An absolute method for calibrating a laser beam rotation positioning device and positioning method

Abstract

A laser beam rotation positioning device and method for accelerometer absolute calibration, belonging to the field of vibration metrology testing equipment, is disclosed. The device comprises a positioning base, a linear adjustment platform, a rotating platform, a prism pressure plate, a 90° V-shaped reflector, a reflector mounting base, a lifting mechanism slider, a lifting mechanism, a prism, a fixed housing, a transmission belt, and a stepper motor. The 90° V-shaped reflector is mounted above the positioning base via the lifting mechanism, forming an integrated optical device together with the rotatable prism assembly consisting of the prism and the fixed housing. The horizontal laser beam emitted by the laser interferometer is reflected vertically downwards by the 90° V-shaped reflector to the prism. By driving the prism to rotate by an angle θ around its optical axis, the emitted laser beam can be synchronously rotated by an angle 2θ around the sensitive axis of the accelerometer being calibrated. This invention can quickly and accurately achieve paired laser beam positioning, and is compatible with B2B type accelerometers with the reference surface at the top of the housing and SE type accelerometers with the reference surface at the bottom of the housing.

Description

Technical Field

[0001] This invention relates to an absolute method for calibrating a laser beam rotation positioning device and its positioning method for accelerometers, belonging to the field of vibration measurement and testing equipment. Background Technology

[0002] Absolute calibration of accelerometers is a core means of establishing a traceability chain for vibration values ​​and ensuring the accuracy and reliability of measurement results. According to the standard GB / T 20485.11-2006 Vibration and Shock Sensor Calibration Method Part 11: Absolute Vibration Calibration by Laser Interferometry, laser interferometry is a key method for achieving absolute calibration of accelerometers. Its calibration accuracy and efficiency are directly limited by the positioning accuracy of the measuring laser beam relative to the reference surface of the accelerometer being calibrated.

[0003] Currently, most mainstream accelerometer calibration devices employ a laser beam positioning scheme using a "beam splitter + linear platform". Specifically, the measuring heads of two laser interferometers are mounted on a four-degree-of-freedom linear platform. After being split by a beam splitter, the laser beam is guided to the reference surface of the accelerometer being calibrated via a right-angle prism. By manually adjusting the X / Y direction translation of the linear platform of the laser head, the laser beam is paired and positioned at 0° / 180° and 90° / 270° around the axis of symmetry of the accelerometer being calibrated, thus compensating for measurement errors caused by non-linear motion.

[0004] Current laser beam positioning schemes suffer from several optical and mechanical drawbacks. First, the beam splitter introduced into the optical path leads to significant power loss. Each time the laser beam passes through the beam splitter, the incident light intensity is divided equally, resulting in a 50% loss of optical power. Since the laser beam must pass through the optical system twice, the final optical power returning to the interferometer detector may be less than 25% of the initial value. Furthermore, most accelerometers lack highly reflective or mirror-like surface finishes, causing the laser beam to be only partially reflected or scattered, further weakening the returned light intensity and degrading the signal-to-noise ratio at high frequencies (e.g., f>5kHz), severely impacting the signal demodulation accuracy based on the sinusoidal approximation method. Second, in typical calibration scenarios, the optical measuring head requires multiple readjustments. Manually adjusting the linear platform to achieve laser beam translation and positioning is prone to positioning errors in the laser spot, causing the laser beam to deviate from the sensor's sensitive axis. This process is cumbersome, time-consuming, and susceptible to human error, resulting in poor positioning repeatability and hindering calibration efficiency and result repeatability.

[0005] Therefore, there is an urgent need for a new type of laser beam positioning device that can significantly reduce light intensity loss, simplify operation procedures, and improve positioning accuracy and repeatability. Summary of the Invention

[0006] To address the problems of significant light intensity loss, cumbersome positioning operations, low accuracy, and low efficiency in existing laser beam positioning devices and methods for absolute accelerometer calibration, this invention aims to provide a laser beam rotation positioning device and method for absolute accelerometer calibration. This device is an integrated optical system composed of a 90° V-shaped reflector and a rotatable prism. The angular positioning of the laser beam around the accelerometer's sensitive axis is directly controlled by driving the prism to rotate. Simultaneously, the lateral spacing of the laser beam is adjusted using the adjustable V-shaped reflector, thereby achieving rapid, accurate, and automated laser beam pairing and positioning. This invention employs a beam-splitter-less optical path for rotational positioning, increasing the return light power intensity and improving the accuracy of accelerometer calibration. It is also adaptable to accelerometers with different reference surfaces.

