Comparison between microscope and endoscope in the endonasal transsphenoidal approach to the sellar: Anatomical study / 中华显微外科杂志

Objective To compraison the of exposure in the endonasal transsphenoidal approach to the sellar between microscope and endoscope. Methods Ten formalin-fixed, silicone-injected adult cadveric heads were studied. A direct endonasal transsphenoidal approach was performed via the right nostril, pushing aside the nasal septum, then reach the sphenoidal sinus. The approach was performed with the operating microscope first, then with the endoscope. For each step (sellar, suprasellar, parasellar and clival), the operative region afforded by direct microscopic view was measured and then compared with that obtained by using the edndoscope. Results It was found that the endoscope provided greater view than microscope in this approach. Although the microscope provides an adequate view of the midline structures and part of the contralateral parasellar areas; under direct endoscopic vision, the lateral extension could be widened by an additional 6.5 mm on the ipsilateral and 4 mm on the contralateral side. At suprasellar region, the microscope provides could expose the posterior part of, optic nerve and optic chiasma; but could not expose the areas anterior and superior the interspace superior the optic chiasma. Compare with the microscope, the endoscope allowed extension of bone removal and dual opening for an additional 4 mm anteriorly at the sagittal axis and an additional 3.5 mm on the ipsilateral and 4 mm on the contralateral side. At the clivus region, the medial surface of the vertical segment of the ICA and the basilar artery could be partially 7 exposed by the microscope. By the endoscope, it could gain an additional 4 mm on the ipsilateral side and 2.5 mm on the contralateral side in width. Because of the anatomical boundaries of the sphenoid sinus, the anatomincal exposure by the microscope same as the endocope at the sagittal axis. Conclusion The endoscope allows for a panoramic view and permits widening of the operative exposure in all directions. The endoscope is more suitable in the the minimal and expanded endonasal transsphenoial approach.

Experiments of a grating light modulator for projection display applications.

A micromechanical optical modulator called a grating light modulator (GLM) with electrostatic actuation, fabricated by the conventional process, is described. The GLM is operated by the interaction of a stationary reflector and a movable sliding grating. The GLM is a micromechanical phase grating. The phase difference is determined by the slide of the movable part (upper grating), allowing different diffraction patterns of reflected light. In addition, 100% modulation in the first/zero order can act as an optical switch and produce bright or dark pixels in a projection display system. Built using microelectromechanical system technology, and designed to be manufactured using mainstream integrated circuit fabrication technology, a 256-pixel GLM array is fabricated. We also describe projection display applications of a GLM as a high efficiency spatial light modulator. The optimized display system with a GLM is theoretically discussed in detail. The single-color and three-color experimental results indicate that the GLM technology has characteristics that make it suitable for projection display applications.

Two-dimensional grating light modulator for projection display.

A novel two-dimensional (2D) phase grating light modulator for projection display is proposed. It consists of an upper moveable grating, a bottom mirror, and four supporting posts between them. After the driving voltage is applied to the modulator, the upper grating will move down, which induces a phase difference and, therefore, leads to a controlled variation of its diffraction pattern. Optical characteristics of the modulator and the modulator array are analyzed with Fourier optics theory. The analysis shows the incident light will be switched from its zero order diffraction fringe to the first order diffraction fringe when the phase difference between the moveable grating and the bottom mirror changes from 2 pi to pi. The diffraction pattern of the light modulator array is the coherent superposition of all single modulators. A 16 x 16 modulator array is fabricated by surface micromachining technology. The test result shows that the device works well when it is actuated by a voltage with a 1 kHz frequency and 10V amplitude. Both theoretical analysis and experiment results indicate that the 2D phase grating light modulator has potential application in a projection display system.