傅立叶分解法荧光层析成像

本文提出一种基于结构光照明和傅立叶分解方法的荧光层析成像技术，该技术首先将激发光的强度沿着光轴方向调制成余弦函数，然后用此激发光对样品作传统的二维扫描，在每一个扫描位置余弦函数的频率在一定的范围内扫描，同时一一对应地记录下所发出的荧光强度。只要对所纪录的荧光序列做一个简单的傅立叶变换，即可以得到此位置样品沿着光轴方向的荧光团分布。这样通过一个传统的二维扫描，就可以得到一个三维的阳样品分布。

展宽器中非对称光谱剪切对输出脉冲对比度的影响

在展宽器中,光谱的剪切情况非常重要,它直接影响输出脉冲的质量。以ffner展宽器为例,参照以往建立的光线追迹模型,建立了分析展宽器中光谱剪切的模型。发现当展宽器的参数确定好后,光栅放置的位置对激光脉冲光谱剪切有非常重要的影响。当光栅相对于光轴中心对称放置时,展宽器容许通过的光谱相对于激光中心波长将是非对称分布的,即此时在展宽器中发生的光谱剪切为非对称光谱剪切,在神光II第9路拍瓦激光装置中,这种非对称光谱剪切将使输出脉冲对比度下降一个数量级。为了使展宽器中通过的光谱相对于激光中心波长对称分布,需要将光栅相对于光轴非中心对称放置。

反射率对入射角扫描测定单轴晶体的折射率

通过分析波矢沿任意方向的单轴晶体的折射率,在光轴位于入射面内时,给出了入射光分别为s光和p光的反射率拟合函数。利用改进的反射率扫描仪,测量了CaCO3晶体的s光和p光反射率随入射角变化情况,由理论拟合获得单轴晶体的两个主折射率,分别为no=1.6559和ne=1.4851。这种方法不需要对样品进行加工,其精度达到0.0001。另外,对于晶体光轴未知的情况,采用改进的布儒斯特技术分别测出三个晶体表面的布儒斯特角,由此可以确定光轴的方向。

Polarization patterns control based on photoinduced anisotropy of photochromic fulgide

We investigate the photoinduced anisotropy of a photochromic material of pyrrylfulgide/PMMA films. It is proven that when the film is illuminated with a linear polarization light, an optical axis that has the same polarization as the excitation light could be induced in the film. A matrix of light spots with different polarizations is recorded on the pyrrylfulgide/PMMA film. When reading out with non-polarization light, the matrix of light spots shows no information of patterns. However, when reading out with different linear polarization lights, different patterns could be observed. The experiment confirms that the pyrrylfulgide/PMMA film could be used to record two different polarization patterns in a matrix of spots. This property may be applied in camouflage technology.

Polarization patterns hide and display using photoinduced anisotropy of photochromic fulgide

Photoinduced anisotropy of a photochromic pyrrylfulgide/PMMA film was investigated by using two linearly polarized beams. Excitation by linearly polarized light induces into the film an optical axis that has the same polarization as the excitation beam. This causes a change of the transmittance and of the polarization state of the detection beam. With a microscope a matrix of 4x4 light spots with different polarizations were recorded in the pyrrylfulgide/PMMA film. If readout with non-polarized light, the matrix of light spots show no information pattern. However, when readout with differently polarized lights, different patterns can be displayed. The experiment demonstrates that pyrrylfulgide/PMMA films can be used to hide two differently polarized patterns, which may be applied in camouflage technology. (C) 2005 Optical Society of America.

Diffractive microlens with a cascade focal plane fabricated by single mask UV-photolithography and common KOH:H2O etching

A diffractive microlens with a cascade focal plane along the main optical axis of the device is fabricated using a low-cost technique mainly including single mask ultraviolet (UV) photolithography and dual-step KOH:H2O etching. Based on the evolutionary behavior of converse pyramid-shaped microholes (CPSMs) preshaped over a {100}-oriented silicon wafer in KOH etchant, the first-step KOH etching is performed to transfer initial square micro-openings in a SiO2 film grown by plasma enhanced chemical vapor deposition (PECVD) and patterned by single mask UV-photolithography, into CPSMs with needed dimension. After completely removing a thinned SiO2 mask, basic annular phase steps with a relatively steep sidewall and scheduled height can be shaped in the overlapped etching region between the neighboring silicon concave-arc microstructures evolved from CPSMs through the second-step KOH etching. Morphological measurements demonstrate a desirable surface of the silicon microlens with a roughness in nanometer scale and the feature height of the phase steps formed in the submicrometer range. Conventional optics measurements of the plastic diffractive microlens obtained by further hot embossing the fine microrelief phase map over the nickel mask made through a common electrochemical method indicate a highly efficient cascaded focusing performance.

