A coaxial laser interferometer transceiver with a reflective target

Abstract

This invention provides a coaxial laser interferometer transceiver with a reflective target, which can control the sensitivity of a plane mirror to reflection angles without changing the lens focal length and the aperture of the emitted beam. Its structure includes a transmitting / receiving waveguide, a collimating lens, and a plane mirror. Light emitted from the transmitting / receiving waveguide is collimated by the collimating lens and then directed onto the plane mirror. The plane mirror is mounted on the measured end to reflect the received light. It also includes a reflective target with a reflective area located around the transmitting / receiving waveguide, the shape and size of which are set as needed. Light from the transmitting / receiving waveguide directed onto the plane mirror is reflected once by the plane mirror, then again by the collimating lens onto the reflective target, and then reflected a second time by the reflective area before being directed back onto the plane mirror by the collimating lens. After a third reflection by the plane mirror, the light is again focused onto the transmitting / receiving waveguide by the collimating lens and received by the transmitting / receiving waveguide.

Description

Technical Field

[0001] This invention relates to the field of interferometer technology, specifically to a coaxial laser interferometer transceiver with a reflective target. Background Technology

[0002] Laser interferometers are among the most important sensors in modern industry. Traditional laser interferometers employ a separate transmit and receive mechanism, with transmission and reception occurring through different optical paths. In recent years, miniaturization and integration have become the development trends of laser interferometers, such as fiber laser interferometers and integrated optical laser interferometers. These types of interferometers typically use a coaxial transmit and receive method, sharing the same optical path to simplify design.

[0003] The basic principle of laser interferometer is as follows: Figure 1 The diagram shows a single-frequency laser beam emitted from a transmitting / receiving waveguide 1 (the optical fiber in a fiber laser interferometer is also a type of waveguide). After being collimated by a collimating lens 2, the beam is emitted into space and reflected back to the interferometer by a cooperative target externally connected to the guide rail slider (the measured end) (first reflection) (i.e., received by the transmitting / receiving waveguide 1). The interferometer performs coherent measurements of the reflected light and the local oscillator of the same origin to calculate the displacement of the slider.

[0004] As mentioned earlier, laser interferometers require a cooperating target to reflect light. Generally, these targets are either corner mirrors or plane mirrors. The advantage of corner mirrors is their insensitivity to the return angle, eliminating the need for precise adjustment of their deflection angle during installation. However, corner mirrors have a complex structure, require extremely high manufacturing precision, and have a small effective reflective area, making them unsuitable for multi-dimensional or multi-point measurement scenarios.

[0005] Another type of cooperative reflective target uses a plane mirror. The advantages of a plane mirror are that the reflective area can be made very large and the cost is low, making it particularly suitable for multi-dimensional, multi-point, and cost-sensitive applications. The disadvantage of a plane mirror is that it is sensitive to the reflection angle; even a small angular deviation can cause a sharp drop in the reflected light intensity. Therefore, on the one hand, precise angle adjustment is required during installation, and on the other hand, strict requirements must be placed on the sway angle of the interferometer's measurement guide rail during operation.

[0006] Meanwhile, the sensitivity of the backlight to the angle is related to the lens focal length and waveguide size. In order to reduce the influence of the angle on the light intensity, the conventional approach is to shorten the lens focal length or use a larger aperture transmitting / receiving waveguide. However, both of these approaches will lead to a decrease in the effective aperture of the measurement beam, that is, a decrease in beam collimation, which limits its application in long-distance measurement scenarios. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a coaxial laser interferometer transceiver with a reflective target, which can control the sensitivity of a plane mirror to the reflection angle without changing the lens focal length and the aperture of the emitted beam.

[0008] The technical solution is as follows: a coaxial laser interferometer transceiver with a reflective target, comprising a transmitting / receiving waveguide, a collimating lens, and a plane mirror. Light emitted from the transmitting / receiving waveguide is collimated by the collimating lens and then directed towards the plane mirror. The plane mirror is installed at the measured end to reflect the received light. The device further comprises a reflective target with a reflective area located around the transmitting / receiving waveguide, the shape and size of which are set as needed. Light emitted from the transmitting / receiving waveguide towards the plane mirror is reflected once by the plane mirror, then again by the collimating lens towards the reflective target, and then reflected a second time by the reflective area before being directed again by the collimating lens towards the plane mirror. After a third reflection by the plane mirror, the light is converged again by the collimating lens onto the transmitting / receiving waveguide and received by the transmitting / receiving waveguide.

[0009] Furthermore, the reflective target also includes a transparent area covering the reflective area and the emitted / received wave output / input area.

[0010] Furthermore, the transmitting / receiving waveguide is a single-mode optical fiber.

[0011] Furthermore, the transmitting / receiving waveguide is a planar optical waveguide.

