CN116931211A - Grating switching device and application method thereof in wide spectrum instrument - Google Patents

Grating switching device and application method thereof in wide spectrum instrument Download PDF

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Publication number
CN116931211A
CN116931211A CN202310929606.2A CN202310929606A CN116931211A CN 116931211 A CN116931211 A CN 116931211A CN 202310929606 A CN202310929606 A CN 202310929606A CN 116931211 A CN116931211 A CN 116931211A
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grating
turntable
switching
wavelength
worm
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Inventor
潘忠泉
陶威
拓锐
王琳琳
刘霞
孙文慧
李昕
张江浩
杨欣欣
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Shandong Non Metallic Material Research Institute
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Shandong Non Metallic Material Research Institute
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/02—Details
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/02—Details
    • G01J3/0202—Mechanical elements; Supports for optical elements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Spectrometry And Color Measurement (AREA)

Abstract

The invention discloses a grating switching device and a using method thereof in a wide spectrum instrument, and belongs to the technical field of measurement of analytical instruments. According to the grating switching device, the center line of the set grating diffraction surface is overlapped with the rotation axis of the grating turntable by rotating the grating switching turntable, so that the influence of light path deviation on wavelength deviation and light intensity of emergent light is eliminated; the grating ruler sensor is used for measuring the rotation angle of the grating turntable, the angle indication value is equivalent to the displacement of the grating ruler sensor, and the influence of step motor step-out and mechanical return stroke difference of the worm gear and worm on the wavelength indication value is eliminated. Thereby reducing the wavelength deviation and improving the measurement accuracy. In addition, the invention has the advantages of simple installation, convenient operation and the like.

Description

Grating switching device and application method thereof in wide spectrum instrument
Technical Field
The invention belongs to the technical field of analytical instrument measurement, in particular to a spectroscopic instrument measurement technology, and particularly relates to a grating switching device.
Background
According to the grating equation, the number of the lines and the blaze angle of the diffraction grating determine the application range of the diffraction grating, and for a wide spectrum instrument, a plurality of gratings are selected according to the spectrum interval, and the requirements of the spectrum range of the instrument are met through switching among the gratings.
At present, a sinusoidal lead screw or a worm and gear mechanism is adopted for grating switching, a sinusoidal lead screw is generally adopted for driving a grating turntable for switching between two gratings, and a worm and gear is generally adopted for driving the grating turntable for switching between three gratings.
In the current sine lead screw structure, a grating is vertically arranged on a grating turntable, the sine lead screw is driven by a stepping motor, the grating turntable is rotated, a photoelectric switch or a micro switch is used for positioning, and the grating is switched according to the rotation angle of the grating turntable; and the grating is vertically arranged on the grating turntable, the worm gear is driven by the stepping motor, the grating turntable is rotated, the photoelectric switch is used for positioning, and the grating is switched according to the rotation angle of the grating turntable.
The sine lead screw and the worm gear mechanism adopt the same turntable to switch and rotate the gratings, and in the rotation process of the grating turntable, the rotation center of the diffraction surface of the grating cannot be kept coincident with the rotation axis of the grating turntable, and the center of the grating deviates from a light path, so that emergent light deviates and the light intensity is reduced; in addition, step-out of the stepping motor and poor mechanical return stroke of the worm gear lead to wavelength indication deviation of emergent monochromatic light.
Disclosure of Invention
Aiming at the defects of deviation and light intensity reduction of emergent light caused by the current sine screw rod and worm gear mechanism, step motor step out, wavelength indication deviation of emergent light caused by mechanical return stroke difference of worm gear and the like, the invention provides a grating switching device and a use method thereof in a wide spectrum instrument.
The invention is realized by the following technical scheme: the invention discloses a grating switching device, which comprises a photoelectric switch, a grating turntable driven by a first stepping motor to rotate and a grating switching turntable driven by a second stepping motor to rotate, wherein the grating switching turntable is provided with a positioning hole and a plurality of gratings positioned on the circumference concentric with the grating switching turntable, the positioning of the mechanical zero position of the grating switching turntable is realized by means of the photoelectric switch and the positioning hole, the grating switching is realized by rotating a fixed angle based on the positioning hole, and the center line of a diffraction surface of the grating coincides with the rotation axis of the grating turntable after the switching is completed, so that the aim of the invention is realized.
The invention relates to a grating switching device, which comprises a grating switching device base, a grating turntable, a photoelectric switch, a grating turntable driving device, a grating turntable positioning measuring device, a grating switching turntable driving device and a grating bracket; the photoelectric switch is arranged on the grating turntable; the grating switching turntable is of a gear disc structure, a positioning hole is formed in the surface of the grating switching turntable, the positioning hole and the grating turntable are arranged in an eccentric and relatively rotatable mode, and when the relative rotation angle of the positioning hole and the grating turntable is proper, the optical path of the photoelectric switch is conducted; the grating turntable driving device is used for driving the grating turntable to rotate around the axis of the grating turntable; the grating turntable positioning and measuring device is used for positioning the rotation position of the grating turntable and measuring the rotation angle of the grating turntable; the grating switching turntable driving device is used for driving the grating switching turntable to rotate; the grating support is positioned above the grating switching turntable and is used for installing the grating, and the center line of the diffraction surface of the grating can be overlapped with the rotation axis of the grating turntable by means of the rotation of the grating switching turntable.
