CN217006939U - Fluorescence spectrum detection device based on DMD - Google Patents

Abstract

The utility model relates to the technical field of fluorescence spectrum detection, and discloses a fluorescence spectrum detection device based on a DMD (digital micromirror device), which comprises a collimating lens, a dispersion unit, the DMD and a detector; and the fluorescence generated by the sample to be detected enters the dispersion unit after being collimated by the collimating lens, then is projected to the DMD, is modulated by the DMD and is received by the detector. The utility model adopts the DMD to selectively output the dispersed light, makes full use of the advantages of the DMD pixel level regulation and control to split, encode and reconstruct the spectrum, and can load various patterns due to the characteristic of the DMD pixel level control, namely, the spectrum patterns with different central wavelengths and different bandwidths can be used for reconstructing the spectrum. Therefore, the spectrum sampling points of the detection device are more than those of a multi-channel detector, and the precision and the mode of spectrum detection are superior to those of the multi-channel detector.

Description

Fluorescence spectrum detection device based on DMD

Technical Field

The utility model relates to the technical field of fluorescence spectrum detection, in particular to a DMD-based fluorescence spectrum detection device.

Background

Unlike spectrometers, imaging spectrometers have the advantage of imaging. The imaging spectrometer may also be operated through pre-spectral calibration plus special experimentation to obtain the spectral profile of the dye. At present, imaging spectrometers have several categories such as multiple filters, movable slits, multi-channel detection, etc. The multi-filter consists of many filters, the method is simple, but the cost is high, and the multi-filter is very limited by the filters, so that the multi-filter is not suitable for detecting the spectrum. The movable slit outputs light of a specific bandwidth by using the movable slit, but the method is not suitable for spectrum detection because of slow speed, complex structure and low precision.

Multichannel detection refers to the use of multiple detectors covering the entire spectral detection band, i.e., each detector is responsible for responding to fluorescence in a particular wavelength range. Compared with the former two methods, the multichannel detection method has the advantages of high speed and high precision, so the method can also be used for detecting the spectrum.

As shown in fig. 1, the optical path of the multispectral module of the Nikon C1si system is schematically illustrated. Where, Emission light is incident fluorescence, Grating 1 is a Grating, and Multi-channel PMT is a multichannel photomultiplier tube.

The working principle of the module is as follows: the fluorescence generated by the sample (Emission light) passes through some optical components and is then irradiated on the Grating (Grating 1). Due to the diffraction effect, the incident fluorescence spreads out spatially. Finally, the dispersed light is totally incident on a Multi-channel photomultiplier tube (Multi-channel pmt) to ensure that the detector can accept all the dispersed light. Since the dispersed fluorescence is fully accepted by the detector, each channel corresponds to a fixed spectral bandwidth. When the spectrum is measured, each channel receives and counts signals, and the signal values are divided by the spectral transmittance coefficient of the system, so that the spectrum of the incident fluorescence can be obtained.

This multi-channel spectroscopic probe is widely used by virtue of its stable performance and simple structure, which is used in addition to many other products, such as the 16-channel probe of Becker & Hick1 GmbH (NW-FLIM-DEFGASP-NDD-NOS).

The multi-channel detector mentioned above, although superior in performance and widely applicable, has some problems. The specific problems are as follows:

(1) due to the structural limitation, the number of channels of the detector cannot be increased without limit. At present, the number of channels can only reach 16 at most, so that only 16 spectrum detection points are provided, and the problem of insufficient spectrum sampling points is often encountered. Since the spectral range of many fluorescent lights is wide (in the example of fluorescein sodium, the emission spectrum of the dye covers 400 nm-700 nm), the more spectral detection points, the more accurate the spectral detection.

(2) Due to the limited number of channels, the bandwidth of each channel is not very narrow, i.e. the spectral resolution is not very high. In a spectrometer, the poorer the spectral resolution, the greater the wavelength difference between two wavelengths that can be resolved, and the poorer the detection effect.

