WO2021180013A1 - 一种光学设备及实现自动聚焦的方法 - Google Patents

一种光学设备及实现自动聚焦的方法 Download PDF

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Publication number
WO2021180013A1
WO2021180013A1 PCT/CN2021/079462 CN2021079462W WO2021180013A1 WO 2021180013 A1 WO2021180013 A1 WO 2021180013A1 CN 2021079462 W CN2021079462 W CN 2021079462W WO 2021180013 A1 WO2021180013 A1 WO 2021180013A1
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light
confocal
optical
lens
objective lens
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PCT/CN2021/079462
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English (en)
French (fr)
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陈鲁
李青格乐
江博闻
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深圳中科飞测科技股份有限公司
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Publication of WO2021180013A1 publication Critical patent/WO2021180013A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined

Definitions

  • This application relates to the field of optical inspection technology, and in particular to an optical device and a method for realizing automatic focusing.
  • high-power optical equipment In the conductor or related manufacturing industries, high-power optical equipment is usually required to detect key indicators of samples or perform other types of optical processing.
  • the focal depth of the objective lens In high-power optical equipment, the focal depth of the objective lens is very limited. Depth of focus, also known as depth of field, means that when using optical equipment to observe and photograph the surface of the sample, starting from the focus position and changing the distance between the objective lens and the sample surface, the focus can maintain a clear range.
  • depth of focus also known as depth of field
  • current high-power optical equipment usually integrates a set of auto-focusing system.
  • the autofocus system uses the laser triangulation method through the lens (TTL, Through-the-lens), and its speed can reach the order of kHz (ie 1 millisecond), but the tracking accuracy is low, usually only a quarter of the depth of field.
  • TTL Through-the-lens
  • the accuracy of auto-focusing that is, the amount of defocus
  • the above-mentioned auto-focusing method obviously cannot meet the accuracy requirements.
  • the present application provides an optical device and a method for realizing automatic focusing, so as to improve the accuracy of automatic focusing.
  • the present application provides an optical device, including: an optical processing module and an auto-focusing module; the optical processing module includes an objective lens; and the auto-focusing module includes: a light source, a first confocal device, a detection element, and a control unit;
  • the light source is used to emit detection light, which irradiates the surface of the object to be measured through the objective lens; the detection light forms signal light through the optical action of the surface of the object to be measured;
  • the objective lens is used to collect the signal light and make the signal light reach the first confocal device
  • the first confocal device is used to limit the signal light to pass through when the object to be measured is out of focus, and the first confocal device is conjugated to the focal plane of the objective lens;
  • the detection element is used to collect the signal light passing through the first confocal device, and convert the collected signal light into an electrical signal;
  • the control unit is used to determine the focal plane position of the objective lens according to the electrical signal, and adjust the relative position of the objective lens and the object to be measured according to the focal plane;
  • the optical processing module is used to perform optical processing on the object to be measured through the objective lens.
  • the first confocal device is also used to pass the probe light; the objective lens is also used to cause the probe light passing through the first confocal device to reach the surface of the object to be measured.
  • the auto-focus module further includes: a second confocal device for limiting the detection light emitted by the light source.
  • the second confocal device includes: one or more light-restricted units, and the second confocal device is conjugated to the focal plane of the objective lens.
  • the detection element includes a plurality of detector units
  • the first confocal device includes a plurality of confocal units
  • the detector units are used to respectively receive signal light passing through the confocal unit.
  • the first confocal device further includes a first lens array, and the first lens array includes a plurality of lens units, and each lens unit is used to collect signal light, and respectively transmit the collected signal light to different confocal units.
  • the confocal unit is a pinhole unit or an optical fiber.
  • the detector unit is a photodiode or a photomultiplier tube.
  • the optical device further includes a second confocal device
  • the second confocal device includes a plurality of light-restricted units
  • the detection light transmitted by each light-restricted unit is a signal formed by the optical action of the surface of the object to be measured The light reaches different confocal units respectively.
  • the signal light formed by the detection light transmitted by each light-restricted unit through the surface of the object to be measured is respectively received by different detector units.
  • the light limited unit is a pinhole unit or an optical fiber.
  • the first confocal device includes an optical fiber;
  • the autofocus module further includes: an optical fiber coupler, the optical fiber coupler includes a first end, a second end, and a third end; the first confocal device is optically connected to the first end, The detection element is optically connected to the second end; the objective lens is optically connected to the third end.
  • the autofocus module further includes: a second lens for collecting signal light passing through the first confocal device; and a detecting element for receiving signal light passing through the second lens.
  • the second lens is a single lens or a lens array
  • the lens units of the lens array are used to collect the signal light passing through different confocal units, and provide the signal light passing through the different confocal units to different detector units of the detection element. .
  • the distance between the detection element and the second lens is greater than or equal to the focal length of the second lens
  • the distance between the detection element and the second lens is greater than the focal length of the second lens.
  • the auto-focusing module further includes: a first light splitting element for splitting the detection light emitted by the light source, and providing one of the beams to the first confocal device;
  • the first light splitting element is also used to provide the signal light from the first confocal device to the detecting element.
  • the optical processing module further includes: a second light splitting element
  • the second light splitting element is used to provide the detection light reflection from the auto-focus module to the objective lens, and to provide the signal light reflection transmitted by the objective lens to the auto-focus module.
  • the auto-focusing module further includes: a light intensity fluctuation detector and a third light splitting element, the third light splitting element is used to split the detection light emitted from the light source, and the light intensity fluctuation detector is electrically connected to the control unit for collecting Convert another beam of light split by the third light splitting element into an electrical signal, and provide the electrical signal to the control unit;
  • the control unit is also used to obtain the light intensity fluctuation compensation amount according to the electric signal provided by the light intensity fluctuation detector; determine the focal plane position of the objective lens according to the light intensity fluctuation compensation amount and the electric signal provided by the detection element column.
  • the first beam splitting element is specifically a polarization beam splitting element; the auto-focusing module further includes: a polarizing plate for receiving the detection light passing through the polarization beam splitting element, and transmitting the signal light returned from the object to be measured to the polarization beam splitting element , And make the probe light passing through the polarization splitting element and the signal light reaching the polarization splitting element have different polarization states.
  • the auto-focusing module further includes: a collimating lens group for receiving the signal light passing through the first confocal element and collimating the signal light of the receiving band; the detecting element is used for receiving the collimated lens group Collimated signal light.
  • the auto-focusing module further includes: a scanning unit; the detection element and the control unit are respectively electrically connected to the scanning unit;
  • the scanning unit is used to move and scan the object to be measured or the objective lens along the optical axis direction of the objective lens;
  • the control unit is used to obtain the relative position between the object to be measured and the objective lens, and the corresponding relationship between the signal light intensity obtained by the detecting element, and determine the focal plane position of the objective lens according to the relative position corresponding to the signal light intensity peak.
  • control unit is configured to control the movement of the optical processing module relative to the object under test or the movement of the object under test relative to the optical processing module according to the determined focal plane position, so as to realize the focus of the object under test.
  • the present application provides a method for applying the optical device provided in the first aspect to realize auto-focusing.
  • the method includes:
  • the detection element is used to obtain electrical signals
  • the focal plane position of the objective lens is determined according to the magnitude of the electrical signal, and the relative position of the objective lens and the object to be measured is adjusted according to the focal plane.
  • the optical device includes an optical processing module and an auto-focusing module.
  • the optical processing module is used to realize the inherent optical processing function of the optical device; and the auto-focusing module is used to realize the optical processing function of the optical device.
  • the auto-focus module includes a light source and a first confocal device, and the application of the light source and the first confocal device adopts the confocal technology, which can improve the accuracy of the automatic focusing of the optical device. Therefore, the optical device can be better used in optical processing links that have higher requirements for auto-focusing accuracy.
  • FIG. 1 is a schematic structural diagram of an optical device provided by an embodiment of the application.
  • 2a is a schematic diagram of an optical path of an optical device provided by an embodiment of this application.
  • 2b is a schematic diagram of the optical path of another optical device provided by an embodiment of the application.
  • FIG. 3 is a schematic diagram of a light intensity calibration optical path provided by an embodiment of the application.
  • FIG. 4 is a schematic diagram of the optical connection relationship between a microlens array, a first light splitting element, and a pinhole array provided by an embodiment of the application;
  • FIG. 5a is a schematic diagram of an optical path of another optical device provided by an embodiment of this application.
  • FIG. 5b is a schematic diagram of an optical path of still another optical device provided by an embodiment of this application.
  • this application proposes an optical device and a method for applying the device to realize automatic focusing.
  • FIG. 1 is a schematic structural diagram of an optical device 100 provided by an embodiment of the application.
  • the optical device 100 includes: an optical processing module 101 and an auto-focusing module 102.
  • the optical processing module 101 may be an overlay detection system, which applies the traditional imaging and image recognition-based overlay measurement technology (IBO, Imaging Based Overlay) or the diffraction light detection-based overlay measurement technology (DBO, Diffraction Based Overlay). Overlay).
  • the optical processing module 101 may also be a dark field defect detection system, a white light interference system, or an ellipsometer. The specific type of the optical processing module 101 is not limited here.
  • the purpose of the optical processing module 101 may be to form an optical path for detecting or measuring an object to be measured.
  • the optical processing module 101 includes an objective lens 1011, and may also include other optical devices, such as a tube lens, a diaphragm, a beam splitter, or a plane mirror.