[0007] The objective of this invention is achieved through the following technical solution.

[0008] The present invention discloses an accelerometer absolute method calibration laser beam rotation positioning device, comprising a positioning base, a linear adjustment platform, a rotating platform, a prism pressure plate, a prism, a fixed housing, a lifting mechanism slider, a 90° V-shaped reflector, a reflector mounting base, a lifting mechanism, a transmission belt, and a stepper motor.

[0009] The positioning base serves as the installation foundation for the entire device. Its upper surface has an optical path hole for the laser beam to pass through, and a standard threaded hole array is provided to facilitate the fixing of the linear adjustment platform and the lifting mechanism.

[0010] The linear adjustment platform uses an X / Y two-dimensional adjustment displacement stage, which is fixed on the positioning base, and is used to make precise lateral position adjustments to the rotating platform and prism assembly.

[0011] The rotary platform is mounted on the linear adjustment platform.

[0012] The prism is fastened to the fixed housing by the prism pressure plate, together forming a prism assembly. The assembly is mounted on a rotating platform so that it can be driven to rotate.

[0013] The 90° V-shaped reflector has a V-shaped symmetrical design and is fixed on the reflector mounting base.

[0014] The lifting mechanism employs a ball screw-type linear displacement stage, vertically fixed to one side of the positioning base. Its lifting mechanism slider is connected to a 90° V-shaped reflector via a reflector mounting base, driving the reflector to move vertically up and down, adjusting the lateral spacing of the laser beam reflected downwards by the prism to the reference surface of the accelerometer being calibrated.

[0015] The stepper motor is fixed to the side of the positioning base and connected to the rotating platform via the transmission belt, and is used to precisely control the rotation angle of the prism assembly around its own optical axis.

[0016] In the device, the 90° V-shaped reflector is fixed above the side of the positioning base by a lifting mechanism and is located in the optical path directly above the prism assembly.

[0017] In the device, the horizontal measuring beams emitted by the two laser interferometers should be aligned with the V-center of the 90° V-shaped reflector, and the axis of symmetry of the 90° V-shaped reflector and the optical axis of the prism should be aligned to be collinear.

[0018] In the device, a horizontal light beam is reflected vertically downwards at a 90° angle by a reflector and then incident directly onto the incident surface of the prism. Inside the prism, the beam is refracted towards the substrate, and after further refraction by the substrate's reflecting surface, it exits from the exit surface, forming two parallel, symmetrical, vertical laser beams with a fixed lateral offset. These two beams ultimately pass vertically downwards through the through-hole of the positioning base and illuminate the reference surface of the accelerometer being calibrated.

[0019] In the device, by adjusting the X and Y directions of the linear adjustment platform, the two laser beams are symmetrically distributed on both sides of the sensitive axis of the accelerometer being calibrated.

[0020] In the device, when the rotary drive mechanism drives the prism assembly to rotate by an angle θ around its optical axis, the laser beam transmitted through the prism rotates synchronously by an angle 2θ around the sensitive axis of the accelerometer being calibrated. During operation, by simply controlling the prism to rotate at angles such as 0°, 45°, 90°, and 135°, the laser beam can be quickly positioned at 0° / 180°, 90° / 270°, etc., on the reference surface of the accelerometer being calibrated.

[0021] In the device, the height change of the 90° V-shaped reflector has a linear positive correlation with the lateral spacing of the laser beams. The V-shaped reflector deflects two horizontal beams of light into vertically downward beams, and the positions of the two light spots on the prism's incident surface are determined by the height of the reflector. The prism then translates these two beams and emits them in parallel, with the amount of translation depending on the incident point. When the lifting mechanism drives the reflector to move up and down along the Z-direction, it changes the propagation path length of the two laser beams in the vertical optical path, thereby adjusting the lateral spacing of the emitted laser beams on the reference surface of the accelerometer being calibrated.

