Japanese scientists have developed a groundbreaking method for measuring hydrogen gas using tunable diode laser absorption spectroscopy (TDLAS). This new technique overcomes previous challenges in quantifying low concentrations of hydrogen, paving the way for enhanced hydrogen safety and quality control. By optimizing the wavelength modulation and pressure in a high-pressure gas cell, the researchers were able to achieve precise measurements within a detection range of 0.01% to 100% concentration. The study's findings suggest that this advancement could significantly improve hydrogen detection systems, making them more reliable for applications such as leak detection in hydrogen fuel cell cars. The researchers also introduced a calibration-free technique that utilizes the ratio of the first and second harmonic signals, allowing for improved gas detection limits and stabilized wavelength locking for the laser diode. Their method demonstrated accurate measurements at different integration times, with the minimum detection limit reaching 0.0055% or 55 ppm at 30 seconds integration time. Despite some limitations related to optical elements and laser properties, the study concluded that the new method exhibits excellent performance in measuring hydrogen concentrations. The researchers believe that this innovative approach holds promise for future applications in trace gas sensing for hydrogen infrastructure and vehicles, as well as quality control processes in hydrogen production. The study was conducted by a collaborative team from Chiba University, Mitsubishi Electric Corporation, Kyushu University, Shikoku Research Institute, and Tokai University, and was published in the journal Optics and Laser Technology.