Optical probe probe based on point self-focusing principle

Abstract

The present invention discloses an optical probe probe based on the point self-focusing principle. Based on the point self-focusing principle, a self-focusing sensor is used to track the position of the objective lens focal point on the measured tooth surface in real time, and the objective lens displacement is recorded using a high-precision linear grating, thereby achieving the acquisition of full tooth surface data of micro gears. The probe comprises an illumination light source, a laser light source, a lens, a self-focusing sensor, a CCD camera, a spectroscope, a z-axis controller, a z-axis moving platform, an objective lens, a z-axis grating, a differential confocal module, and a reflector. When the measured object moves toward or away from the probe, the position of the laser beam reflected by the measured object surface on the self-focusing sensor moves. The self-focusing sensor sends the generated deviation signal to the z-axis controller, which in turn controls the movement of the z-axis moving platform to restore the position of the objective lens focal point to the center position of the self-focusing sensor. The z-axis grating records the displacement of the probe movement, and this displacement is used as the change in the measured object surface position data.

Description

Technical Field

[0001] The present invention relates to the field of precision measurement, and in particular to an optical probe probe based on the point self-focusing principle. Background Art

[0002] Micro gears generally refer to miniature gears with a module less than 0.1mm and a tooth top circle diameter less than 1mm. Measuring the geometric accuracy of miniature parts with complex geometries, such as micro gears, is a global challenge. This is mainly because the tooth gap width is too small. Traditional contact measurement methods are unable to detect the roots of tiny tooth gaps due to the size of the stylus ball, meaning they cannot measure the complete tooth profile. Optical measurement methods are also unable to effectively obtain tooth root data due to tooth obstruction and tooth surface inclination. Therefore, the development of "optical probe probes" with smaller probe sizes has become an effective means of solving these problems. Summary of the Invention

[0003] The present invention aims to measure the full tooth surface data of tiny gears with a module less than 0.1 mm. This paper proposes an optical probe based on the point self-focusing principle. This probe uses a self-focusing sensor to track the position of the objective lens focal point on the measured tooth surface in real time. It also records the objective lens displacement using a high-precision linear grating, thereby acquiring full tooth surface data for tiny gears.

[0004] The above purpose is achieved through the following technical solutions:

[0005] The optical probe head, based on the point autofocus principle, includes an illumination light source, a laser light source, a first lens, a second lens, an autofocus sensor, a CCD camera, a first beam splitter, a second beam splitter, a z-axis controller, a z-axis motion platform, an objective lens, a z-axis grating, a differential confocal module, a first reflector, a second reflector, a third reflector, and a fourth reflector. The laser beam emitted by the laser light source is reflected by the second reflector, then passes through the first beam splitter, is reflected by the second beam splitter, and is focused by the objective lens before irradiating the surface of the object being measured. The light reflected back to the objective lens is collimated, and a portion of the light, after reflecting from the second beam splitter and the first beam splitter, is focused by the first lens onto the autofocus sensor. Another portion of the light is reflected by the second beam splitter, transmitted through the first beam splitter, and then reflected by the fourth and third reflectors to illuminate the interior of the differential confocal module; the position of the objective lens focus corresponds to the center position of the autofocus sensor, that is, when the laser beam is focused on the surface of the object to be measured, the reflected laser beam can also be focused by the first lens to the center of the autofocus sensor; the differential confocal module is used to calibrate the correspondence between the position of the objective lens focus and the center position of the autofocus sensor; the white light beam emitted by the illumination light source is reflected by the first reflector, transmitted through the first beam splitter, and then reflected by the second beam splitter. After being focused by the objective lens, it illuminates the surface of the object to be measured. The light reflected back to the objective lens is collimated and then transmitted through the second beam splitter, and is focused by the second lens onto the CCD camera; the CCD camera is used to monitor real-time information on the surface of the object being measured; when the objective lens does not focus the laser beam on the surface of the object being measured, the first lens will not focus the laser beam on the center of the autofocus sensor. The autofocus sensor will send the generated deviation signal to the z-axis controller, which in turn controls the z-axis moving platform to move along the direction of the probe movement, so that the position of the objective lens focus and the center position of the autofocus sensor are balanced again; the z-axis grating is used to record the displacement of the probe movement.

[0006] As the object moves closer to the probe, the position of the laser beam reflected by the surface shifts leftward on the autofocus sensor. The resulting deviation signal is sent to the z-axis controller, which in turn controls the z-axis motion stage to move away from the object, restoring equilibrium between the focal point of the objective lens and the center of the autofocus sensor. The z-axis grating records the displacement of the probe, which is used as the change in the surface position data.