Preferably, the grating turntable driving device comprises a first thrust bearing seat, a first thrust bearing, a worm wheel, a first stepping motor, a coupler, a first worm support, a worm and a second worm support; the first thrust bearing seat is fixed on the base of the grating switching device; the first thrust bearing is embedded between the first thrust bearing seat and the turbine, the grating turntable is fixed on the worm wheel, and the first thrust bearing seat and the turbine are coaxial; the worm is concentrically connected with the rotating shaft of the first stepping motor through a coupler, and the worm wheel is kept connected with the gear of the worm through a first worm bracket and a second worm bracket.
Preferably, the grating turntable positioning and measuring device is a grating ruler, and is attached to the outer circumference of the grating turntable.
Preferably, the grating switching turntable driving device comprises a second thrust bearing seat, a second thrust bearing and a second stepping motor; the second thrust bearing seat and the second stepping motor are arranged on the grating turntable; the second thrust bearing is embedded between the second thrust bearing seat and the grating switching turntable, and the grating switching turntable is driven by the second stepping motor through a gear.
Preferably, the gratings installed on the grating support are perpendicular to the plane of the grating switching turntable; the grating switching turntable driving device is used for driving the grating switching turntable to rotate around the axis of the grating switching turntable; the diffraction centerlines of all gratings are located on a circumference concentric with the grating switching turntable.
The invention also relates to a using method of the grating switching device in the wide spectrum instrument, which is characterized by comprising the following operation steps:
1) Determining the number and the type of the applicable gratings according to the requirements of the measured wavelength interval;
2) Mounting the grating switching device to a broad spectrum instrument; mounting the determined grating on a grating support of a grating switching device;
3) Mechanical zero point of positioning grating switching turntable
The grating switching turntable is driven to rotate by using the grating switching turntable driving device until the optical path of the photoelectric switch is conducted, namely the mechanical zero point of the grating switching turntable;
4) Calculating zero position wavelength compensation value of grating and displacement equivalent of grating turntable positioning measurement device
Calculating a zero wavelength compensation value of the grating and a displacement equivalent of the grating turntable positioning measurement device based on a main light path included angle of the incident light and the emergent light of the grating and a curvature radius of the grating turntable by taking the radiation wavelength of the spectrum lamp used by the grating as a reference;
5) Measurement work of open-spread spectrum instrument
Rotating the grating switching turntable by a proper angle from a mechanical zero position by using a grating switching turntable driving device, so that the center line of a diffraction surface of a required grating is overlapped with the rotation axis of the grating turntable; rotating the grating turntable to a mechanical zero position by using a grating turntable switching device; setting a zero position wavelength compensation value of a corresponding grating and displacement equivalent of a grating turntable positioning measurement device, and adjusting the grating turntable to a wavelength zero position; carrying out measurement work in a wavelength interval corresponding to the grating by using a wide spectrum instrument; returning the grating switching turntable to the mechanical zero position after the measurement is completed;
repeating the above operation until the measurement work in all the grating corresponding wavelength intervals is completed by using the wide spectrum instrument.
Preferably, the grating switching turntable driving device comprises a second stepping motor; the rotation angle of the grating switching turntable is controlled by the number of pulses received by the second stepping motor.
Further preferably, before the measurement starts, the mechanical zero point of the grating switching turntable is used as a starting point to determine the angle and the rotation direction of the grating required to complete switching, and the number of pulses required to be received by the second stepping motor is calculated based on the angle.
Preferably, the grating turntable driving device comprises a first stepping motor, a coupler, a turbine, a worm, a first worm support and a second worm support.
According to the grating switching device, the grating switching turntable driven by the second stepping motor to rotate is provided with the positioning hole and the grating bracket, the mechanical zero position of the grating switching turntable is positioned by means of the photoelectric switch and the positioning hole, and the grating switching is realized by rotating a fixed angle by taking the mechanical zero position as a reference, so that the grating switching efficiency and precision are improved; after the grating required by measurement is mounted on the grating support, the diffraction center line of the grating is positioned on the circumference concentric with the grating switching turntable, so that after the grating is switched, the center lines of all gratings can be ensured to coincide with the rotation axis of the grating turntable, and the influence of light path deviation on the wavelength deviation and the light intensity of emergent light is eliminated; the grating ruler sensor is used for measuring the rotation angle of the grating turntable, the angle indication value is equivalent to the displacement of the grating ruler sensor, and the influence of step motor step-out and mechanical return stroke difference of the worm gear and worm on the wavelength indication value is eliminated. Thereby greatly reducing the measured value of the wavelength deviation and improving the measurement accuracy. In addition, the invention has the advantages of simple installation, convenient operation and the like.
Drawings
FIG. 1 is a schematic diagram of a grating switching device according to an embodiment of the invention
FIG. 2 is a schematic diagram of a grating switching turret and a grating arrangement according to an embodiment of the invention
FIG. 3 is a schematic diagram of a grating switching turret and a grating arrangement according to a second embodiment of the invention
Fig. 4 is a schematic diagram of a grating switching turret and a grating arrangement according to a third embodiment of the present invention
In the figure, a 1-grating switching device base, a 2-first thrust bearing seat, a 3-first thrust bearing, a 4-worm wheel, a 5-grating rotary table, a 6-first stepping motor, a 7-second thrust bearing seat, an 8-second thrust bearing, a 9-grating switching rotary table, a 10-first grating, a 11-second grating, a 12-third grating, a 13-fourth grating, a 14-grating bracket, a 15-photoelectric switch, a 16-second stepping motor, a 17-grating ruler sensor, an 18-coupling, a 19-first worm bracket, a 20-worm and a 21-second worm bracket.
