Design of a novel high resolution holography concave grating spectroscopy for tongue coating analyzer

The tongue coating diagnosis is an important part in the traditional Chinese medicine (TCM). TCM usually uses the visual method to determine the severity of the disease, but this method mainly relies on the experience of doctor and will not avoid generating the error. In addition, the application of the method based on the digital image processing is restricted by the complicated algorithm, expensive cost and slow processing rate, etc. So, a novel tongue coating analyzer(TCA) based on the spectrum analysis is developed in this paper. And, the holography concave grating spectroscopy (HCGS) is the critical unit in the TCA, a high resolution custom-built HCGS for TCA based on the linear CCD and virtual instrument is designed. In the HCGS, the holography concave grating is used as the dispersion device instead of the plane grating, high resolution linear CCD with combined high-speed PCI data acquisition (DAQ) card are used to design the tongue coating(TC) spectrum acquisition, measurement and analysis system. In addition, the virtual instrument (VI) technology based on LabVIEW is used to design a virtual-HCGS for TCA software platform to control the TC spectrum acquisition and data analysis. Experimental results show that the spectral range of the HCGS for TCA can reach 300-1000nm, its wavelength resolution can reach 1nm, and it uses the back-split-light technology and 8-channel parallel analysis. Compared with other same types, this HCGS for TCA has many advantages, such as, more compact volume, simpler algorithm, higher accuracy, cheaper cost and fewer stray-light and higher imaging quality, etc. Therefore, the TCA based on HCGS will have the greatly potential values in the fields of the TCA for TCM.