rus
Issue #2/2023
B.G.Turukhano, N.Turukhano, Yu.M.Lavrov, O.G.Ermolenko, S.N.Khanov
CERTIFICATION OF NM LHE NANO-LINEAR HOLOGRAPHIC SENSOR (RUSSIAN FEDERATION) AND AT715 SENSOR (JAPAN)
CERTIFICATION OF NM LHE NANO-LINEAR HOLOGRAPHIC SENSOR (RUSSIAN FEDERATION) AND AT715 SENSOR (JAPAN)
DOI: https://doi.org/10.22184/1993-8578.2023.16.2.152.158
Nano-measuring linear holographic encoder (NM LHE) and AT715 sensor are high-precision displacement and length measurement devices. The measuring element of the NM LHE is a linear holographic diffraction grating. The AT715 linear scale operates on the base of electromagnetic induction. The NM LHE and AT715 sensors have an operating range of more than 1000 mm.
Nano-measuring linear holographic encoder (NM LHE) and AT715 sensor are high-precision displacement and length measurement devices. The measuring element of the NM LHE is a linear holographic diffraction grating. The AT715 linear scale operates on the base of electromagnetic induction. The NM LHE and AT715 sensors have an operating range of more than 1000 mm.
Теги: linear holographic diffraction grating nano-measuring linear holographic encoder линейная голографическая дифракционная решетка наноизмерительный линейный датчик голографический
PURPOSE OF NM LHE-500
NM LHE-500 (Fig.1) are high-precision nano-measuring devices whose measuring elements are high-frequency linear holographic diffraction gratings (LHDG). These encoders were developed for precision coordinate measurements in the control system of the measured product.
This paper compares technical characteristics of linear holographic encoders of two types (Table 1).
THE NM LHE-500 ARE DESIGNED FOR A LENGTH OF 500 MM
NM LHE-500 sensors consist of:
optical-mechanical part (OMP);
electronic part (Fig.2).
Laser module:
Laser module supply voltage (V, not less than) 3.0;
Ambient temperature, °C (20 ± 5).
Principle of operation of NM LHE-500
The principle of operation of NM LHE is based on the following physical phenomenon: wavefront phase of the coherent light beam diffracted on the measuring holographic array linearly and synchronously changes in time with the array shift along the device movement direction.
In sensor operation, this physical principle is realised as follows (Fig.2): the collimated light beam 1 from the laser falls on the measuring 3 and display 4 gratings (display grating 4 installed behind measuring grating 3) (Fig.3).
After first grating, we will distinguish two beams: beam 5 passing without diffraction and going in direction of incident beam, and diffracted beam 6 falls at an angle to the incident one. Diffracted beam changes wavefront phase linearly with a shift magnitude of the measuring grating, while the beam falls in direction of the incident beam does not change its phase. Two beams are brought back to the same direction by the display and measuring gratings. As a result, two aligned beams emerging from the output, both in two directions. The interference of these two beams produces wide interference moiré or obturation fringes (Fig.4 a, b), and their position changes synchronously with the measuring grating movement. Photodetectors convert intensity of the interference fringes into sinusoidal electrical signals with a spatial period corresponding to the pitch of the measuring grating.
To achieve resolutions up to 0.01 µm, the high quality sinusoidal output signals are interpolated electronically. To pick up direction of grating shift (reversal), two systems of output signals, phase-shifted to each other by 90 ° are arranged. These signals were analysed and processed in the electronic control unit to detect a linear size of the object or direction and magnitude of the grating movement.
In order to realise all advantages of a holographic reference system, a special motion mechanism is used:
The guide consists of a glass substrate of a holographic grating and a glass substrate glued down to the former face by special technology;
The carriage moves using bearings.
METROLOGICAL CHARACTERISTICS OF ENCODERS
On the attestation unit (AU) of the Laboratory of Holographic Information Measurement Systems (LHIMS) of SRC PNPI (Fig.5) the linear holographic encoder LHIMS – ЛДГ 500 mm long and ЛЭМ of 1000 mm long were located successively. The ЛЭМ sensor was used in the PNPI research and development at the Large Hadron Collider (LHC) in Switzerland. ЛЭМ attestation was carried out at the length L = 500 mm. Note that according to the D.I. Mendeleev All-Russian Research Institute of Metrology certification, ЛЭМ accuracy is defined by the formula:
Δ ЛДГ = ± (0.02 + 0.4L) мкм | μm, (1)
where L is in metres. Therefore, the LHE error on a length of 500 mm does not exceed a value:
Δ ЛДГ = ± 0.2 мкм | μm. (2)
Table 1 presents characteristics of the 500 mm long LHE (first column) and the 1000 mm long LHE sensor (second column). The graph and diagrams of difference values (500 mm long ЛДГ and 1 metre long ЛЭМ sensor) are shown in Fig.6 and Fig.7 a, b, c.