Detailed Description
The invention will now be further illustrated by means of non-limiting examples in conjunction with the accompanying drawings.
Example 1
In this embodiment, three gratings of the Spectra-1000G spectrophotometer are switched by using a grating switching device.
According to the measurement requirement, three gratings are selected in this embodiment: first grating 10, GGR02-5050-18UV, spectral range 200 nm-500 nm; a second grating 11, GGR01-5050-1250, with a spectral range of 330-1000 nm; and a third grating 12, GGR01-5050-6012, with a spectral range of 830nm to 2500nm.
The grating switching device of the present embodiment is composed of a grating switching device base 1, a first thrust bearing seat 2, a first thrust bearing 3, a worm wheel 4, a grating turntable 5, a first stepping motor 6, a second thrust bearing seat 7, a second thrust bearing 8, a grating switching turntable 9, a grating bracket 14, a photoelectric switch 15, a second stepping motor 16, a grating scale sensor 17, a coupling 18, a first worm bracket 19, a worm 20, and a second worm bracket 21, as shown in fig. 1.
The grating turntable 5 has a disc structure of R50 mm. The grating switching turntable 9 is of a gear disc structure, a through hole with the diameter of 2mm is arranged in the plane and is used as a positioning hole, and the through hole is positioned in the 130-degree direction of the disc and is 2mm away from the base circle contour line in the radial direction.
The gear ratio of the turbine 4 and the worm 20 is 180:1, and the gear ratio of the grating switching turntable 9 is 1:5.
The first stepper motor 6 has a step angle of 1.8 ° and 128 is subdivided, and the pulse equivalent is 0.0140625 °/P, as known from formula (1); the second stepper motor 16 has a step angle of 0.9 ° and 16 is subdivided, the pulse equivalent of which is 0.05625 °/P as known from equation (1).
E=δ/N（1）
Wherein: e-pulse equivalent, °/p; delta-stepper motor step angle, °; a subdivision of the N-stepper motor drive.
The resolution of the grating scale sensor 17 is 5 μm,4 sub-division for positioning the grating turret 5 and recording its rotation angle.
In the grating switching device of the embodiment, a first thrust bearing seat 2 is fixed on a grating switching device base 1 through bolts; the first thrust bearing 3 is embedded between the first thrust bearing seat 2 and the turbine 4, and the first thrust bearing seat 2 and the turbine 4 are kept coaxial and are tightly matched through a rotating shaft. The grating turntable 5 is fixed on the worm wheel 4 through bolts and keeps coaxial with the worm wheel 4; the grating ruler sensor 17 is attached to the outer circumference of the grating turntable 5 and is kept in close fit with the outer circumference of the grating turntable 5. The second thrust bearing seat 7 is arranged on the grating turntable 5; the second thrust bearing 8 is embedded between the second thrust bearing seat 7 and the grating switching turntable 9, and the three parts keep coaxial and are tightly matched through a rotating shaft. The three grating supports 14 are vertically arranged on the grating switching turntable 9, and the projections of the central lines of the grating supports are respectively positioned in the directions of 90 DEG, 210 DEG and 330 DEG in the plane. The photoelectric switch 15 and the second stepping motor 16 are arranged on the grating rotary table 5, when the grating rotary table rotates to the 135-degree position, the center line of the first grating diffraction surface coincides with the rotating shaft of the grating rotary table, the grating rotary table 9 is driven by the second stepping motor 16 through a gear, when the positioning hole of the grating rotary table rotates to the optical path of the photoelectric switch 15, the photoelectric switch 15 is conducted, the mechanical zero position of the grating rotary table 9 is recorded, then the grating rotary table rotates clockwise for 5 degrees, and the center line of the first grating diffraction surface coincides with the rotating shaft of the grating rotary table. The worm 20 is concentrically connected to the rotation shaft of the first stepping motor 6 via the coupling 18, and the inner diameter of the worm wheel 4 is kept coincident with the outer diameter of the worm 20 via the first worm support 19 and the second worm support 21. The rotation axes of the grating turntable 5, the grating switching turntable 9 and the worm wheel 4 are coincident with the respective circle centers.
When the grating switching device of the embodiment is used for measurement, the grating switching device base 1, the first worm support 19, the second worm support 21, the coupler 18 and the first stepping motor 6 are fixed on a monochromator bottom plate of a Spectra-1000G spectrophotometer; the first grating 10, the second grating 11, and the third grating 12 are respectively fixed on three grating supports 14, as shown in fig. 2, the center line of the grating diffraction surface is located on the circumference of phi 80mm concentric with the grating switching turntable 9, and the projection of the circumference on the grating turntable 5 passes through the rotation axis of the grating turntable 5.
The specific measurement steps are as follows:
(1) Mechanical zero positioning of grating switching turntable 9
After the grating switching device is electrified, the second stepping motor 16 drives the grating switching turntable 9 to rotate anticlockwise through the gear structure until the photoelectric switch 15 is conducted, namely the mechanical zero point of the grating switching turntable 9.
(2) Calculating the number of pulses required to be received by the second stepper motor 16 for raster switching
The grating switching turret 9 is rotated 5 ° clockwise from the mechanical zero point, and the center line of the diffraction plane of the first grating 10 coincides with the rotation axis of the grating turret 5, so that the number of pulses to be received by the second stepping motor 16 is about 444 according to the formula (2).
s=α/(E×i) （2）
Wherein: the s-grating switches the pulse number of the second stepping motor 16 corresponding to the rotation of the turntable 9 to a specific angle; the rotation angle of the alpha-grating switching turntable 9; pulse equivalent, °/p of E-stepper motor; i-gear ratio.