Broadband high-gain optical parametric chirped-pulse amplification near 780 nm with LBO-I near-degenerate near-collinear phase match

Near-degenerative near-collinear phase-match geometry for broadband optical parametric chirped-pulse amplification (OPCPA) at approximate to 780 nm is calculated in comparison with nondegenerate noncollinear phase-match geometry. In an experiment on LBO-I near-degenerate near-collinear OPCPA, high gain with broad gain bandwidth (approximate to 71 nm, FWHM) at approximate to 780 nm is achieved by using an approximate to 390-nm pumping pulse. The stretched broadband chirped signal pulse near 780 nm is amplified to approximate to 412 mu J with a pumping energy of approximate to 15 mJ, and the total gain is > 3.7 X 10(6), which agrees well with the calculation. For a broadband (covering approximate to 100 nm) chirped signal pulse, the theoretical gain bandwidth has been attained experimentally for the first time. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

Broadband high-gain optical parametric chirped-pulse amplification near 780 nm with LBO-I near-degenerate near-collinear phase match

Near-degenerative near-collinear phase-match geometry for broadband optical parametric chirped-pulse amplification (OPCPA) at approximate to 780 nm is calculated in comparison with nondegenerate noncollinear phase-match geometry. In an experiment on LBO-I near-degenerate near-collinear OPCPA, high gain with broad gain bandwidth (approximate to 71 nm, FWHM) at approximate to 780 nm is achieved by using an approximate to 390-nm pumping pulse. The stretched broadband chirped signal pulse near 780 nm is amplified to approximate to 412 mu J with a pumping energy of approximate to 15 mJ, and the total gain is > 3.7 X 10(6), which agrees well with the calculation. For a broadband (covering approximate to 100 nm) chirped signal pulse, the theoretical gain bandwidth has been attained experimentally for the first time. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

Investigation of near-collinear degenerated quasi-phase matching optical parametric amplification using PPKTP crystal

The gain properties of near-collinear degenerated phase-matched optical parametric amplification (OPA) using PPKTP crystal are investigated theoretically. The results indicate that the type-0 phase matching of PPKTP has larger accepted angle and better gain spectrum by tuning crystal temperature or rotating crystal angle.

Optical near-field simulation of Sb thin film thermal lens and its application in optical recording

Using the finite-difference-time-domain method, the near-field optical distribution and properties of Sb thin film thermal lens are calculated and simulated. The results show as follows. Within the near-field distance to the output plane of thermal lens, the spot size is approximately 100 nm, and its intensity is greatly enhanced, which is higher than that of incident light. The spot shape gradually changes from ellipse to round at the distance of more than 12 nm to the output plane. The above-simulated results are further demonstrated by the static optical recording experiment. (C) 2005 American Institute of Physics.

Optical recording properties of metal-azo dye as recording medium with super-resolution near-field structure

A novel metallized azo dye has been synthesized. The absorption spectra of the thin film and thermal characteristic are measured. Static optical recording properties with and without the Bi mask layer super-resolution near-field structure (Super-RENS) of the metal-azo dye are investigated. The results show that the metal-azo dye film has a broad absorbance band in the region of 450-650 nm and the maximum absorbance wavelength is located at 603 nm. It is also found that the new metallized azo dye occupies excellent thermal stability, initiatory decomposition temperature is at 270 degrees C and the mass loss is about 48% in a narrow temperature region (15 degrees C). The complex refractive index N (N = n + ik) is measured. High refractive index (n = 2.45) and low extinction coefficient (k = 0.2) at the recording wavelength 650nm are attained. Static optical recording tests with and without Super-RENS are carried out using a 650nm semiconductor diode laser with recording power of 7mW and laser pulse duration of 200ns. The AFM images show that the diameter of recording mark on the dye film with the Bi mask layer is reduced about 42%, compared to that of recorded mark on the dye film without Super-RENS. It is indicated that Bi can well performed as a mask layer of the dye recording layer and the metallized azo dye can be a promising candidate for recording media with the super-resolution near-field structure.

Propagation properties of off-axis Hermite-cosh-Gaussian beam combinations through a first-order optical system

Based on the Collins integral formula, the analytic expressions of propagation of the coherent and the incoherent off-axis Hermite-cosh-Gaussian (HChG) beam combinations with rectangular symmetry passing through a paraxial first-order optical system are derived, and corresponding numerical examples are given and analysed. The resulting beam quality is discussed in terms of power in the bucket (PIB). The study suggests that the resulting beam cannot keep the initial intensity shape during the propagation and the beam quality for coherent mode is not always better than that for incoherent mode. Reviewing the numerical simulations of Gaussian, Hermite-Gaussian (HG) and cosh Gaussian (ChG) beam combinations indicates that the Hermite polynomial exerts a chief influence on the irradiance profile of composite beam and far field power concentration.

Optical amplification near 1300 nm in bismuth-doped strontium germanate glass

We demonstrate the broadband optical amplification in bismuth-doped strontium germanate glass with 808 nm and 980 nm laser diodes (LDs) as excitation sources. The net optical gain has been obtained within the wavelength region of 1272 to 1348 nm with 808 nm laser diode under 0.97 W power. The maximum gain and gain coefficients are 1.23 and 1.03 cm(-1) at 1315 nm, respectively. The signal increment at 1300 nm is 2.8 times with 980 nm LD, under 3 W power. The differential thermal analysis measurement reveals the good thermal stability of the studied glass. This glass could be suggested as a promising gain medium for broadband optical amplifiers.