(3) For a spectrometer, the energy utilization efficiency of the grating is much lower than that of the prism, especially the working wavelength range of the grating is small and more stray light and reflected light have a larger influence on the detection system.

(4) Multi-channel detectors are expensive. This type of detector is costly due to the superposition of several or a dozen detectors.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a fluorescence spectrum detection device based on a DMD (digital micromirror device), and aims to solve the problem that sampling points of spectrum detection are insufficient in the prior art.

The utility model is realized in this way, the fluorescence spectrum detection device based on DMD, including collimating lens, dispersive unit, DMD and detector; and the fluorescence generated by the sample to be detected enters the dispersion unit after being collimated by the collimating lens, then is projected to the DMD, is modulated by the DMD and is received by the detector.

Optionally, the dispersion unit is a prism.

Optionally, an optical filter is disposed between the collimating lens and the dispersing unit.

Optionally, the detector is a single photon detector or an area array detector.

Optionally, the detector is a CCD.

Optionally, a focusing lens is disposed between the DMD and the detector, and light emitted from the DMD is focused by the focusing lens and then received by the detector.

Optionally, the fluorescence detector further comprises an incoupling lens and an optical fiber, wherein fluorescence generated by the sample to be detected is coupled into the optical fiber through the incoupling lens and is emitted from an exit end of the optical fiber, and the exit end is located at a front focus of the collimating lens.

Optionally, the DMD further comprises a beam terminator, and the light emitted from the DMD is received by the beam terminator.

Optionally, the DMD is driven by a DMD driver, and a spectrum pattern is loaded on the DMD driver to modulate light incident on the DMD.

Optionally, the center wavelength of the spectrum pattern is 400-700 nm; the spectral bandwidth of the spectral pattern is between 6nm and 20 nm.

Compared with the prior art, the fluorescence spectrum detection device based on the DMD provided by the utility model adopts the DMD to selectively output the dispersed light, and makes full use of the advantage of DMD pixel level regulation to split, encode and reconstruct the spectrum. Therefore, the spectrum sampling points of the detection device are more than those of a multi-channel detector, and the precision and the mode of spectrum detection are superior to those of the multi-channel detector.

Drawings

FIG. 1 is a schematic diagram of the optical path of a multispectral module of a prior art Nikon C1si system;

FIG. 2 is a schematic optical path diagram of a device for DMD-based fluorescence spectrum detection according to the present invention;

FIG. 3 is a schematic diagram of a spectrum pattern loaded on a DMD in a device for fluorescence spectrum detection based on the DMD provided by the present invention;

FIG. 4 is a schematic diagram of the result of the experiment of detecting EOSIN Y dye by the DMD-based fluorescence spectrum detection device provided by the utility model.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the utility model and are not intended to limit the utility model.

The following describes the implementation of the present invention in detail with reference to specific embodiments.

The same or similar reference numerals in the drawings of the present embodiment correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", etc. based on the orientation or positional relationship shown in the drawings, it is only for convenience of describing the present invention and simplifying the description, but it is not intended to indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and are not to be construed as limiting the present patent, and the specific meaning of the terms may be understood by those skilled in the art according to specific circumstances.

Referring to fig. 2-4, preferred embodiments of the present invention are shown.

The device for detecting the fluorescence spectrum based on the DMD comprises a collimating lens, a dispersion unit, the DMD and a detector; the fluorescence generated by the sample to be detected is collimated by the collimating lens, then enters the dispersion unit, is projected to the DMD, is modulated by the DMD, and is received by the detector.

The fluorescence spectrum detection device based on the DMD provided by the utility model adopts the DMD to selectively output the dispersed light, makes full use of the advantages of pixel level regulation and control of the DMD to split, encode and reconstruct the spectrum, and can load various patterns due to the characteristic of pixel level control of the DMD, namely, the spectrum patterns with different central wavelengths and different bandwidths can be used for reconstructing the spectrum. Therefore, the spectrum sampling points of the detection device are more than those of a multi-channel detector, and the precision and the mode of spectrum detection are superior to those of the multi-channel detector.