The grating switching turntable 9 returns to the mechanical zero point and then rotates anticlockwise by 120 ° -5 ° =115°, so that the center line of the diffraction surface of the second grating 11 coincides with the rotation axis of the grating turntable 5, and therefore, according to formula (2), the number of pulses to be received by the second stepper motor 16 is about 10222.
The grating switching turntable 9 returns to the mechanical zero point and then rotates anticlockwise by 120 ° +120 ° -5 ° =235°, so that the center line of the diffraction surface of the third grating 12 coincides with the rotation axis of the grating turntable 5, and therefore, according to formula (2), the number of pulses to be received by the second stepping motor 16 is about 20889.
(3) Calculating zero wavelength compensation value of grating and displacement equivalent of grating scale sensor 17
Firstly, calculating a displacement equivalent theoretical value of the grating scale sensor 17 corresponding to the grating according to the formula (3): the theoretical displacement equivalent value of the first grating 10 is 20.4557, the theoretical displacement equivalent value of the second grating 11 is 30.6835, and the theoretical displacement equivalent value of the third grating 12 is 61.3670.
（3）
Wherein:theoretical value of displacement equivalent of the grating sensor 17, nm/mm; />-a grating constant; />-the main light path angle of the grating incident light and the outgoing light, in this embodiment +.>=46°；/>The radius of curvature of the grating, i.e. the radius of the grating turret 5, mm.
Then, the zero wavelength compensation value of the grating and the displacement equivalent of the grating scale sensor 17 are calculated according to the formula (4) by taking the radiation wavelength of the low-pressure mercury lamp as a reference. The radiation wavelength of the low-pressure mercury lamp is 253.651nm and 435.834nm respectively, the zero-position wavelength compensation value of the first grating 10 is 39.47nm, the displacement equivalent of the grating ruler sensor 17 is 19.897nm/mm, and the indication values of the first grating 10 are 220.2nm and 407.5nm respectively; the radiation wavelength of the low-pressure mercury lamp is 404.657nm and 546.075nm respectively, the zero-position wavelength compensation value of the second grating 11 is 91.54nm, and the displacement equivalent of the grating ruler sensor 17 is 29.782nm/mm, wherein the indication values of the second grating 11 are 322.6nm and 468.3nm respectively; the radiation wavelength of the low-pressure mercury lamp is 1014.000nm and 2325.300nm respectively, the zero-position wavelength compensation value of the third grating 12 with the indication values of 928.3nm and 2226.1nm is 76.04nm, and the displacement equivalent of the grating ruler sensor 17 is 62.005nm/mm.
（4）
Wherein:-an indication of the wavelength of the mercury lamp radiation, nm, before adjustment; />-mercury lamp radiation wavelength, nm; />Zero wavelength compensation value of the grating, nm; />Displacement equivalent of the grating scale sensor 17, nm/mm.
(4) Measurement of different wavelength intervals
At the mechanical zero point of the grating switching turntable 9, the second stepping motor 16 receives 444 pulses, and the grating switching turntable 9 rotates 5 degrees clockwise, so that the center line of the diffraction surface of the first grating 10 coincides with the rotation axis of the grating turntable 5; through the turbine 4 and the worm 20, the grating turntable 5 is rotated to a mechanical zero position, the displacement equivalent of the grating scale sensor 17 is 19.897nm/mm, the grating zero position wavelength compensation value is 39.47nm, the grating turntable 5 is adjusted to a wavelength zero point, and a spectrum-1000G spectrophotometer is utilized to carry out measurement test in a wavelength interval of 200 nm-500 nm.
The grating switching turntable 9 returns to a mechanical zero point, the second stepping motor 16 receives 10222 pulses, the grating switching turntable 9 rotates anticlockwise by 115 degrees, the center line of the diffraction surface of the second grating 11 coincides with the rotation axis of the grating turntable 5, the grating turntable 5 is rotated to the mechanical zero point through the turbine 4 and the worm 20, the displacement equivalent of the grating scale sensor 17 is 29.782nm/mm, the grating zero point wavelength compensation value is 91.54nm, the grating turntable 5 is adjusted to the wavelength zero point, and a spectrum-1000G spectrophotometer is utilized to perform measurement test in a wavelength range of 330 nm-1000 nm.
The grating switching turntable 9 returns to a mechanical zero point, the second stepping motor 16 receives 20889 pulses, the grating switching turntable 9 rotates 235 degrees anticlockwise, the center line of the diffraction surface of the third grating 12 coincides with the rotation axis of the grating turntable 5, the grating turntable 5 is rotated to the mechanical zero point through the turbine 4 and the worm 20, the displacement equivalent of the grating scale sensor 17 is 62.005nm/mm, the grating zero point wavelength compensation value is 76.04nm, the grating turntable 5 is adjusted to the wavelength zero point, and a spectrum-1000G spectrophotometer is utilized to perform measurement test in a wavelength range of 830 nm-2500 nm.
When the grating switching device of the embodiment is used for measurement, the deviation values are as follows:
(1) Raster switching bias
According to formula (5), the positioning angle deviation of the grating switching turret 9 is 0.01125 °.
△α=E×i×△s（5）
Wherein: step-out of the Δs-stepper motor is calculated as Δs=1; the angle deviation of the positioning of the delta alpha-grating switching turret 9 is by degrees.
