TWI620917B - Measuring device for linear motion stage - Google Patents

Abstract

A measuring device for a linear motion platform. The linear motion platform includes a movable first carrier member and a movable second carrier member. The measurement device includes a two-dimensional grating disposed on the first carrier, and a measurement unit disposed on the second carrier. The measurement unit includes a light source, a two-dimensional sensor and a processing module. The light source is used to emit an incident light, which will be converted into a reflected light when the incident light is irradiated to the two-dimensional grating. The two-dimensional sensor is used to receive the reflected light and convert it into a reflected signal. The processing module receives the reflected signal to calculate multiple dynamic information and errors of the linear motion platform.

Description

Measuring device for linear motion platform

The invention relates to a measuring device, in particular to a measuring device of a linear motion platform.

A linear motion platform includes a first carrier member that moves along a first path, and a second carrier member that moves along a second path, so an article is placed on the first carrier member or the The second carrier can precisely control the movement of the article. Therefore, in today's industry, the linear motion platform has been widely used in a variety of high-precision processes, such as optoelectronic semiconductor processes, precision machining, etc.

Generally speaking, the user wants to design the first path and the second path to be perpendicular to each other, for example, the first path moves along the x-axis direction of the rectangular coordinate, and the second path is along the right angle The coordinates move in the z-axis direction, but in fact, there is no way to design so ideally. As a simple example, suppose that the first path does not move perfectly along the x-axis direction, but it is sandwiched with the x-axis It moves in the direction of a very small angle. As a result, the farther the first carrier moves, the more the first carrier deviates from the x axis, that is, the error will become larger. The aforementioned example is just one of many errors. In reality, there are various small errors. These errors will prevent users from accurately controlling the movement of the item. This is also the main reason why the process accuracy in the industry is difficult to improve. one of the reasons.

In order to make the process more accurate, the current industry practice is to use a measuring device installed on the linear motion platform. The measuring device can not only accurately measure various dynamic information of the linear motion platform, such as the moving distance of the first carrier and the second carrier, etc., but also obtain various error values. As long as the user refers to the measured error value, the linear motion platform can be slowly corrected to reduce the error value to an acceptable tolerance.

Existing measurement devices as disclosed in TW-I245878 and TW-I220688 mainly use multiple sets of laser light sources to illuminate the measurement device of the linear motion platform, and then use multiple sets of sensors to receive reflected laser light And converted into multiple signals, and finally after further calculation of these signals, you can know the various error values of the measurement device of the linear motion platform. However, the above methods all require the use of multiple sets of laser light sources and sensors, so they have the disadvantages of high cost and troublesome installation, and are not suitable for mass production.

Therefore, the object of the present invention is to provide a measuring device for a linear motion platform using only one light source and one sensor.

Therefore, the measuring device of the linear motion platform of the present invention first defines an x axis, a y axis perpendicular to the x axis, and a z axis perpendicular to the x axis and the y axis. The linear motion platform includes a first carrier member that moves along a first path, and a second carrier member that can move along a second path, and the first carrier member moves along the first path There is a first movement component in the xy plane and a second movement component in the xz plane.

The measurement device includes a two-dimensional grating disposed on the first carrier, and a measurement unit disposed on the second carrier. The measuring unit emits an incident light using the conventional two-dimensional grating, and when the incident light irradiates the two-dimensional grating, it will be converted into a reflected light.

The measuring unit includes a light source for emitting the incident light, a two-dimensional sensor for receiving the reflected light and converting it into a reflected signal, and a processing module for receiving the reflected signal.

After receiving the reflection signal, the processing module can calculate the first movement component, the second movement component, and the rotation angle of the first carrier when the z-axis is used as the rotation axis.

The effect of the present invention is that the two-dimensional grating and the measuring unit are respectively disposed on the first carrier and the second carrier, so that the two-dimensional grating and the measuring unit can be made different Direction of movement. The incident light is then emitted by the light source to detect the state of the linear motion platform in space. Finally, by the two-dimensional sensor and the processing module, the angular error between the first carrier and the second carrier can be calculated, and the first of the first carrier in the xy plane The movement component and the second movement component of the first carrier in the xz plane. Therefore, only one light source and one two-dimensional sensor can be used to obtain a plurality of dynamic information and errors of the linear motion platform, so the purpose of the invention can indeed be achieved.

Before the present invention is described in detail, it should be noted that in the following description, similar elements are denoted by the same number.