[0012] Beneficial effects: After the light is reflected for the first time by the plane mirror, the effective receiving area of ​​the beam is the area of ​​the reflection zone on the reflecting target. Its size can be controlled artificially. Therefore, without changing the lens focal length and the aperture of the transmitting / receiving waveguide, the plane mirror can be adjusted during the installation process to reflect the light emitted from the transmitting / receiving waveguide to the reflection zone with more flexible position and size, which reduces the installation difficulty. Subsequent reflections do not affect the sensitivity to angle deviation due to the conjugation of the optical path and can ensure that the light can return to the transmitting / receiving waveguide. Attached Figure Description

[0013] Figure 1 A schematic diagram of an existing coaxial laser interferometer transceiver;

[0014] Figure 2 This is a schematic diagram of the structure of the present invention;

[0015] Figure 3 A schematic diagram of the output surface of a single-mode fiber for transmitting / receiving waveguides;

[0016] Figure 4This is a schematic diagram of the light-emitting surface of a planar optical waveguide for transmitting / receiving. Detailed Implementation

[0017] like Figure 2 The diagram shows a coaxial laser interferometer transceiver with a reflective target, comprising a transmitting / receiving waveguide 1, a collimating lens 2, and a plane mirror 3. The transmitting / receiving waveguide 1 can be, for example,... Figure 3 The single-mode fiber shown can also be as follows: Figure 4 The planar optical waveguide shown has a transmitting / receiving waveguide 1 with an output surface. The light beam exits from the output surface and is emitted into space. After being collimated by a collimating lens 2, it is directed towards a plane mirror 3 on the measured end of the interferometer. The plane mirror 3 is mounted on the measured end to reflect the received light. It also includes a reflective target 4 mounted on the output surface. The reflective target 4 includes at least one reflective region 41 and a transparent region 42. The reflective region 41 is located around the transmitting / receiving waveguide 1, and its shape and size are set as needed. The transparent region 42 covers the transmitting / receiving waveguide 1. The light emitted by the transmitting / receiving waveguide 1 can... The light beam passes through the transparent area 42 and the collimating lens 2, and is then reflected once by the plane mirror 3 (forming beam A). After passing through the collimating lens 2 again, it is directed towards the reflecting target 4, and then reflected a second time by the reflecting area 41 (forming beam B). After passing through the collimating lens 2 again, it is directed towards the plane mirror 3. After being reflected a third time by the plane mirror 3 (forming beam C; the beams in the figure are only used to indicate their orientation and do not represent the actual beam positions), the light beam is focused again by the collimating lens 2 onto the transmitting / receiving waveguide 1. Due to the conjugate nature of the multiple reflection paths, the collimating lens 2 will focus the beam onto the transmitting / receiving waveguide 1, thus completing one transmission-reception process.

[0018] The difference between this implementation scheme and the traditional transceiver based on single reflection is that the traditional scheme is directly received by the transmitting / receiving waveguide after reflection, and its effective receiving area is the area of ​​the waveguide. The waveguide is usually small in size, so it is sensitive to angular deviation.

[0019] In this implementation scheme, after the first reflection, the effective receiving area of ​​the beam is the area of ​​the high-reflectivity zone on the reflecting target, the size of which can be artificially controlled. Therefore, without changing the aperture of the transmitting and receiving waveguides, the sensitivity of the plane mirror installation angle can be adjusted (i.e., by increasing the sensitivity of the plane mirror installation angle through multiple reflections, and by controlling the size and shape of the high-reflectivity zone on the target, the sensitivity of the plane mirror installation angle can be controlled), improving tolerance, reducing installation difficulty (i.e., speeding up the adjustment of the plane mirror installation angle and improving installation efficiency) and reducing the requirements for the guide rail. Subsequent reflections, due to the conjugation of the optical path, do not affect the sensitivity to angle deviation.

[0020] In this embodiment, the reflective target is fabricated on a planar transparent material substrate, such as glass or silicon wafer. A highly reflective metal pattern is formed on one side of the substrate to create a high-reflection area, which is used to reflect the light that was first reflected back to the light-emitting surface back to the plane mirror.

[0021] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A coaxial laser interferometer transceiver with a reflective target, comprising a transmitting / receiving waveguide, a collimating lens, and a plane mirror, wherein light emitted from the transmitting / receiving waveguide is collimated by the collimating lens and then directed towards the plane mirror, and the plane mirror is mounted at the measured end to reflect the received light, characterized in that: It also includes a reflective target with a reflective area located around the transmitting / receiving waveguide, the shape and size of which are set as needed. Light rays from the transmitting / receiving waveguide toward the plane mirror are reflected once by the plane mirror and then collimated by the collimating lens toward the reflective target. After being reflected a second time by the reflective area, the light rays are again reflected by the collimating lens toward the plane mirror. After being reflected a third time by the plane mirror, the light rays are again focused onto the transmitting / receiving waveguide by the collimating lens and received by the transmitting / receiving waveguide.

2. The coaxial laser interferometer transceiver with a reflective target according to claim 1, characterized in that: The reflective target also includes a transparent area covering the reflective area and the emitted / received wave output / input area.

3. A coaxial laser interferometer transceiver with a reflective target according to claim 1 or 2, characterized in that: The transmitting / receiving waveguide is a single-mode optical fiber.

4. A coaxial laser interferometer transceiver with a reflective target according to claim 1 or 2, characterized in that: The transmitting / receiving waveguide is a planar optical waveguide.

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