[0007] As the object moves away from the probe, the position of the laser beam reflected by the surface shifts to the right on the autofocus sensor. The autofocus sensor generates a deviation signal that is sent to the z-axis controller, which in turn controls the z-axis motion stage to move closer to the object, restoring equilibrium between the objective lens's focal point and the center of the autofocus sensor. The z-axis grating records the probe's displacement, which is used as the change in the object's surface position data.

[0008] The present invention has the following characteristics and beneficial effects:

[0009] 1. The present invention uses a 632.8nm wavelength laser and a 100x microscope objective lens, capable of producing a laser spot with a diameter of less than 1μm. This can be used to measure the tooth grooves of tiny gears with a module less than 0.1mm.

[0010] 2. The differential confocal module included in this invention can be used to calibrate the correspondence between the objective lens focal point and the center position of the autofocus sensor, ensuring that the objective lens focal point is on the surface of the measured object while the reflected laser spot is also focused on the center of the autofocus sensor. This improves the measurement accuracy of the optical probe head.

[0011] The device of the present invention has a wide range of uses, and is particularly suitable for optical probes for measuring the geometric accuracy of micro-complex parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of the optical probe head structure based on the point self-focusing principle.

[0013] Figure 2 Schematic diagram of the probe movement when the object being measured approaches the probe.

[0014] Figure 3 Schematic diagram of the probe movement when the object to be measured is far away from the probe.

[0015] Markings in the figure: 1-illumination light source; 2-laser light source; 3-first lens; 4-autofocus sensor; 5-CCD camera; 6-second lens; 7-second beam splitter; 8-z-axis controller; 9-z-axis moving platform; 10-probe movement direction; 11-objective lens; 12-z-axis grating; 13-first beam splitter; 14-third reflector; 15-differential confocal module; 16-fourth reflector; 17-first reflector; 18-second reflector; 19-measured object; 20-measurement object movement direction toward the probe; 21-measurement probe movement direction away from the measured object; 22-measurement object movement direction away from the probe; 23-measurement probe movement direction toward the measured object. DETAILED DESCRIPTION

[0016] The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments. All technologies implemented based on the present invention fall within the scope of the present invention.

[0017] like Figure 1As shown, the optical probe probe based on the point autofocus principle includes an illumination light source 1, a laser light source 2, a first lens 3, a second lens 6, a autofocus sensor 4, a CCD camera 5, a first beam splitter 13, a second beam splitter 7, a z-axis controller 8, a z-axis moving platform 9, an objective lens 11, a z-axis grating 12, a differential confocal module 15, a first reflector 17, a second reflector 18, a third reflector 14, and a fourth reflector 16. The laser beam emitted by the laser light source 2 is reflected by the second reflector 18, transmits through the first beam splitter 13, is reflected by the second beam splitter 7, is focused by the objective lens 11, and irradiates the surface of the object to be measured 19. The light reflected back to the objective lens 11 is collimated, and a portion of the light is focused by the first lens 3 onto the autofocus sensor 4 after being reflected by the second beam splitter 7 and the first beam splitter 13. Another part of the light is reflected by the second beam splitter 7, transmits through the first beam splitter 13, and then is reflected by the fourth reflector 16 and the third reflector 14 to irradiate the inside of the differential confocal module 15; the position of the focus of the objective lens 11 corresponds to the center position of the autofocus sensor 4, that is, when the laser beam is focused on the surface of the object to be measured 19, the reflected laser beam can also be focused by the first lens 3 to the center of the autofocus sensor 4; the differential confocal module 15 is used to calibrate the correspondence between the position of the focus of the objective lens 11 and the center position of the autofocus sensor 4; the white light beam emitted by the illumination light source 1 is reflected by the first reflector 17, transmits through the first beam splitter 13, and then is reflected by the second beam splitter 7. After being focused by the objective lens 11, it is irradiated onto the surface of the object to be measured 19. The light reflected back to the objective lens 11 is collimated and then transmitted through the second beam splitter 7, and is focused by the second lens 6 onto the CCD camera 5; the CCD camera 5 is used to monitor the real-time information of the surface of the object 19 to be measured; when the objective lens 11 does not focus the laser beam on the surface of the object 19 to be measured, the first lens 13 will not focus the laser beam on the center of the autofocus sensor 4. The autofocus sensor 4 will send the generated deviation signal to the z-axis controller 8, and then control the z-axis moving platform 9 to move along the probe movement direction 10, so that the position of the focus of the objective lens 11 and the center position of the autofocus sensor 4 are balanced again; the z-axis grating 12 is used to record the displacement of the probe movement.

