RU108844U1 - LASER FLUORIMETER - Google Patents

Abstract

 1. A laser fluorimeter containing an optically coupled laser radiation source, an optical device, an optical cuvette, a light filter, an optical analyzer consisting of a polychromator, an electron-optical converter, an optical image transmission system and connected to a computer via a digital video camera, are also connected to the computer salinity and temperature measurement sensors, characterized in that the laser fluorimeter is made at least 2-channel, the number of optical devices, expanders, o cally cuvette and a fluorimeter filters corresponding to the number of channels, wherein the filters are connected to optical fibers through the analyzer. ! 2. The laser fluorimeter according to claim 1, characterized in that a mirror is used as an optical device. ! 3. The laser fluorimeter according to claim 1, characterized in that a spectrograph is used as a polychromator. ! 4. The laser fluorimeter according to claim 1, characterized in that the expander is designed to coordinate the size of the laser beam with the cell used.

Description

The utility model relates to a device for non-contact study of the aquatic environment through its irradiation with a laser pulse and can be used in environmental monitoring of water areas, their plankton community, extensive sub-satellite measurements (for sea-color scanners), as well as for other tasks of analyzing the composition of mixtures and suspensions.

Known marine laser fluorimeter for the study of fluorescence spectra of sea water (A.Yu. Mayor, OA Bukin, A.N. Pavlov, V.D. Kiselev "Marine laser fluorimeter for the study of fluorescence spectra of sea water." Instruments and experimental equipment , 2001, No. 4, p. 151-154). The well-known laser fluorimeter consists of a laser source, the radiation of which through a rotary prism enters the optically transparent entrance window of the flow cell, into which outboard liquid is pumped using a pump. The fluorescence radiation through the exit window of the flow cell, the filter and the focusing lens is directed to an optical analyzer, including a scanning monochromator, PMT (photoelectron multiplier), an integrator and an ADC (analog-to-digital converter). The scanning monochromator contains a diffraction grating, the position of which is changed using a stepper motor controlled from a computer. The spectral lines obtained in the monochromator using a photomultiplier, integrator and ADC are digitized and fed to a computer for further processing. The fluorimeter also contains a cuvette with sensors for measuring salinity and temperature of sea water connected to a computer.

However, the known fluorimeter does not allow simultaneous measurement of the entire spectrum due to the use of a scanning receiving system with a stepper motor. In addition, the known fluorimeter contains movable mechanical parts that require separate control, structurally complex, has significant dimensions.

Closest to the claimed device is a marine flow laser fluorimeter for studying the fluorescence spectra of sea water (RF patent for utility model No. 53016, IPC G01N 21/64, published April 27, 2006). The known fluorimeter consists of a laser source, an optically coupled laser source, an optical device in the form of a rotary prism, an optical flow cell, an optical filter, an optical analyzer connected to a computer, as well as sensors for measuring salinity and temperature, while the optical analyzer is based on polychromator and also includes an electron-optical converter (EOC), an optical image transfer system and a black-and-white digital video camera.

A disadvantage of the known laser fluorimeter is the impossibility of simultaneously recording several fluorescence spectra excited by different pump sources (lasers).

The technical task of the claimed utility model is the creation of a laser fluorimeter, which allows you to simultaneously measure the amount of dissolved organic matter and plankton pigments, and provides increased reliability and quality of the results.

The technical essence of the solution. A laser fluorimeter made of at least 2 channels contains an optically coupled laser source, an optical device, an expander, an optical cuvette, a light filter, an optical analyzer consisting of a polychromator, an electron-optical converter, an optical image transmission system, and is connected to a computer by means of a digital video camera, sensors for measuring salinity and temperature are also connected to the computer. The number of optical devices, expanders, optical ditches and filters corresponds to the number of channels of the fluorimeter. The filters are connected to the optical analyzer by means of a light guide.

The utility model is illustrated by drawings, where figure 1 shows a diagram of a two-channel laser fluorimeter; figure 2 - shows the fluorescence spectra of sea water excited by the second harmonic of the Nd: YAG laser; figure 3 - shows the fluorescence spectra of sea water excited by the third harmonic of an Nd: YAG laser; figure 4 - laying of optical fiber in the fiber from the spectrograph.

The following notation is used in the drawings: 1 — laser radiation source, 2 — an optical device in the form of a mirror, 3 — an expander, 4 — an optical cuvette equipped with optically transparent windows, 5 — a light filter; 6 - optical fiber, 7 - spectrograph as a polychromator, 8 - image intensifier tube (electron-optical converter), 9 - optical image transmission system (lens), 10 - digital video camera, 11 - computer, 12 - pump, 13 - measuring cell equipped with sensors (not shown in FIG. 1) for measuring temperature and salinity of running water.

Laser fluorimeter operates as follows. The radiation is generated by the laser radiation source 1, and passing through the mirror 2 and expander 3 expanding the laser beam to the size of the cell window, enters the optical cell 4 through the input window. The fluorescence signal induced in the optical cuvette 4 passes through a side window to the input of the optical fiber 6, which is located behind the optical filter 5, which is installed to suppress laser scattered radiation. From the output of the optical fiber 6 of the first channel (Fig. 4), combined with the slit of the spectrograph 7, the radiation enters the spectrograph 7. Simultaneously, the radiation from the laser source 1 passes through the second channel through the mirror 2 and the expander 3 and enters the optical cuvette 4 through the input window . The fluorescence signal induced in the optical cuvette 4 passes through a side window to the input of the light guide 6, which is located behind the light filter 5. From the output of the light guide 6 of the second channel (Fig. 4), combined with the slit of the spectrograph 7, the radiation enters the spectrograph 7. Directly behind the spectrograph 7 there is an image intensifier tube 8, which enhances the image of the fluorescence spectra, and the optical image transmission system 9 transfers the image of the spectrum from the output window of the image intensifier 8 to a digital video camera 10, the signal from which is digitized Computer 11. The pump 12 provides the pumping of sea water through an optical cuvette 4 and a measuring cuvette 13, in which there are sensors connected to the computer 11 for measuring the temperature and salinity of sea water, the information from which is required for the subsequent calculation of the concentrations of organic substances. The location of the measuring cell 13, shown in figure 1 is one of the options for its location. It can be located both in front of the optical cell 4, and after it.

