The combination of outstanding properties, such as high thermal conductivity, high refractive index, extreme hardness, radiation resisting, and high insulation, makes diamond an ideal material for optical application under extreme requirements. The relationship between the optical absorbance of diamond doped with nitrogen and the nitrogen concentration were studied. The calculation method of nitrogen concentration used in this study was a modification of the typical calculation method. The high nitrogen concentration diamond was synthesized in Fe80Ni20-carbon and sodium azide system. The absorbant intensity of diamond increases in 800—1400 cm-1 range. The nitrogen concentration in diamond increases with the increasing contents of NaN3. The color of diamond changes with the increase of NaN3 content, in the order of green, dark green and black. The diamond synthesized with addition of NaN3 contains nitrogen exceeding 1450 ppm which is much higher than the normal diamond. The optical transmission of diamond decreases with the increase of nitrogen concentration. The diamond with nitrogen doping can be used as optical material with better absorbance and many physical characters at some wavenumber.

The field enhancement is one of the important factors that indicate the performance of field emission cold cathode devices. It is intimately related to the field emission current density and the threshold voltage of the device. In our paper, the field enhancement factor of a normal-gated field emission nanowire cold cathode model was analytically deduced on the basis of classical electrostatic theory, and it is given by the equation. β=k1{N2·(L-d1)2+［1/k1+(L-d1)］2}1/2. The effect of geometrical parameters of the device on the field enhancement factor was explored. The theoretical analysis showed that the larger the length (L-d1) of nanowire above the gate and the gate hole radius, the larger the enhancement factor is; but the larger the nanowire radius, the smaller the enhancement factor is. When the L is much larger thand1, the enhancement factor satisfies the relation. β∝Ｌ／r0, for which N=N1(k1r0)/N0(k1r0), N0(k1r0) and N1(k1r0) are both Neumann functions and k1=0.8936/R. R, L, r0 and d1 are the gate hole radius, the nanowire length, the nanowire radius and the gate-cathode distance, respectively.

To achieve the miniaturization and the static state of the Fourier transform spectrometer, two stepped mirror arrays are introduced into the time-modulation Fourier transform spectrometer to replace of the plane mirrors. The two stepped mirrors can sample the interferogram data in two-dimensional space, which can reduce the size of the instrument and increase the stability of the system. Due to the precision restriction on the stepped mirrors in the fabrication process, the various sub-mirrors of the stepped mirrors may contain various thickness errors and angle errors, which can affect the distribution of the interferogram and the quality of the spectrum. We regard the thickness error and the angle error of all the sub-mirrors as random variables, and synthesize all the error terms into a Fourier transform integration function using Monte Carlo method. By means of statistic analysis on the spectrum error factor, we can appraise the recovered spectrum affected by the thickness error and the angle error of the sub-mirror. The statistical result indicates that the statistical mean of the spectrum error factor increases with thickness standard deviation and angle standard deviation increasing. According to the statistical analysis on spectrum error factor, the tolerances of the thickness standard deviation and the angle standard deviation of the sub-mirror can be determined in the fabrication process of the stepped mirrors.

The solar radiation has significant impact on the earth climate and environment, so it’s important to detect it. High thermal conductivity and high absorptivity material for absorbing radiation is highly needed to improve the performance of the radiation detector. The compound diamond films were deposited using microwave plasma chemical vapor deposition （MW-PCVD） and hot cathode direct current plasma chemical vapor deposition （DC-PCVD） methods. The absorptivity of the compound diamond film is 99%—99.2%. With the increase of the thickness of black diamond layer, the thermal conductivity of the compound diamond film decreases a little, but the thermal conductivity is always larger than 16 W/K·cm when the thickness of black diamond layer is less than 15 μm and so it is still a high thermal conductivity material. The black diamond layer deposited on high purity diamond film by hot cathode DC-PCVD method has apparent wide Raman peaks at 1500—1600 cm-1and 1350 cm-1 which correspond to non-diamond carbon phase. With the increase of methane, this non-diamond carbon phase also increases. As the non-diamond carbon phase, like graphite, increases, the transmissivity of the compound diamond films decreases. The black diamond layer deposited on the high purity diamond acts as the heat sink and has high surface adhesion property, and high thermal conductivity.

To estimate the field enhancement factor of the gated nanowire, the image charge model of floating sphere between parallel gate and cathode plates is proposed. The field enhancement factor of the gated nanowire is expressed by β=1/2（3.5+L/r0+W）, where L and r0 are the length and tip radius of nanowire, respectively, and W is a function of the gate-hole radius R, gate-cathode distance d and the geometrical parameters of the nanowire. The calculation results show that the influence of the aspect ratio of the nanowire on the enhancement factor is remarkable, i.e., the enhancement factor increases rapidly with the increase of the length and top curvature of the nanowire. Furthermore, the enhancement factor decreases with the increase of the gate-cathode distance and is equal to β0=3.5+L/r0 when the gate-cathode distance tends to infinite. The smaller the gate-hole radius, the larger the enhancement factor, and the enhancement factor will be equal to β=β0+1.202（L/d）3 when the gate-hole radius tends to zero.