Study On The Key Technology And Application Of Planar Waveguide Infrared Spectrometer

Mid-infrared spectroscopy is a method to detect organic compounds in the mid-infrared band by using their optical properties.The fundamental frequency phenomena of the vibrational transition of organic compounds are mainly studied,which can be used to obtain the structural information of compounds.Mid-infrared spectroscopy has the outstanding performance of strong characteristics,short analysis time and small sample size.It plays an important role in the field of organic chemistry,ecological environment and pharmaceutical engineering.The small infrared spectrometer based on planar waveguide has the advantages of small size,light weight and no moving parts,which makes it irreplaceable in the analysis of mid-infrared spectroscopy and has its own style in miniature mid-infrared spectrometer.On the basis of the previous research in the laboratory,the infrared characteristic analysis and extended application of the spectrometer based on planar waveguide technology are described in detail.The main work is summarized as follows:1.Analysis and suppression of stray radiation on the small planar waveguide infrared spectrometer.On the basis of studying the basic energy transfer equation of stray radiation transmission,combining with the basic radiation quantity and basic law of stray radiation theory,the main factors affecting the internal background stray radiation of the small planar waveguide infrared spectrometer are analyzed.The simulation study is carried out by using Trace Pro software,which provides a theory for the research of the internal background stray radiation of the spectrometer.The simulation results show that the effect of background stray radiation can be suppressed by adding cold shield and detector secondary refrigeration.The stray radiation coefficients of the planar waveguide infrared spectrometer system before and after the suppression measures are compared experimentally.It is proved that the planar waveguide infrared spectrometer system can be significantly reduced by adding cold shield and detector secondary refrigeration.2.Spectral calibration and radiation calibration of the small planar waveguide infrared spectrometer.The advantages and disadvantages of the current laboratory spectral calibration method for infrared spectrometer are analyzed.A new method of spectral calibration for the small planar waveguide infrared spectrometer is proposed,which combines laser with integral sphere.A calibration device based on laser and integrating sphere has been built in the laboratory.The spectral calibration of the small planar waveguide infrared spectrometer has been carried out by using this experimental device.It can solve the problem of wavelength offset and spectral bandwidth of the light source.At the same time,the calibration of spectral center wavelength and spectral resolution is completed.The calibration method of measuring two narrow-band filters is compared,and the applicability of the spectral calibration device is verified.3.Radiation calibration of the small planar waveguide infrared spectrometer.In view of the fact that the small planar waveguide infrared spectrometer is sensitive to ambient temperature in the mid-infrared band,the influence of ambient temperature on the output gray value of the small planar waveguide infrared spectrometer is analyzed,and a radiometric calibration method based on the compensation of the output gray value of the small planar waveguide infrared spectrometer is proposed.The influence of ambient temperature change on target radiation measurement accuracy during calibration and measurement of the small planar waveguide infrared spectrometer is reduced.Finally,through the corresponding drift compensation experiment,the maximum error between the output gray value and the theoretical value is less than 2.4%,which verifies the accuracy of the calibration model for infrared radiation measurement at different ambient temperatures.4.Performance testing and extended application of the small planar waveguide infrared spectrometer.Aiming at the application of attenuated total reflectance(ATR)spectroscopy,the design and development of ATR accessories were carried out,and corresponding experiments were carried out on typical samples(liquids and thin films).On the basis of the above research,the typical gases(ammonia and sulfur hexafluoride)were measured by a small planar waveguide infrared spectrometer,and the results were compared with those measured by Fourier transform spectrometer.Experiments show that the small infrared spectrometer developed independently can complete on-line real-time detection of liquid,film and gas.In addition,Attenuated Total Reflection(ATR)accessories are small in size,easy to carry and easy to operate,and are very suitable for non-laboratory detection.