Rotary grating spectrometer capable of calibrating wavelength

Abstract

The utility model relates to a spectral analysis technology, and particularly discloses a wavelength-calibratable rotating grating spectrometer which comprises a wavelength screening element, a first collimating element, a rotating grating, a focusing element and a detector which are sequentially arranged along a light path of incident light, and further comprises a standard light source and a second collimating element, the standard light source is arranged between the wavelength screening element and the detector along the light path of the incident light, the light emitting side of the standard light source faces the rotating grating, and the second collimating element is arranged on the light emitting side of the standard light source. The rotating grating spectrometer capable of calibrating the wavelength can realize real-time wavelength calibration.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of spectral analysis technology, and in particular to a wavelength-calibratable rotating grating spectrometer. BACKGROUND

[0002] A rotating grating spectrometer is a spectral analysis instrument that uses a rotating grating to disperse and select wavelengths based on the principle of grating diffraction. Unlike traditional fixed grating spectrometers, a rotating grating spectrometer uses a rotating grating to adjust the diffraction angle, thereby selecting different wavelengths of light, so that the rotating grating spectrometer has good resolution and a wide wavelength range.

[0003] The rotating grating of a rotating grating spectrometer generally uses a high-precision mechanical drive and feedback system, and the accuracy of the angle affects the wavelength accuracy of the spectrometer. Wavelength calibration of a rotating grating spectrometer is an important step to ensure accurate and reliable measurement results. The wavelength calibration of a rotating grating spectrometer is based on the grating diffraction equation. For a rotating grating spectrometer, the diffraction equation can be expressed as: nλ=d(sinθ i +sinθ m ). Wherein: n is the diffraction order, usually taking 1; λ is the wavelength of light; d is the grating constant; θ i is the incident angle, and θ m is the diffraction angle.

[0004] When the rotating grating rotates, the diffraction angle θ m of the grating changes, and the diffraction angles of different wavelengths also differ. During calibration, a standard light source with known characteristics is usually used to calibrate the position of the slit, and the positions of the CCD for different wavelengths are measured to establish the relationship between the grating angle and the wavelength. The calibration process requires the user to hold the standard light source and identify the characteristic peaks of the standard light source, but the user often does not have the ability to identify the characteristic peaks and needs to return to the factory for calibration. Wavelength calibration cannot be performed in real time during instrument use, which affects the accuracy of the measurement results.

[0005] For example, a prior art wavelength calibration method for a grating spectrometer is disclosed, which includes: moving a plurality of characteristic peaks of a calibration light source to a center position of a detector by rotating a rotatable grating, determining a functional relationship between a grating rotation angle of the rotatable grating and a center wavelength; and determining parameters in a physical model used to calculate a corresponding wavelength at each pixel within an imaging range of the detector when the center wavelength is determined by analyzing a plurality of spectral images obtained at a plurality of center wavelengths. This technology requires a professional to identify the characteristic peak positions of the standard light source and move the characteristic peak positions to the center position of the detector. It does not have the ability to calibrate the wavelength in real time, and at the same time, it has high requirements for the ability of the user.

[0006] The prior art also discloses a wavelength correction device and method of an intelligent grating monochromator, which adds a temperature sensor, a digital temperature meter, an A / D converter, a computer interface and a wavelength correction program to the grating monochromator to form a new device. The wavelength correction device utilizes the functional relationship between the temperature, the wavelength, the system error of the monochromator and the wavelength drift of the outgoing light, and controls the rotation of the grating through the computer to reduce the wavelength drift of the outgoing light of the grating monochromator caused by the temperature, the wavelength and the system error to within ±0.05 angstrom. However, the prior art cannot calibrate the wavelength in real time during the measurement process, and the wavelength error exists during the test, which reduces the accuracy of the measurement. Content of the utility model

[0007] In order to solve the above problems, the application provides a rotatable grating spectrometer which can calibrate the wavelength and realizes real-time wavelength calibration.

[0008] The application provides a rotatable grating spectrometer, which adopts the following technical scheme:

[0009] A rotatable grating spectrometer which can calibrate the wavelength comprises a wavelength screening element, a first collimating element, a rotatable grating, a focusing element and a detector which are arranged in sequence along the light path of an incident light, and further comprises a standard light source and a second collimating element, wherein the standard light source is arranged between the wavelength screening element and the detector along the light path of the incident light, the light emitting side of the standard light source faces the rotatable grating, and the second collimating element is arranged on the light emitting side of the standard light source.

