Dr. Dwaipayan Deb

How can we measure the wavelength of a laser beam with simple, low-cost tools? In our recent work, " Measuring wavelength of laser beam using single slit diffraction: a simple but precise experiment using webcam and ImageJ software " we revisited the classic single-slit diffraction experiment but gave it a modern upgrade. Traditionally, this experiment involves photodiodes and optical benches, with painstaking manual measurements that are often error-prone. Instead, we used a paper screen, a regular webcam, and free software to make the process faster, easier, and more accurate. The setup is simple: a laser beam passes through a narrow slit, producing a diffraction pattern on the screen. A webcam captures this pattern, and the free image-processing software ImageJ is used to measure the span of the central bright region. From this, we calculate the wavelength of the laser. Using this method, we tested both a known red He–Ne laser and a green diode laser , achieving resu...

Gnuplot Helper is an open-source tool hosted on SourceForge that offers a graphical user interface to simplify working with gnuplot , a powerful command-line plotting utility. Designed for users who may find gnuplot’s command syntax challenging or error-prone, Gnuplot Helper automatically generates and runs gnuplot scripts in a visual mode, reducing runtime mistakes and enabling quicker results. It requires gnuplot to be installed first, and then this GUI wrapper can be used to streamline tasks like creating 2D and 3D plots. The latest update to the project was on April 10, 2021 . You can download or learn more about Gnuplot Helper from its SourceForge page: https://sourceforge.net/projects/gnuplot-helper/

Arduino: A Beginner-Friendly Microcontroller Platform Arduino is an open-source electronics platform designed to make building digital devices and interactive systems simple and accessible. At its core, an Arduino board is a small microcontroller that can be programmed to sense inputs—such as light, sound, motion, or temperature—and respond with outputs like activating motors, turning on LEDs, or sending signals to other devices. What makes Arduino popular is its ease of use: it uses a straightforward programming language based on C/C++ and comes with an intuitive integrated development environment (IDE). The hardware itself is inexpensive, widely available, and supported by countless online tutorials and community projects. Arduino boards are used in education, hobby projects, research, and even industry for prototyping. From basic tasks like blinking lights to advanced robotics and Internet of Things (IoT) applications, Arduino empowers learners and innovators to bring their ideas in...

Estimating Surface Roughness from a Single Image Measuring surface roughness is vital in fields from manufacturing to planetary science, yet traditional methods—profilometers, laser scanners—are costly and limited in scope. My 2025 Measurement paper presents a simple, computational technique that uses just one digital image of a surface illuminated at a known angle. The method analyzes shadow patterns cast by microscopic “hills” onto “valleys” and compares them with computer-generated profiles until the best match is found. From this, key roughness parameters—average height deviation (Ra) and average slope angle—are calculated. The technique works for a wide range of scales, from microscopic samples to landscapes, and requires minimal equipment. Open-source software, Shadow2Profile , was developed for Windows and Linux, enabling anyone to apply this approach to their own images. This innovation could benefit remote sensing missions, material testing, and any scenario where convention...

  Building a Low-Cost Automated Goniometer for Light Scattering Studies In my 2020 work published in the European Journal of Physics , I described the design and fabrication of a self-made, fully automated goniometer for studying light scattering in planetary science. Commercial systems are often expensive and purpose-specific, so I set out to create a cost-effective, versatile alternative without compromising accuracy. My design uses Arduino microcontrollers , stepper motors , and a green diode laser with a sensitive light-to-frequency detector. The setup automates movement of both the light source and detector arms, enabling measurements over a wide range of scattering angles. Calibration with Lambertian surfaces ensures reliable bidirectional reflectance data. This instrument successfully measured scattering from regolith analogs such as sugar and NaCl, producing phase curves consistent with known scattering behavior. Beyond planetary science, it offers educational and res...