  • the objective lens 1011 may include one or more lenses, and the objective lens 1011 is the lens or lens group closest to the object to be measured in the entire optical processing module 101.
  • the distance between the optical processing module 101 and the object to be measured is adjustable, and the adjustment methods include: electric control adjustment and manual adjustment.
  • the optical processing module 101 if the object to be measured is in the focal plane of the objective lens 1011 or within a preset interval before and after the focal plane, it is said to be in focus and the image is relatively clear; if the object to be measured is not in the focal plane or focal plane of the objective lens 1011 The preset interval before and after the plane is called out of focus, and the image is blurred.
  • the auto-focus module 102 may include, but is not limited to: a light source 1021, a first confocal device 1023, a detection element 1024, and a control unit 1025.
  • a light source 1021 a first confocal device 1023
  • a detection element 1024 a detection element 1024
  • a control unit 1025 a control unit 1025.
  • the dotted line represents the relationship of optical connection
  • the solid line represents the relationship of electrical connection.
  • the light source 1021 is used to emit probe light, and the probe light is irradiated to the surface of the object to be measured through the objective lens 1011; the probe light forms signal light through the optical function (can be reflection) of the surface of the object to be measured 1011.
  • the optical function can be reflection
  • the light beam before reaching the object to be measured is called the probe light
  • the light beam after the optical action of the object to be measured 1011 is called the signal light.
  • the light source 1021 may be a laser, a light emitting diode, or the like.
  • the specific type of the light source 1021 is not limited here. In the following description, a laser is used as the light source 1021 for exemplary description.
  • the objective lens 1011 is used to collect signal light and make the signal light reach the first confocal device 1023;
  • the first confocal device 1023 is used to limit the signal light to pass through when the object to be measured is out of focus, and the first confocal device 1023 is conjugated to the focal plane of the objective lens 1011;
  • the detection element 1024 is used to collect the signal light passing through the first confocal device 1023, and convert the collected signal light into an electrical signal;
  • the control unit 1025 is configured to determine the focal plane position of the objective lens 1011 according to the electrical signal, and adjust the relative position of the objective lens 1011 and the object to be measured according to the focal plane;
  • the optical processing module 101 is used to perform optical processing on the object under test through the objective lens 1011.
  • the same confocal device may pass the detection light and the signal light. That is, the first confocal device 1023 completes the above-mentioned functions.
  • the objective lens 1011 is also used to make the detection light transmitted through the first confocal device 1023 reach the surface of the object to be measured.
  • different confocal devices may also be used to pass the probe light and the signal light respectively. That is, the signal light passes through the first confocal element 1023, and the probe light passes through the second confocal element, wherein the second confocal element is conjugate to the focal plane of the objective lens 1011.
  • the function of the first confocal device 1023 is to limit the signal light to pass through when the object to be measured is out of focus.
  • the meaning of restriction is not to completely prevent. For example, when a whole beam of signal light passes through the first confocal device 1023, the first confocal device 1023 restricts the passage of a part of the signal light.
  • the detection light it may pass through the first confocal device 1023 or another confocal device (ie, the second confocal device) in different implementations.
  • the function of the confocal device that it passes through is to limit the detection light emitted by the light source. Similarly, restrictions are also partial restrictions rather than absolute prohibitions.
  • the first confocal component 1023 is a key component of the optical device 100 to achieve confocality.
  • the first confocal device 1023 can be used to limit the range of light collected by the detection element 1024 when the object to be measured is out of focus.
  • the first confocal device 1023 is conjugate to the focal plane of the objective lens 1011. Because the focal planes of the first confocal device 1023 and the objective lens 1011 are conjugated, the autofocus module 102 where the first confocal device 1023 is located can be used to determine the focal plane position of the objective lens 1011.
  • the light spot formed on the confocal plane is smaller, and the first confocal device 1023 has a smaller effect on the range of light collected by the detection element 1024.
  • Most of the light beams on the signal light transmission path can pass through the first confocal device 1023, so the light intensity detected by the detection element 1024 is relatively strong.
  • the light spot formed on the confocal plane is larger, and the first confocal device 1023 has a greater effect on limiting the range of light collected by the detection element 1024.
  • the first confocal device 1023 On the signal light transmission path, only a small part of the light beam can pass through the first confocal device 1023, and most of it is blocked by the opaque part of the first confocal device 1023, so the light intensity detected by the detection element 1024 is relatively weak.
  • the detection element 1024 is used to convert the collected light into an electrical signal, and the amplitude of the electrical signal can reflect the magnitude of the collected light intensity. The greater the electrical signal amplitude, the stronger the collected light intensity; the smaller the electrical signal amplitude, the smaller the collected light intensity.
  • the first confocal device 1023 From the above description of the first confocal device 1023, it can be understood that if the object to be measured is in the focal plane of the objective lens 1011, the first confocal device 1023 has a small restriction on the light passing on the confocal plane, and the signal light is large. It can pass through the first confocal device 1023 instead of being blocked. Therefore, the light intensity collected by the detection element 1024 should be the maximum when the object to be measured is in focus. If the relative position between the object under test and the objective lens 1011 changes, for example, the object lens 1011 moves relative to the object under test or the object under test moves relative to the objective lens 1011, the light intensity collected by the detection element 1024 will change. When in the focal plane of the objective lens 1011, the electrical signal converted by the detecting element 1024 reaches a peak value.
  • control unit 1025 and the detection element 1024 can be electrically connected, that is, the detection element 1024 can send the converted electrical signal to the control unit 1025, and the control unit 1025 can use certain processing algorithms (for example, Gaussian fitting) obtain the peak value, and finally determine the focal plane position of the objective lens 1011.
  • processing algorithms for example, Gaussian fitting
  • the control unit 1025 determines the focal plane position of the objective lens 1011
  • the relative position of the objective lens 1011 and the object to be measured can be adjusted according to the focal plane. For example, if the object to be measured is out of focus, the control module 1025 adjusts the distance between the objective lens 1011 and the object to be measured.
  • the optical processing module 101 performs optical processing on the object to be measured through the objective lens 1011 after the position adjustment.
  • the specific optical processing method is related to the inherent optical processing function of the optical processing module 101. For example, it can be imaging detection of the object to be tested. Since the specific type of the optical processing module 101 is not limited, accordingly, the specific function performed by the optical processing module 101 after the focal plane position of the objective lens 1011 is known is also not limited.
  • the auto-focus module 102 includes a light source 1021 and a first confocal device 1023.
  • the light source 1021 and the first confocal device 1023 are used to adopt confocal technology to improve the accuracy of auto-focusing. Therefore, the optical device 100 can be well applied to optical processing links that have higher requirements for auto-focusing accuracy.
  • the detection element 1024 may be a detector unit, such as a photodiode or a photomultiplier tube; in another possible implementation manner, the detection element 1024 may be a detection array, such as a photodiode array Detector (PDA, Photo-diode Array), which includes multiple detector units.
  • the first confocal device 1023 may include a plurality of confocal units, and the detector units of the detection element 1024 are used to respectively receive the signal light transmitted through the confocal unit.
  • the detection array can be used for multi-point laser confocal.
  • the response speed is extremely fast, which can reach the order of microseconds or nanoseconds, and accordingly, the autofocus speed of the optical device in this embodiment is improved accordingly. Meet the high requirements for auto focus speed in practical applications.
  • the second confocal device may include one or more light-restricted units. It should be noted that when the second confocal device includes multiple light-limited units, the detection element 1024 includes multiple detector units, and the first confocal device 1023 includes multiple confocal units, each of the second confocal device The detection light transmitted by the light-limited unit reaches different confocal units through the optical action of the surface of the object to be measured, and is received by different detector units.
  • the position of the object to be measured shown in FIG. 1 can also be replaced with a flat mirror, and the flat mirror is used instead of the real object to be measured to achieve automatic focusing. After focusing, replace the plane mirror with the object to be measured.
  • the first confocal device 1023 includes multiple possible implementation forms.
  • the first confocal device 1023 may include any one of the following:
  • a pinhole array which includes a plurality of pinhole units; one pinhole is equivalent to a confocal unit;
  • a pinhole array + a first lens array the pinhole array includes a plurality of pinhole units, the first lens array includes a plurality of lens units, the lens units collect the signal light passing through the pinhole units, and collect the The signal light is transmitted to different confocal units; a pair of pinhole unit and lens unit corresponding to each other is equivalent to a confocal unit;
  • the second confocal device may be a pinhole array or an optical fiber splitter. Therefore, the light-limited unit of the second confocal device may be a pinhole unit or an optical fiber.
  • the light-limited unit is an optical fiber, as an example, it may specifically be an optical fiber of an exit port of an optical fiber splitter.
  • Fig. 2a is a schematic diagram of an optical path of an optical device provided by an embodiment of the application.
  • the electrical connection relationship of the optical device and the components related to the electrical connection are not shown in the figure one by one.
  • the optical processing module 101 may be a microscopic imaging system with a relatively high numerical aperture.
  • the optical processing module 101 includes an objective lens 1011, a second beam splitter 202, a first tube lens 204, and an imaging detector 205.
  • the auto-focusing module may further include: a first beam splitting element 1022, a first plane mirror 201, a second tube lens 203, a beam shaper 206, and a collimating lens group 207.
  • the first confocal device includes a first lens array 1023a and a pinhole array 1023b.
  • the first beam splitting element 1022 is located between the laser light source 1021 and the first confocal device. In this embodiment, both the probe light and the signal light pass through the first confocal device.