In particular, a DMD (digital micromirror device) is an array of multiple high-speed digital light reflections. The DMD is constructed of a number of tiny mirrors, the number of which is determined by the display resolution, one mirror for each pixel. The DMD device has pixel-level controllability and high-speed switching frequency.

The DMD is driven by a DMD driver, and a spectrum pattern is loaded on the DMD driver to realize modulation of light incident on the DMD. The center wavelength of the spectrum pattern is 400-700 nm; the spectral bandwidth of the spectral pattern is between 6nm and 20 nm.

For example, 19 spectral patterns can be loaded in sequence, wherein the central wavelengths are 505nm, 515nm, 525nm, 535nm, 545nm, 555nm, 565nm, 575nm, 585nm, 595nm, 605nm, 615nm, 625nm, 635nm, 645nm, 665nm, 675nm and 685nm respectively, and the spectral bandwidths are between 6nm and 20 nm.

The dispersion unit can adopt a prism, can generate a better dispersion effect and has small energy loss.

The collimating lens can adopt a convex lens or a double-cemented lens, light enters from the front focus of the collimating lens and becomes parallel light after passing through the collimating lens, so that the dispersion of subsequent light is conveniently expanded without confusion.

An optical filter is arranged between the collimating lens and the dispersive unit, and the optical filter is an optical device used for selecting a required radiation wave band and filtering out some unwanted noise. According to the spectral band, there are ultraviolet filter, visible filter, infrared filter. According to the spectral characteristics, the method comprises the following steps: band pass filter, cut-off filter, spectral filter, neutral density filter, reflection filter. In the fluorescence spectrum detection device based on the DMD, a proper optical filter is selected according to the spectrum range of a sample to be detected.

The fluorescence spectrum detection device based on the DMD further comprises an incoupling lens and an optical fiber, wherein fluorescence generated by a sample to be detected is coupled into the optical fiber through the incoupling lens and is emitted from an emitting end of the optical fiber, and the emitting end is located at the front focus of the collimating lens. The coupling-in lens can adopt a convex lens, a double-cemented lens and the like, and focuses and couples light into the optical fiber. Due to the transmission characteristic of the optical fiber, the light path can be conveniently folded, the position of a sample to be detected can be conveniently adjusted, and the whole device for detecting the fluorescence spectrum based on the DMD is convenient to reduce.

The detector can adopt a single photon detector or an area array detector without great limitation. In principle, any detector can be used. Compared with the prior art that a plurality of detectors are needed in a multi-channel detector, the fluorescence spectrum detection device based on the DMD only needs one detector.

The CCD can be used for replacing high-sensitivity detectors such as a photomultiplier tube (PMT) and a single photon counter (APD), so that the cost can be saved, and the utilization rate of a single detector can be fully exerted.

A focusing lens is arranged between the DMD and the detector, and light emitted from the DMD is focused by the focusing lens and then received by the detector. The receiving of useful signals is convenient, and excessive energy loss is avoided.

The DMD-based fluorescence spectrum detection apparatus further includes a beam terminator, and a signal unnecessary in the light emitted from the DMD is received by the beam terminator. And the interference of the useless signals to the useful signals to the detection result is avoided.

In the following specific examples:

firstly, an optical system for fluorescence spectrum detection is built, and as shown in fig. 2, the optical system based on the DMD spectrum detection method mainly comprises a lens, an optical fiber, an optical filter, a dispersion prism, a Digital Micromirror Device (DMD), a detector and a beam terminator.

Fluorescence generated from the sample is coupled into the optical fiber 202 through the objective lens or lens 201; the fluorescence is emitted from the other end of the optical fiber 202, and then enters the prism 205 after passing through the lens 203 and the filter 204 in this order. After the multi-wavelength fluorescence passes through the prism 205, an angle difference is generated, that is, the light with different wavelengths has different exit angles, so that the fluorescence is dispersed and spread, and the dispersed and spread fluorescence finally falls on the digital micromirror device DMD 206. The pattern on the DMD is adjusted so that the fluorescent light falls on the beam stop 209 or is focused by the lens 207 and received by the detector 208. Where ON is the optical path of the filtered light along which the useful signal propagates; and OFF represents the optical path of the filtered light through which unwanted signals travel to beam stop 209.