[0018] As the object 19 moves closer to the probe, the position of the laser beam reflected by the surface of the object 19 shifts leftward on the autofocus sensor 4. The autofocus sensor 4 generates a deviation signal that is sent to the z-axis controller 8, which in turn controls the z-axis motion platform 9 to move away from the object 19, restoring equilibrium between the focal point of the objective lens 11 and the center of the autofocus sensor 4. The z-axis grating 12 records the displacement of the probe and uses this displacement as the change in the surface position data of the object 19.

[0019] As the object 19 moves away from the probe, the position of the laser beam reflected by the surface of the object 19 shifts to the right on the autofocus sensor 4. The autofocus sensor 4 generates a deviation signal that is sent to the z-axis controller 8, which in turn controls the z-axis motion platform 9 to move closer to the object 19, restoring equilibrium between the focal point of the objective lens 11 and the center of the autofocus sensor 4. The z-axis grating 12 records the displacement of the probe and uses this displacement as the change in the surface position data of the object 19.

[0020] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention, and various modifications to the embodiments will be apparent to those skilled in the art. The general principles defined herein may be embodied in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown in the present method, but is intended to be applied to the widest range consistent with the principles and novel features disclosed herein.

Claims

1. An optical probe based on the point self-focusing principle, characterized by: The invention comprises an illumination light source, a laser light source, a first lens, a second lens, a self-focusing sensor, a CCD camera, a first beam splitter, a second beam splitter, a z-axis controller, a z-axis moving platform, an objective lens, a z-axis grating, a differential confocal module, a first reflector, a second reflector, a third reflector and a fourth reflector; the laser beam emitted by the laser light source is reflected by the second reflector, passes through the first beam splitter, is reflected by the second beam splitter, is focused by the objective lens and irradiates the surface of the object to be measured; the light reflected back to the objective lens is collimated, and a part of the light is focused by the first lens onto the self-focusing sensor after being reflected by the second beam splitter and the first beam splitter; the other part of the light is reflected by the second beam splitter, passes through the first beam splitter, and is reflected by the fourth reflector and The reflection from the third reflector is irradiated into the interior of the differential confocal module; the position of the objective lens focal point corresponds to the center position of the autofocus sensor, that is, when the laser beam is focused on the surface of the object to be measured, the reflected laser beam can also be focused by the first lens to the center of the autofocus sensor; the differential confocal module is used to calibrate the correspondence between the position of the objective lens focal point and the center position of the autofocus sensor; the white light beam emitted by the illumination light source is reflected by the first reflector, transmitted through the first beam splitter, then reflected by the second beam splitter, and after being focused by the objective lens, it is irradiated onto the surface of the object to be measured; the light reflected back to the objective lens is collimated, then transmitted through the second beam splitter, and focused by the second lens onto the CCD camera; the CCD camera is used to monitor real-time information on the surface of the object to be measured; When the objective lens does not focus the laser beam onto the surface of the object being measured, the first lens will not focus the laser beam onto the center of the autofocus sensor. The autofocus sensor will send the generated deviation signal to the z-axis controller, which will then control the z-axis moving platform to move along the direction of the probe movement so that the position of the objective lens focus and the center position of the autofocus sensor are balanced again; the z-axis grating is used to record the displacement of the probe movement.

2. The optical probe probe based on the point self-focusing principle according to claim 1, characterized in that: When the object moves closer to the probe, the position of the laser beam reflected by the surface of the object on the autofocus sensor will move to the left. The autofocus sensor sends the generated deviation signal to the z-axis controller, which in turn controls the z-axis moving platform to move away from the object, so that the position of the objective lens focal point and the center position of the autofocus sensor are balanced again. The z-axis grating records the displacement of the probe and uses the displacement as the change in the position data of the surface of the object being measured.

3. The optical probe probe based on the point self-focusing principle according to claim 1, characterized in that: When the object moves away from the probe, the position of the laser beam reflected by the surface of the object on the autofocus sensor will move to the right. The autofocus sensor sends the generated deviation signal to the z-axis controller, which controls the z-axis moving platform to move closer to the object, so that the position of the objective lens focus and the center position of the autofocus sensor are balanced again. The z-axis grating records the displacement of the probe and uses the displacement as the change in the position data of the surface of the object being measured.

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