WO2017045641A1 - 分光片及其激光共轴测距仪和应用 - Google Patents

分光片及其激光共轴测距仪和应用 Download PDF

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Publication number
WO2017045641A1
WO2017045641A1 PCT/CN2016/099212 CN2016099212W WO2017045641A1 WO 2017045641 A1 WO2017045641 A1 WO 2017045641A1 CN 2016099212 W CN2016099212 W CN 2016099212W WO 2017045641 A1 WO2017045641 A1 WO 2017045641A1
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Prior art keywords
beam splitter
region
lens
light
optical axis
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PCT/CN2016/099212
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English (en)
French (fr)
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王治霞
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王治霞
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/10—Beam splitting or combining systems
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06—Systems determining position data of a target
    • G01S17/08—Systems determining position data of a target for measuring distance only
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
    • G02B27/283—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising used for beam splitting or combining

Definitions

  • the invention relates to the field of optical measurement and observation technology, and in particular to a beam splitter and a laser coaxial distance meter and application thereof.
  • Laser range finder is widely used in industrial, military, scientific research and other fields.
  • the general laser measuring instrument uses the laser emitting optical axis and the laser receiving optical axis to separate the working mode. This method is not only large in size, but also high in manufacturing cost. As well as low signal-to-noise ratio of measurement signals, there are large measurement difficulties for both close-range and long-distance measurements.
  • the conventional method adopts a method of transmitting and receiving a common aperture (coaxial method), and currently there are mainly three methods of coaxial methods, one is a semi-transparent/semi-reverse method, and the method is Approximately 50% of the emitted light energy is passed through the beam splitter to illuminate the object, and only 50% of the light energy returned from the object reaches the detector for detection, enabling laser emission and reception in the same optical path.
  • the semi-transparent/semi-reverse spectroscopy method is simple, reliable and easy to use, and is widely used in instrument manufacturing and laboratory. However, due to the low coupling efficiency of this method, it can only be used for the distance measurement of strong reflective objects at close range.
  • the other is the method of digging holes.
  • the method couples the laser beam through a small aperture of the boring beam splitter into the measurement system, using only a portion of the emission aperture.
  • the laser that returns the object is reflected to the receiving detector through the remaining part of the beam splitter.
  • the principle of the hole-cutting method is simple, and the efficiency of coupling splitting is relatively high. Only one hole-punching mirror is needed in the entire coupled beam splitting path, and there is no movable part, and the performance is stable.
  • the digging method divides the beam splitter into a transmitting aperture part (opening part) and a receiving aperture part (reflecting part), in order to make the emission energy as far as possible
  • the opening on the beam splitter it is necessary to increase the opening on the beam splitter as much as possible, but this will reduce the acceptance aperture, and a part of the laser light returned from the object leaks from the digging air, reducing the sensitivity of the system measurement.
  • the laser light reflected by the object is mainly distributed at the opening, so that the object cannot be detected normally, and the blind spot is easily formed.
  • the third coaxial method is a polarization coupling spectrometry method.
  • the basic principle of the technique is to use a polarization splitting device to reflect and transmit two beams perpendicular to each other in the polarization direction.
  • the polarized light in the emission direction is reflected by the polarization beam splitter, and becomes circularly polarized after passing through the ⁇ /4 wave plate.
  • the circularly polarized light returned from the object passes through the ⁇ /4 wave plate and becomes polarized light having a polarization direction of p.
  • the direction is perpendicular to the original polarization direction, and the polarization splitting light transmits all of the light, so that the polarization splitting sheet can realize efficient coupling splitting.
  • US20100321669 discloses a coaxial laser ranging laser range finder using a simple boring method.
  • the laser beam emitted by the laser diode is irradiated onto the lens through the boring hole in the beam splitter, and then becomes a parallel beam to illuminate the object.
  • the scattered light scattered by the object is concentrated on the beam splitter through the lens, and is reflected by the reflective portion on the beam splitter to the detector for detection.
  • This method is simple and the manufacturing cost is low.
  • the difficulty in laser ranging in this way is that the diode laser is a divergence angle of about 10°*40°, and the laser emitted from the diode will spread rapidly as the propagation distance increases.
  • This patent is for the lens output.
  • the laser is very thin, the hole on the beam splitter (slice) must be small, and the hole must be a large distance from the beam splitter, so that most of the laser light from the diode does not illuminate the object through the small hole, causing distant objects and light reflection.
  • Very weak objects are difficult to measure, such as directly increasing the hollowing out. Although more laser energy can be used to illuminate the object, more light returning from the object will leak through the hollowing, still unable to target distant objects or reflections. Objects with poor performance are detected.
  • the hollowing is on the optical axis of the measuring system, the energy of the reflected light will gradually attenuate with the center of the optical axis, and the energy of the reflected light outside the opening is very high. Low, there is little light reflected from the reflector to the detector, making it difficult to detect such objects.
  • the optical input surface and the output surface of the dichroic prism are generally perpendicular to the optical axis of the optical system, and the spectroscope is split (including transflective and transflective).
  • Polarization splitting In order to avoid the introduction of astigmatism and other aberrations, the beam splitter is generally placed in a parallel optical path, which not only complicates the optical system, but also limits the use of the beam splitter in the optical system.
  • the laser that emits the laser generally uses a semiconductor laser. Due to the limitation of the illumination principle of the laser, the laser itself has an inherent astigmatism, which is also difficult for the range finder to measure far. An important reason for the object.
  • the prism spectroscopy or boring splitting is used to eliminate the astigmatism of the LED, but in the optical system, the non-parallel optical path is split by the spectroscopic tilting arrangement, the incident light is transmitted through the spectroscope/splitter, and the reflected light is transmitted through the spectroscope/ The beam splitter is reflected to the receiving target. Both the intrinsic astigmatism of the light source and the astigmatism of the beam splitter are present, which seriously affects the performance of the optical system.
