We present a xenon arc source-based illumination system designed to achieve high spatial uniformity and efficient light collection across a wide spectral range. The proposed optical system comprised an ellipsoid reflector, diffuser, motorized iris, and collimation lens to optimize beam homogenization. Non-sequential ray-tracing simulations were performed to evaluate angular irradiation distributions of various diffusers and the overall beam profile uniformity. The system was experimentally implemented using a fused silica holographic diffuser optimized for high-power operation, with a motorized iris enabling precise control of light intensity. The resulting beam profile exhibited a well-defined flat-top shape, with a beam uniformity of approximately 95% evaluated according to the ISO 13694 standard. The developed illumination system demonstrated its ability to produce highly uniform illumination, suitable for various optical applications including spectroscopy, precision measurement, and optical imaging.

In this study, we present a numerical simulation approach for designing Fresnel zone plate (FZP) patterns. By optimizing surface phase parameters using desired merit functions in ray-tracing software, the obtained surface phase was converted into an FZP pattern through a 5-step procedure. A comparison between our numerical simulation approach and the traditional analytical method showed a negligible zone size difference of 0.606 nm and nearly absolute agreement of 17.549 μm in focal spot size. The FZP pattern was experimentally verified by an expected focal spot size of 18.55 μm. Our approach demonstrated design flexibility and has potential applications in simulating various functionalities in FZP patterns and refractive-diffractive hybrid lenses to address specific optical challenges. The surface phase can be freely modified based on optimization objectives that cannot be achieved using the analytical approach, ensuring high-precision design for accurate extraction.

We present a rotating pair of mirrors based optical autocorrelator which is capable of providing a 0.1 m scanning range. The rotating mirror-pair technique enables rapid data update-rate, compactness, and simpler data post-processing compared to that of conventional linear motion-based optical autocorrelators. We optimized the geometrical design of the mirror-pair configuration by using off-the-shelf mirrors and conducted a simulation to calculate the expected capability of the scanning range. By exploiting a He-Ne laser as a light source, we validated the performance of the autocorrelator in its provision of a 100 mm scanning range and 0.2 Hz data update-rate, which was limited by the adopted commercial data sampling device, and not limited by the proposed principle. The developed autocorrelator is expected to be adopted for various applications that require sub-cm^-1 spectroscopic resolution.

In this paper, we describe high-stable RF-frequency generation using a low-cost 8-bit microcontroller for amplitudemodulation based distance measurement, which is one of the indispensable technologies for cost-effective Lidar application. The RF frequency generator using the microcontroller was implemented by externally referencing to an atomic clock and 8- bit timer/pulse width modulation (PWM) functions, which are embedded in a microcontroller. The microcontroller we used was ATmega128 of Microchip with 16 MHz clock and 8-bit timer, which generates the maximum frequency of up to 62.5 kHz, enabling 2.4-kilometer ranging without phase ambiguity. The stability of RF-frequency generated from the implemented system was evaluated in terms of Allan deviation using a commercial frequency counter. The stability indicated 10^-11 at 1-s averaging time and 10^-12 at 100 s averaging time, which represents a 1/10 degradation compared to the stability of the commercial function generator. Along with the stability evaluation, we interrogated frequency tunability, which extends a measurable range without phase ambiguity.