A first embodiment of the measuring device of the linear motion platform of the present invention, the description of which must refer to FIG. 1, together with FIGS. 2 and 3 for auxiliary description. First define an x axis, a y axis perpendicular to the x axis, and a z axis perpendicular to the x axis and the y axis. The linear motion platform 1 includes a first carrier 11 that moves along a first path D1, and a second carrier 12 that can move along a second path D2. Wherein, the first path D1 is designed to be parallel to the x-axis, and the second path D2 is designed to be parallel to the z-axis. In addition, it should be particularly noted that, in order to highlight the error of the first embodiment, although the first path D1 is designed to be parallel to the x axis, as shown in FIG. 1, there is still a certain angle error , And when the first carrier 11 moves along the first path D1, in addition to a first movement component a1 in the xy plane, and a second movement component a2 in the xz plane, thereby representing the first The rider 11 oscillates up and down when moving.

The measuring device includes a two-dimensional grating 2 disposed on the first carrier 11 and a measuring unit 3 disposed on the second carrier 12. The surface morphology of the two-dimensional grating 2 is shown as 2, and the contour equation of the two-dimensional grating 2 is Where A _{x, z} are the sine wave amplitudes of the two-dimensional grating 2 on the x axis and the z axis _, respectively, P _{x, z} are the sine wave wavelengths of the two dimensional grating 2 on the x axis and the z axis, In addition, for the convenience of presentation, the surface appearance of the two-dimensional grating 2 in FIG. 2 is presented with the x-axis as the rotation axis and rotated 90 degrees clockwise.

The measuring unit 3 emits an incident light I using the two-dimensional grating 2 in the past, and when the incident light I irradiates the two-dimensional grating 2, it will be converted into a reflected light R. As shown in FIG. 3, the measurement unit 3 includes a light source 31 for emitting the incident light I, a first lens 32 disposed in front of the light source 31, and a beam splitter disposed in front of the first lens 32 33. A polarizer 34 disposed in front of the beam splitter 33, a second lens 35 disposed in front of the polarizer 34, and a two-dimensional sensor for receiving the reflected light R and converting it into a reflected signal 36. A third lens 37 between the two-dimensional sensor 36 and the beam path of the beam splitter 33, and a processing module 38 for receiving the reflected signal. The two-dimensional sensor 36 is a four-quadrant sensor, and the two-dimensional sensor 36 defines an i-axis and a j-axis perpendicular to the i-axis.

Therefore, the incident light I will be sequentially irradiated to the two-dimensional grating 2 through the first lens 32, the beam splitter 33, the polarizing plate 34, and the second lens 35, and then converted into the reflected light R. Then, the reflected light R is sequentially irradiated to the two-dimensional sensor 36 through the second lens 35, the polarizing plate 34, the beam splitter 33, and the third lens 37, and is converted into the reflected signal. After receiving the reflected signal, the processing module 38 will use (1) a first formula: To calculate the rotation angle of the first carrier 11 when the z-axis is used as the rotation axis _z . Where, f represents the distance between the center of the third lens 37 and the two-dimensional sensor 36, and d _i represents the position of the i-axis when the reflected light irradiates the two-dimensional sensor 36. (2) A second formula: To calculate the rotation angle of the first carrier 11 when the x-axis is used as the rotation axis . Where, f represents the distance between the center of the third lens 37 and the two-dimensional sensor 36, and d _j represents the position of the j-axis when the reflected light irradiates the two-dimensional sensor 36.

(3) Using the method disclosed in TW-I507663, calculate the first movement component a1 of the first carrier 11 in the xy plane and the second movement component a2 of the first carrier 11 in the xz plane. In particular, in the first embodiment, since the length of the two-dimensional grating 2 in the z-axis direction is shorter, the first embodiment is more suitable for measuring the first carrier 11 in The movement error of the xz plane, but of course, the length of the two-dimensional grating 2 in the z-axis direction can be designed to be longer, thereby measuring the movement distance of the first carrier 11 in the xz plane.

Therefore, the difference between the first embodiment and the conventional measurement device is that through only one light source 31 and one two-dimensional sensor 36, various dynamic information and errors of the first embodiment can be learned The numerical value of this can save the equipment cost of using multiple light sources and multiple sensors, and avoid the trouble of installation.

Referring to FIG. 4, a second embodiment of the measurement device of the linear motion platform of the present invention has substantially the same structure as the first embodiment, except that the second path D2 is parallel to the y-axis, and The rotation angle of the first carrier 11 when the z-axis is used as the rotation axis can still be calculated through the first formula 1. A first movement component a1 of the first carrier member in the xy plane and a second movement component a2 of the first carrier member in the xz plane, thereby providing another implementation aspect for the user to choose.

In summary, the measuring device of the linear motion platform of the present invention emits the incident light I to the two-dimensional grating 2 through the light source 31 to detect the state of the linear motion platform 1 in space. Then, the two-dimensional sensor 36 and the processing module 38 are used to calculate the rotation angle, the first movement component a1, and the second when the first carrier 11 uses the z-axis as the rotation axis The moving component a2, and the number of the light source 31 and the two-dimensional sensor 36 are only one, so it can indeed achieve the purpose of the invention.