  • the boring method utilizes a binary spectroscopic method in which the distribution of the illumination light and the signal light on the beam splitter is different, that is, (the illumination light is all-pass, the region has no reflected signal light, and the whole The anti-region is totally anti-signal light and the region does not pass the illumination light.
  • the semi-transparent/semi-reverse and polarization splitting methods use the whole region to uniformly process the illumination light and the signal light.
  • the illumination light and The signal light is different in the distribution area of the beam splitter.
  • the hollowing out method utilizes this feature, the binary value of the illumination area makes the method difficult to achieve the desired effect for many detections.
  • a beam splitter comprising a beam splitter body, the beam splitter body having a first region for reflection and a second region for light transmission and reflection, the first region being a reflective region, the second region
  • the transflective or polarized light splitting region in use, the light beam emitted by the beam source is irradiated to the target through the second region, and the reflected light of the target is reflected by the second region and the first region.
  • the beam splitter When the beam splitter is applied in an optical system, the beam emitted by the beam source is irradiated to the target through the transflective or polarization splitting region, and the reflected light of the target passes through the reflective region and the second region (semi-transflective region or polarization). Spectral zone) reflection.
  • the transflective region referred to herein means a transflective region that is transmissive and reflective, and does not limit its half reflection to half transmission.
  • the second region is located at a central portion of the beam splitter body, the first region is located outside the beam splitter body; or the second region is located outside the beam splitter body, and the first region is located at the beam splitter body a central portion; or the first region and the second region are dispersed on the beam splitter body; the transflective region has a transmittance/reflectance of 0.2-9.
  • the middle portion here indicates the center of the beam splitter body, and the outside indicates the area on the beam splitter body with respect to the center periphery.
  • the transmittance/reflectance of the transflective region is greater than 1, and in the case of the ratio, the light beam can be transmitted more.
  • the beam splitter body comprises an optical glass
  • the first region of the optical glass is plated with a full-reflection film
  • the second region of the optical glass is plated with a transflective film or a polarizing beam splitting film.
  • the invention also provides a laser coaxial range finder, comprising the beam splitter, further comprising a beam source, a first lens and a detector, the first lens being located between the beam splitter and the target, the beam source The emitted light beam is irradiated to the target through the second region of the beam splitter and the first lens, and the reflected beam of the target is collected by the first lens and reflected by the first region and the second region to the detector.
  • the transflective or polarized light splitting region can also reflect a part of the light beam through a part of the light beam, so that the light beam reflected by the target object can also be partially reflected on the detector through the transflective or polarized light splitting region. , while reducing the loss of reflected light, making the results more accurate.
  • the range finder not only enables coaxial measurement of general objects, but also achieves coaxial measurement of distant objects, weak reflections, and specular objects.
  • a second lens for collecting the divergent light is disposed between the beam source and the beam splitter.
  • the first lens is a lens and the second lens is a collimating lens.
  • the beam splitter is disposed obliquely with respect to the optical axis, and the optical axis is the center line of the light beam.
  • the beam splitter has an elliptical shape centered on the optical axis, and the angle between the beam splitter and the optical axis is 30-60 degrees.
  • the elliptical center of the elliptical beam splitter may be offset from the incident optical axis.
  • the incident optical axis of the beam source is parallel to the optical axis of the first lens
  • the beam splitter is obliquely disposed
  • the astigmatism of the beam splitter partially cancels or cancels out the intrinsic astigmatism of the beam source
  • the beam source is The optical axis of the incident optical axis is offset from the optical axis of the first lens along a side close to the normal of the beam splitter such that the incident light passes through the beam splitter and approaches the optical axis of the first lens or coincides with the optical axis of the first lens.
  • the beam source is an illuminator having astigmatism, such as the semiconductor laser itself has an inherent astigmatism, the astigmatism generated by the beam splitter and the astigmatism of the semiconductor laser cancel each other, so that after the laser passes through the collimating/receiving first lens, Obtaining good parallel light, and adjusting the optical fiber axis of the parallel light to the optical axis of the first lens by adjusting the mounting position of the beam source relative to the first lens, so that the laser range finder has good performance. .
  • the astigmatism of the beam splitter is equal to the astigmatism of the beam source, positive and negative, and the astigmatism of the beam splitter and the tilt angle I, the index of refraction n and the thickness t of the beam splitter satisfy the following relationship:
  • the astigmatism of the beam splitter is equal to the inherent astigmatism of the laser diode, and the fast axis of the laser diode is In the meridian plane, and the slow axis is in the sagittal plane, the astigmatism of this system will be 0, which can get very parallel illumination light, thus obtaining a high performance laser ranging system.
  • the intrinsic astigmatism of the beam source can be matched to the eigen dispersion of the beam source by the parameters such as the refractive index, tilt angle (incident angle), thickness, etc. of the beam splitter.
  • the fast axis of the beam source is located in the meridional plane, the slow axis is in the sagittal plane, and the incident optical axis of the beam source is offset in the meridional plane with respect to the optical axis of the first lens; the incident optical axis of the beam source
  • the offset distance with respect to the optical axis of the first lens is D, and the inclination angle I, the refractive index n, and the thickness t of the beam splitter satisfy the following relationship:
  • the axis of the scattered light of the object is no longer perpendicular to the optical axis of the first lens after being reflected by the beam splitter, in order to obtain a better effect, not only
  • the position of the receiving target should be at the focus, and the receiving target surface should be perpendicular to the reflected optical axis of the scattered light, that is, the target surface of the detector and the reflected optical axis after the spectroscopic reflection vertical.
  • the astigmatism generated by the beam splitter and the astigmatism of the semiconductor laser cancel each other out, and the incident position of the beam source and the optical axis of the first lens is adjusted, so that the incident light passes through the beam splitter and then goes to the first
  • the optical axis of the lens is close to or coincides with the optical axis of the first lens, so that the laser passes through the first lens, and the parallel light is obtained, which improves the performance of the laser ranging system and can be adapted by changing various parameters of the beam splitter.