  • the laser light source 1021 may directly emit light to the first confocal device, or may emit light to the first confocal device through the first light splitting element 1022.
  • the first beam splitting element 1022 can divide the detection beam provided by the laser light source 1021 into a transmitted beam and a reflected beam, one of which is provided to the first confocal device for automatic focusing.
  • the first light splitting element 1022 can also provide the detection element 1024 with signal light from the first confocal device (including 1023a and 1023b). For example, if the first dichroic element 1022 provides the transmitted light beam to the first confocal device 1023, the reflection of the light beam from the first confocal device may be provided to the detection element 1024.
  • the first beam splitter 1022 may be a beam splitter, a cubic beam splitter, or a polarization beam splitter (PBS, Polarization Beam Splitter).
  • PBS Polarization Beam Splitter
  • the first light splitting element 1022 is used to divide the light emitted by the laser light source 1021 into a transmitted light beam and a first reflected light beam.
  • the transmitted light beam generated by the first beam splitting element 1022 is specifically applied.
  • the transmitted light beam generated by the first beam splitter 1022 passes through the objective lens 1011 of the optical processing module 101 and is directed to the object to be measured, and is reflected by the object to be measured into a second reflected beam, which can follow the original path or be similar to the original path Return of the route: the second reflected beam passes through the objective lens 1011 and enters the first beam splitting element 1022.
  • the first beam splitting element 1022 then reflects the beam to the detection element 1024, and is collected by the detection element 1024.
  • the beam shaper 206 is located between the laser light source 1021 and the first light splitting element 1022, and is used to shape the light emitted by the laser light source 1021 and send it to the first light splitting element 1022, so that the first light splitting element can reshape the light.
  • the latter beam is split, and then one of the probe beams is provided to the first confocal device.
  • the transmission path of the light beam is described below.
  • the light emitted by the laser light source 1021 is shaped by the beam shaper 206, is beam expanded and collimated, and enters the first beam splitting element 1022.
  • the first light emitting element 1022 divides the incident light beam into a first reflected light beam (not shown in FIG. 2a) and a transmitted light beam.
  • the transmitted light beam continues to enter the lens 1023a, is condensed by the lens, and enters the pinhole unit of the pinhole array 1023b.
  • the rest are all light-shielded.
  • the light beam is transmitted from the pinhole unit, and is refracted to the first plane mirror 201 by the first mirror group.
  • the first plane mirror 201 reflects the light beam to the second beam splitting element 202.
  • the second spectroscopic element 202 also has functions of transmitting light and reflecting light.
  • the second beam splitter 202 reflects the light reflected by the first plane mirror 201 again, and the light beam passes through the objective lens 1011 and is incident on the object to be measured or the plane mirror used to calibrate the position of the focal plane.
  • the second light splitting element is used to reflect the detection light from the auto-focus module to the objective lens 1011, and to reflect the signal light transmitted by the objective lens 1011 to provide the auto-focus module.
  • the object to be measured or the plane mirror can reflect the light beam.
  • the reflected light beam is referred to as the second reflected light beam.
  • the second reflected light beam returns along the original path, that is, sequentially transmitted through the objective lens 1011, reflected by the second beam splitter 202, reflected by the first flat mirror 201, and transmitted by the second tube mirror 203 to the pinhole array 1023b.
  • the light spot on the pinhole array 1023b is small, and the beam can pass through and return from the pinhole unit more accurately; if the object to be measured or the calibration plane mirror is out of focus, the pinhole array
  • the light spot on 1023b is relatively large, most of the energy of the light spot is blocked and blocked by the part of the non-pinhole unit of the pinhole array 1023b, and only a small part can pass through the pinhole unit.
  • the light beam passing through the pinhole array passes through the first lens array 1023a and enters the first beam splitting element 1022.
  • the detection element 1024 here may be a detection array.
  • a micro lens array may also be arranged between the detection array 1024 and the collimating lens group 207, which is specifically arranged at the position 333 as shown in FIG. 2a.
  • each microlens unit corresponds to the detector unit of the detection array 1024 on a one-to-one basis.
  • the micro lens unit is used to refract the light from the collimating lens group 207 so that it converges into the detector unit corresponding to the micro lens unit.
  • the collimating lens group 207 can also be replaced with a second lens.
  • the second lens 208 in this figure is located in front of the detecting element 1024, that is, it is also on the transmission path of the detecting element 1024 receiving signal light.
  • the second lens 208 may be a lens array or a single lens.
  • the detection element 1204 should be a detection array, that is, it includes a plurality of detector units. The lens units of the lens array are used to collect signal light passing through different confocal units, and provide the signal light to different detector units of the detection element.
  • the distance between the detection element 1024 and the second lens 208 is greater than or equal to the focal length of the second lens 208;
  • the distance between the detection element 1024 and the second lens 208 is greater than or equal to The focal length of the second lens 208.
  • the distance between the detection element 1024 and the second lens 208 is greater than the focal length of the second lens 208.
  • the first beam splitter 1022 may specifically be a polarization beam splitter PBS.
  • the auto-focusing module may further include a polarizing plate for receiving the detection light passing through the PBS, and transmitting the signal light returned by the object to be measured to the PBS, and making the detection light passing through the PBS and the signal reaching the PBS Light has different polarization states.
  • the polarizing wave plate may be a quarter wave plate 222.
  • the quarter wave plate 222 may be arranged between the second tube lens 203 and the first plane mirror 201 shown in FIG. 2a.
  • the angle between the optical axis of the quarter wave plate 222 and the incident light bearing is 45°.
  • the PBS divides the light beam from the laser light source 1021 into a transmitted light beam and a first reflected light beam (not shown in FIG. 2a), wherein the transmitted light beam is high-purity linearly polarized light (for example, p light). Due to the 45° included angle between the optical axis of the quarter wave plate 222 and the incident optical axis, the transmitted light beam can be converted into circularly polarized light.
  • the light beam reflected by the objective lens or the calibrated plane mirror, and the polarization state of the light beam focused on the pinhole array 1023b is different from the polarization state of the light beam in the opposite direction by 90° (that is, s light). Since the s light will not be transmitted along the PBS, it will not enter the laser light source 1021, so that the device performance of the laser light source 1021 will not be damaged. In addition, since the light beam reflected by the PBS to the detection element 1024 is high-purity s light, compared with natural light, the influence of interference light beams on detection accuracy is reduced.
  • the detection light received by the quarter wave plate 222 is s light (s Optical signal light (referred to as p signal light).
  • the intensity of the light beam provided by the laser light source 1021 may fluctuate to a certain extent, which may affect the accuracy of the focal plane position determined by the control unit 1025.
  • Fig. 3 is a schematic diagram of the light intensity calibration light path, in which only a part of the light path diagram shown in Fig. 2a is cut out.
  • the first beam splitting element 1022 divides the light beam provided by the laser light source 1021 and shaped by the beam shaper 206 into a transmitted light beam (not fully shown in FIG. 3) and a first reflected light beam.
  • the third mirror group 301 After the first emitted light beam passes through the third mirror group 301, it is directed to the light intensity fluctuation detector 302.
  • the third lens group 301 and the light intensity fluctuation detector 302 also belong to the autofocus module 102.
  • the light intensity fluctuation detector 302 may be a light detecting element, or a plurality of light detecting elements arranged in an array.
  • the light intensity fluctuation detector 302 is used to detect the light, and the first reflected light beam can be collected and converted into an electrical signal.
  • the light intensity fluctuation detector 302 is electrically connected to the control unit 1025, and the converted electrical signal can be provided to the control unit 1025 so that it can perform arithmetic processing on the electrical signal.
  • the control unit 1025 is further configured to obtain the light intensity fluctuation compensation amount according to the electric signal provided by the light intensity fluctuation detector 302; determine the focal plane position of the objective lens 1011 according to the light intensity fluctuation compensation amount and the electric signal provided by the detection element 1024.
  • the intensity fluctuation of the light provided by the laser light source 1021 will be reflected in the first reflected beam and the transmitted beam in equal proportions.
  • the former corresponds to the light intensity fluctuation detector 302, and the latter corresponds to the detection element, so the light intensity
  • the amount of fluctuation compensation is suitable for compensating the intensity of the light reflected by the electrical signal provided by the detection element, so as to reduce the accuracy impact caused by the fluctuation of the light intensity.
  • the light intensity calibration optical path shown in Fig. 3 can improve the accuracy of the determined focal plane position and achieve a more precise auto-focusing effect.
  • the microlens array 1023a and the pinhole array 1023b are located on the same side of the first beam splitting element 1022, that is, on the transmission path of the transmitted light beam (also on the transmission path of the second reflected light beam). ).
  • the relative positional relationship between the first light splitting element 1022 and the microlens array 1023a can also be adjusted.
  • the microlens array 1023a is arranged between the laser light source 1021 and the first beam splitting element 1022, so that the microlens array 1023a and the pinhole array 1023b are located on both sides of the first beam splitting element 1022.
  • FIG. 4 is a schematic diagram of the optical connection relationship of the microlens array 1023a, the first light splitting element 1022, and the pinhole array 1023b.
  • Fig. 5a is a schematic diagram of an optical path of another optical device provided by an embodiment of the application.
  • the electrical connection relationship of the optical device and the components related to the electrical connection are not shown in the figure one by one.
  • the first confocal device is a receiving optical fiber 1023d; the second confocal device is an optical fiber splitter 1023c, and the optical fiber of each exit port of the optical fiber splitter 1023c serves as a light limited unit.