The corresponding grating switching position deviation is 0.008mm, and is calculated according to the formula (6):
L′=R 1 ×△α（6）
wherein: l' -grating switching position deviation; r is R 1 On the grating switching turret 9, the circumference radius of the midpoint of the diffraction plane of the tri-grating.
In theory, the grating switching deviation is smaller than the general machining precision, and the grating switching has no obvious influence on the light intensity and the position of the emergent light.
(2) Wavelength deviation of outgoing monochromatic light
The resolution of the grating scale sensor 17 of the embodiment is 5 μm, after 4 is subdivided, the resolution is 1.25 μm, the outer diameter of the grating turntable 5 is R50mm, and the rotation angle deviation of the grating turntable 5 is 2.5X10 -5 Degree, calculated according to formula (7):
△θ=△L/R （7）
wherein: the rotation angle deviation of the delta theta-grating turntable 5; resolution of the Δl-grating ruler sensor 17; radius of R-grating turntable 5, mm.
When the light beam is incident along the normal of the grating plane, the wavelength deviation at a specific wavelength is calculated according to formula (8), as shown in table 1.
△λ=2dcos2θ b △θ （8）
Wherein: the wavelength deviation of the delta lambda-emergent monochromatic light is nm; d-grating constant; θ b -blaze angle, °.
Table 1 wavelength deviation counted by the grating scale sensor 17
When the rotation angle of the grating turret 5 is measured by the pulse of the stepping motor, the rotation angle deviation of the grating turret 5 is 7.8125 ×10 calculated according to the formula (9) after the step angle 128 of the first stepping motor 6 is subdivided -5 °：
△θ=E×△s/i 1 （9）
Wherein: step-out of the Δs-stepper motor is calculated as Δs=1; i.e 1 The gear ratio of the worm wheel 4 to the worm 20.
Wavelength deviation of blazed wavelength was calculated according to the formula (9) as shown in table 2.
Table 2 wavelength deviation using pulse counting of stepper motor
The method of the embodiment adopts the grating ruler sensor 17 to measure the rotation angle of the grating turntable 5, and when the light beam is incident along the normal of the grating plane, the maximum wavelength deviation is 0.060nm; when the rotation angle of the grating turntable 5 is measured by adopting the pulse number of the stepping motor, the maximum wavelength deviation is 0.187nm which is about 1/3 of the measured value of the current method, and the method of the embodiment can also eliminate the influence of the mechanical cooperation return stroke difference on the wavelength indication.
Example two
One difference from the embodiment is that:
in this embodiment, two gratings of the Spectra-1000G spectrophotometer are switched by using a grating switching device.
According to the measurement requirement, the two gratings selected in the embodiment are the first grating 10, GGR02-5050-18UV, and the spectral range is 200 nm-500 nm; the second grating 11, GGR01-5050-1250, has a spectral range of 330-1000 nm.
And a through hole with the diameter of 3mm is arranged on the grating switching turntable 9 and is used as a positioning hole, and the through hole is positioned in the direction of 140 degrees and is 3mm away from the base circle contour line in the radial direction.
The two grating supports 14 are respectively positioned in the 90 DEG and 270 DEG directions in the plane of the grating switching turntable 9.
When the grating switching device of the present embodiment is used for measurement, the first grating 10 and the second grating 11 are fixed on two grating supports 14, as shown in fig. 3, the midpoint of the grating diffraction surface is located at a circumference of phi 60mm concentric with the grating switching turntable 9, and the projection of the circumference on the grating turntable 5 passes through the rotation axis of the grating turntable 5.
The specific operation steps are as follows:
(1) Mechanical zero positioning of grating switching turntable 9
After the grating switching device is electrified, the second stepping motor 16 drives the grating switching turntable 9 to rotate anticlockwise through the gear structure until the photoelectric switch 15 is conducted, namely the mechanical zero point of the grating switching turntable 9.
(2) Calculating the number of pulses required to be received by the second stepper motor 16 for raster switching
At the mechanical zero point of the grating switching turntable 9, the grating switching turntable 9 must be rotated counterclockwise by 5 ° so that the center line of the diffraction surface of the first grating 10 coincides with the rotation axis of the grating turntable 5.
The pulses received by the second stepper motor 16 are approximately 444, per equation (2).
The grating switching turntable 9 returns to the mechanical zero point and then rotates 180 ° +5° =185° counterclockwise, so that the center line of the diffraction surface of the second grating 11 coincides with the rotation axis of the grating turntable 5. The number of pulses received by the second stepper motor 16 is approximately 16444, as per equation (2).
3) Calculating zero wavelength compensation value of grating and displacement equivalent of grating scale sensor 17
Calculating a displacement equivalent theoretical value of the grating corresponding to the grating ruler sensor according to the formula (3): the theoretical displacement equivalent value of the first grating 10 is 20.4557, and the theoretical displacement equivalent value of the second grating 11 is 30.6835.
And (3) calculating a zero wavelength compensation value of the grating and displacement equivalent of the grating ruler sensor according to a formula (4) by taking the radiation wavelength of the low-pressure mercury lamp as a reference. The radiation wavelength of the low-pressure mercury lamp is 253.651nm and 435.834nm respectively, the zero-position wavelength compensation value of the first grating 10 is 59.53nm, and the displacement equivalent of the grating ruler sensor 17 is 20.353nm/mm, wherein the indication values of the first grating 10 are 195.1nm and 378.2nm respectively; the radiation wavelength of the low-pressure mercury lamp is 404.657nm and 546.075nm respectively, the zero-position wavelength compensation value of the second grating 11 with the indication values of 338.6nm and 478.7nm is 62.87nm, and the displacement equivalent of the grating ruler sensor 17 is 30.972nm/mm.