  • the astigmatism of the beam source and the offset distance of the incident optical axis relative to the optical axis of the first lens make it easier to manufacture.
  • the invention also provides an application of a beam splitter in an optical measuring system or viewing system.
  • the beam emitted by the beam source is irradiated to the target through the transflective or polarized beam splitting region, and the reflected light of the target is reflected by the reflective region and the beam is reflected to the measuring position or the viewing position through the transflective or polarizing beam splitting region.
  • the most important of these is the application of the beam splitter in the measurement and observation system.
  • the present invention provides a new coaxial spectroscopic method.
  • Applying such a beam splitter and a splitting method to the ranging method not only overcomes the problem that the system has a large volume, a complicated optical path, a high manufacturing cost, and a large adjustment difficulty in the measurement of the non-coaxial system.
  • it has the advantages of simple system, low manufacturing cost, high detection signal-to-noise ratio and convenient carrying, and it also overcomes the return of laser leakage of objects existing in current coaxial laser ranging.
  • For similar coaxial system ranging it can detect objects at a greater distance. Measurements can also be made for weak reflections and specular objects.
  • This beam splitter can be used not only for laser ranging, but also for epi-illumination microscopes, laser topography systems, stimulated raman spectroscopy, and more.
  • FIG. 1 is a schematic structural view of a beam splitter according to Embodiment 1 of the present invention.
  • Figure 2 is a cross-sectional view of the beam splitter of Figure 1;
  • Figure 3 is a cross-sectional view showing another structure of the beam splitter of Figure 1;
  • FIG 4, 5 and 6 are schematic views showing another structure of the distribution of the first region and the second region in the beam splitter.
  • FIG. 7 is a schematic diagram of a detection optical path of Embodiment 2 of the laser coaxial range finder of the present invention.
  • Embodiment 8 is a schematic diagram of a detection optical path of Embodiment 3 of the laser coaxial range finder of the present invention.
  • Embodiment 4 of a laser coaxial range finder according to the present invention.
  • Embodiment 5 is a schematic structural view of Embodiment 5 of a laser coaxial range finder according to the present invention.
  • Figure 11 is a schematic view showing the structure of a sixth embodiment of the laser coaxial range finder of the present invention.
  • a beam splitter includes a beam splitter, and the beam splitter body 31 has a first region B for reflection and a second region A for light transmission and reflection, the first A region B is a reflective region, and the second region A is a transflective or polarized light splitting region.
  • a light beam emitted by a beam source also called a light source
  • a beam source also called a light source
  • the target object The reflected light is reflected by the second area A and the first area B.
  • the second area A is located in the central portion of the beam splitter body 31, and the first area B is located in the outer area of the beam splitter body 31; the middle portion here indicates the center of the beam splitter body 31, and the outside The area on the beam splitter body 31 with respect to the center periphery is indicated.
  • Zone A is a transflective or polarized beam splitting zone. It causes the light from the beam source to pass through the area and illuminate the area. Some of the signal light returned from the object is leaked, but unlike the boring method, a part of it is reflected into the detection path. Outside the light-transmitting zone (A zone), it is a fully-reflected zone B, which will illuminate the zone, and all the signal light returned from the object is reflected into the probe beam path, thereby realizing beam splitting.
  • Zone B is the total reflection zone.
  • the transmittance of the region is generally required to be higher. Since the B region totally reflects the signal light, the reflection in the A region can be lower, and the transmittance/reflectance split ratio of the region is generally designed to be greater than 1.
  • Such a beam splitter can be fabricated on a flat plate or on a glued surface of a cemented prism.
  • the manufacturing method is similar to that of a phase contrast plate of a phase contrast microscope. For example, a semi-transparent film is first fabricated on a plate. The anti-splitting film is then shielded from the A region by a mask, and the total reflection film is vapor-deposited. Since the A region is blocked, the B region is the full-reverse region.
  • the spectrograph can also be made by other methods.
  • the beam splitter substrate 31 can be used as an optical glass or other transparent material such as a transparent plastic.
  • the central portion of the optical glass is covered with a beam splitting film 33, and the beam splitting film is a transflective film or a polarizing beam splitting film.
  • the beam splitting film is a transflective film or a polarizing beam splitting film.
  • the second region A adopts a reflective material 35 which is opaque and has a good surface smoothness, such as a silver-plated material or a steel plate; or may be directly opened in the middle of the reflective material 35 without using the optical glass 34 or the transparent plastic.
  • the hole is fixed to the reflective material 35 on the reflective material 35 to seal the hole, or the hole is provided as a stepped hole, and the spectral film 33 is fixed on the step of the hole. That is, the beam splitter body 31 is formed of a middle portion transparent material and an outer region opaque light reflecting material.
  • the material of the beam splitter body can also be made of other light transmissive materials.
  • the second area A is located outside the beam splitter body, and the first area B is located in the middle of the beam splitter body; or as shown in FIG. 5 and FIG. 6, the first area B and the The two regions A are dispersed on the beam splitter body or the like, and the distribution of the first region B and the second region A may be set according to the optical path.
  • the manner and structure of the production can also be as shown in FIG. 2 or FIG. 3.
  • the transflective region has a transmittance/reflectance of 0.2 to 9.
  • the invention also provides a spectroscopic system, which mainly adopts a beam splitter having a transflective region (or a polarization splitting region) and a reflective region.
  • the beam passes through a transflective region (or polarization) of the beam splitter.
  • the reflected light of the target is partially reflected by the reflective region, and can be reflected to a specified position for measurement or observation, etc.; part of the reflected light is reflected by the transflective region (or polarization splitting region) to Specify the position, which ensures the stability of the emitted beam and reduces the loss of reflected light.
  • the leakage of the reflected light from the hole portion is reduced, and the accuracy of the measurement or observation result is improved.
  • a structure such as a lens may be disposed on the optical axis before and after the beam splitter to shape the optical path.
