Study on defect imaging technology of optical elements based on micro-Raman spectroscopy.

An optical element defect detection imaging method based on micro-Raman spectroscopy is proposed to achieve high-precision imaging of optical element defects and their distribution. The detection precision of the system is immediately reflected in the imaging quality. The sharpness value of the mapping images is calculated using the Sum of Modulus of Gray Difference function. The selection of the Raman peak is an important step, and when a borosilicate glass sample with standard defects is measured for verification, it is found that the Raman peak light intensity changes at -37 and 28 cm-1. When these two peaks were used for 2D mapping, obvious defect contours can be obtained, while the light intensity at other sites could not be used for imaging, and remained essentially constant. Through the detection of laser burning defects, new peaks appear at the burned defect location that could be used for imaging, and the burning defect area can be clearly distinguished from the non-burning area. By changing the laser burning conditions, the Raman shift changes, which verifies that there is a certain correlation between the laser burning degree and the Raman shift, which also provides a basis for 2D mapping imaging of defect detection.

Path planning and optimization for micro-robot in a vessel-mimic environment.

Manipulating micro-robots in blood vessels is an essential technology for medical researchers in applications such as drug delivery and thrombus removal. The usage of micro-robots in medicine can help overcome the limitations of many conventional clinical methods. In this study, we aimed to make the micro-robot more intelligent while moving through blood vessels. First, the skeleton of an image of the blood vessels is extracted, which is further used for path planning. Then, the skeleton-extraction-based A* algorithm was used for determining a best route for the movement of the microrobot at a safe distance from the vascular wall. Finally, the gradient descent algorithm was utilized to smooth the planned path. Simulations were conducted to verify the effectiveness of the proposed algorithms. The proposed methods would improve the efficiency for the further manipulation of the micro-robot in the blood vessel environment.

Method for designing phase-retrieval algorithms for Ronchi phase-shifting lateral-shearing interferometry.

We propose a general method of designing phase-analysis algorithms for Ronchi phase-shifting lateral-shearing interferometry. Based on the expression and method, three new phase-shifting algorithms are designed to eliminate negative error effects of interference from unwanted diffraction orders, which limits the accuracy of wavefront aberration measurement. The proposed eight-, 10-, and 13-frame algorithms can eliminate the effects of the first ±5, ±9, and ±15 multi-diffraction orders, respectively. Simulation works and experimental results verify the general expression and corresponding designed method.