(4) Measurement of different wavelength intervals
At the mechanical zero point of the grating switching turntable 9, the second stepping motor 16 receives 444 pulses, the grating switching turntable 9 rotates anticlockwise by 5 degrees, the center line of the diffraction surface of the first grating 10 coincides with the rotation axis of the grating turntable 5, the grating turntable 5 is rotated to the mechanical zero point through the turbine 4 and the worm 20, the displacement equivalent of the grating scale sensor 17 is 20.353nm/mm, the grating zero point wavelength compensation value is 59.53nm, the grating turntable 5 is adjusted to the wavelength zero point, and a spectrum-1000G spectrophotometer is utilized to perform measurement test in a wavelength range of 200 nm-500 nm.
The grating switching turntable 9 returns to a mechanical zero point, the second stepping motor 16 receives 16444 pulses, the grating switching turntable 5 rotates 185 degrees anticlockwise, the center line of the diffraction surface of the second grating 11 coincides with the rotation axis of the grating turntable 5, the grating turntable 5 is rotated to the mechanical zero point through the turbine 4 and the worm 20, the displacement equivalent of the grating scale sensor 17 is 30.972nm/mm, the grating zero point wavelength compensation value is 62.87nm, the grating turntable 5 is adjusted to the wavelength zero point, and a spectrum-1000G spectrophotometer is utilized to perform measurement test in a wavelength range of 330 nm-1000 nm.
When the grating switching device of the present embodiment is used for measurement, the deviation value is calculated as follows according to the method described in the first embodiment:
wavelength deviation of blazed wavelength when incident along the grating plane normal is shown in table 3.
Table 3 wavelength deviation counted by the grating scale sensor 17
When the rotation angle of the grating turntable 5 was measured using the pulse number of the stepping motor, the corresponding wavelength deviation at the blazed wavelength was measured as shown in table 4.
Table 4 wavelength deviation using pulse counting of stepper motor
The method of the embodiment adopts the grating ruler sensor 17 to measure the rotation angle of the grating turntable 5, and when the light beam is incident along the normal of the grating plane, the maximum wavelength deviation is 0.034nm; when the rotation angle of the grating turntable 5 was measured by using the pulse number of the stepping motor, the maximum wavelength deviation was 0.107nm.
Example III
One difference from the embodiment is that:
in this embodiment, the grating switching device is used to switch four gratings of the Spectra-1000G spectrophotometer.
According to the measurement requirement, the four gratings selected in the implementation are the first grating 10, GGR02-5050-24UV, and the spectral range is 200 nm-500 nm; a second grating 11, GGR01-5050-1250, with a spectral range of 330-1000 nm; a third grating 12, GGR01-5050-6012, with a spectral range of 830 nm-2500 nm; fourth grating 13, GGR01-5050-6016, spectrum range 1200-3000 nm.
The grating switches the locating hole on the rotary table 9, locate at 135 degrees direction in the surface.
The four grating supports 14 are respectively positioned in the directions of 90 DEG, 180 DEG, 270 DEG and 360 DEG in the plane of the grating switching turntable 9.
When the grating switching device of the present embodiment is used for measurement, the first grating 10, the second grating 11, the third grating 12, and the fourth grating 13 are fixed on four grating supports 14, as shown in fig. 4, the center line of the grating diffraction surface is located at a circumference concentric with the grating switching turntable 9, and the projection of the circumference on the grating turntable 5 passes through the rotation axis of the grating turntable 5. The specific operation steps are as follows:
(1) Mechanical zero positioning of grating switching turntable 9
After the grating switching device is electrified, the second stepping motor 16 drives the grating switching turntable 9 to rotate anticlockwise through the gear structure until the photoelectric switch 15 is conducted, namely the mechanical zero point of the grating switching turntable 9.
(2) Calculating the number of pulses required to be received by the second stepper motor 16 for raster switching
At the mechanical zero point of the grating switching turntable 9, the center line of the diffraction surface of the first grating 10 coincides with the rotation axis of the grating turntable 5.
The grating switching turntable 9 returns to the mechanical zero point and rotates 90 ° counterclockwise, so that the center line of the diffraction surface of the second grating 11 coincides with the rotation axis of the grating turntable 5, and the number of pulses received by the second stepping motor 16 is about 8000 according to formula (2).
The grating switching turret 9 returns to the mechanical zero point, and then rotates counterclockwise by 90 ° +90° =180°, so that the center line of the diffraction surface of the third grating 12 coincides with the rotation axis of the grating turret 5, and the number of pulses received by the second stepping motor 16 is about 16000 according to formula (2).
The grating switching turret 9 returns to the mechanical zero point and then rotates 90 ° +90 ° +90=270° counterclockwise, so that the center line of the diffraction surface of the fourth grating 13 coincides with the rotation axis of the grating turret 5, and the number of pulses received by the second stepping motor 16 is about 24000 according to formula (2).
(3) Calculating zero wavelength compensation value of grating and displacement equivalent of grating scale sensor 17
Calculating a displacement equivalent theoretical value of the grating corresponding to the grating ruler sensor according to the formula (3): the theoretical displacement equivalent value of the first grating 10 is 15.3333, the theoretical displacement equivalent value of the second grating 11 is 30.6667, the theoretical displacement equivalent value of the third grating 12 is 61.3333, and the theoretical displacement equivalent value of the fourth grating 13 is 61.3333.