  • the ideal effective utilization rate is 25%, but if the spectroscopic method of the spectroscopic sheet of the present invention is employed Because the B area is all-reverse, and many In the case, the area of the outer zone is much larger than the semi-transparent/semi-reverse zone (zone A), so that the reflected light energy is mostly distributed in the outer zone. If the transmittance/reflectance is 4, the light energy is generally The utilization rate can reach about 70%.
  • the ideal light energy utilization rate can reach 100%, but in reality, due to the lens action on the transmission channel and the reflection of the object, the polarization direction Rotation will occur, so that the actual light energy utilization rate can reach 50%. Since the windshield of the present invention has a large outer area and a high reflectance, the use of the spectroscopic sheet of the present invention for a general object can easily achieve a light energy utilization rate of 80% or more.
  • a laser coaxial range finder includes a laser 1 and a detector 5, and further includes a laser along the laser 1
  • the second lens 2, the beam splitter 3 and the first lens 4 are disposed in the optical axis direction, wherein the beam splitter 3 adopts any one of the structures of Embodiment 1, and the splitter 3 is provided with a transflective region (or a polarization splitting region).
  • the laser 1 is a laser diode, and in other embodiments, it may be a laser emitting device.
  • the first lens 4 and the second lens 2 are collimating lenses, and the beam splitter 3 is disposed obliquely with respect to the optical axis.
  • the laser 1, the second lens 2, the beam splitter 3 and the lens 4 constitute a transmitting system.
  • the object to be tested 6, the first lens 4, the beam splitter 3, and the detector 5 constitute a detection light path receiving system.
  • the splitting and reflecting area of the beam splitter 3 is as shown in FIG. 3, and the reflecting surface of the beam splitter 3 is realized by the laser reflecting optical axis and the receiving optical axis.
  • the splitting surface is divided into a transflective zone (or polarization splitting zone) and a reflective zone.
  • the region B in the figure is required. Reflect as much of the reflected light as possible, thus plating into a highly reflective area.
  • the inner region A of the beam splitter 3 is a transflective region (or a polarization splitting region).
  • the beam splitter 3 Since the beam splitter 3 is used obliquely, its shape can be selected as an ellipse centered on the optical axis, and the transmittance of the transflective region. / reflectance ratio of 0.2-9, in order to allow as much laser energy as possible to illuminate the object through the beam splitter 3, while allowing the light reflected by the object to reach the detector 5 as much as possible, in this case generally greater than 1, such as 7/3 Even 9/1 is OK.
  • the size and collimation of the transflective zone in the beam splitter 3 The area of the beam emitted by the mirror is matched on the area irradiated on the beam splitter 3.
  • the focal length of the collimating lens is generally short, so that the diameter of the beam emitted from the collimating lens is small, so that the half of the beam splitter 3
  • the size of the transflective zone can be smaller, which is beneficial to improve the signal-to-noise ratio of the detection signal.
  • the light emitting face of the laser diode is near the focus of the lens 4 and the collimating lens forming system.
  • the receiving system lens 4 is reflected by the beam splitter 3 to focus the light on the target surface of the detector 5, and therefore, the target surface of the detector 5 should be at the focus position of the receiving system.
  • the diverging laser light emitted by the laser diode is compressed to a small angle by the collimating lens, and the semi-transparent region of the optical sheet 3 is passed through with a very thin beam, so that most of the laser energy reaches the first lens 4 Then, it becomes a thin strong parallel beam, and is irradiated on the object 6 to be tested.
  • the laser light returned from the object to be tested 6 is concentrated by the first lens 4 and reflected by the beam splitter 3, and the laser light returned from the object is focused on the detector 5. On the target surface.
  • the beam splitter 3 is placed obliquely, and the tilt angle thereof is generally 45 degrees, and other angles of 30-60 degrees are also used as needed, as long as the target surface of the detector 5 is placed.
  • the object can be measured by determining the relationship (time relationship or phase relationship) between the received return signal and the light wave emitted by the laser diode in the vicinity of the focus of the first lens 4 deflected by the reflecting surface of the beam splitter 3. the distance.
  • the second lens 2 is removed from the second embodiment, and the light emitted by the laser 1 is collected by the aperture stop 7 of the obstructing object and then incident on the spectroscopic sheet 3.
  • This structure can also be Solve the problem of detecting blind spots.
  • the rest of the structure and principle are the same as in Embodiment 2.
  • the arrangement of the invention can be used for a laser phase ranging instrument, and can also be used for a laser pulse time ranging instrument.
  • This coaxial method can not only realize the detection of long-distance and weakly reflective objects, but also effectively avoid the blind spot problem of the specular reflection object. .
  • the beam splitter of the present invention can be applied to the field of optical measurement and observation.
  • the beam splitter comprises a transflective region and a reflective region, and the light beam emitted by the beam source is irradiated to the object to be tested through the transflective region, the object to be tested The reflected light is reflected by the reflective region and the transflective region to the detector or observer.
  • the performance of the laser ranging system is improved; in this example, on the basis of the embodiment 8,
  • the improvement is that the beam source is a semiconductor laser or a light emitting diode.
  • the fast axis of the beam source is located in the meridional plane, and the slow axis is located in the sagittal plane.
  • the astigmatism is also generated due to the tilting of the beam splitter 3.
  • the astigmatism generated by the beam splitter 3 and the beam source is at least partially offset, thereby improving the quality of the incident light, most preferably splitting.
  • the astigmatism of the slice 3 and the beam source are all cancelled out.
  • the incident optical axis O2 of the beam source is parallel to the optical axis O1 of the first lens 4, and the incident optical axis O2 of the beam source is offset in the meridional plane with respect to the optical axis O1 of the first lens 4, and the offset direction is near the beam splitter.
  • One side of the 3 normal line that is, when manufacturing the ranging system, the position of the optical axis O1 of the first lens 4 can be determined first, and then the mounting position of the beam source is along the beam splitter 3 with reference to the optical axis O1 of the first lens 4.