[0010] By adopting the above technical scheme, the width of the light beam is controlled by the wavelength screening element, the incident light is collimated and reflected to the rotatable grating through the first collimating element, the incident light is dispersed into light of different wavelengths by the rotatable grating and reflected to the detector through the focusing element. On this basis, different from the existing wavelength calibration method which calibrates the wavelength by connecting a known standard light source outside the wavelength screening element (slit), the application arranges the standard light source between the wavelength screening element and the detector along the light path, and arranges the second collimating element on the light emitting side of the standard light source. The light of the standard light source is collimated to the rotatable grating through the second collimating element, the light of the standard light source is diffracted and dispersed into light of different known wavelengths by the rotatable grating, and then the light is converged to the detector through the focusing element. Therefore, a standard light source collimating light path is formed inside the rotatable grating spectrometer. Since each characteristic peak of the standard light source is known, in application, the wavelength can be calibrated automatically inside by cooperating with the hardware control switch and the software algorithm for identifying the characteristic peak of the standard light source, that is, the wavelength can be calibrated in real time during the use of the instrument.

[0011] Preferably, the standard light source is located between the first collimating element and the focusing element.

[0012] By adopting the technical scheme, as a specific structural example, the standard light source is arranged between the first collimating element and the focusing element, and the distribution is more reasonable.

[0013] Preferably, the standard light source is a linear light source.

[0014] By adopting the technical scheme, as a structural example, the standard light source is a linear light source, for example, an element lamp.

[0015] Preferably, the second collimating element is a cemented lens.

[0016] By adopting the technical scheme, as a structural example, the second collimating element is a cemented lens, which is used to collimate the light of the standard light source into parallel light and then disperse the parallel light through the rotating grating.

[0017] Preferably, the direction of the light of the standard light source collimated by the second collimating element is parallel to the direction of the incident light collimated by the first collimating element.

[0018] By adopting the technical scheme, as a structural example, the orientation of the light emitting side of the standard light source can be adjusted so that the direction of the light of the standard light source collimated by the second collimating element is parallel to the direction of the incident light collimated by the first collimating element. The overall optical path design is optimized.

[0019] Preferably, the first collimating element and the focusing element are concave mirrors, respectively.

[0020] Preferably, the reflecting surfaces of the first collimating element and the focusing element are both provided with silver plating layers.

[0021] Preferably, the R values of the first collimating element and the focusing element are the same.

[0022] By adopting the technical scheme, as a structural example, the first collimating element and the focusing element are both concave mirrors, the reflecting surfaces of which are both provided with silver plating layers, and the R values of the first collimating element and the focusing element are the same. The first collimating element is used to collimate the incident light of the wavelength screening element into parallel light, and the focusing element is used to converge the dispersed spectrum, i.e., parallel light with different wavelength diffraction angles.

[0023] Preferably, the rotating grating is composed of three planar gratings which are sequentially distributed and can be switched.

[0024] By adopting the technical scheme, as a structural example, the rotating grating is composed of three planar gratings which are sequentially distributed, for example, connected head to tail along two opposite ends. The three planar gratings are driven by a driving component, and the rotation is controlled by the driving component.

[0025] Preferably, the wavelength screening element is a slit.

[0026] By adopting the technical scheme, as a structural example, the wavelength screening element is a slit, and the position of the slit depends on the angle design and focal length of the first collimating element, and is used for adjusting the luminous flux and direction of the incident light.

[0027] To sum up, the present application has at least the following beneficial effects:

[0028] The wavelength-calibratable rotating grating spectrometer of the present application sets a standard light source along an optical path between the wavelength screening element and the detector, and forms a standard light source collimating light path inside the rotating grating spectrometer. Since each characteristic peak of the standard light source is known, the wavelength can be calibrated internally automatically by cooperating with the hardware control switch and the software algorithm for identifying the characteristic peak of the standard light source, that is, the wavelength calibration can be performed in real time during the use of the instrument. The wavelength accuracy during the sample measurement process of the spectrometer can be improved, the instrument is more intelligent, and the wavelength calibration function can not be restricted by the ability of the user. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a schematic diagram of the wavelength-calibratable rotating grating spectrometer of the embodiment of the present application;

[0030] Figure 2 is a structural schematic diagram of the wavelength-calibratable rotating grating spectrometer of the embodiment of the present application.

