The performance of radio frequency (RF) exciting He-Ne laser is exposed. This text sets out from power circuit, aiming at providing the pumping of gain medium. In order to study the frequency characteristic of RF excitation in He- Ne laser, the frequency ranging from 300MHz to 700MHz is chose to test the discharge property of active medium. It also obtains the optimal RF frequency (432MHz) through experiment, which is important to the improved design of RF exciting He-Ne laser.
The performance of radio frequency (RF) exciting He-Ne laser is exposed. This text sets out from kinetics property of the electronics inside the high-frequency, aiming at getting the relationship between radio frequency and plasma energy. In order to study the frequency characteristic of RF excitation in He-Ne laser, the frequency ranging from 300MHz to 700MHz is chose to test the discharge property of active medium. It also obtains the optimal RF frequency (432MHz) through experiment, which is important to the improved design of RF exciting He-Ne laser.
A laser Doppler angular vibrometer using a He–Ne dual-frequency ring laser (DF-RL) is demonstrated. By detecting the interference signal of two beams which are diffracted by the surface of two gratings, the displacement of angular vibration can be measured. To our knowledge, this is the first time that a DF-RL has been utilized as the source of a Doppler angular vibrometer. It shows in theory and experiment that this dual-differential laser Doppler angular vibrometer possesses a high precision and can suppress the error in horizontal vibration at the same time, which can be applied to high-frequency microangular vibration measurement.
Considering the problem of low and nonuniform resolution in omnidirectional imaging, a complementary catadioptric imaging method is proposed by using multiple mirrors. Due to the reflection of mirrors, each spatial object has two imaging positions, in the inner and outer of sampled omnidirectional images, respectively, which are generated from two different optical paths. For instance, a prototype of omnidirectional sensor based on complementary double imaging is designed, which contains two convex mirrors (cone and hyperboloid) in conjunction with a plane mirror. The design constraints and optical geometric model of imaging are analyzed in detail. By mathematical analysis, two improvements of resolution have been achieved: (1) more uniform distribution of resolution and (2) complementary resolution distribution in the radial and tangential directions between the inner and outer. To prove and demonstrate the remarkable complementarity, a simple fusion experiment based on wavelet decomposition and reconstruction is performed on a pair of cylindrical panoramic images unwrapped from an omnidirectional image.
A novel automatic Video Object (VO) segmentation method is presented in this paper, which is based on intersection of frame differences. Horizontal scan is used to acquire coarse VO mask and edge detection is performed on VO boundaries to remove uncovered background contained in the intersection. And morphological operator open is applied to smooth VO contours after extraction. Experimental results show that it is accurate and especially efficient, and can wonderfully meet the real-time requirements of applications such as stationary camera video surveillance.