  • the side where the normal line is offset the specific offset distance can be determined according to the accuracy range that the ranging system can accept, so that the incident light passes through the beam splitter and closes to the optical axis of the first lens as much as possible.
  • the optical axes of the lenses coincide.
  • the principle that the astigmatism generated by the beam splitter 3 and the inherent astigmatism of the laser diode cancel each other out is that since the astigmatism of the laser diode is caused by its waveguide structure, the fast axis has a small light-emitting area and a large divergence angle, and its light-emitting position is generally at On the laser output surface, the slow axis has a large divergence angle due to the light-emitting output surface, and its light-emitting position is behind the laser output surface.
  • the distance difference between the two is astigmatism.
  • Different manufacturers have different astigmatism values for different lasers. Values typically range from a few microns to a few hundred microns. To take full advantage of the laser, the effects of astigmatism on the ranging system must be considered.
  • the beam splitter 3 When the beam splitter 3 is in the converging beam, the ideal converging light will cause aberrations. Although the beam splitter 3 has an influence on various aberrations of the optical system, for parallel thin plates, mainly astigmatism, this astigmatism makes The ray convergence position of the meridional plane no longer coincides with the ray ray convergence position of the sagittal plane, and the separation distance is the astigmatism caused by the slanting plate.
  • the astigmatism size of the beam splitter 3 is related to the thickness, the tilt angle, and the refractive index of the beam splitter 3. If the thickness of the beam splitter 3 is t, the tilt angle is I, and the refractive index is n, the astigmatism value l generated by the beam splitter 3 is :
  • the intrinsic astigmatism of the beam source can be matched by changing the refractive index, the tilt angle (incident angle), the thickness and the like of the beam splitter 3, so that the astigmatism of the beam splitter 3 is equal to and completely equal to the intrinsic astigmatism of the beam source.
  • the specific value may be deviated according to the degree of acceptance of the ranging system.
  • the astigmatism of the beam splitter 3 cancels the astigmatism of most of the beam sources.
  • the astigmatism of the beam splitter 3 is equal to the inherent astigmatism of the laser diode or laser 1, and the laser diode is made.
  • the fast axis of the laser 1 is in the meridian plane, that is, the paper surface in the figure; and the slow axis is in the sagittal plane, the astigmatism of the system will be 0, so that the parallel illumination light can be obtained, thereby obtaining high performance.
  • Laser ranging system the fast axis of the laser 1 is in the meridian plane, that is, the paper surface in the figure; and the slow axis is in the sagittal plane, the astigmatism of the system will be 0, so that the parallel illumination light can be obtained, thereby obtaining high performance.
  • the laser emitted by the laser diode having intrinsic astigmatism is offset by a half-reverse splitting plate astigmatism of thickness t placed at an angle of 45 degrees, so that the laser beam passes through the first lens 4 to form a parallel beam illumination.
  • Object due to beam splitter 3 There is a certain thickness in order to achieve the astigmatism offset generated by the laser diode intrinsic astigmatism and the tilt 45 transflective sheet 3 in the concentrated light.
  • the incident optical axis O2 of the laser diode is translated by a distance D in the meridional plane with respect to the optical axis O1 of the first lens 4.
  • the distance value D and the tilt angle I, the refractive index n and the thickness t of the beam splitter 3 satisfy the following relationship:
  • the thickness and refractive index of the direct material splitting film are calculated; for the multilayer material, it is necessary to integrate Considering the refractive index of the light-splitting film 33 and the substrate of the beam splitter body 31 (such as the optical glass 34), it is usually calculated by taking the intermediate value of the two; the thickness t of the beam splitter is the splitting film 33 and the beam splitter body 31 base. The total thickness of the material (such as optical glass 34) is superimposed.
  • the difference from the embodiment 4 in this example is that the obstruction with the small hole is replaced with the second lens 2, and the inclination angle of the beam splitter 3 in this example is changed, and is no longer 45°. Since the tilt angle is changed, the axis of the object scattered light is no longer perpendicular to the optical axis of the first lens 4 after being reflected by the beam splitter 3, as shown in FIG. 10, in order to obtain a better effect, not only the position of the detector 5 should be at the focus, Further, the target surface of the detector 5 should be perpendicular to the reflected optical axis of the scattered light, and the rest are the same as in the fourth embodiment.
  • the difference from the fifth embodiment is that the oblique direction of the beam splitter 3 is different in this example.
  • the normal line O1 of the beam splitter 3 is located above the optical axis O1.
  • the beam splitter 3 method is used.
  • the line N is located below the optical axis of the first lens 4, and the corresponding beam source shift direction and the position of the detector 5 change.

