IJEID Published Articles

Abstract Accurate measurement of linear displacement is essential in engineering laboratories, materials testing, and instructional settings. However, many commercially available displacement measuring instruments such as Linear Variable Differential Transformers (LVDTs) and optical encoders, are costly and often require complex signal conditioning systems. This study presents the design, development, and experimental validation of a Low-Cost Laser-Assisted Linear Displacement Measuring Instrument (LALDI) intended to provide an accessible and reliable alternative. The instrument operates using a laser diode directed toward a laminated greyscale strip, where displacement is quantified through variations in light intensity detected by a light-dependent resistor (LDR). A signal conditioning circuit and microcontroller process the analog signal into measurable displacement data. The development process followed a structured design–prototype–test–evaluation framework. Experimental validation was conducted within a 0–4 inch (0–101.6 mm) displacement range and compared against a commercial dial indicator. Statistical analysis using paired t-test and standard deviation assessment demonstrated no significant difference between the measurements of LALDI and the reference instrument at the 0.05 level of significance. Repeatability analysis confirmed stable measurement performance across incremental testing. Cost analysis revealed that the fabricated device achieved substantial cost reduction compared with commercial displacement measuring systems while maintaining acceptable accuracy and precision. The findings indicate that LALDI provides a practical, cost-effective solution for academic laboratories and small-scale engineering applications, with potential for further refinement and scalability.