  • the number of receiving fibers 1023d is the same as the number of exit ports of the fiber splitter 1023c; the entrance port of the receiving fiber 1023d is located on the transmission path of the second reflected beam (signal light), and the exit port of the receiving fiber 1023d is detected by the detection element 1024 Optical connection between the unit.
  • the arrow s501 indicates the direction in which the light beam emitted from the exit port of the fiber splitter 1023c transmits from the first beam splitter 1022, that is, the direction of the transmitted light beam (probe light);
  • the arrow s502 indicates the measured object of the transmitted light beam Or the calibrated plane mirror reflects the direction of the second reflected light beam (signal light), that is, the direction of the second reflected light beam;
  • arrow s503 indicates that the second reflected light beam enters the incident port of the receiving fiber 1023d and follows the transmission direction of the receiving fiber 1023d.
  • the receiving optical fiber 1023d can also be replaced with a lens in practical applications.
  • the lens condenses the light reflected by the first dichroic element 1022 and provides it to the detecting element 1024.
  • the number of light beams included in each of the transmitted light beam and the second reflected light beam is the same as the number of exit ports of the fiber beam splitter 1023c.
  • the fiber splitter 1023c is located between the laser light source 1021 and the first light splitting element 1022, and the light emitted by the laser light source 1021 is split by the fiber splitter 1023c and then enters the first light splitting element 1022.
  • the detection element 1024 can provide the converted electrical signal to the control unit (not shown in FIG. 5a). Furthermore, the control unit can determine the peak value according to the change in the magnitude of the electrical signal when the distance between the objective lens and the object to be measured (or the calibration plane mirror) changes, and the position of the object to be measured or the calibration plane lens at the moment when the peak occurs is the focal plane of the objective lens 1011 Location.
  • the light intensity calibration light path may also be included.
  • the first light splitting element 1022 shown in FIG. 5a is specifically a PBS
  • the light path shown in FIG. 5a may further include a quarter wave plate, thereby improving the quality and accuracy of light collected by the detecting element 1024.
  • a quarter wave plate may be provided between the PBS and the objective lens 1011.
  • the first confocal device includes a fiber splitter 1023c; the autofocus module also includes: 1 ⁇ 2 fiber coupler 1023e, 1 ⁇ 2 fiber coupler 1023e includes a first end, a second end, and a third end , Where the first end and the second end are on the same side, and the third end is the opposite side of the first end and the second end; the first confocal device is the fiber splitter 1023c, and the fiber at the exit port (ie, the light-limited unit ) Is optically connected to the first end, the detection element 1024 and the second end light are connected through an optical fiber (that is, a confocal unit); the objective lens is optically connected to the third end.
  • the exit port ie, the light-limited unit
  • the laser light source 1021 is connected to the fiber splitter 1023c, and the light emitted by the fiber splitter 1023c enters the first end of the fiber coupler 1023e through a set of coupling mirrors (as shown in Figure 5b, branch 1), and then exits from the third end;
  • the three ends transmit light to the lens 501, the third beam splitting element 502, and the objective lens 1011 in the lower part of FIG. 5b through the optical fiber.
  • the third light splitting element 502 is used to transmit light to the objective lens.
  • the object to be measured or the plane mirror used to calibrate the focal plane position reflects the light, returns to the third end along the original path, and returns to the second end through the fiber coupler (see branch 2 in Fig. 5b), and is detected by the detection element 1024.
  • the light beam reflected by the third beam splitting element 502, the condenser lens and another light intensity fluctuation detector are used for calibration.
  • the third light splitting element 502 is used to split the detection light emitted by the light source, and the light intensity fluctuation detector PD is electrically connected to the control unit (not shown in FIG. 5b) for collecting another beam of light split by the third light splitting element 502 , Convert it into an electrical signal, and provide the electrical signal to the control unit;
  • the control unit is also used to obtain the light intensity fluctuation compensation amount according to the electric signal provided by the light intensity fluctuation detector PD; and determine the focal plane position of the objective lens 1011 according to the light intensity fluctuation compensation amount and the electric signal provided by the detection element 1024.