And (3) calculating a zero wavelength compensation value of the grating and displacement equivalent of the grating ruler sensor according to a formula (4) by taking the radiation wavelength of the mercury lamp as a reference. The radiation wavelength of the low-pressure mercury lamp is 253.651nm and 435.834nm respectively, the zero-position wavelength compensation value of the first grating 10 is-65.72 nm, the displacement equivalent of the grating ruler sensor 17 is 20.635nm/mm, and the indication values of the first grating 10 are 316.6nm and 497.2nm respectively; the radiation wavelength of the low-pressure mercury lamp is 404.657nm and 546.075nm respectively, the zero-position wavelength compensation value of the second grating 11 is-63.15 nm, the displacement equivalent of the grating ruler sensor 17 is 30.862nm/mm, and the indication values of the second grating 11 are 465.1nm and 605.7nm respectively; the radiation wavelength of the low-pressure mercury lamp is 1014.0nm and 2325.3nm respectively, the indication value of the third grating 12 is 970.5nm and 2272.7nm respectively, the zero wavelength compensation value of the third grating is 36.72nm, and the displacement equivalent of the grating ruler sensor 17 is 61.796nm/mm; the radiation wavelength of the low-pressure mercury lamp is 1357.0nm and 2325.3nm respectively, the zero-position wavelength compensation value of the fourth grating 13 with the indication values of 1401.2nm and 2371.4nm is-41.46 nm, and the displacement equivalent of the grating ruler sensor 17 is 61.247nm/mm.
(4) Measurement of different wavelength intervals
At the mechanical zero point of the grating switching turntable 9, the center line of the diffraction surface of the first grating 10 coincides with the rotation axis of the grating turntable 5, the grating turntable 5 is rotated to the mechanical zero position through the turbine 4 and the worm 20, the displacement equivalent of the grating scale sensor 17 is set to 20.635nm/mm, the grating zero position wavelength compensation value is set to-65.72 nm, the grating turntable 5 is adjusted to the wavelength zero point, and a Spectra-1000G spectrophotometer is used for measurement test in a wavelength interval of 200 nm-500 nm.
The grating switching turntable 9 returns to a mechanical zero point, the second stepping motor 16 receives 8000 pulses, the grating switching turntable 9 rotates 90 degrees anticlockwise, so that the center line of the diffraction surface of the second grating 11 coincides with the rotation axis of the grating turntable 5, the grating turntable 5 is rotated to the mechanical zero point through the turbine 4 and the worm 20, the displacement equivalent of the grating scale sensor 17 is 30.862nm/mm, the grating zero point wavelength compensation value is-63.15 nm, the grating turntable 5 is adjusted to the wavelength zero point, and a spectrum-1000G spectrophotometer can be used for measurement test in a wavelength range of 330 nm-1000 nm.
The grating switching turntable 9 returns to a mechanical zero point, the second stepping motor 16 receives 16000 pulses, the grating switching turntable 9 rotates 180 degrees anticlockwise, so that the center line of the diffraction surface of the third grating 12 coincides with the rotation axis of the grating turntable 5, the grating turntable 5 is rotated to the mechanical zero point through the turbine 4 and the worm 20, the displacement equivalent of the grating scale sensor 17 is 61.796nm/mm and the grating zero point wavelength compensation value is 36.72nm, the grating turntable 5 is adjusted to the wavelength zero point, and a spectrum-1000G spectrophotometer can be used for measurement test in a wavelength interval of 830 nm-2500 nm.
The grating switching turntable 9 returns to a mechanical zero point, the second stepping motor 16 receives 24000 pulses, the grating switching turntable 9 rotates 270 degrees anticlockwise, the center line of the diffraction surface of the fourth grating 13 coincides with the rotation axis of the grating turntable 5, the grating turntable 5 is rotated to the mechanical zero point through the turbine 4 and the worm 20, the displacement equivalent of the grating scale sensor 17 is set to 61.247nm/mm, the grating zero point wavelength compensation value is set to-41.46 nm, the grating turntable 5 is adjusted to the wavelength zero point, and a measurement test can be performed in a wavelength range of 1200 nm-3000 nm by using a Spectra-1000G spectrophotometer.
When the grating switching device of the present embodiment is used for measurement, the deviation value is calculated as follows according to the method described in the first embodiment:
wavelength deviation of blazed wavelength when incident along the normal of the grating plane is shown in table 5.
Table 5 wavelength deviation counted by the grating scale sensor 17
When the rotation angle of the grating turntable 5 was measured using the pulse number of the stepping motor, the corresponding wavelength deviation at the blazed wavelength was measured as shown in table 6.
Table 6 wavelength deviation using pulse counting of stepper motor
The method of the embodiment adopts the grating ruler sensor 17 to measure the rotation angle of the grating turntable, and when the light beam is incident along the normal of the grating plane, the maximum wavelength deviation is 0.060nm; when the rotation angle of the grating turntable is measured by adopting the pulse number of the stepping motor, the maximum wavelength deviation is 0.187nm.