[0031] Label explanation:

[0032] 1, wavelength screening element; 2, first collimating element; 3, rotating grating; 4, focusing element; 5, detector; 6, standard light source; 7, second collimating element. DETAILED DESCRIPTION

[0033] Although the present application can be easily embodied in different forms of embodiments, only some specific embodiments are shown in the drawings and will be described in detail in the present specification, and it can be understood that the present specification should be regarded as a demonstrative description of the principles of the present application, and is not intended to limit the present application to that described herein.

[0034] Therefore, one feature indicated in the present specification will be used to explain one feature of one embodiment of the present application, and is not intended to imply that each embodiment of the present application must have the explained feature. In addition, it should be noted that the present specification describes many features. Although certain features can be combined together to show possible system designs, these features can also be used in other combinations that are not explicitly described. Therefore, unless otherwise specified, the described combinations are not intended to be limiting.

[0035] In the embodiments shown in the drawings, the indications of directions, such as up, down, left, right, front and back, are used to explain the structure and movement of various elements of the present application and are not absolute but relative. These indications are appropriate when the elements are in the positions shown in the drawings. If the positions of the elements change, the indications of directions change accordingly.

[0036] The present application is further described in detail below with reference to the drawings and embodiments.

[0037] Embodiment 1

[0038] An embodiment according to the present embodiment can be seen in Figures 1-2 wherein, throughout the view, identical reference signs designate corresponding parts. It should be understood that the rotating grating spectrometer according to the present application can be applied to the wavelength calibration of all grating spectrometers.

[0039] As shown in Figure 1 and Figure 2 , the wavelength-calibratable rotating grating spectrometer of the present embodiment comprises a wavelength selection element 1, a first collimating element 2, a rotating grating 3, a focusing element 4, a detector 5, a standard light source 6 and a second collimating element 7, which are arranged in sequence along the optical path (indicated by the dashed arrow) of the incident light.

[0040] The wavelength selection element 1 of the present embodiment is a slit, the position of which is determined according to the angle design and focal length of the first collimating element 2, and is used to adjust the luminous flux and direction of the incident light. As a specific example, the width of the slit is 25 μm and the length is 2 mm.

[0041] The rotating grating 3 of the present embodiment is composed of three plane gratings, the two opposite ends of which are connected in sequence and driven by an external driving member, such as a motor, and the rotation of the three plane gratings is controlled by an external control member. The specific structural arrangement can be achieved by using existing designs, which will not be described here. The rotating grating 3 is used to disperse the parallel light collimated by the first collimating element 2 and decompose the composite light into spectral lines. As a specific example, the size of the rotating grating 3 of the present embodiment is 70*70*10 mm 3 , the number of lines is 1200 l / mm, and the blaze wavelength is 500 nm.

[0042] The first collimating element 2 is used to collimate the incident light from the slit's approximate point light source into parallel light. The spectral lines dispersed by the rotating grating 3 are parallel light with diffraction angles at different wavelengths, and the focusing element 4 is used to converge this parallel light. In this embodiment, both the first collimating element 2 and the focusing element 4 are concave mirrors, and their reflective surfaces are both coated with a silver layer. As a specific example, the dimensions of both the first collimating element 2 and the focusing element 4 are 75*75*9mm. 3 The R-values ​​of the first collimating element 2 and the focusing element 4 are both 700.

[0043] Detector 5 is used to convert optical signals into electrical signals. In this embodiment, detector 5 is selected as an area array detector with 2048*256 pixels.

[0044] A standard light source 6 is positioned between the first collimating element 2 and the focusing element 4 along the optical path of the incident light. The light-emitting side of the standard light source 6 faces the rotating grating 3. A second collimating element 7 is positioned between the standard light source 6 and the rotating grating 3, located on the light-emitting side of the standard light source 6. The direction of the light from the standard light source 6 after collimation by the second collimating element 7 (the direction of the solid arrow in the diagram) is parallel to the direction of the incident light after collimation by the first collimating element 2 (the direction of the dashed arrow in the diagram). In this embodiment, the standard light source 6 is an element lamp; as a specific example, a neon lamp is selected as the standard light source 6. The second collimating element 7 is used to collimate the light from the standard light source 6 into parallel light, which is then dispersed by the rotating grating 3. As a specific example, the second collimating element 7 in this embodiment is a cemented doublet lens with a numerical aperture NA of 0.4 and a diameter of 12.7 mm.