  • the auto-focusing module may further include: a scanning unit.
  • the detection element 1024 and the control unit 1025 are electrically connected to the scanning unit, respectively.
  • the scanning unit is used to move and scan the object to be measured or the objective lens 1011 along the optical axis direction of the objective lens 1011;
  • the control unit 1025 is used to obtain the relative position between the object to be measured and the objective lens 1011 and the corresponding relationship before the signal light intensity acquired by the detecting element 1024, and determine the focal plane position of the objective lens 1011 according to the relative position corresponding to the signal light intensity peak.
  • control unit 1025 obtains the amplitude distribution curve of the electrical signal converted by the detection element 1024 or the light intensity distribution curve corresponding to the electrical signal. According to the amplitude distribution curve or the light intensity distribution curve, determine the position corresponding to the peak value, determine the focal plane position of the objective lens 1011 according to the position corresponding to the peak value, control the optical processing module to move relative to the object under test, or control the object under test relative to optical processing The module moves to achieve the focus of the object to be measured.
  • the present application also provides a method for realizing automatic focusing.
  • the description will be given below in conjunction with embodiments.
  • the optical device provided in the foregoing device embodiment is used to realize automatic focusing and detection of the object to be measured.
  • This method needs to determine the focal plane position.
  • the detection element is used to obtain the electrical signal; then the focal plane position of the objective lens is determined according to the magnitude of the electrical signal, and the objective lens and the objective lens are adjusted according to the focal plane.
  • the relative position of the object to be tested For example, when the electric signal reaches the peak value, the position of the calibration plane mirror (or the object to be measured) at the acquisition time of the peak electric signal is used as the focal plane position of the objective lens.
  • the optical device is any optical device provided in the foregoing embodiments.
  • the auto-focus module includes a light source and a confocal device, and the application of the laser light source and the confocal device adopts confocal technology to improve the accuracy of auto-focusing.
  • detection elements are used in optical equipment to realize light collection and photoelectric conversion. When detecting arrays, the response speed is fast (up to microseconds or nanoseconds), and multi-point confocal is performed, which improves the speed of autofocus.
  • the optical device not only satisfies the speed requirement but also the accuracy requirement, and can be well applied in the optical processing link with higher requirements for auto-focusing accuracy.

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Abstract

一种光学设备（100）及实现自动聚焦的方法。光学设备（100）包括光学处理模块（101）和自动聚焦模块（102），光学处理模块（101）用于实现光学设备（100）固有的光学处理功能；而自动聚焦模块（102）则用于实现对光学设备（100）的自动聚焦。自动聚焦模块（102）中包括光源（1021）和第一共聚焦器件（1023），采用共聚焦技术，提升自动聚焦的精度。因此，光学设备（100）可以很好地应用在对于自动聚焦精度具有较高要求的光学处理环节。

Description

一种光学设备及实现自动聚焦的方法
本申请要求于2020年03月09日提交中华人民共和国国家知识产权局、申请号为202010157863.5、发明名称为“一种光学设备及实现自动聚焦的方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及光学检测技术领域，特别是涉及一种光学设备及实现自动聚焦的方法。
背景技术
在本导体或相关制造产业中，通常需要高倍的光学设备来对样品的关键指标进行检测或进行其他类型的光学处理。在高倍的光学设备中，物镜的焦深非常有限。焦深又称为景深，是指利用光学设备观察和拍摄样品表面时，从对准焦点的位置开始，改变物镜与样品表面的距离时，对焦能够保持清晰的范围。为了避免利用光学设备时因样品(例如晶元)翘曲或者样品表面结构起伏导致离焦，目前高倍光学设备通常会集成一套自动聚焦功能的系统。
自动聚焦系统使用通过透镜(TTL，Through-the-lens)的激光三角法，其速度能够达到kHz量级(即1毫秒)，但是追踪精度较低，通常只有景深的四分之一。在套刻对准测量等光学处理应用中，要求自动聚焦的精度(即离焦量)小于景深的十分之一，而上述自动聚焦的方式显然无法满足该精度要求。
发明内容
基于上述问题，本申请提供了一种光学设备及实现自动聚焦的方法，以提升自动聚焦的精度。
本申请实施例公开了如下技术方案：
第一方面，本申请提供一种光学设备，包括：光学处理模块和自动聚焦模块；光学处理模块包括物镜；自动聚焦模块包括：光源、第一共聚焦器件、探测元件和控制单元；
光源用于发射探测光，探测光经过物镜照射至待测物表面；探测光经待测物表面的光学作用形成信号光；
物镜用于收集信号光，并使信号光到达第一共聚焦器件；
第一共聚焦器件用于在待测物离焦时限制信号光穿过，第一共聚焦器件与物镜的焦平面共轭；
探测元件用于采集穿过第一共聚焦器件的信号光，并将采集到的信号光转换为电信号；
控制单元用于根据电信号确定物镜的焦平面位置，并根据焦平面调整物镜和待测物的相对位置；
光学处理模块用于通过物镜对待测物进行光学处理。
可选地，第一共聚焦器件还用于使探测光穿过；物镜还用于使穿过第一共聚焦器件的探测光到达待测物表面。
可选地，自动聚焦模块还包括：第二共聚焦器件，用于对光源发射的探测光进行限制。
可选地，第二共聚焦器件包括：一个或多个光受限单元，第二共聚焦器件与物镜焦平面共轭。
可选地，探测元件包括多个探测器单元，第一共聚焦器件包括多个共聚焦单元，探测 器单元用于分别接收穿过共聚焦单元的信号光。
可选地，第一共聚焦器件还包括第一透镜阵列，第一透镜阵列包括多个透镜单元，各透镜单元用于收集信号光，分别将收集的信号光传递至不同的共聚焦单元。
可选地，共聚焦单元为针孔单元或光纤。
可选地，探测器单元为光电二极管或光电倍增管。
可选地，当光学设备还包括第二共聚焦器件，第二共聚焦器件包括多个光受限单元时，各光受限单元透过的探测光经待测物表面的光学作用形成的信号光分别到达不同的共聚焦单元。
可选地，各光受限单元透过的探测光经待测物表面形成的信号光分别被不同的探测器单元接收。
可选地，光受限单元为针孔单元或光纤。
可选地，第一共聚焦器件包括光纤；自动聚焦模块还包括：光纤耦合器，光纤耦合器包括第一端、第二端和第三端；第一共聚焦器件与第一端光连接，探测元件与第二端光连接；物镜与第三端光连接。
可选地，自动聚焦模块还包括：第二透镜，用于收集穿过第一共聚焦器件的信号光；探测元件用于接收穿过第二透镜的信号光。
