在国产化、技术自主化的大型飞机项目上，对孔位精度的标准正逐步升高，钻头的垂直度又是这一标准中最受关注的条件。机器人自动钻铆系统工作时，所产生的装配误差、磕碰、偏移等状况，不仅降低了制造及检测的准确度，还影响了整个结构件的疲劳性能。针对这一问题，提出了基于多激光传感器装配的自适应自由曲面法线检测技术，搭建了以该方法进行姿态找正的数学模型，并研究了检测装置的标定方法及流程。同时，着重讨论了在自适应方法检测时，利用电子经纬仪等装置进行误差补偿的相关技术。该方法的验证实验结果显示，多组实验数据均达到了法向精度＜±0.5°的关键技术指标要求，找正后的法线平均偏差值为0.0667°。该方法能有效补偿在制孔工作中所产生的相关误差，进一步提高机器人的定位精度及法线方向检测精度。

Remotely sensing an object with light is essential for burgeoning technologies, such as autonomous vehicles. Here, an object’s rotational orientation is remotely sensed using light’s orbital angular momentum. An object is illuminated by and partially obstructs a Gaussian light beam. Using an SLM, the phase differences between the partially obstructed Gaussian light beam’s constituent OAM modes are measured analogous to Stokes polarimetry. It is shown that the phase differences are directly proportional to the object’s rotational orientation. Comparison to the use of a pixelated camera and implementation in the millimeter wave regime are discussed.

This work demonstrates the Nd:YAG waveguide laser as an efficient platform for the bio-sensing of dextrose solutions and tumor cells. The waveguide was fabricated in an Nd:YAG crystal with the cooperation of ultrafast laser writing and ion irradiation. The laser oscillation in the Nd:YAG waveguide is ultrasensitive to the external environment of the waveguide. Even a weak disturbance leads to a large variation of the output power of the laser. According to this feature, an Nd:YAG waveguide coated with graphene and WSe2 layers is used as substrate for the microfluidic channel. When the microflow crosses the Nd:YAG waveguide, the laser oscillation in the waveguide is disturbed and induces fluctuation of the output laser. According to the fluctuation, the microflow is detected with a sensitivity of 10 mW/RIU.

This paper reports a coherent random microcavity laser that consists of a disordered cladding (scattering) layer and a light-amplification core filled with dye solution. Cold cavity analysis indicates that the random resonance modes supported by the proposed cavity can be effectively excited. With introducing the gain material, random lasing by specific modes is observed to show typical features of coherent random lasers, such as spatially incoherent emission of random modes. By inserting a metal nanoparticle into the gain region, emission wavelength/intensity of the random lasers can be considerably tuned by changing the position of the inserted nanoparticle, opening up new avenues for controlling output of random lasers and sensing applications (e.g., small particle identification, location, etc.).

This Letter introduces a trigger-controlled Geiger-mode avalanche photodiode (GM-APD). A hierarchical look-back-upon tree recurrence method is given to predict the performance of trigger-controlled GM-APDs under different trigger-count upper limits. In addition, the normalized detection probability is defined to evaluate the detection performance of trigger-controlled GM-APDs in typical weak optical signal detection (impulse noise and continuous noise situations). Theoretical analyses show that the trigger-controlled GM-APD improves the detection performance of GM-APDs in weak optical signal detection via the optimization of the trigger-count upper limit, compared with single-trigger and multi-trigger GM-APDs.

We report on temperature compensation for beat-frequency-encoded dual-polarization fiber laser sensors based on a cleave-rotate-splice method. By cleaving the laser cavity into two segments with comparable lengths, aligning them with a rotated angle of 90°, and then fusion splicing the two halves, the temperature sensitivity in terms of beat-frequency variation can be greatly reduced from 1.99 to 0.30 MHz/°C (or by 84.9%). In contrast, the sensitivity to point loaded mass hardly changes. We also find that the beat-frequency fluctuation decreases from ±30 to ±25 kHz as a result of the temperature compensation.

A dual-frequency laser Doppler velocimeter implemented by a dual-polarization fiber grating laser is proposed, with the two laser frequencies produced by the two orthogonally polarized laser outputs of the fiber grating laser. The reflected laser outputs from a moving target experience the Doppler frequency shift, which is shown to be linearly related to the velocity and the beat note frequency difference between the laser outputs and the reflected light. With a digital frequency demodulation scheme, a high sensitivity of 0.64 MHz/(m/s) and a velocity resolution of less than 0.5% of the velocity for velocity measurement are demonstrated, which shows that the proposed laser Doppler velocimeter is capable of measurement of wide range of velocity.