[0045] Based on the above structure, the working principle of this embodiment is explained in detail as follows:

[0046] The internal optical path design of the calibrable wavelength rotating grating spectrometer in this embodiment is as follows: See Figure 1 In the direction of the dashed arrow, the incident light beam passes through the wavelength filtering element 1 to control the beam width, and is collimated and reflected by the first collimating element 2 to the rotating grating 3. The rotating grating 3 disperses the incident light beam into light of different wavelengths, which are then reflected and converged to the detector 5 by the focusing element 4.

[0047] The wavelength calibration optical path of the calibrable wavelength rotating grating spectrometer in this embodiment is as follows: See Figure 1 In the direction of the solid arrow, the light from the standard light source 6 is collimated by the second collimating element 7 until it reaches the rotating grating 3. The rotating grating 3 diffracts and disperses the light from the standard light source 6 into light of different known wavelengths, which are then converged to the detector 5 by the focusing element 4. That is, a collimated light path for the standard light source is formed inside the rotating grating spectrometer.

[0048] Since each characteristic peak of the standard light source is known, in application, the characteristic peak of the standard light source is identified by hardware control switch and internal automatic calibration wavelength by software algorithm, so that wavelength calibration in real time during instrument use can be realized. As a specific example, the wavelength calibration steps of the rotating grating spectrometer of the embodiment are as follows:

[0049] 1. The host computer runs the function of automatic wavelength calibration;

[0050] 2. The hardware controls the motor to run the standard light source 6 to the specified position and turn on the standard light source 6;

[0051] 3. The lower computer acquires the signal of the standard light source 6 on the photosensitive surface of the detector 5;

[0052] 4. The host computer identifies the characteristic peak according to the signal intensity, matches the pixel position with the pre-stored wavelength position, and generates a data set;

[0053] 5. The data set is fitted by a polynomial to expand the wavelength position corresponding to all pixels of the detector 5, and the wavelength calibration is completed.

[0054] The rotating grating spectrometer of the embodiment can realize real-time wavelength calibration, is not affected by external factors, improves the wavelength accuracy during the sample measurement process of the rotating grating spectrometer, and makes the instrument more intelligent, so that the wavelength calibration function can not be restricted by the ability of the user.

[0055] The specific embodiment is only an explanation of the present application, and is not a limitation of the present application. Those skilled in the art can make modifications to the embodiment without creative contribution after reading the present specification, but as long as the modifications are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A wavelength-calibratable rotating grating spectrometer comprising, in order along an optical path of an incident light ray, a wavelength selection element, a first collimating element, a rotating grating, a focusing element, and a detector, characterized in that, The standard light source is located between the first collimating element and the focusing element.

2. The calibratable wavelength, rotating grating spectrometer of claim 1, wherein, The standard light source is a line light source.

3. The calibratable wavelength, rotating grating spectrometer of claim 1, wherein, The second collimating element is a cemented lens.

4. The calibratable wavelength, rotating grating spectrometer of claim 1, wherein, The direction of the light rays of the standard light source collimated by the second collimating element is parallel to the direction of the incident light rays collimated by the first collimating element.

5. The calibratable wavelength, rotating grating spectrometer of claim 1, wherein, The first collimating element and the focusing element are respectively concave mirrors.

6. The calibratable wavelength, rotating grating spectrometer of claim 1, wherein, The reflecting surfaces of the first collimating element and the focusing element are both provided with silver plating layers.

7. The calibratable wavelength of a rotating grating spectrometer of claim 6, wherein, The R values of the first collimating element and the focusing element are the same.

8. The calibratable wavelength of a rotating grating spectrometer of claim 7, wherein, The rotating grating is composed of three sequentially distributed plane gratings which can be switched.

9. The calibratable wavelength, rotating grating spectrometer of claim 1, wherein, The wavelength screening element is a slit.

10. The calibratable wavelength, rotating grating spectrometer of claim 1, wherein, ​

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