Claims (9)

1. The utility model provides a grating auto-change over device, includes grating auto-change over device base, grating revolving stage and photoelectric switch, its characterized in that: the device also comprises a grating turntable (5) driving device, a grating turntable (5) positioning measuring device, a grating switching turntable (9) driving device and a grating bracket (14); the photoelectric switch (15) is arranged on the grating turntable (5); the grating switching turntable (9) is of a gear disc structure, a positioning hole is arranged in the plane and is eccentrically and relatively rotatably arranged with the grating turntable (5), and when the relative rotation angle of the positioning hole and the grating turntable is proper, the optical path of the photoelectric switch (15) is conducted; the grating turntable (5) driving device is used for driving the grating turntable (5) to rotate around the axis of the grating turntable; the grating turntable (5) positioning measurement device is used for positioning the rotation position of the grating turntable (5) and measuring the rotation angle of the grating turntable; the grating switching turntable (9) driving device is used for driving the grating switching turntable (9) to rotate; the grating support (14) is positioned above the grating switching turntable (9) and is used for installing a grating, and the center line of a diffraction surface of the grating can be overlapped with the rotation axis of the grating turntable (5) by means of rotation of the grating switching turntable (9).
2. The grating switching device of claim 1, wherein: the grating turntable (5) driving device comprises a first thrust bearing seat (2), a first thrust bearing (3), a worm wheel (4), a first stepping motor (6), a coupler (18), a first worm support (19), a worm (20) and a second worm support (21); the first thrust bearing seat (2) is fixed on the grating switching device base (1); the first thrust bearing (3) is embedded between the first thrust bearing seat (2) and the turbine (4), the grating turntable (5) is fixed on the worm wheel (4), and the first thrust bearing seat and the turbine (4) are coaxial; the worm (20) is concentrically connected with the rotating shaft of the first stepping motor (6) through a coupler (18), and the worm wheel (4) is kept connected with the gear of the worm (20) through a first worm bracket (19) and a second worm bracket (21).
3. The grating switching device of claim 1, wherein: the grating turntable (5) positioning and measuring device is a grating ruler sensor (17) and is attached to the outer circumference of the grating turntable (5).
4. The grating switching device of claim 1, wherein: the grating switching turntable (9) driving device comprises a second thrust bearing seat (7), a second thrust bearing (8) and a second stepping motor (16); the second thrust bearing seat (7) and the second stepping motor (16) are arranged on the grating turntable (5); the second thrust bearing (8) is embedded between the second thrust bearing seat (7) and the grating switching rotary table (9), and the grating switching rotary table (9) is driven by a second stepping motor (16) through a gear.
5. The grating switching device of claim 1, wherein: the gratings arranged on the grating supports (14) are perpendicular to the plane of the grating switching turntable (9); the grating switching turntable (9) driving device is used for driving the grating switching turntable (9) to rotate around the axis of the grating switching turntable; the diffraction plane center lines of all gratings are located on a circumference concentric with the grating switching turntable (9).
6. A method of using the grating switching device of claim 1 in a broad spectrum instrument, comprising the steps of:
1) Determining the number and the type of the applicable gratings according to the requirements of the measured wavelength interval;
2) Mounting the grating switching device to a broad spectrum instrument; mounting the determined grating on a grating support (14) of a grating switching device;
3) Mechanical zero point of positioning grating switching turntable (9)
The grating switching turntable (9) is driven to rotate by using a driving device of the grating switching turntable (9), and the optical path to the photoelectric switch (15) is conducted, namely the mechanical zero point of the grating switching turntable (9);
4) Calculating zero wavelength compensation value of grating and displacement equivalent of grating turntable (5) positioning measurement device
Calculating a zero wavelength compensation value of the grating and displacement equivalent of a positioning measurement device of the grating turntable (5) based on a main light path included angle of the incident light and the emergent light of the grating and the curvature radius of the grating turntable (5) by taking the radiation wavelength of the spectrum lamp used by the grating as a reference;
5) Measurement work of open-spread spectrum instrument
The grating switching turntable (9) is rotated by a proper angle from a mechanical zero position by using a grating switching turntable (9) driving device, so that the center line of a diffraction surface of a required grating is overlapped with the rotation axis of the grating turntable (5); rotating the grating turntable (5) to a mechanical zero position by utilizing a grating turntable (5) switching device; setting a zero wavelength compensation value of a corresponding grating and displacement equivalent of a grating turntable (5) positioning measurement device, and adjusting the grating turntable (5) to a wavelength zero position; carrying out measurement work in a wavelength interval corresponding to the grating by using a wide spectrum instrument; returning the grating switching turntable (9) to the mechanical zero position after the measurement is completed;
repeating the above operation until the measurement work in all the grating corresponding wavelength intervals is completed by using the wide spectrum instrument.
7. The method of using the grating switching device according to claim 6 in a broad spectrum instrument, wherein: the grating switching turntable (9) driving device comprises a second stepping motor (16); the rotation angle of the grating switching turntable (9) is controlled by the number of pulses received by the second stepping motor (16) and the set rotation direction.
8. The method of using the grating switching device according to claim 7 in a broad spectrum instrument, wherein: before the measurement starts, the mechanical zero point of the grating switching turntable (9) is used as a starting point, the angle and the rotation direction of the grating required to complete the switching are determined, and the number of pulses required to be received by the second stepping motor (16) is calculated based on the angle.
9. The method of using the grating switching device according to claim 6 in a broad spectrum instrument, wherein: the grating turntable (5) driving device comprises a turbine (4) and a worm (20) which are connected through gears.
CN202310929606.2A 2023-07-27 2023-07-27 Grating switching device and application method thereof in wide spectrum instrument Pending CN116931211A (en)

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CN202310929606.2A CN116931211A (en) 2023-07-27 2023-07-27 Grating switching device and application method thereof in wide spectrum instrument

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