A coma-free super-high resolution optical spectrometer using 44 high dispersion sub-gratings.

Unlike the single grating Czerny-Turner configuration spectrometers, a super-high spectral resolution optical spectrometer with zero coma aberration is first experimentally demonstrated by using a compound integrated diffraction grating module consisting of 44 high dispersion sub-gratings and a two-dimensional backside-illuminated charge-coupled device array photodetector. The demonstrated super-high resolution spectrometer gives 0.005 nm (5 pm) spectral resolution in ultra-violet range and 0.01 nm spectral resolution in the visible range, as well as a uniform efficiency of diffraction in a broad 200 nm to 1000 nm wavelength region. Our new zero-off-axis spectrometer configuration has the unique merit that enables it to be used for a wide range of spectral sensing and measurement applications.

Ultrahigh-resolution spectrometer based on 19 integrated gratings.

Optical spectrometers play a key role in acquiring rich photonic information in both scientific research and a wide variety of applications. In this work, we present a new spectrometer with an ultrahigh resolution of better than 0.012 nm/pixel in the 170-600 nm spectral region using a grating-integrated module that consists of 19 subgratings without any moving parts. By using two-dimensional (2D) backsideilluminated complementary metal-oxide-semiconductor (BSI-CMOS) array detector technology with 2048 × 2048 pixels, a high data acquisition speed of approximately 25 spectra per second is achieved. The physical photon-sensing size of the detector along the one-dimensional wavelength direction is enhanced by a factor of 19 to approximately 428 mm, or 38912 pixels, to satisfy the requirement of seamless connection between two neighboring subspectral regions without any missing wavelengths throughout the entire spectral region. As tested with a mercury lamp, the system has advanced performance capabilities characterized by the highest k parameter reported to date, being approximately 3.58 × 104, where k = (working wavelength region)/(pixel resolution). Data calibration and analysis as well as a method of reducing background noise more efficiently are also discussed. The results presented in this work will stimulate further research on precision spectrometers based on advanced BSI-CMOS array detectors in the future.

[Ultrasound-guided percutaneous radiofrequency ablation of hepatic malignancies with cool-tip needle].

OBJECTIVE: To investigate the efficacy, indication and complication of radiofrequency ablation (RFA) with cool-tip needle in patients with hepatic malignancies. METHODS: 421 patients with hepatic malignancies underwent ultrasound-guided RFA with cool-tip needle under local anaesthesia. The tumor size was from 1.0 to 15 cm in diameter with an average diameter of 4.3 cm. RESULTS: The complete ablation (CA) rate was 91.4% (382/418) in the patients with a tumor < 3 cm, 78.9% (97/123) in those with a tumor of 3 to 5 cm and 37.6% (35/93) in the patients with a tumor > 5 cm. No patient died or changed to celiotomy during the 1121 times of RFA for 634 lesions in 421 patients. No hemorrhage occurred in any of these patients after the RFA treatment. The complications included abdominal pain in 32.3% (136/421), nausea in 9.0% (38/421), fever in 34.9% (147/421) and biliary leakage in 0.2% (1/421) of the patients. CONCLUSION: Ultrasound-guided percutaneous radiofrequency ablation with cool-tip needle is effective and safe in the treatment of liver tumors.