From the analysis of the graph data and diagrams (Fig.7 a, b, c) it follows that as the measured length increases, the difference values increase and do not exceed the specified ΔЛЭМ value (3). Due to the fact that the ЛЭМ has a minimum resolution of 1.0 µm and the NM LHE-500 has a resolution of 0.01 µm, the current values of the ЛДГ length within ± 1.0 µm are not fixed.
Based on the above, ЛЭМ accuracy formula can be written as:
ΔЛЭм = ± (2.0 ± 1.0 L) мкм | μm. (3)
PEER REVIEW INFO
Editorial board thanks the anonymous reviewer(s) for their contribution to the peer review of this work. It is also grateful for their consent to publish papers on the journal’s website and SEL eLibrary eLIBRARY.RU.
Declaration of Competing Interest. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
NM LHE-500 (Fig.1) are high-precision nano-measuring devices whose measuring elements are high-frequency linear holographic diffraction gratings (LHDG). These encoders were developed for precision coordinate measurements in the control system of the measured product.
This paper compares technical characteristics of linear holographic encoders of two types (Table 1).
THE NM LHE-500 ARE DESIGNED FOR A LENGTH OF 500 MM
NM LHE-500 sensors consist of:
optical-mechanical part (OMP);
electronic part (Fig.2).
Laser module:
Laser module supply voltage (V, not less than) 3.0;
Ambient temperature, °C (20 ± 5).
Principle of operation of NM LHE-500
The principle of operation of NM LHE is based on the following physical phenomenon: wavefront phase of the coherent light beam diffracted on the measuring holographic array linearly and synchronously changes in time with the array shift along the device movement direction.
In sensor operation, this physical principle is realised as follows (Fig.2): the collimated light beam 1 from the laser falls on the measuring 3 and display 4 gratings (display grating 4 installed behind measuring grating 3) (Fig.3).
After first grating, we will distinguish two beams: beam 5 passing without diffraction and going in direction of incident beam, and diffracted beam 6 falls at an angle to the incident one. Diffracted beam changes wavefront phase linearly with a shift magnitude of the measuring grating, while the beam falls in direction of the incident beam does not change its phase. Two beams are brought back to the same direction by the display and measuring gratings. As a result, two aligned beams emerging from the output, both in two directions. The interference of these two beams produces wide interference moiré or obturation fringes (Fig.4 a, b), and their position changes synchronously with the measuring grating movement. Photodetectors convert intensity of the interference fringes into sinusoidal electrical signals with a spatial period corresponding to the pitch of the measuring grating.
To achieve resolutions up to 0.01 µm, the high quality sinusoidal output signals are interpolated electronically. To pick up direction of grating shift (reversal), two systems of output signals, phase-shifted to each other by 90 ° are arranged. These signals were analysed and processed in the electronic control unit to detect a linear size of the object or direction and magnitude of the grating movement.
In order to realise all advantages of a holographic reference system, a special motion mechanism is used:
The guide consists of a glass substrate of a holographic grating and a glass substrate glued down to the former face by special technology;
The carriage moves using bearings.
METROLOGICAL CHARACTERISTICS OF ENCODERS
On the attestation unit (AU) of the Laboratory of Holographic Information Measurement Systems (LHIMS) of SRC PNPI (Fig.5) the linear holographic encoder LHIMS – ЛДГ 500 mm long and ЛЭМ of 1000 mm long were located successively. The ЛЭМ sensor was used in the PNPI research and development at the Large Hadron Collider (LHC) in Switzerland. ЛЭМ attestation was carried out at the length L = 500 mm. Note that according to the D.I. Mendeleev All-Russian Research Institute of Metrology certification, ЛЭМ accuracy is defined by the formula:
Δ ЛДГ = ± (0.02 + 0.4L) мкм | μm, (1)
where L is in metres. Therefore, the LHE error on a length of 500 mm does not exceed a value:
Δ ЛДГ = ± 0.2 мкм | μm. (2)
Table 1 presents characteristics of the 500 mm long LHE (first column) and the 1000 mm long LHE sensor (second column). The graph and diagrams of difference values (500 mm long ЛДГ and 1 metre long ЛЭМ sensor) are shown in Fig.6 and Fig.7 a, b, c.
From the analysis of the graph data and diagrams (Fig.7 a, b, c) it follows that as the measured length increases, the difference values increase and do not exceed the specified ΔЛЭМ value (3). Due to the fact that the ЛЭМ has a minimum resolution of 1.0 µm and the NM LHE-500 has a resolution of 0.01 µm, the current values of the ЛДГ length within ± 1.0 µm are not fixed.
Based on the above, ЛЭМ accuracy formula can be written as:
ΔЛЭм = ± (2.0 ± 1.0 L) мкм | μm. (3)
PEER REVIEW INFO
Editorial board thanks the anonymous reviewer(s) for their contribution to the peer review of this work. It is also grateful for their consent to publish papers on the journal’s website and SEL eLibrary eLIBRARY.RU.
Declaration of Competing Interest. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Readers feedback