However, the above are only examples of the present invention, and should not be used to limit the scope of implementation of the present invention, any simple equivalent changes and modifications made in accordance with the scope of the patent application of the present invention and the contents of the patent specification are still Within the scope of the invention patent.

1‧‧‧ linear motion platform

11‧‧‧ First Carrier

12‧‧‧ Second carrier

2‧‧‧Two-dimensional grating

3‧‧‧Measurement unit

31‧‧‧Light source

32‧‧‧First lens

33‧‧‧Spectroscope

34‧‧‧Polarizer

35‧‧‧Second lens

36‧‧‧Two-dimensional sensor

37‧‧‧third lens

38‧‧‧Processing module

D1‧‧‧ First Path

D2‧‧‧Second path

I‧‧‧incident light

R‧‧‧reflected light

f‧‧‧Distance

a1‧‧‧ First moving component

a2‧‧‧Second mobile component

‧‧‧The rotation angle when the z axis is used as the rotation axis

‧‧‧Rotation angle when the x-axis is used as the rotation axis

Other features and functions of the present invention will be clearly presented in the embodiment with reference to the drawings, in which: FIG. 1 is a perspective view illustrating a first embodiment of the measuring device of the linear motion platform of the present invention; FIG. 2 is A perspective view illustrating the surface morphology of a two-dimensional grating of the first embodiment; FIG. 3 is a schematic view illustrating a measurement unit of the first embodiment; and FIG. 4 is a perspective view illustrating the linear motion platform of the present invention A second embodiment of the measuring device.

Claims (4)

A linear motion platform measuring device defines an x axis, a y axis perpendicular to the x axis, and a z axis perpendicular to the x axis and the y axis. The linear motion platform includes a A first carrier member that moves along the first path, and a second carrier member that can move along a second path, and when the first carrier member moves along the first path, there is a first on the xy plane The moving component has a second moving component in the xz plane. The measuring device includes: a two-dimensional grating, which is arranged on the first carrier, wherein the contour equation of the two-dimensional grating is

, Where A _{x, z} are the sine wave amplitudes of the two-dimensional grating on the x and z axes _, respectively, and P _{x, z} are the sine wave wavelengths of the two dimensional grating on the x and z axes, respectively; and A measuring unit is installed on the second carrier and emits an incident light to the two-dimensional grating. When the incident light irradiates the two-dimensional grating, it will be converted into a reflected light. The measuring unit includes A light source is used to emit the incident light, and a two-dimensional sensor is used to receive the reflected light and convert it into a reflected signal. A first lens is arranged in front of the light source, and a beam splitter is arranged on the In front of the first lens, a polarizer is arranged in front of the beam splitter, a second lens is arranged in front of the polarizer, and a third lens is arranged between the optical path of the two-dimensional sensor and the beam splitter, The incident light will be irradiated to the two-dimensional grating sequentially through the first lens, the beam splitter, the polarizer and the second lens, and the reflected light will sequentially pass through the second lens, the beam splitter and the third The lens illuminates the two-dimensional sensor, a processing module, used Receiving the reflected signal and the reflected signal is calculated by the first movement component, the second component of movement, and a rotation angle of the seating member to the first z axis as a rotation axis when. The measurement device for a linear motion platform according to claim 1, wherein the two-dimensional sensor is a four-quadrant sensor, and the two-dimensional sensor defines an i-axis and an i-axis The vertical j-axis, after receiving the reflected signal, the processing module will use a first formula

This calculates the rotation angle of the first carrier when the z-axis is used as the rotation axis, where,

Represents the rotation angle when the z-axis is used as the rotation axis, f represents the distance between the center of the third lens and the two-dimensional sensor, and d _i represents the i-axis when the reflected light strikes the four-quadrant sensor s position. According to the measurement device of the linear motion platform according to claim 2, the second path is parallel to the z-axis, wherein after receiving the reflection signal, the processing module can also calculate the first carrier part using the The rotation angle when the x-axis is used as the rotation axis. The measurement device for a linear motion platform according to claim 3, wherein the two-dimensional sensor is a four-quadrant sensor, and the four-quadrant sensor defines an i-axis and an i-axis Vertical j-axis, after the processing module receives the reflected signal, it will use a second formula

Calculate the rotation angle of the first carrier with the x axis as the rotation axis,

Represents the rotation angle when the x-axis is used as the rotation axis, f represents the distance between the center of the third lens and the two-dimensional sensor, and d _j represents the j-axis when the reflected light strikes the four-quadrant sensor s position.