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Abstract

一种分光片（3）及其激光共轴测距仪和应用，包括光束源，还包括沿光轴方向依次设置的第二透镜（2）、分光片（3）和第一透镜（4），所述分光片（3）上设有半透半反区（A）和反射区（B），所述光束源发出的光束经半透半反区（A）和第一透镜（4）后形成平行光束照射至目标物（6），目标物（6）反射光束经第一透镜（4）聚拢并由反射区（B）和半透半反区（A）反射至测量位置或观察位置，该分光系统，可应用于测量系统或观察系统中。解决了挖孔法中存在的物体返回激光泄露造成检测盲点的问题，提高了检测的信噪比，对一般物体实现了共轴测量，也对远处物体、弱反射和镜面物体实现了共轴测量。

Description

分光片及其激光共轴测距仪和应用 技术领域
本发明涉及光学测量、观察技术领域，具体涉及一种分光片及其激光共轴测距仪和应用。
背景技术
激光测距仪目前已广泛应用于工业、军事、科学研究等领域，一般的激光测量仪器采用激光发射光轴和激光接收光轴分离的工作方式，这种方式不但仪器体积大、制造成本高、以及测量信号信噪比低，而且对近距离测量和远距离测量都存在较大的测量困难。
为了解决分离光轴存在的困难，传统的方法是采用发射和接收共孔径的方法(共轴方法)，目前采用的方法共轴方法主要有三种，一种是半透/半反方法，该方法使大约50％的发射光能量通过分光片来照明物体，而从物体返回的光能量也只有50％达到检测器用于检测，实现在同一光路中实现激光的发射和接收。半透/半反分光法简单可靠、使用方便，在仪器制造和实验室中得到广泛应用。但是由于这种方法耦合效率低，在只能用于近距离的强反射物体的测距。
另一种为挖孔法。该方法使激光束通过挖孔分光片的一个小孔耦合到测量系统中，发射激光仅使用了一部分发射口径。使物体返回的激光通过分光片的剩余部分反射到接收检测器，挖孔法原理简单，耦合分光的效率也比较高，整个耦合分光光路中只需要一块挖孔镜，没有可动部分，性能稳定,是一种简单可靠的共轴方法，在很多测距仪器中得到应用，但挖孔法将分光片分为发射孔径部分(开口部分)和接收孔径部分(反射部分)，为了使发射能量尽量的进入测量系统，需要尽量增大分光片上的开口，但这样会减少接受孔径，从物体返回的激光的一部分从挖空中泄露，降低了系统测量的灵敏度。另外，由于开孔的存在，当物体很接近镜面反射物体时，物体反射的激光主要分布在开口处，使得这种物体不能正常检测，容易形成测量盲点。
第三种共轴方法是一种偏振耦合分光方法，该技术的基本原理是用偏振分光器件将偏振方向相互垂直的两束线按偏振方向分别进行反射和透射。发射方向的偏振光被偏振分光片反射，在经过λ/4波片变为圆偏光，从物体返回的圆偏振光再次通过λ/4波片后将变为偏振方向为p的偏振光，偏振方向与原偏振方向垂直，偏振分光经将这种光全部透过，这样用偏振分光片就可以实现高效的耦合分光。这种方式的优点是全孔径分光，但由于要求激光是线偏振光，需要在系统中加入偏振片和波片，不但成本高，而且调制困难，由于在传输过程中偏 振方向很容易改变，使得测量很容易受到干扰。
US20100321669公开了一种采用简单的挖孔方式实现共轴激光测距激光测距仪，激光二极管发出的激光束经过分光片中的挖孔照射在透镜上后变成平行光束照射在物体上，经物体散射的散射光经透镜汇聚在分光片上，由分光片上的反射部分反射到检测器上进行检测。这种方式简单、制造成本低。但是这种方式在激光测距中的困难在于：二极管激光器是一种发散角在10°*40°左右，从二极管发出的激光随着传播距离的增加将很快扩散，该专利为了使透镜输出的激光很细，必须使分光片(片)上的孔很小，同时该孔必须距离分光片较大距离，使得大部分二极管激光发出的激光不通过小孔照明物体，造成远处物体和光反射很弱的物体测量困难，如直接增大挖空，虽然可以使更多的激光能量用于照明物体，但从物体返回的更多光将通过挖空泄露掉，仍然无法对远处物体或反射性能差的物体进行检测，另外，由于挖空处在测量系统的光轴上，对比较光滑的物体，反射光能量将随与光轴为中心程逐渐衰减的分布，造成开口外反射光能量很低，从反射板反射到过检测器的光很少，造成对这种物体的检测困难。
在光学系统中，为了避免分光系统的引入产生光学系统像差，一般都使分光棱镜的光输入面与输出面全部垂直于光学系统的光轴，而对分光板分光(包括半透半反和偏振分光)，为了避免引入像散和其他像差，一般都将分光板放置在平行光路中，这不但使光学系统变得复杂，而且限制了分光板在光学系统的使用。
在非平行光路中引入分光板，将产生附加的像差，影响系统性能，这些像差中影响系统性能最大的是像散。在美国专利申请20100321669和中国发明CN102798848A中，由于透过光是一个空气孔，相当于是一个反射镜，因此不会引起分光板分光光路中的附加相差。
另外，在这种测距仪中，发射激光的激光器一般都采用半导体激光器，由于这种激光器的发光原理限制，使得这种激光器本身就具有固有像散，这也是这种测距仪难以测量远处物体的重要原因。采用棱镜分光或挖孔分光，使发光二极管的像散消除，但在光学系统中对非平行光路，由于分光板倾斜设置进行分光，入射光透过分光镜/分光片，反射光经分光镜/分光板反射至接收靶。光源的本征像散和分光板的像散都存在，严重影响光学系统性能。
分析上面的这些分光方法发现：挖孔法利用的是照明光和信号光在分光板上的分布区域不同而采取的二值分光方法，即(照明光全通，该区域无反射信号光，全反区全反信号光而该区域不通过照明光。而半透/半反和偏振分光都采用全区域对照明光和信号光均匀处理方式。在很多情况，由于目标的多样性，照明光和信号光在分光板的分布区域是不同的，挖空法尽管利用了这一特点，但它照明区的二值性使得该方法对很多检测难以达到理想的效果。 为了弥补半透/半反和偏振分光在检测中的问题，有必要在设计分光光路上，将它们的分光方式与照明光和检测光在分光板上不同分布结合起来，得到更有效的分光系统。
