass fractions of end members as used at the RHS of Eq. 5.…”

“…Hence it turns out that, the effect of textural roughness on abundance determination may be neglected for normal illumination of light and phase o . Yoldi et al (2015 and2020) experimented with real water-ice samples of two different sizes (i) SPIPA-A (4.5 ± 2.5 µm) and (ii) SPIPA-B (67 ± 31 µm), and intimate mixtures with regolith JSC Mars-1 (24 µm) and Dark Basalt (50wt% of the particles > 109 µm and 50 % < 109 µm). Yoldi et al 2015 concluded that bigger ice particles (i.e.…”

A photometric study of regolith intimate mixing with ice-like impurity

“…was not possible and therefore the work was limited to moderate and high albedo samples only. A comprehensive discussion of the theory and description of a subsequent and recently developed more sophisticated version of the instrument is described in [10]. The Fig.…”

“…1c shows the improved set-up which differs from the test-setup in terms of more sensitive detector (photo-sensitive IC TSL237), microcontroller controlled arms, better angular resolution, digital clinometers in place of earlier analog clinometers for angle detection, etc. which are described in detail in [10].…”

“…However, other factors like particle shape and particle porosity also plays some role in the scattering of light, but these are generally considered in mathematical simulations rather than experimental, because it is not easy to control these factors from experimental point of view. Table 1 summarizes the optical properties of water ice, quartz, (c) The improved goniometer device [10].…”