消偏振分光片是空间光学中的重要分光元件，为了实现780 nm波段激光在大分光比条件下的稳定分光输出，设计并制备了一种高分光比消偏振分光片。使用TFCalc软件仿真设计了双面消偏振分光膜系，通过离子束辅助电子束热蒸镀技术制备了消偏振分光片样品。然后，使用透射电子显微镜、分光光度计对所制备样品进行了测量表征，得到了分光片的实际薄膜结构及透射光谱，光谱结果显示该分光片的透射率接近98%，s偏振光与p偏振光的透射率偏差小于0.3%。最后，搭建测试光路对分光片进行变偏振方向、变波长及长时间稳定性等测试。实验结果表明：该分光片在目标波段内的透射率接近98%，偏振方向大范围变化时透射率偏差小于0.2%，波长在772~792 nm内变化时透射率波动小于0.12%；10 h长时结果显示，当平均时间为100 s时，分光比与透射率的Allan方差分别为1.41×10-3和4.12×10-5。所提出的消偏振分光片具有良好的消偏振性能，可直接应用于光学测试计量和量子传感探测等精密测量领域。

We present a compact, low-noise, and inexpensive optical phase-lock loop (OPLL) system to synchronize the frequency and the phase between two external cavity diode lasers. Based on a direct digital synthesizer technique, a programmable radio-frequency generator is implemented as the reference signal source. The OPLL has a narrow beat note linewidth below 1 Hz and a residual mean-square phase error of 0.06 rad2 in a 10 MHz integration bandwidth. The experimental test results prove the competent performance of the system, which is promising as a low-budget choice in atomic physics applications.

We present a laser frequency locking system based on acousto-optic modulation transfer spectroscopy (AOMTS). Theoretical and experimental investigations are carried out to optimize the locking performance mainly from the view of the modulation frequency and index for the specific scheme of AOMTS. An FWHM linewidth of 63 kHz is achieved and the frequency stability in terms of Allan standard deviation reaches 1.4×10 12 at 30 s. The frequency shifting capacity is validated throughout the acousto-optic modulator bandwidth while the laser is kept locked. This work offers a different but efficient choice for applications calling for both stabilized and tunable laser frequencies.

We present a compact displacement measurement system possessing the capability of nanometer-scale precision. On basis of integrating single grating with 3×3 coupler for phase shift in interference signal, the present scheme features advantages of simple structure, convenient alignment, and insensitivity to air turbulence. Linear comparisons between our system and HP5530 show a residual error less than 81 nm during step motions along a 10 mm round-trip, and a discrepancy less than 15 nm in the case of 200 μm movement. We also demonstrate a measurement stability test in a duration of 300 s, which shows the proposed scheme potentially performs better than HP5530 in terms of long-term stability.

A symmetrical heterodyne grating interferometer with both a short period and high signal-to-noise ratio is proposed. It possesses good immunity to environmental disturbances and can simultaneously achieve high resolution and stability. The experimental results show that the standard deviation of 24.67 nm can be realized for the long range of 10 mm. The measurement resolution of better than 2 nm is achieved with the theoretical resolution of 12 pm. Additionally, system stability at less than ±1.5 nm is obtained in just over 10 min. The measurement errors, including cosine error, nonlinear error and non-common path error, are discussed as well.