发明内容
鉴于以上所述现有技术的不足，本发明的目的在于提供一种分光片，应用于光学系统中时，能够减少反射光的流失，使检测或观察结果更准确。
为实现上述目的及其他相关目的，本发明技术方案如下：
一种分光片，包括分光片本体，所述分光片本体上具有用于反射的第一区域以及用于透光和反射的第二区域，所述第一区域为反射区，所述第二区域为半透半反区或偏振分光区，在使用时，通过光束源发出的光束经第二区域照射至目标物，目标物的反射光经第二区域和第一区域反射。
该分光片应用于光学系统中时，光束源发出的光束经半透半反区或偏振分光区照射至目标物，目标物的反射光经反射区和第二区域(半透半反区或偏振分光区)反射。此处所说的半透半反区表示能够透射和反射的透射反射区，并不是限制其一半反射一半透射。
作为优选：所述第二区域位于分光片本体的中部，所述第一区域位于分光片本体的外部；或所述第二区域位于分光片本体的外部，所述第一区域位于分光片本体的中部；或所述第一区域和第二区域分散于分光片本体上；所述半透半反区的透射率/反射率为0.2-9。此处的中部表示分光片本体的中央，外部表示分光片本体上相对于中央外围的区域。
作为优选：所述半透半反区的透射率/反射率大于1，该比例的情况下能使光束透过更多。
作为优选：所述分光片本体包括光学玻璃，在所述光学玻璃的第一区域上镀有全反膜，在光学玻璃的第二区域上镀有半透半反膜或偏振分光膜。
本发明同时提供一种激光共轴测距仪，包括所述的分光片，还包括光束源、第一透镜和检测器，所述第一透镜位于分光片与目标物之间，所述光束源发出的光束经分光片的第二区域和第一透镜后形成平行光束照射至目标物，目标物反射光束经第一透镜聚拢并由第一区域和第二区域反射至检测器。
其中半透半反区或偏振分光区，能够透过一部分光束也能反射一部分光束，因此在经目标物反射后的光束也可以部分地经半透半反区或偏振分光区反射到检测器上，而减少反射光的流失，使结果更准确。该测距仪不但能够实现对一般物体的共轴测量，也对远处物体、弱反射和镜面物体实现共轴测量。
作为优选：所述光束源与分光片之间设置有用于将发散光聚拢的第二透镜。
作为优选：所述第一透镜为透镜，第二透镜为准直透镜。
作为优选：所述分光片相对于光轴倾斜设置，光轴为光束的中心线。
作为优选：所述分光片为以光轴为中心的椭圆形，所述分光片与光轴的夹角为30-60度。为了充分利用光能量，减小分光片尺寸，所述椭圆分光片的椭圆中心可以偏离于入射光轴。
作为优选：所述光束源的入射光轴与第一透镜的光轴平行，所述分光片倾斜设置，分光片的像散与光束源的本征像散部分抵消或全部抵消，且光束源被配置为入射光轴相对于第一透镜的光轴沿靠近分光片法线的一侧偏移，使得入射光穿过分光片后向第一透镜的光轴靠拢或与第一透镜光轴重合。
由于光束源为具有像散的发光器，如半导体激光器本身就具有固有像散，让分光片产生的像散和半导体激光器的像散互相抵消，从而使得激光通过准直/接收第一透镜后，得到很好的平行光，并且通过调整光束源相对于第一透镜的安装位置，使平行光的光轴尽量向第一透镜的光轴靠拢，从而使这种激光测距仪得到很好的性能。
所述分光片的像散与光束源的像散相等，正负抵消，分光片的像散l与分光片的倾斜角度I、折射率n和厚度t满足如下关系：
Figure PCTCN2016099212-appb-000001
从该关系可看出，在材料一定的情况下，即折射率不变，如果选择适当的厚度或倾角，使分光片的像散等于激光二极管的固有像散，并使激光二极管的快轴处在子午面内，而慢轴在弧矢面内，则这个系统的像散将为0，这样可以得到很平行的照明光，从而得到高性能的激光测距系统。
可以通过改变分光片的折射率、倾角(入射角)、厚度等参数，来匹配光束源的本征像散，使其与光束源的本征像散相等并抵消。
所述光束源的快轴位于子午面内，慢轴位于弧矢面内，所述光束源的入射光轴相对于第一透镜的光轴在子午面内偏移；所述光束源的入射光轴相对于第一透镜的光轴的偏移距离为D，D与分光片的倾斜角度I、折射率n和厚度t满足如下关系：
Figure PCTCN2016099212-appb-000002
由于可采用改变倾角的方法，当分光片与光轴的夹角不是45度时，物体散射光的轴线经分光片反射后不再与第一透镜光轴垂直，为了得到更好的效果，不但接收靶的位置应在焦点处，而且接收靶面应与散射光的反射光轴垂直，即检测器的靶面与分光片反射后的反射光轴 垂直。
通过改变分光片的各项参数，使分光片产生的像散和半导体激光器的像散互相抵消，通过调整光束源与第一透镜光轴的布置位置，使入射光穿过分光片后向第一透镜的光轴靠拢或与第一透镜光轴重合，从而使得激光通过第一透镜后，得到很好的平行光，提高了激光测距系统的性能，并且能够通过改变分光片的各个参数来适应光束源的像散以及决定入射光轴相对于第一透镜光轴的偏移距离，使其制造更容易。
本发明同时提供一种分光片在光学测量系统或观察系统中的应用。光束源发出的光束经半透半反区或偏振分光区照射至目标物，目标物反射光经反射区以及光束经半透半反区或偏振分光区反射至测量位置或观察位置。其中最主要的是分光片在测量、观察系统中应用。
如上所述，本发明的有益效果是：在光学系统中，本发明提供了一种新的共轴分光方式。将这种分光片和分光方式应用于测距，不但克服了非共轴系统测量中的存在的系统体积大，光路复杂、制造成本高、调整难度大的问题。即使相对于目前的共轴测距系统，它也具有系统简单、制造成本低、检测信噪比高、携带方便等优点，同时它还克服了目前共轴激光测距中存在的物体返回激光泄露造成检测盲点的问题。对同类的共轴系统测距，可检测更远处距离的物体。对弱反射和镜面物体也能进行测量。这种分光片不但可以用于激光测距，也可用于落射照明显微镜、激光形貌检测系统、受激raman光谱测量等。
