This study aims to investigate the performance of sensor heads with different configurations of low-finesse fiber Fabry-Pérot interferometers in displacement sensing. A systematic analysis was conducted to examine the effects of parameters such as target reflectivity, tilt angle, and working distance on interference signals under different interference models. The primary goal is to simplify the design and development process of sensor heads, thereby supporting the optimization of new sensor designs. Additionally, this study addresses the lack of systematic performance comparisons for different configurations in the existing literature, offering a comprehensive evaluation of how various configurations impact the sensor's overall performance in practical applications.An experimental system was constructed using a 1550 nm laser, and both simulation and experimental methods were employed to evaluate the performance of the sensor heads. The study analyzed the interference signal characteristics of four typical sensor configurations in both collimation and focusing modes. The working distance and tilt angle of the target reflectors were varied during the experiments to assess the contrast, angular tolerance, and measurement range of the interference signals. To verify the reliability of the proposed model, experimental data were compared with simulation results. Furthermore, targets with reflectivities ranging from low (4%) to high (96%) were tested to ensure the general applicability of the research findings across various real-world scenarios.Existing studies often focus on single-reflectivity targets and fail to fully consider how configuration differences affect the performance of low-finesse systems. This study proposes an improved optical interference model that encompasses a broad range of target reflectivities, from low reflectivity (4%) to high reflectivity (96%). The performance of the sensor heads in both collimation and focusing modes was systematically compared and optimized.In the collimation mode, for high-reflectivity targets, as shown in Fig.6(a) and Fig.6(b), the configuration demonstrates a self-alignment mechanism with a large angular tolerance, exceeding ±0.5° as illustrated in Fig.7(b). This configuration also achieves a measurement range of over 60 mm, making it suitable for long-distance displacement measurements. However, for low-reflectivity targets, as shown in Fig.4, this configuration becomes more sensitive to tilt changes. As illustrated in Fig.5, precise control of the tilt angle is essential to maintain signal quality and measurement accuracy in practical applications. In the focusing mode, high-reflectivity targets, as shown in Fig.11, achieve peak contrast (approximately 1.0) in the defocus mode (Fig.12(b)), making this configuration suitable for high-precision measurement scenarios. The working distance must be maintained within ±5 mm of the focal point to ensure accurate displacement measurement. For low-reflectivity targets, as shown in Fig.9, the configuration provides a larger angular tolerance, reaching ±0.75°, as depicted in Fig.10(b). Over a wide range of working distances, the contrast remains above 0.9, making it suitable for complex measurement environments that may involve significant variation in tilt angles. By combining simulation and experimental data, the accuracy of the proposed model was validated, with deviations between experimental and simulation results being less than 5%. This confirms the reliability of the model and ensures that it can be applied to a wide range of practical applications. A comprehensive analysis of target reflectivities, ranging from 4% to 96%, was conducted in both modes (Fig.13(a) and 13(b)), ensuring the universality of the research findings. This highlights the model’s ability to predict sensor performance in real-world scenarios with varying target characteristics.This study has clarified the performance of low-finesse fiber Fabry-Pérot interferometers under different configurations and conditions through systematic experimental and simulation analysis. The collimation mode demonstrates superior long-distance measurement capability, making it ideal for high-precision applications involving high-reflectivity targets. In contrast, the focusing mode exhibits higher fault tolerance in environments with large tilt angles and is more adaptable to low-reflectivity targets. These findings not only validate the reliability of the proposed model but also provide a theoretical basis for optimizing sensor head designs. By streamlining the development and testing process, the model contributes to the efficient creation of new sensor heads for a wide range of applications. Future work will focus on further optimizing the performance of high-finesse fiber Fabry-Pérot interferometers, addressing the potential impact of complex environments on interferometer performance, and integrating multi-mode measurement technologies to meet the diverse and evolving demands of various industries.