[0022] The lateral spacing of the laser beam, 2R = kΔZ + D, where k is a proportionality coefficient, mainly determined by the refractive index and size of the prism, and D is the inherent offset of the system. This linear relationship allows for continuous and predictable adjustment of the lateral spacing 2R of the laser beam through precise control of ΔZ via a lifting mechanism. Reducing the distance Z of the reflecting mirror... SE At that time, the laser beam spacing can be adjusted from 2R to fit the B2B type accelerometer. B2B Extended to 2R for SE-type accelerometers SE This enables compatibility between different types of accelerometers.

[0023] Beneficial effects:

[0024] 1. This invention discloses a laser beam rotation positioning device and method for absolute accelerometer calibration. It employs a beam-splitter-less optical path design, eliminating the need for beam splitting. Only a small amount of reflection loss occurs at the prism's incident and exit surfaces, significantly improving the returned light intensity compared to traditional beam-splitter schemes. Even with low reflectivity of the accelerometer reference surface, sufficient signal-to-noise ratio is ensured during high-frequency calibration, thereby improving the accuracy of the sinusoidal approximation demodulation method. This invention significantly reduces laser beam intensity loss.

[0025] 2. This invention discloses an absolute method for accelerometer calibration, specifically a laser beam rotation positioning device and its positioning method. This invention achieves a precise angular control relationship where "the prism rotates by an angle θ, and the emitted laser beam rotates synchronously by an angle 2θ". During calibration, simply controlling the prism to rotate to a specific angle (e.g., 0°, 45°, 90°, 135°) via a stepper motor allows the laser beam to quickly and accurately switch to the required paired positions (0°, 90°, 180°, 270°, etc.) on the accelerometer reference plane. This completely replaces the traditional, cumbersome manual translation adjustment, significantly improving positioning speed, reducing random errors caused by manual operation, and enhancing the repeatability and accuracy of calibration measurements. This invention simplifies the laser beam positioning process while maintaining high precision.

[0026] 3. This invention discloses a laser beam rotation positioning device and method for absolute accelerometer calibration. By changing the height of the 90° V-shaped reflector through a lifting mechanism, the lateral distance between the two emitted laser beams on the reference surface of the accelerometer being calibrated can be linearly adjusted. This distance adjustment range (e.g., 20mm ~ 50mm) is designed to cover the sizes of common accelerometers. The same device can be adapted to both B2B type accelerometers with the reference surface at the top of the housing and SE type accelerometers with the reference surface at the bottom of the housing without changing the core optical components, demonstrating strong versatility. This invention enables adjustable laser beam spacing to meet the calibration requirements of different types of accelerometers. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a laser beam rotation positioning device for accelerometer absolute calibration according to the present invention.

[0028] Figure 2 This is a schematic diagram of the optical path for rotating and positioning a laser beam for absolute calibration of an accelerometer according to the present invention.

[0029] Where a) is the optical path diagram adapted to the B2B type accelerometer, and b) is the optical path diagram adapted to the SE type accelerometer.

[0030] In the diagram: 1—Positioning base, 2—Linear adjustment platform, 3—Rotating platform, 4—Prism pressure plate, 5—90° V-shaped reflector, 6—Reflector mounting base, 7—Lifting mechanism slider, 8—Lifting mechanism, 9—Prism, 10—Fixed housing, 11—Transmission belt, 12—Stepper motor, 13—Laser interferometer, 14—Laser interferometer, 15—Standard accelerometer (B2B type), 16—Standard accelerometer (SE type). Detailed Implementation

[0031] To illustrate the technical problems solved by the present invention and its beneficial effects, the invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0032] An embodiment of the present invention provides an accelerometer absolute calibration laser beam rotation positioning device and its positioning method. Figure 1 This is a schematic diagram of the overall structure of a laser beam rotation positioning device for accelerometer absolute calibration according to the present invention. Figure 2 This is a schematic diagram of the optical path for the rotational positioning of a laser beam for absolute accelerometer calibration according to the present invention, including a positioning base 1, a linear adjustment platform 2, a rotation platform 3, a prism pressure plate 4, a 90° V-shaped reflector 5, a reflector mounting base 6, a lifting mechanism slider 7, a lifting mechanism 8, a prism 9, a fixed housing 10, a transmission belt 11, a stepper motor 12, a laser interferometer 13, a laser interferometer 14, a standard accelerometer 15, and a standard accelerometer 16.