The method of spectral reconstruction is described initially below:

(1) and calculating the spectral correction coefficient of the system. Due to the existence of a series of optical elements such as lenses, filters, optical fibers and the like, the spectrum of any fluorescence is changed after passing through the optical system. Therefore, calculating the spectral correction factor of the system is an important step in reconstructing the spectrum. The calculation method is as follows:

the standard light sources (tungsten lamp, LED, etc.) are measured with a spectrometer and spectral data L thereof is obtained. The standard light source is then directed into the system to load the DMD with the pattern shown in FIG. 3. The center wavelength and spectral bandwidth of these patterns need to be calibrated with a spectrometer before loading. The detector collects a signal every time the DMD is loaded with a pattern, this data is denoted as S. The detector 208 may be a single photon detector or an area array detector, and in order to save cost, a CCD may be used to replace a high-sensitivity detector such as a photomultiplier tube (PMT), a single photon counter (APD), or the like. Then, the signal S obtained by the detector is subtracted by the noise B generated during measurement and then is divided by the spectral data L of the standard light source to obtain the spectral correction coefficient R, namely

The noise B is mainly dark noise of the detector, and the measuring method is as follows: turning off all light sources, namely not inputting any light signals into the system; the detector continuously collects signals for three times, and the average value of the obtained signals is the dark noise of the detector. In the above measurement of noise B, any parameter settings of the detector (including exposure time, gain, etc.) need to be consistent with the parameters when reconstructing the spectrum.

In fig. 3 are the patterns loaded on the DMD, each pattern corresponding to one spectral channel. The center wavelengths in fig. 3(a) to 3(s) are: 505nm, 515nm, 525nm, 535nm, 545nm, 555nm, 565nm, 575nm, 585nm, 595nm, 605nm, 615nm, 625nm, 635nm, 645nm, 665nm, 675nm and 685nm, and the spectral bandwidth is between 6nm and 20 nm. Wherein the white part of the pattern represents the light propagating in the detector direction and vice versa.

(2) The fluorescence spectrum is reconstructed. Similar to the previous step, the standard light source is first replaced with the sample to be measured, and the excitation light excites the sample to generate fluorescence and introduces the fluorescence into the system. The DMD is loaded with the pattern shown in fig. 3 in sequence. The same operation as in (1) applies a pattern to the DMD and the detector captures a signal, denoted as I. The spectrum f of the fluorescence of the sample is obtained by dividing the value by the spectrum correction coefficient R, i.e. the spectrum

When reconstructing the spectrum, in order to obtain better detection effect, the pattern loaded by the DMD needs to satisfy the following requirements:

the number 19 of patterns shown in fig. three is the basis for the reconstruction of the spectrum, and if there are fewer measured patterns, the accuracy of the spectrum reconstruction is lower. It is of course also possible to increase the number of patterns appropriately (e.g. increase the detection range), but care should be taken to the effect of spectral cross talk.

The pattern is required to meet the requirement of minimum spectral resolution, i.e. the spectral bandwidth is minimum when the pattern is loaded. The patterns that satisfy this condition will be different for different system designs. The smaller the slit width in a typical pattern, the lower the resolution, but there may be a limit.

And thirdly, the pattern bit depth must be set to 1 bit, so that the advantage of high refresh rate of the DMD can be fully exerted, and the spectrum acquisition speed is improved.

To check the accuracy, the true spectrum F of this fluorescence can be measured with a spectrometer and compared with the spectrum F obtained with the present DMD-based fluorescence spectroscopy detection method.

The fluorescence spectrum detection device based on DMD provided by the utility model is verified theoretically and experimentally, and FIG. 4 shows an experimental result.

