## 3 Results
### Repeatability, Field of View, and Climate Tests
The condition tests indicate that any variations in the parameters are noticeable up to 30 min after the sample is taken out of the climate chamber. After that, the operating parameters of the NLC device stabilize and remain consistent with the initial level. This suggests that there is no significant impact on the OPL parameters due to changes in temperature over time. The devices were re-evaluated over the course of a year to confirm long-term functionality and durability, indicating that the OPL maintains its original performance. Figure 5d shows the light transmission versus the optical power (intensity) of the incident beam on the OPL (12 \(\upmu\)m cell thickness, 6 CHBT NLC + 1% SBII \(w/w\)), re-measured after a period of more than one year, which almost perfectly matches the characteristic of freshly fabricated NLC cells shown in Figure 5e. It is essential to ensure that the liquid-crystal cells are adequately sealed in order to prevent the NLC medium from degrading over time. No aggregation of SBII dye molecules has been observed over an extended period. The NLC cells maintain a consistent blue color due to the absorption spectrum of Sudan Blue II. During the final phase of our research, we conducted a crucial experiment to demonstrate the practical value of our NLC TN optical power limiter, which features integrated  
Figure 5: Repeatability and durability tests for the TN cells (6 CHBT doped with 1% of SBII \(w/w\), for a cell of thickness d = 12 \(\upmu\)m, the light beam of a wavelength \(\lambda\) = 532 nm and a width of about 2 mm): (**a**) the normalized transmission acquired for 24 samples (black dots) and the average value (brown solid line), plotted as a function of the optical power of a light beam. The gray area indicates the standard deviation of the mean value; (**b**) Transmission as a function of the angle of incidence of the beam on a liquid crystal cell. The inset shows the geometry of the experimental measurements. Plotted for \(\alpha\) = 0\({}^{\circ}\), \(\alpha\) = 10\({}^{\circ}\), \(\alpha\) = 20\({}^{\circ}\), \(\alpha\) = 25\({}^{\circ}\), and \(\alpha\) = 30\({}^{\circ}\), yellow to green markers; (**c**) Effect of the high-temperature conditions on the performance of an NLC optical power limiter. Transmission for a: “freshly fabricated” NLC cell (blue circles) and the same cell kept for 1 h in a climatic chamber (temperature +70 \({}^{\circ}\)C, the humidity 50%), measured about 30 min after removing the sample from the climate chamber; (**d**) Light transmission as a function of beam power (intensity) and (**e**) transmission versus time characteristics related to the beam of a \(\lambda\) = 532 nm, a diameter of 2 mm, and an optical power of P = 200 mW, re-measured after over one year. plastic polarizers. The experiment was designed to simulate real-world scenarios and evaluate the performance of the device under these conditions. The experimental setup is shown in Figure 6a,b, and it aimed to replicate the actual usage conditions of the device. For this experiment, a CCD camera equipped with an objective lens was utilized to image an object featuring a central aperture, allowing a laser beam to pass through and strike the camera directly at normal incidence. This setup is illustrated in Figure 6c with auto-exposure settings capturing the direct impact of the beam on the camera. A continuous-wave (CW) laser with a wavelength of 532 nm and power output of 200 mW served as the light source, combined with our designed NLC optical power limiter, which includes internal foil polarizers and dye-doped NLC (6 CHBT + 1% SBII \(w/w\)). Initially, without the protective device, the intense laser exposure led to significant overexposure in the captured images (Figure 6d), causing the camera to malfunction or even be permanently damaged. However, with the optical power limiter in place, the images showed only partial saturation at the center while maintaining excellent visibility around the periphery.