[0033] The positioning base 1 provides a rigid and stable mounting foundation, reducing environmental vibration interference, and has an optical through-hole with a diameter of approximately 50mm inside. The linear adjustment platform 2 is used for fine-tuning the prism position and precisely adjusting the collinear alignment of the optical axes. The rotating platform 3 is mounted on the linear adjustment platform 2, supporting the prism assembly and enabling its rotation. The prism assembly consists of the prism 9, the fixed housing 10, and the prism pressure plate 4. The prism 9 is stress-free secured within the fixed housing 10 by the prism pressure plate 4, ensuring that its optical axis coincides with the rotation axis of the housing. The entire prism assembly is mounted on the rotating platform 3. The stepper motor 12 is fixed to the side of the base 1 and drives the rotating platform 3 to rotate via the transmission belt 11. The 90° V-shaped reflector is used to achieve 90° vertical reflection of the laser beams from the laser interferometers 13 and 14, ensuring the symmetry of the two laser beams. The lifting mechanism is used to adjust the height of the 90° V-shaped reflector; the slider 7 of the lifting mechanism is connected to the V-shaped reflector 5 via the reflector mounting base 6. Laser interferometers 13 and 14 are used to emit measurement lasers and receive return signals.

[0034] The geometric dimensions (width W, height H, base length L) of prism 9 are obtained by the following method:

[0035] The reference surface diameter of the accelerometer being calibrated is D, the symmetrical distribution distance between the two measuring laser beams on the sensor reference surface is 2R, the refractive index of the prism is n, the laser beam spot diameter is d, and the edge safety distance of the prism's light-transmitting area is h0.

[0036] To ensure that both measuring laser beams fall completely within the sensor reference plane, the symmetrical spacing between the laser beams must satisfy the constraint relationship of the sensor diameter. For a B2B type accelerometer, 2R B2B ≤D; For SE type accelerometers, 2R SE ≥D. The width of the prism must completely cover the incident area of ​​the two laser beams, therefore the prism width W≥D.

[0037] The prism height H must ensure unobstructed transmission of the laser beam in the vertical direction. H must satisfy the following conditions:

[0038]

[0039] If the incident angle of the laser beam onto the prism is α, and the refraction angle of the beam within the prism is β, then the lateral offset Δx of the laser beam within the prism is:

[0040]

[0041]

[0042] To ensure that the offset laser beam falls entirely within the sensor reference plane, the lateral offset Δx must satisfy the sensor diameter constraint: Δx≤D / 2.

[0043] Therefore, the relationship between the diameter D of the reference surface of the accelerometer being calibrated and the length L of the prism base is obtained as follows:

[0044]

[0045] By using the above method, the width, height, and base length of the prism are determined to achieve full coverage adaptation for sensors of different diameters.

[0046] Fix the linear adjustment platform 2 onto the positioning base 1. Install the prism 9 into the fixed housing 10 and tighten it evenly with the prism pressure plate 4, then install this assembly onto the rotary platform 3. Install the stepper motor 12 on the side of the base, install the drive belt 11 and adjust the tension. Fix the 90° V-shaped reflector 5 onto the lifting mechanism slider 7 via the reflector mounting base 6, and then erect the entire lifting mechanism 8 on the mounting position on one side of the positioning base 1.

[0047] Control the lifting mechanism 8 to position the 90° V-shaped reflector 5 near the working height. Adjust the position and height of the two laser interferometers 13 and 14 so that the two horizontal laser beams emitted by them are incident on the center of symmetry of the V-shaped reflector 5. Operate the X / Y knobs of the linear adjustment platform 2 to fine-tune the position of the prism assembly, while observing the laser path, until the two beams of light emitted from the prism 9 are perpendicular and symmetrical, and the axis of symmetry of the V-shaped reflector 5 is collinear with the optical axis of the prism 9.

[0048] Control the stepper motor to rotate at a small angle and observe whether the two laser spots illuminating the surface of the accelerometer rotate along a concentric circle trajectory.

[0049] In one embodiment, the absolute calibration of a B&K Model 8305 standard accelerometer (B2B type) is taken as an example.

[0050] S1: The reference surface size D of the accelerometer (15) being calibrated is 15.5mm. According to the above calculation method for prism geometry, the size of prism (9) is selected as 30mm×30mm×115mm.