In fig. 4, the results of the experiment with the EOSIN Y dye are shown, the line with the origin is the result obtained by the DMD-based fluorescence spectroscopy detection method, and the other curve is the result obtained by measurement with a commercial spectrometer. As can be seen from FIG. 4, the reconstruction accuracy of the fluorescence spectrum detection method based on DMD is high. Since the dye has weak signal above 640nm, more noise and undesirable reconstruction results, the data after 640nm are deleted.

Has the advantages that:

compared with the prior art, the fluorescence spectrum detection device based on the DMD has the following advantages:

(1) the spectrum has more sampling points than the multi-channel detector. Due to the pixel-level control nature of the DMD, a wide variety of patterns can be loaded, i.e., patterns of different center wavelengths, different bandwidths can be used to reconstruct the spectrum. Therefore, the accuracy and manner of spectral detection is superior to that of multi-channel detectors.

(2) The spectral resolution is high. The spectral resolution of a multi-channel detector depends mainly on the number of detectors, the higher the resolution. However, the number of detectors can only reach 16 at most at present, and the spectral resolution is not very high under the condition of ensuring the spectral detection range. In this device, however, the system can be made to achieve higher spectral resolution with the same spectral detection range by optical design.

(3) The energy utilization rate is high. The dispersion unit in the light path of the device is a prism, and compared with the grating, the energy utilization rate, the working wavelength, the stray light and the like of the prism are superior to those of the grating. Since the fluorescence signal is weak, it is a very important step to reduce the optical loss.

(4) And detecting by a single detector. Compared with a multi-channel detector, the device only needs one detector, the structure can save cost and fully play the utilization rate of a single detector. Due to the limitation of space size, each detector of the multi-channel detector has performance which is certainly not the same as that of a single detector, such as signal-to-noise ratio and detector receiving area, and performance difference exists between the detectors, so that the single detector can fully exert the performance of the single detector.

The above description is intended to be illustrative of the preferred embodiment of the present invention and should not be taken as limiting the utility model, but rather, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the utility model.

Claims (10)

1. The device for detecting the fluorescence spectrum based on the DMD is characterized by comprising a collimating lens, a dispersion unit, the DMD and a detector; and the fluorescence generated by the sample to be detected enters the dispersion unit after being collimated by the collimating lens, then is projected to the DMD, is modulated by the DMD and is received by the detector.

2. The DMD based fluorescence spectrum detection apparatus of claim 1, wherein the dispersion unit is a triangular prism.

3. The DMD based fluorescence spectrum detection apparatus of claim 2, wherein a filter is disposed between the collimating lens and the dispersive unit.

4. The DMD based fluorescence spectroscopy apparatus of claim 3, wherein the detector is a single photon detector or an area array detector.

5. The DMD based fluorescence spectroscopy apparatus of claim 4, wherein the detector is a CCD.

6. The DMD-based fluorescence spectrum detection device according to claim 5, wherein a focusing lens is disposed between the DMD and the detector, and light emitted from the DMD is focused by the focusing lens and then received by the detector.

7. The DMD-based fluorescence spectrum detection device according to any of claims 1-6, further comprising an in-coupling lens and an optical fiber, wherein the fluorescence generated by the sample to be detected is coupled into the optical fiber through the in-coupling lens and exits from the exit end of the optical fiber, and the exit end is located at the front focal point of the collimating lens.

8. The DMD based fluorescence spectrum detection apparatus of any one of claims 1-6, further comprising a beam stop, wherein unwanted signals in light exiting the DMD are received by the beam stop.

9. The DMD based fluorescence spectrum detection apparatus of any one of claims 1-6, wherein the DMD is driven by a DMD driver, and a spectral pattern is loaded on the DMD driver to realize modulation of light incident on the DMD.

10. The DMD based fluorescence spectroscopy device of claim 9, wherein the spectral pattern has a center wavelength of 400 to 700 nm; the spectral bandwidth of the spectral pattern is between 6nm and 20 nm.

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