TYDEX 滤波器PDF， 363 KB

TYDEX 滤波器PDF， 363 KB

Tydex生产用于热粪和热成像的BBAR涂层锗光学元件。所有元素都经过严格测试，以提供最佳质量和涂层。

Germanium_Windows_and_Lenses_for_Thermography

分光光度计测量

我们使用光学等级最高的单晶锗进行光学生产。但是，在涂覆之前，我们始终检查抛光窗口在透明孔径上的透射率在2.0 - 14.0μm范围内（见图1）。

镀膜前的透射锗窗口

图 1.1.直径为 180 mm、厚度为 12.7 mm 且不含 BBAR 涂层的 Ge 窗口的透射光谱（3.0 - 5.0 μm 和 8.0 - 12.0 μm）。

BBAR涂层锗窗的传输

Fig. 1.2. Transmission spectrum of a Ge window with the diameter of 180 mm and thickness of 12.7 mm with BBAR coating (3.0 - 5.0 µm and 8.0 - 12.0 µm).

Good optical transmission is very important for optical elements; it is the most important parameter for pyrometric applications. However, for the elements of imaging systems it is not enough to have good transmission only. That is why for such elements we carry out more complicated tests.

First, we measure the coefficient of internal scattering. This coefficient determines the part of energy that deviates from incident beam direction after transmitting through the window (routine spectrophotometer measurements cannot separate radiation spreading at different angles). Test beam wavelength is 2.5 µm and it is known that for longer wavelengths scattering losses are smaller. Thus, this coefficient can serve as an adequate parameter for estimation of the material internal quality. The aperture diameter of testing setup is about 35 mm. In cases when it is significantly smaller than the window aperture we measure internal scattering in several spots lying on the perpendicular radii (see Tab. 1 and Fig. 2).

Tab. 1.  Coefficients of Internal Scattering at l = 2.5 mm. 

Spot #

1 2 3 4 5 6 7 8 9

center R1 R2 R3 R4

1.2% 1.2% 1.3% 1.4% 1.3% 1.4% 1.5% 1.3% 1.6%

  Scheme of location of internal scattering measurements spots

 Fig. 2. Scheme of location of internal scattering measurements spots and measurements results.

After that we measure directional transmission at 2.5 µm. This parameter determines the fraction of energy that propagates in the same direction as incident beam. The optical setup for these measurements is constructed in such a way that multiple internal reflections inside the window are eliminated. Testing beam diameter is 5 mm. We provide measurements in several spots as described above. The value of directional transmission for above mentioned window is 40.2 +/- 0.2 % in all spots, which is practically equal to the theoretical maximum.

 Finally we measure the transmission of the coated window (see Fig. 1).

干涉仪测量

适用于某些应用，如一氧化碳2-激光光学波前形状的保持非常重要。对于此类光学元件，我们使用以下程序通过干涉仪测量来检查透射波前失真（TWD）：

在10.6μm处测量，干涉仪图案被转移到个人计算机。在第一阶段，我们使用常规图形软件消除噪声并提高图像的对比度（参见图3）。

以下操作由专门设计的干涉仪图形分析软件执行。首先，我们确定条纹的坐标。然后，我们用二维幂多项式近似条纹。在计算TWD之后，提供参数和测量精度估计（见表2）。最后，我们重建波前地形并将其呈现在平面和3D图上（见图4）。

Interferometer graph of transmitted wavefront after noise removal and contrast boost

图 3.噪声消除和对比度增强后透射波前的干涉仪图。窗口直径为50.8毫米，厚度为5毫米。

选项卡 2.TWD参数和测量精度。直径为 50.8 毫米、厚度为 5.0 毫米的窗口。

均方根F 光伏F D B4 光伏Z 均方根

（W-Z） s

0.044 0.26 0.11 0.16 0.12 0.027 0.009

均方根F- 与最近平面相比，均方根波前失真;

光伏F- 与最近平面相比的峰谷波前失真;

D - 样品的聚焦系数;

二4- 4阶泽尼克带误差系数;

光伏Z- 带状误差的峰谷值;

均方根（W-Z）- 均方根波前畸变，无区域误差;

s - 波前重建不准确;