Here a refractometer with broad refractive index measurement range is proposed. This refractometer uses the measured liquid as a liquid prism and utilizes CCD and a set of computer software based on Borland C++ to measure the refractive index of liquid. The proposed refractometer has a small volume. Meanwhile the structure and working principle of the proposed refractometer are introduced. Now the mainly used refractometer is Abbe refractometer which has a refractive index measurement range of 1.30-170. While the theoretical results of our work indicate the measurement range can be up to 1.00-3.60 when the vertex angle of the liquid prism is 30°, and the experimental results have proved it is viable.
Compression is a kernel procedure in hyperspectral image processing due to its massive data which will bring great difficulty in date storage and transmission. In this paper, a novel hyperspectral compression algorithm based on hybrid encoding which combines with the methods of the band optimized grouping and the wavelet transform is proposed. Given the characteristic of correlation coefficients between adjacent spectral bands, an optimized band grouping and reference frame selection method is first utilized to group bands adaptively. Then according to the band number of each group, the redundancy in the spatial and spectral domain is removed through the spatial domain entropy coding and the minimum residual based linear prediction method. Thus, embedded code streams are obtained by encoding the residual images using the improved embedded zerotree wavelet based SPIHT encode method. In the experments, hyperspectral images collected by the Airborne Visible/ Infrared Imaging Spectrometer (AVIRIS) were used to validate the performance of the proposed algorithm. The results show that the proposed approach achieves a good performance in reconstructed image quality and computation complexity.The average peak signal to noise ratio (PSNR) is increased by 0.21~0.81dB compared with other off-the-shelf algorithms under the same compression ratio.