Research on simultaneous measurement of refractive index and thickness of bilogical tissue by low coherence interferometry

研究了一种新型的低相干干涉仪，它可以同时测量生物组织的折射率和厚度。主要研究成果如下：1.我们提出并证明了一种新的技术，同时测量折射率n和厚度t的被测对象。该技术是基于低相干干涉与精确的平移阶段相结合。适用于生物组织折射率的精确测量。对于大于1mm的厚度，预期测量精度<0.1%。在使用物体扫描方法的实验中，对于近1 mm厚的透明板，精度达到0.2%或更低。2.在此基础上，成功地实现了对人指甲、牙齿、鸡组织和甲壳类多层组织的折射率和厚度的测量.我们认为，这种方法适用于没有任何偏振控制的双折射测量。测量了X切LiNbO_3板的寻常折射率和非寻常折射率n_o和n_e.此外，我们还提出并演示了一种新的技术，利用低相干干涉仪，以单个超辐射发光二极管为光源，同时测量透明板的相位和群光密度n_p和n_g，以及厚度t.为了实现稳定和紧凑的测量系统，低相干干涉仪由50 x 50 cm ^2的试验板上的微光学元件组成。

The research has been made to demonstrated a novel low coherence interferometer which can provide simultaneous measurement of the refractive index and thickness of biological tissue. Major research results are described in the following.1. We proposed and demonstrated a novel technique for simultaneous measurement of refractive index n and thickness t of a measured object. The technique is based on the low coherence interferometry combined with precise translation stages. It is applicable for accurate measurement of refractive index of biological tissue. The measurement accuracy of <0.1% is expected for a thickness of more than 1mm. In the experiment using the object scanning method, the accuracy of 0.2% or less was attained for nearly 1-mm thick transparent plates.2. On the basis of our proposed method, refractive index and thickness measurement were successfully achieved for a human nail, tooth, chicken tissue and a crustacean which has multiple layrs.3. We suggest that this method is applicable for birefringence measurement without any polarization control. The ordinary and extraordinary indices, n_o and n_e of a X-cut LiNbO_3 plate were measured.4. Moreover, we propose and demonstrate a novel technique for simultaneous measurement of plase and group lidices n_p and n_g of a transparent plate, as well as the thickness t, using the low coherence interferometer where a single superluminescent diode is used as the light source.5. To realize a stable and compact measurement system, the low coherence interferometer consisted of micro-optic components on a breadboard of 50 x 50cm^2.