可选地，第二透镜为单个透镜或透镜阵列；
当第二透镜为透镜阵列时，该透镜阵列的透镜单元用于分别收集穿过不同共聚焦单元的信号光，并将穿过不同共聚焦单元的信号光分别提供给探测元件的不同探测器单元。
当第二透镜为单个透镜，且第一共聚焦器件位于第二透镜的傅里叶平面处时，探测元件与第二透镜之间的距离大于或等于第二透镜的焦距；
当第二透镜为单个透镜，且第一共聚焦器件不包括单个透镜时，探测元件与第二透镜之间的距离大于第二透镜的焦距。
可选地，自动聚焦模块还包括：第一分光元件，用于将光源发射的探测光分束，将其中的一束提供给第一共聚焦器件；
第一分光元件，还用于将来自第一共聚焦器件的信号光提供给探测元件。
可选地，光学处理模块还包括：第二分光元件；
第二分光元件用于将来自自动聚焦模块的探测光反射提供给物镜，以及用于将物镜传输的信号光反射提供给自动聚焦模块。
可选地，自动聚焦模块还包括：光强波动探测器和第三分光元件，第三分光元件用于对光源出射的探测光进行分光，光强波动探测器与控制单元电连接，用于采集第三分光元件分出的另一束光，将其转换成电信号，将该电信号提供给控制单元；
控制单元还用于根据光强波动探测器提供的电信号获得光强波动补偿量；根据光强波动补偿量以及探测元件列提供的电信号，确定物镜的焦平面位置。
可选地，第一分光元件具体为偏振分光元件；自动聚焦模块还包括：偏振波片，用于接收穿过偏振分光元件的探测光，并将待测物返回的信号光传递至偏振分光元件，且使穿过偏振分光元件的探测光与到达偏振分光元件的信号光具有不同的偏振态。
可选地，自动聚焦模块还包括：准直透镜组，用于接收穿过第一共聚焦元件的信号光， 并对接收带的信号光进行准直；探测元件用于接收经准直透镜组准直的信号光。
可选地，自动聚焦模块还包括：扫描单元；探测元件和控制单元分别与扫描单元电连接；
扫描单元用于使待测物或物镜沿着物镜的光轴方向移动扫描；
控制单元用于获取待测物和物镜之间的相对位置，以及探测元件获取的信号光强度之间的对应关系，并根据信号光强度峰值对应的相对位置确定物镜的焦平面位置。
可选地，控制单元用于根据确定的焦平面位置，控制光学处理模块相对于待测物移动，或者控制待测物相对于光学处理模块移动，以实现对待测物的聚焦。
第二方面，本申请提供一种应用第一方面提供的光学设备实现自动聚焦的方法，方法包括：
在光学处理模块与待测物发生相对移动的过程中，利用探测元件获得电信号；
根据电信号的大小确定出物镜的焦平面位置，并根据焦平面调整物镜和待测物的相对位置。
相较于现有技术，本申请具有以下有益效果：
在本申请提供的技术方案中，光学设备包括光学处理模块和自动聚焦模块，其中，光学处理模块用于实现该光学设备固有的光学处理功能；而自动聚焦模块则用于实现对该光学设备的自动聚焦。自动聚焦模块中包括光源和第一共聚焦器件，应用该光源和第一共聚焦器件即采用共聚焦技术，能够提升光学设备自动聚焦的精度。因此，该光学设备可以较好地应用在对于自动聚焦精度具有较高要求的光学处理环节。
附图说明
为了更清楚地说明本申请具体实施方式或现有技术中的技术方案，下面将对具体实施方式或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图是本申请的一些实施方式，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本申请实施例提供的一种光学设备的结构示意图；
图2a为本申请实施例提供的一种光学设备的光路示意图；
图2b为本申请实施例提供的另一种光学设备的光路示意图；
图3为本申请实施例提供的一种光强校准光路的示意图；
图4为本申请实施例提供的一种微透镜阵列、第一分光元件以及针孔阵列的光连接关系示意图；
图5a为本申请实施例提供的又一种光学设备的光路示意图；
图5b为本申请实施例提供的再一种光学设备的光路示意图。
具体实施方式
正如前文描述，目前的光学设备无法满足对自动聚焦的高精度要求。为了解决此问题，本申请中提出一种光学设备及应用该设备实现自动聚焦的方法。
为了使本技术领域的人员更好地理解本申请方案，下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没 有做出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
设备实施例一：
图1为本申请实施例提供的一种光学设备100的结构示意图。
图1所示，该光学设备100包括：光学处理模块101和自动聚焦模块102。
作为示例，光学处理模块101可以是套刻检测系统，应用了传统的基于成像和图像识别的套刻测量技术(IBO，Imaging Based Overlay)或者基于衍射光探测的套刻测量技术(DBO，Diffraction Based Overlay)。此外，光学处理模块101还可以是暗场缺陷检测系统、白光干涉系统或者椭偏仪等。此处对光学处理模块101的具体类型不加限定。
光学处理模块101的用途可以是形成对于待测物进行检测或测量的光路。光学处理模块101中包括物镜1011，还可以包括其他光学器件，例如管镜、光阑、分光器或平面镜等。物镜1011可以包括一个或多个透镜，物镜1011是整个光学处理模块101中距离待测物最近的透镜或透镜组。
光学处理模块101与待测物的距离是可调的，调节方式包括：电控调节和手动调节。对于光学处理模块101，如果待测物处在物镜1011的焦平面或者焦平面前后预设区间内，则称为在焦，成像较为清晰；如果待测物未处在物镜1011的焦平面或焦平面前后预设区间内，则称为离焦，成像较为模糊。
在本申请实施例中，自动聚焦模块102可以包括但不限于：光源1021、第一共聚焦器件1023、探测元件1024和控制单元1025。在图1中所示的各个器件之间，虚线表示光连接的关系，实线表示电连接的关系。
光源1021用于发射探测光，探测光经过物镜1011照射至待测物表面；探测光经待测物1011表面的光学作用(可以是反射)形成信号光。为便于区分光束的走向，本实施例中将到达待测物之前的光束称为探测光，将待测物1011进行光学作用后的光束称为信号光。
光源1021可以是激光器或者发光二极管等。此处对光源1021的具体类型不进行限定。在以下的描述中以激光器作为光源1021进行示例性的描述。
物镜1011用于收集信号光，并使信号光到达第一共聚焦器件1023；
第一共聚焦器件1023用于在待测物离焦时限制信号光穿过，第一共聚焦器件1023与物镜1011的焦平面共轭；
探测元件1024用于采集穿过第一共聚焦器件1023的信号光，并将采集到的信号光转换为电信号；
控制单元1025用于根据电信号确定物镜1011的焦平面位置，并根据焦平面调整物镜1011和待测物的相对位置；
光学处理模块101用于通过物镜1011对待测物进行光学处理。
需要说明的是，在本申请实施例中，作为一种可能的实现方式，可以由同一个共聚焦器件使探测光经过以及使信号光经过。即由第一共聚焦器件1023完成上述功能。对于此种实现方式，物镜1011还用于使传过第一共聚焦器件1023的探测光到达待测物表面。本申请实施例中，作为另一种可能的实现方式，还可以由不同的共聚焦器件分别使探测光经过和使信号光经过。即，由第一共聚焦器件1023使信号光经过，由第二共聚焦器件使探测光经过，其中第二共聚焦器件与物镜1011的焦平面共轭。
需要说明的是，在实际应用中，第一共聚焦器件1023的作用是在待测物离焦时限制信号光的穿过。此处，限制的含义不是完全阻止。例如，一整束信号光经过第一共聚焦器件1023时，第一共聚焦器件1023会约束一部分信号光的经过。
对于探测光，其在不同的实现方式中可能经过第一共聚焦器件1023或者另一共聚焦器件(即第二共聚焦器件)。对于探测光，其经过的共聚焦器件的作用是对光源发射的探测光进行限制。类似地，限制也是部分约束而不是完全绝对地阻止。
本实施例中，第一共聚焦器件1023是该光学设备100实现共聚焦的关键器件。第一共聚焦器件1023可以用于在待测物离焦时限制探测元件1024采集的光的范围。另外，第一共聚焦器件1023与物镜1011的焦平面共轭。因为第一共聚焦器件1023与物镜1011二者的焦平面共轭，因此，该第一共聚焦器件1023所在的自动聚焦模块102可以用于确定物镜1011的焦平面位置。
需要说明的是，在实际应用中，如果待测物在焦，则在共聚焦平面上形成的光斑较小，第一共聚焦器件1023对探测元件1024采集的光的范围限制作用较小。信号光的传输路径上光束绝大多数能够通过第一共聚焦器件1023，因此探测元件1024探测到的光强较强。
而如果待测物离焦，则在共聚焦平面上形成的光斑较大，第一共聚焦器件1023对探测元件1024采集的光的范围限制作用较大。信号光的传输路径上光束仅有少部分能够通过第一共聚焦器件1023，大部分被第一共聚焦器件1023的不透光部分遮挡，因此探测元件1024探测到的光强较弱。
探测元件1024用于将采集到的光转换为电信号，电信号的幅度可以反映采集到的光强的大小。电信号幅度越大，采集的光强越强；电信号幅度越小，采集的光强越小。
通过上文中对第一共聚焦器件1023的描述，可以理解的是，如果待测物正处于物镜1011的焦平面，则第一共聚焦器件1023对共聚焦平面上通光限制较小，信号光大多能够通过第一共聚焦器件1023而非被阻挡。因此，待测物在焦时探测元件1024采集的光强应该是最大的。如果待测物和物镜1011之间的相对位置发生变化，例如物镜1011相对于待测物移动或者待测物相对于物镜1011移动，则探测元件1024采集的光强会发生变化，当待测物处于物镜1011的焦平面时，探测元件1024转换出的电信号达到峰值。
本实施例中，控制单元1025与探测元件1024之间可以进行电连接，即探测元件1024可以将转换的电信号发送给控制单元1025，进而控制单元1025能够根据电信号利用某些处理算法(例如高斯拟合)求取峰值，最后确定物镜1011的焦平面位置。
当控制单元1025确定出物镜1011的焦平面位置后，可以根据焦平面调整物镜1011和待测物的相对位置。例如，如果待测物离焦，则控制模块1025调节物镜1011和待测物的距离。光学处理模块101通过位置调整后的物镜1011对待测物进行光学处理。
具体的光学处理方式与光学处理模块101固有的光学处理功能相关。例如，可以是对待测物进行成像检测等。由于光学处理模块101的具体类型不进行限定，因此相应地，对其在获知物镜1011的焦平面位置后执行的具体功能也不进行限定。
在本申请实施例提供的技术方案中，自动聚焦模块102中包括光源1021和第一共聚焦器件1023，应用该光源1021和第一共聚焦器件1023即采用共聚焦技术，提升自动聚焦的精度。因此，该光学设备100可以很好地应用在对于自动聚焦精度具有较高要求的光学处 理环节。
在一种可能的实现方式中，探测元件1024可以为一个探测器单元，例如一个光电二极管或者光电倍增管；在另一种可能的实现方式中，探测元件1024可以为探测阵列，例如光电二极管阵列检测器(PDA，Photo-diode Array)，其包括多个探测器单元。对于后面一种实现方式，第一共聚焦器件1023可以包括多个共聚焦单元，探测元件1024的探测器单元用于分别接收传过共聚焦单元的信号光。
实际应用中，探测阵列可以用于多点激光共聚焦。其响应速度极其快，能够达到微秒或纳秒的量级，因此相应地，提升了本实施例中光学设备的自动聚焦速度。满足实际应用中对于自动聚焦速度的高要求。
如果自动聚焦模块102还采用了前述的第二共聚焦器件用以对光源1021发射的探测光进行限制，第二共聚焦器件可以包括一个或多个光受限单元。需要说明的是，当第二共聚焦器件包括多个光受限单元，探测元件1024包括多个探测器单元，第一共聚焦器件1023包括多个共聚焦单元时，第二共聚焦器件的各光受限单元透过的探测光经待测物表面的光学作用形成的信号光分别到达不同的共聚焦单元，并被不同的探测器单元接收。