[0051] S2: Install the accelerometer to be calibrated (15) on the moving surface of the vibration table and adjust its position so that its sensitive axis is as coaxial as possible with the optical axis of the prism (9).

[0052] S3: Fine-tune the X / Y direction of the linear adjustment platform to correct the optical axis offset until the laser beams of the laser interferometer (13) and the laser interferometer (14) irradiate the reference surface of the accelerometer symmetrically and adjust to a suitable lateral spacing.

[0053] S4: Set the rotation parameters of the stepper motor (12) through the controller to make the laser beam rotate 0°, 90°, 180° and 270° respectively. Adjust the motor control parameters to establish a precise control relationship that the laser beam rotates synchronously by 2θ angles when the prism assembly rotates by θ angles.

[0054] S5: Drive the stepper motor (12) to rotate the prism assembly to 0°. At this time, the laser beam is positioned at 0° / 180° on the accelerometer reference plane. Start the vibration table for sinusoidal excitation and record the acceleration signal measured by the laser interferometer (13), the laser interferometer (14) and the output voltage signal of the accelerometer.

[0055] S6: Drive the stepper motor (12) to rotate the prism assembly by 45°. At this time, the laser beam rotates synchronously by 90° and is positioned at the 90° / 270° position. Repeat the excitation and data acquisition process of S4.

[0056] S7: When replacing with SE type accelerometer (16), lower the height of the lifting mechanism (8), move the 90° V-shaped reflector (5) down, and expand the distance between the two laser beams to fit the bottom reference surface of the SE type accelerometer. Repeat the positioning and measurement steps of S2-S5.

[0057] S8: For all the acquired multiple sets of laser interference signals and accelerometer output signals, the sinusoidal approximation method is used for demodulation and calculation, and finally the calibration results such as the sensitivity amplitude of the accelerometer under calibration at each frequency point are obtained.

[0058] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A laser beam rotation positioning device for absolute accelerometer calibration, characterized in that: It includes a positioning base (1), a linear adjustment platform (2), a rotating platform (3), a prism pressure plate (4), a 90° V-shaped reflector (5), a reflector mounting base (6), a lifting mechanism slider (7), a lifting mechanism (8), a prism (9), a fixed housing (10), a transmission belt (11), and a stepper motor (12). The upper surface of the positioning base (1) is provided with a circular optical passage hole and a distributed array of threaded holes for fixing the linear adjustment platform (2) and the lifting mechanism (8). The linear adjustment platform (2) is fixedly installed on the positioning base (1), and the rotating platform (3) is installed on the linear adjustment platform (2); The prism (9) is fixedly installed in the fixed housing (10) by the prism pressure plate (4) to form a prism assembly; The fixed housing (10) is mounted on the rotating platform (3) so that the prism assembly can rotate with the rotating platform (3); The lifting mechanism (8) is fixedly installed on the positioning base (1), and its lifting mechanism slider (7) is connected to the 90° V-shaped reflector (5) through the reflector mounting base (6) to drive the 90° V-shaped reflector (5) to move in the vertical direction and adjust the lateral spacing of the laser beam. The stepper motor (12) is fixed to the side of the positioning base (1) and drives the rotating platform (3) and the prism assembly to rotate around its optical axis via the transmission belt (11). The axis of symmetry of the 90° V-shaped reflector (5) is collinear with the optical axis of the prism (9); the horizontal laser beams emitted by the two laser interferometers are reflected by the 90° V-shaped reflector (5) and then incident vertically onto the prism (9), and after being transmitted through the prism (9), they form two symmetrically distributed measurement laser beams on both sides of the sensitive axis of the accelerometer being calibrated.