The specific hardware composition of the device depends on the task of measurement, the necessary accuracy and conditions of use. So, standard laser sources are used as a laser radiation source, for example, an Nd-YAG laser or any other laser emitting in the visible range of 350-535 nm, with a pulse duration of about 10-20 nsec and an energy of about 20 mJ and continuously with a power of about 10 -40 mW. The polychromator used in the device should provide registration of the spectrum in the range 390 nm - 780 nm without superposition, an inverse linear dispersion of the order of 15-30 nm / mm, an image size of at least 5 × 25 mm and a relative aperture of at least 1: 2, for coordination with standard quartz fibers Na = 0.22, for example, to study phytoplankton, use the CP-140 spectrograph or a similar one. The optical image transfer system is a lens that allows you to transfer the image from the output screen of the image intensifier tube to the CCD matrix of the camera. The technical characteristics of the lens are selected in the usual way in order to coordinate the image size on the image intensifier tube and the size of the CCD matrix. Any black-and-white digital video camera with a sensitivity of at least 10 ^-3 lK is used as a recording device.

The second harmonic of 532 nm excites the fluorescence of chlorophyll A of phytoplankton, the Chl A line (680 nm) of Fig. 2, mainly through the photoantenna of the photosynthetic cell, chlorophyll A itself is weakly absorbed in this region. With this excitation, the main contribution to its fluorescence is made by living phytoplankton cells. The close location of the Raman water scattering (Raman) line, the Raman line (649 nm) of Fig. 2, to the fluorescence of chlorophyll A, the Chl A line (680 nm) of Fig. 2, allows it to be used as a reference - the optical properties of water change slightly in the region of these lines in a wide range of external conditions, which is especially convenient when calculating the absolute values of the concentration of chlorophyll A. However, the Raman line overlaps the region where other, weakly fluorescent phytoplankton pigments are highlighted. With such excitation, studies of pigments whose fluorescence lines lie in the region shorter than 560 nm are not available.

The second harmonic of 532 nm excites DOM broadband fluorescence, mainly related to the activity of phytoplankton or pollution by aromatic and other hydrocarbons in the region from 550 to 750 nm.

The third harmonic of 355 nm excites the fluorescence of phytoplankton pigments less efficiently, but the width of the spectrum is much wider (Fig. 3). This makes it possible to register a greater number of phytoplankton pigments, and at high phytoplankton concentrations, weakly fluorescent pigments, which makes it possible to determine the change in species composition, developmental stages, and other characteristics of phytoplankton.

DOM fluorescence the third harmonic of 355 nm excites much more efficiently. DOM fluorescence is recorded due to both natural phenomena (currents, dust storms, terrigenous drifts, etc.) and anthropogenic influence. For some hydrocarbons (fuels, oils), identification by characteristic broadband spectrum lines is possible.

The use of information from two channels will significantly increase the reliability and quality of studies of phytoplankton communities and their environment, as well as expand the range of tasks in light of the growing anthropogenic impact and climate change. In addition, it is possible to identify new dependences while recording spectra with different excitations.

The signals from all channels are converted and amplified by the same receiving system, containing: spectrograph, image intensifier tube, lens and CCD camera (in Fig. 1, positions 7-10). This significantly reduces the measurement errors associated with the temperature and time instability of the receiving system in a wide range of ambient temperatures (from 10 to 30 ° C). Quite stable conversion (gain) coefficients are obtained both for different fluorescence channels and for different parts of the signal spectrum.

Using a fiber to deliver radiation to the receiving system allows you to use not only cuvettes of various designs, but also to receive radiation directly from the medium under study, for example, to conduct fluorescence studies of marine phytoplankton and DOM in depth, deepening only the fiber with a nozzle (cuvette). The fiber can also allow the use of a fluorometer without laser pumping, for example, as a photometer for studying the depth of the rising radiation of the ocean, excited by the sun, ocean bioluminescence, etc.

Unlike the prototype containing an optical single-channel analyzer, the inventive device uses an optical multi-channel analyzer, which allows you to get several fluorescence spectra of the studied fluid flow, excited by different sources (lasers), in one measurement, while the prototype in one measurement makes it possible to study only one the spectrum and its tuning to another excitation source will take a lot of time and may require additional calibration, which is not acceptable during the measurement erenium.

Claims (4)

1. A laser fluorimeter containing an optically coupled laser radiation source, an optical device, an optical cuvette, a light filter, an optical analyzer consisting of a polychromator, an electron-optical converter, an optical image transmission system and connected to a computer via a digital video camera, are also connected to the computer salinity and temperature measurement sensors, characterized in that the laser fluorimeter is made at least 2-channel, the number of optical devices, expanders, o cally cuvette and a fluorimeter filters corresponding to the number of channels, wherein the filters are connected to optical fibers through the analyzer. 2. The laser fluorimeter according to claim 1, characterized in that a mirror is used as an optical device. 3. The laser fluorimeter according to claim 1, characterized in that a spectrograph is used as a polychromator. 4. The laser fluorimeter according to claim 1, characterized in that the expander is designed to coordinate the size of the laser beam with the cell used.