另外需要说明的是，在实际应用中图1所示的待测物的位置还可以置换为一个平面镜，利用该平面镜而非真实的待测物来实现自动聚焦。聚焦完成后再以待测物替换该平面镜。
实际应用中，第一共聚焦器件1023包括多种可能的实现形式。作为一示例，第一共聚焦器件1023可以包括以下任意一种：
1)一个针孔单元；
2)一个针孔单元+单个透镜；
3)针孔阵列，该针孔阵列包括多个针孔单元；一个针孔相当于一个共聚焦单元；
4)针孔阵列+第一透镜阵列，该针孔阵列包括多个针孔单元，该第一透镜阵列包括多个透镜单元，透镜单元收集从针孔单元经过的信号光，并分别将收集的信号光传递至不同的共聚焦单元；相互对应的一对针孔单元和透镜单元相当于一个共聚焦单元；
5)针孔阵列+第一透镜阵列+单个透镜；
6)多根光纤；一根光纤相当于一个共聚焦单元。
作为示例，第二共聚焦器件可以为针孔阵列或光纤分束器。因此，第二共聚焦器件的光受限单元可以是针孔单元或者光纤。当光受限单元为光纤时，作为示例，其具体可以是光纤分束器的出射端口的光纤。
下面通过实施例描述光学设备的变型实现方式。
设备实施例二：
图2a为本申请实施例提供的一种光学设备的光路示意图。该光学设备的电连接关系以及电连接相关的器件没有逐一在该图中示出。在图2a中，光学处理模块101可以是数值孔径较高的显微成像系统，光学处理模块101包括物镜1011、第二分光元件202、第一管镜204和成像探测器件205。
对于图2a所示的光学设备，其中的自动聚焦模块还可以包括：第一分光元件1022、第一平面镜201、第二管镜203、光束整形器206和准直透镜组207。
该实施例提供的光学设备的自动聚焦模块中，第一共聚焦器件包括第一透镜阵列1023a和针孔阵列1023b。
第一分光元件1022位于激光光源1021与第一共聚焦器件之间。在本实施例中，探测光和信号光均经过该第一共聚焦器件。激光光源1021可以直接将光发射到第一共聚焦器件，也可以经过该第一分光元件1022将光发射到第一共聚焦器件。例如，第一分光元件1022可以将激光光源1021提供的探测光束分为透射光束和反射光束，其中的一束提供给第一共聚焦器件用作自动聚焦用。另外，第一分光元件1022还可以将来自第一共聚焦器件(包括1023a和1023b)的信号光提供给探测元件1024。例如，如果第一分光元件1022将透射光束提供给第一共聚焦器件1023，则可以将来自第一共聚焦器件的光束反射提供给探测元件1024。
作为示例，第一分光元件1022可以是分光平片、立方分光镜、偏振分光棱镜(PBS，Polarization Beam Splitter)。
本实施例中，第一分光元件1022用于将激光光源1021发射的光分为透射光束和第一反射光束。本实施例具体应用了第一分光元件1022产生的该透射光束。第一分光元件1022产生的透射光束经过光学处理模块101的物镜1011射向待测物，并被待测物反射成为第二反射光束，该第二反射光束能够沿着原路或者与原路近似的路线回返：第二反射光束经过物镜1011后进入到第一分光元件1022，第一分光元件1022再将光束反射到探测元件1024，由探测元件1024采集得到。
可选地，光束整形器206位于激光光源1021和第一分光元件1022之间，用于对激光光源1021发射的光进行整形后，发送给第一分光元件1022，以便于第一分光元件对整形后的光束进行分光，再将其中一束探测光提供给第一共聚焦器件。
下面描述光束的传输路径。
激光光源1021发射的光经过光束整形器206整形，被扩束和准直化，进入到第一分光元件1022。第一发光元件1022将入射的光束分为第一反射光束(图2a未示出)和透射光束。其中透射光束继续进入到透镜1023a，被透镜会聚，入射到针孔阵列1023b的针孔单元。在针孔阵列1023b中，除了针孔单元可以透光，其余部分均是遮光的。光束从针孔单元透射而出，由第一镜组折射到第一平面镜201。第一平面镜201将光束反射到第二分光元件202上。第二分光元件202也具备透射光和反射光的功能。第二分光元件202将第一平面镜201反射的光再次反射，光束经过物镜1011入射到待测物或用于标定焦平面位置的平面镜。此处可以理解为，第二分光元件用于将来自自动聚焦模块的探测光反射给物镜1011，以及用于将物镜1011传输的信号光反射提供给自动聚焦模块。
入射后，待测物或者该平面镜可以将光束反射，本实施例中将该反射光束称为第二反射光束。第二反射光束沿着原路返回，即依次经过物镜1011透射、第二分光元件202反射、第一平面镜201反射、第二管镜203，透射到针孔阵列1023b。如果待测物或者标定平面镜在焦，则针孔阵列1023b上的光斑较小，并且光束能够较准确地从针孔单元穿过和返回；如果待测物或者标定平面镜离焦，则针孔阵列1023b上的光斑较大，大部分光斑能量被针孔阵列1023b的非针孔单元的部分遮挡和阻拦，仅有一小部分能够穿过针孔单元。穿过针孔阵列的光束穿过第一透镜阵列1023a，进入到第一分光元件1022。在第一分光元件1022 的作用下，反射到准直透镜组207，光束经过准直透镜组207后平行进入到探测元件1024，被探测元件1024所采集。此处的探测元件1024可以是探测阵列。
需要说明的是，在实际应用中，探测阵列1024和准直透镜组207之间还可以设置有微透镜阵列，具体设置于如图2a中所示的位置333。位置333处设置的微透镜阵列上，每个微透镜单元与探测阵列1024的探测器单元一一对应。微透镜单元用于将来自准直透镜组207的光折射，使其会聚进入该微透镜单元对应的探测器单元。
另外，图2a所示的结构中，准直透镜组207还可以替换为第二透镜。如图2b所示，该图中第二透镜208位于探测元件1024的前方，即也在探测元件1024承接信号光的传输路径上。第二透镜208可以是透镜阵列或单个透镜。当第二透镜208为透镜阵列时，探测元件1204应当为探测阵列，即包括多个探测器单元。该透镜阵列的透镜单元用于分别收集穿过不同共聚焦单元的信号光，并将信号光分别提供给探测元件的不同探测器单元。
当第二透镜208为单个透镜，且第一共聚焦器件位于第二透镜的傅里叶平面处时，探测元件1024与第二透镜208之间的距离大于或等于第二透镜208的焦距；
具体的，当第二透镜208为单个透镜，且第一共聚焦器件至第一分光元件1022之间的光路中不具有单个透镜时，探测元件1024与第二透镜208之间的距离大于或等于第二透镜208的焦距。
当第二透镜208为单个透镜，且第一共聚焦器件不包括单个透镜时，探测元件1024与第二透镜208之间的距离大于第二透镜208的焦距。
依照上述描述的方式进行设置，可保证采集信号光的效果。
在实际应用中，为了进一步提升探测元件采集信号光的质量和准确性，第一分光元件1022具体可以是偏振分光元件PBS。此时，自动聚焦模块还可以进一步包括偏振波片，用于接收穿过PBS的探测光，并将待测物返回的信号光传递至PBS，且使穿过PBS的探测光与到达PBS的信号光具有不同的偏振态。
举例来说，该偏振波片可以是四分之一波片222。该四分之一波片222可以是设置在图2a所示的第二管镜203与第一平面镜201之间。四分之一波片222的光轴与入射光轴承45°夹角。本实施例中，PBS将来自激光光源1021的光束分为透射光束和第一反射光束(图2a中未示出)，其中透射光束是高纯度的线偏振光(例如p光)。由于四分之一波片222的光轴相对于入射光轴的45°夹角，能够将透射光束转换为圆偏振光。而经过物镜或标定平面镜对光束的反射，再次聚焦到针孔阵列1023b的光束的偏振态与反方向的光束的偏振态相差90°(即s光)。由于s光不会沿PBS透射，因此不会进入到激光光源1021，从而不会损伤到激光光源1021的器件性能。另外，由于PBS向探测元件1024反射的光束为高纯度的s光，因此相比于自然光，减少干扰光束对探测准确性的影响。
另外，如果四分之一波片222接收的探测光是s光(简称s探测光)，则其用于将s探测光转化为圆偏振探测光，以及将接收的圆偏振信号光转换为p光信号光(简称p信号光)。
在实际应用中，激光光源1021提供的光束的强度可能存在一定程度的波动，有可能影响控制单元1025确定出的焦平面位置的准确性。为了避免上述影响，可以通过对第一分光元件分出的另一光束的探测，实现对光强波动的补偿。从而提升确定出的焦平面位置的准确性。
可参见图3，该图是光强校准光路的示意图，其中仅截取了图2a所示光路图的局部。在图3中，第一分光元件1022将激光光源1021提供且经过光束整形器206整形后的光束分为透射光束(图3未完整示出)和第一反射光束。第一发射光束经过第三镜组301后，射向光强波动探测器302。其中，第三镜组301以及光强波动探测器302也属于自动聚焦模块102。该光强波动探测器302可以是一个光探测元件，还可以是阵列形式排布的多个光探测元件。可以理解的是，当激光光源1021发光不稳定，发出的光的强度存在波动时，透射光束和第一反射光束均发生相应的波动。利用光强波动探测器302来探测光，其及可以将第一反射光束采集后转换为电信号。
光强波动探测器302与控制单元1025存在电连接的关系，可以将转换的电信号提供给控制单元1025，以便其对电信号进行运算处理。控制单元1025还用于根据光强波动探测器302提供的电信号获得光强波动补偿量；根据光强波动补偿量以及探测元件1024提供的电信号，确定物镜1011的焦平面位置。
可以理解的是，激光光源1021提供的光的强度波动会等比例地反映在第一反射光束和透射光束，其中，前者对应于光强波动探测器302，后者对应于探测元件，因此光强波动补偿量适用于对探测元件提供的电信号所反映出的光的强度进行补偿，减少因为光强波动带来的准确性影响。可见，图3所示的光强校准光路能够提升确定出的焦平面位置的准确性，实现更加精准的自动聚焦效果。
在图2a所示的光路图中，微透镜阵列1023a和针孔阵列1023b共同位于第一分光元件1022的同一侧，即位于透射光束的传输路径上(同样也是位于第二反射光束的传输路径上)。作为另一种可能的实现方式，还可以调整第一分光元件1022和微透镜阵列1023a的相对位置关系。例如，将微透镜阵列1023a设置在激光光源1021和第一分光元件1022之间，如此，微透镜阵列1023a和针孔阵列1023b分处于第一分光元件1022的两侧。参见图4所示，该图为微透镜阵列1023a、第一分光元件1022以及针孔阵列1023b的光连接关系示意图。
设备实施例三：
图5a为本申请实施例提供的另一种光学设备的光路示意图。该光学设备的电连接关系以及电连接相关的器件没有逐一在该图中示出。
在本实施例中，第一共聚焦器件为接收光纤1023d；第二共聚焦器件为光纤分束器1023c，该光纤分束器1023c的每一个出射端口的光纤作为一个光受限单元。接收光纤1023d的数量与光纤分束器1023c的出射端口的数量一致；接收光纤1023d的入射端口位于第二反射光束(信号光)的传输路径上，接收光纤1023d的出射端口与探测元件1024的探测器单元之间光连接。
在图5a中，箭头s501表示从光纤分束器1023c的出射端口出射的光束从第一分光元件1022透射的方向，即表示透射光束(探测光)的方向；箭头s502表示透射光束被待测物或标定平面镜反射为第二反射光束(信号光)的方向，即表示第二反射光束的方向；箭头s503表示第二反射光束进入接收光纤1023d的入射端口后，沿着接收光纤1023d的传输方向。
需要说明的是，实际应用中接收光纤1023d还可以替换为透镜。该透镜将第一分光元 件1022反射的光会聚后提供给探测元件1024。
如图5a所示，透射光束及第二反射光束各自包括的光束数量与光纤分束器1023c的出射端口的数量一致。光纤分束器1023c位于激光光源1021与第一分光元件1022之间，激光光源1021发射的光经过光纤分束器1023c分束后入射到第一分光元件1022。