2. The apparatus as described in claim 1, characterized in that: The geometric dimensions of the prism (9) are obtained by the following method: The reference surface diameter of the accelerometer being calibrated is D, the symmetrical distribution distance between the two measuring laser beams on the sensor reference surface is 2R, the refractive index of the prism is n, the laser beam spot diameter is d, and the edge safety distance of the prism's light-transmitting area is h0. To ensure that both measuring laser beams fall completely within the sensor reference plane, the symmetrical spacing between the laser beams must satisfy the constraint relationship of the sensor diameter; for the B2B type accelerometer, 2R B2B ≤D; For SE type accelerometers, 2R SE ≥D; The width of the prism must completely cover the incident area of ​​the two laser beams, so the prism width W≥D; The prism height H must ensure unobstructed transmission of the laser beam in the vertical direction. H must satisfy the following conditions: If the incident angle of the laser beam onto the prism is α, and the refraction angle of the beam within the prism is β, then the lateral offset Δx of the laser beam within the prism is: To ensure that the offset laser beam falls entirely within the sensor reference plane, the lateral offset Δx must satisfy the sensor diameter constraint: Δx≤D / 2; The relationship between the diameter D of the reference surface of the accelerometer being calibrated and the length L of the prism base is obtained as follows: By using the above method, the width, height, and base length of the prism are determined to achieve full coverage adaptation for sensors of different diameters.

3. The apparatus as described in claim 1, characterized in that: The linear adjustment platform (2) is a two-dimensional adjustment displacement stage in the X / Y direction. Its base is fixed to the positioning base (1), and its upper surface is fixedly connected to the rotating platform (3). It is used to finely adjust the position of the prism assembly to ensure that the axis of symmetry of the 90° V-shaped reflector (5) is precisely collinear with the optical axis of the prism (9).

4. The apparatus as described in claim 1, characterized in that: When the prism (9) rotates by an angle θ around its optical axis, the measuring laser beam rotates synchronously by an angle 2θ around the sensitive axis of the accelerometer being calibrated.

5. The apparatus as described in claim 1, characterized in that: By controlling the stepper motor (12) to drive the prism (9) to rotate 0°, 45°, 90° or 135°, the measuring laser beam can be quickly switched to the 0° / 180° pairing position or the 90° / 270° pairing position on the reference surface of the accelerometer being calibrated.

6. The apparatus as claimed in claim 1, characterized in that: The lifting mechanism (8) is a ball screw linear displacement stage with an effective stroke of 0-50mm. By controlling the lifting of the 90° V-shaped reflector (5), the lateral spacing of the measuring laser beam can be continuously adjusted within the range of 20mm to 50mm.

7. The apparatus as claimed in claim 1, characterized in that: By adjusting the lateral spacing of the measuring laser beams, the device can be adapted to both the B2B type accelerometer with its reference surface located at the top of the housing and the SE type accelerometer with its reference surface located at the bottom of the housing.

8. The apparatus as claimed in claim 1, characterized in that: Both the lifting mechanism (8) and the stepper motor (12) can be connected to an external controller to automate the lifting and adjusting of the 90° V-shaped reflector and the rotation and positioning of the measuring laser beam.

9. The apparatus as claimed in claim 1, characterized in that: The device adopts a structure of "beam splitter-free optical path + rotation positioning". The reflecting surface of the 90° V-shaped reflector (5) is a V-shaped symmetrical structure. The size of the prism (9) is 30mm×30mm×115mm.

10. A method for positioning using any one of the devices described in claims 1 to 9, characterized in that: Includes the following steps: S1: The accelerometer to be calibrated is mounted on the moving surface of the vibration table, so that its sensitive axis is as coaxial as possible with the optical axis of the prism (9); S2: Operate the linear adjustment platform (2) to make X / Y fine adjustments so that the laser beams emitted by the two laser interferometers pass through the 90° V-shaped reflector (5) and prism (9) to form two symmetrically distributed measurement laser beams on both sides of the sensitive axis of the accelerometer being calibrated, and irradiate its reference surface; S3: Control the stepper motor (12) to drive the prism (9) to rotate around its optical axis, verify and establish the control relationship that the measuring laser beam rotates synchronously around the sensitive axis of the accelerometer being calibrated by 2θ angle when the prism rotates by an angle θ; S4: Drive the prism (9) to rotate to a specific angle by the stepper motor (12), so that the measuring laser beam switches to the target pairing position on the accelerometer reference surface; At each pairing position, the vibration table is activated to perform sinusoidal excitation, and the laser interference signal and the accelerometer output signal are acquired simultaneously. S5: When calibrating different types of accelerometers, the height of the 90° V-shaped reflector (5) is adjusted by the lifting mechanism (8) to continuously change the lateral distance between the two measuring laser beams on the reference surface of the accelerometer being calibrated, so as to adapt to the B2B type accelerometer with the reference surface located at the top of the housing or the SE type accelerometer with the reference surface located at the bottom of the housing.

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