图5a中，多个圆圈分别代表共聚焦点。实际应用中，如果待测物或标定平面镜离焦，则很多光束在共聚焦点处形成的光斑较大，光强不汇集，导致探测元件1024探测到的光强较弱。而如果待测物或标定平面镜在焦，则第二反射光束在共聚焦点处形成的光斑较小，光强汇集，进而探测元件1024探测到的光强较强。
可以理解的是，探测元件1024可以将转换的电信号提供给控制单元(图5a中未示出)。进而控制单元可以在物镜与待测物(或标定平面镜)的距离发生变化时根据电信号的大小变化确定出峰值，该峰值发生时刻待测物或标定平面镜所在的位置即为物镜1011的焦平面位置。
在本实施例中，也可以包括光强校准光路，光强校准光路可以参见图3，此处不做赘述。另外，如果图5a所示的第一分光元件1022具体为PBS时，图5a所示的光路中还可以进一步包括四分之一波片，从而提升探测元件1024采集光的质量和准确性。作为示例，四分之一波片可以设置在PBS和物镜1011之间。
下面结合图5b介绍本申请光学设备的再一种实现方式。
在图5b中，第一共聚焦器件包括光纤分束器1023c；自动聚焦模块还包括：1×2光纤耦合器1023e，1×2光纤耦合器1023e包括第一端、第二端和第三端，其中第一端和第二端位于同侧，第三端为第一端和第二端的对侧；第一共聚焦器件即光纤分束器1023c，其出射端口的光纤(即光受限单元)与第一端光连接，探测元件1024与第二端光通过光纤(即共聚焦单元)实现连接；物镜与第三端光连接。
激光光源1021与光纤分束器1023c连接，光纤分束器1023c出射的光经过一组耦合镜进入到光纤耦合器1023e的第一端(如图5b分支1)，再从第三端出射；第三端通过光纤将光传递给图5b下方的透镜501、第三分光元件502和物镜1011。其中，第三分光元件502用于将光透射给物镜。待测物或用于标定焦平面位置的平面镜将光反射，沿着原路回到第三端，并经过光纤耦合器回归到第二端(如图5b分支2)，被探测元件1024探测。
第三分光元件502反射的光束、聚光镜和另一光强波动探测器则用于校准。第三分光元件502用于对光源出射的探测光进行分光，光强波动探测器PD与控制单元(图5b未示出)电连接，用于采集第三分光元件502分出的另一束光，将其转换成电信号，将该电信号提供给控制单元；
控制单元还用于根据光强波动探测器PD提供的电信号获得光强波动补偿量；根据光强波动补偿量以及探测元件1024提供的电信号，确定物镜1011的焦平面位置。
由于校准原理已经在前述实施例中描述过，故在此不做赘述。
在以上提供的各设备实施例中，作为可能的实现方式，自动聚焦模块还可以包括：扫描单元。探测元件1024和控制单元1025分别与扫描单元电连接。
扫描单元用于使待测物或者物镜1011沿着物镜1011的光轴方向移动扫描；
控制单元1025用于获得待测物和物镜1011之间的相对位置，以及探测元件1024获取的信号光强度之前的对应关系，并根据信号光强度峰值对应的相对位置确定物镜1011的焦平面位置。
例如，控制单元1025获得探测元件1024转换出的电信号的幅度分布曲线或电信号对应的光强分布曲线。根据幅度分布曲线或光强分布曲线，确定出峰值对应的位置，根据峰值对应的位置确定物镜1011的焦平面位置，控制光学处理模块相对于待测物移动，或者控制待测物相对于光学处理模块移动，以实现对待测物的聚焦。
基于前述实施例提供的光学设备，相应地，本申请还提供一种实现自动聚焦的方法。下面结合实施例进行描述。
方法实施例：
本实施例方法在具体实现时，利用前述设备实施例提供的光学设备来实现对待测物的自动聚焦和检测。
该方法需要确定出焦平面位置。在光学设备的光学处理模块与待测物发生相对移动的过程中，利用探测元件获得电信号；再根据电信号的大小确定出物镜的焦平面位置，并根据所述焦平面调整所述物镜和所述待测物的相对位置。例如，当电信号达到峰值时，将该峰值电信号的采集时刻标定平面镜(或待测物)所在的位置作为物镜的焦平面位置。确定该焦平面位置后，可以手动直接将待测物放置到该焦平面位置，也可以手动调节物镜的位置(远离或靠近待测物)，以使待测物能够恰巧处于物镜的焦平面上。
在本申请提供的技术方案中，光学设备为前述实施例提供的任意一种光学设备。其自动聚焦模块中包括光源和共聚焦器件，应用该激光光源和共聚焦器件即采用共聚焦技术，提升自动聚焦的精度。另外，在光学设备中以探测元件实现对光的采集和光电转换，其位探测阵列时，响应速度快(达到微秒或纳秒)，进行多点共聚焦，提升了自动聚焦的速度。该光学设备既满足了速度要求又满足了精度要求，可以很好地应用在对于自动聚焦精度具有较高要求的光学处理环节。
需要说明的是，本说明书中的各个实施例均采用递进的方式描述，各个实施例之间相同相似的部分互相参见即可，每个实施例重点说明的都是与其他实施例的不同之处。尤其，对于方法实施例而言，由于其基本相似于设备实施例，所以描述得比较简单，相关之处参见设备实施例的部分说明即可。以上所描述的设备及系统实施例仅仅是示意性的，其中作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元提示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部模块来实现本实施例方案的目的。本领域普通技术人员在不付出创造性劳动的情况下，即可以理解并实施。
以上所述，仅为本申请的一种具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到的变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应该以权利要求的保护范围为准。

Claims (22)

  1. 一种光学设备，其特征在于，包括：光学处理模块和自动聚焦模块；所述光学处理模块包括物镜；所述自动聚焦模块包括：光源、第一共聚焦器件、探测元件和控制单元；
    所述光源用于发射探测光，所述探测光经过所述物镜照射至待测物表面；所述探测光经所述待测物表面的光学作用形成信号光；
    所述物镜用于收集所述信号光，并使所述信号光到达所述第一共聚焦器件；
    所述第一共聚焦器件用于在所述待测物离焦时限制所述信号光穿过，所述第一共聚焦器件与所述物镜的焦平面共轭；
    所述探测元件用于采集穿过所述第一共聚焦器件的信号光，并将采集到的信号光转换为电信号；
    所述控制单元用于根据所述电信号确定所述物镜的焦平面位置，并根据所述焦平面调整所述物镜和所述待测物的相对位置；
    所述光学处理模块用于通过所述物镜对所述待测物进行光学处理。
  2. 根据权利要求1所述的光学设备，其特征在于，所述第一共聚焦器件还用于使所述探测光穿过；所述物镜还用于使穿过所述第一共聚焦器件的探测光到达待测物表面。
  3. 根据权利要求1所述的光学设备，其特征在于，所述自动聚焦模块还包括：第二共聚焦器件，用于对所述光源发射的探测光进行限制。
  4. 根据权利要求3所述的光学设备，其特征在于，所述第二共聚焦器件包括：一个或多个光受限单元，所述第二共聚焦器件与所述物镜焦平面共轭。
  5. 根据权利要求1、2或4所述的光学设备，其特征在于，所述探测元件包括多个探测器单元，所述第一共聚焦器件包括多个共聚焦单元，所述探测器单元用于分别接收穿过所述共聚焦单元的信号光。
  6. 根据权利要求5所述的光学设备，其特征在于，所述第一共聚焦器件还包括第一透镜阵列，所述第一透镜阵列包括多个透镜单元，各透镜单元用于收集信号光，分别将收集的信号光传递至不同的共聚焦单元。
  7. 根据权利要求5所述的光学设备，其特征在于，所述共聚焦单元为针孔单元或光纤。
  8. 根据权利要求5所述的光学设备，其特征在于，所述探测器单元为光电二极管或光电倍增管。
  9. 根据权利要求5所述的光学设备，其特征在于，当所述光学设备还包括所述第二共聚焦器件，所述第二共聚焦器件包括多个光受限单元时，各光受限单元透过的探测光经待测物表面的光学作用形成的信号光分别到达不同的共聚焦单元。
  10. 根据权利要求9所述的光学设备，其特征在于，各光受限单元透过的探测光经待测物表面形成的信号光分别被不同的探测器单元接收。
  11. 根据权利要求4所述的光学设备，其特征在于，所述光受限单元为针孔单元或光纤。
  12. 根据权利要求2所述的光学设备，其特征在于，所述第一共聚焦器件包括光纤；所述自动聚焦模块还包括：光纤耦合器，所述光纤耦合器包括第一端、第二端和第三端；所述第一共聚焦器件与所述第一端光连接，所述探测元件与所述第二端光连接；所述物镜与所述第三端光连接。
  13. 根据权利要求5所述的光学设备，其特征在于，所述自动聚焦模块还包括：第二透镜，用于收集穿过所述第一共聚焦器件的信号光；所述探测元件用于接收穿过所述第二透镜的信号光。
  14. 根据权利要求13所述的光学设备，其特征在于，所述第二透镜为单个透镜或透镜阵列；
    当所述第二透镜为透镜阵列时，该透镜阵列的透镜单元用于分别收集穿过不同共聚焦单元的信号光，并将穿过不同共聚焦单元的信号光分别提供给所述探测元件的不同探测器单元。
  15. 根据权利要求2所述的光学设备，其特征在于，所述自动聚焦模块还包括：第一分光元件，用于将所述光源发射的探测光分束，将其中的一束提供给所述第一共聚焦器件；
    所述第一分光元件，还用于将来自所述第一共聚焦器件的信号光提供给所述探测元件。
  16. 根据权利要求2所述的光学设备，其特征在于，所述光学处理模块还包括：第二分光元件；
    所述第二分光元件用于将来自所述自动聚焦模块的探测光反射提供给所述物镜，以及用于将所述物镜传输的信号光反射提供给所述自动聚焦模块。
  17. 根据权利要求1所述的光学设备，其特征在于，所述自动聚焦模块还包括：光强波动探测器和第三分光元件，所述第三分光元件用于对光源出射的探测光进行分光，所述光强波动探测器与所述控制单元电连接，用于采集所述第三分光元件分出的另一束光，将其转换成电信号，将该电信号提供给所述控制单元；
    所述控制单元还用于根据所述光强波动探测器提供的电信号获得光强波动补偿量；根据光强波动补偿量以及所述探测元件提供的电信号，确定所述物镜的焦平面位置。
  18. 根据权利要求15所述的光学设备，其特征在于，所述第一分光元件具体为偏振分光元件；所述自动聚焦模块还包括：偏振波片，用于接收穿过偏振分光元件的探测光，并将待测物返回的信号光传递至所述偏振分光元件，且使穿过所述偏振分光元件的探测光与到达所述偏振分光元件的信号光具有不同的偏振态。
  19. 根据权利要求1所述的光学设备，其特征在于，所述自动聚焦模块还包括：准直透镜组，用于接收穿过所述第一共聚焦元件的信号光，并对接收带的信号光进行准直；所述探测元件用于接收经所述准直透镜组准直的信号光。
  20. 根据权利要求1-4任一项所述的光学设备，其特征在于，所述自动聚焦模块还包括：扫描单元；所述探测元件和所述控制单元分别与所述扫描单元电连接；
    所述扫描单元用于使待测物或所述物镜沿着物镜的光轴方向移动扫描；
    所述控制单元用于获取待测物和物镜之间的相对位置，以及所述探测元件获取的信号光强度之间的对应关系，并根据所述信号光强度峰值对应的所述相对位置确定所述物镜的焦平面位置。
  21. 根据权利要求1-4任一项所述的光学设备，其特征在于，所述控制单元用于根据确定的所述焦平面位置，控制所述光学处理模块相对于所述待测物移动，或者控制所述待测物相对于所述光学处理模块移动，以实现对所述待测物的聚焦。
  22. 一种应用权利要求1-21任一项所述的光学设备实现自动聚焦的方法，其特征在于， 包括：
    在光学处理模块与待测物发生相对移动的过程中，利用探测元件获得电信号；
    根据电信号的大小确定出物镜的焦平面位置，并根据所述焦平面调整所述物镜和所述待测物的相对位置。
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