附图说明
图1为本发明实施例1中分光片的结构示意图；
图2为图1中分光片的剖视示意图；
图3为图1中分光片另一种结构的剖视图；
图4、图5和图6为分光片中第一区域和第二区域分布的另一种结构示意图。
图7为本发明激光共轴测距仪实施例2的检测光路原理图；
图8为本发明激光共轴测距仪实施例3的检测光路原理图；
图9为本发明激光共轴测距仪实施例4的结构示意图；
图10为本发明激光共轴测距仪实施例5的结构示意图；
图11为本发明激光共轴测距仪实施例6的结构示意图。
零件标号说明
1   激光器
2   第二透镜
3   分光片
31  分光片本体
32  全反膜
33  分光膜
34  光学玻璃
35  反光材料
4   第一透镜
5   检测器
6   待测物体
7   小孔光栏
O1  第一透镜的光轴
O2  入射光轴
具体实施方式
以下由特定的具体实施例说明本发明的实施方式，熟悉此技术的人士可由本说明书所揭露的内容轻易地了解本发明的其他优点及功效。
实施例1
如图1和图2所示，一种分光片，包括分光片，所述分光片本体31上具有用于反射的第一区域B以及用于透光和反射的第二区域A，所述第一区域B为反射区，所述第二区域A为半透半反区或偏振分光区，在使用时，通过光束源(也称光源)发出的光束经第二区域照射至目标物，目标物的反射光经第二区域A和第一区域B反射。
如图1所示，本例中所述第二区域A位于分光片本体31的中部区域，第一区域B位于分光片本体31的外部区域；此处的中部表示分光片本体31的中央，外部表示分光片本体31上相对于中央外围的区域。
一般情况，信号光由于物体的散射，在分光片上的分布区域都比照明光的分布区域大得多，最直观的设计是如图1所示，图中，在分光片被分为A区和B区，A区为半透半反区或偏振分光区。它使光束源发出的光透过该区，而照射在该区上，从物体返回的信号光有一部分虽然被泄露掉一些，但与挖孔法不同，仍然有一部分被反射到探测光路中。在透光区(A区)外，则是全反射的B区，它将照射在该区上，从物体返回的信号光全部反射到探测光路中，从而实现光束分光。对偏振分光，由于是通过旋转偏振方向分别实现S光和P光的透射 和反射，所以，它的A区就是普通的偏振分光膜。而B区则是全反射区。对于半透/半反分光法，由于A区既要使光源的透过区，也是信号光的反射区，为了使光源发出的光有效的照明物体，一般该区的透过率要求高一些，而由于B区对信号光全反射，所以A区的反射可以低一些，该区的透射率/反射率分光比一般设计为大于1。
这种分光片的制作即可制造在平板上，也可以制造在胶合棱镜的胶合面上，其制造方法类似于相衬显微镜的相衬板的制造方法，比如，先在板上制造半透半反分光膜，然后，在用掩膜遮挡A区，在蒸镀全反射膜，由于，A区被遮挡，所以，B区就是全反区。这里只是一个例子，分光片也可采取其他方法制造。
进一步如图2所示，分光片基材31可使用为光学玻璃或其他透明材料如透明塑料，在光学玻璃的中部区域覆盖有分光膜33，分光膜为半透半反膜或者偏振分光膜，从而形成可以透光和反射的第二区域A，在光学玻璃的外部区域覆盖全反膜32从而形成全反射的第一区域B；当然如图3所示，第一区域B仍然采用光学玻璃34上镀分光膜33的方式，第二区域A采用不透明且表面光洁度较好的反射材料35，如镀银的材料或者钢板等；也可不使用光学玻璃34或透明塑料，直接在反射材料35中部开孔，将分光膜33固定在反射材料35上，封住该孔；或者将孔设置成阶梯孔，将分光膜33固定在孔的台阶上。即分光片本体31采用中间部分透明材料和外区不透明反光材料制成的结构。其中分光片本体的材料也可以采用其他透光材质。
如图4所示，所述第二区域A位于分光片本体的外部，所述第一区域B位于分光片本体的中部；或如图5和图6所示，所述第一区域B和第二区域A分散于分光片本体上等，第一区域B与第二区域A的分布可以根据光路设置。其制作方式及结构也可以采用图2或图3的方式。本例中，所述半透半反区的透射率/反射率为0.2-9均可。
本发明同时提供一种分光系统，该分光系统主要采用了具有半透半反区(或偏振分光区)和反射区的分光片，使用时，光束经分光片的半透半反区(或偏振分光区)后照射至目标物上，目标物的反射光线部分经反射区反射，可以反射至指定位置进行测量或观察等；部分的反射光线经半透半反区(或偏振分光区)反射至指定位置，如此即保证了发射光束的稳定，又减少了反射光线的流失。特别是相对于挖孔法以及测镜面物体，减少了反射光从孔部的泄露，提高了测量或者观察结果的准确性。当然根据需求，还可以在分光片前后的光轴上布置透镜等结构，以便对光路进行整形。
本发明分光板较传统均匀分光板的优势：
对于半透/半反分光镜，由于均匀分光，在光源的有效利用率发生在分关比1:1时，这时理想的有效利用率为25％，但如果采用本发明分光片的分光方式，由于B区是全反，而很多 情况下，外区的区域比半透/半反区(A区)大得多，使得反射的光能量大部分分布在外区，如采用透射率/反射率为4，则一般情况下，光能利用率可达70％左右。
对均匀偏振分光，由于在分光板上，光源入射光与信号光偏振方向垂直，理想情况光能利用率可达100％，但实际上，由于传输通道上的透镜作用和物体的反射，偏振方向会发生旋转，使得实际光能利用率能达到50％就不错了。本发明的风光片，由于外区大，而且反射率很高，对一般物体，采用本发明的分光片，光能利用率很容易达到80％以上。
对挖空方式分光，对散射很大的物体，由于信号光在分光板散射很开，它的光能利用率可达到70％～80％，但如果对散射不高的反射物体或对光有汇聚能力的物体，到达分光板的信号光虽然很强，但返回的信号光时主要分布在挖孔内，将不会产生反射，光能利用率几乎为0，所以对这种物体探测困难，而本发明的分光方式，由于采用半透/半反方式或偏振分光方式，即使在这种情况，仍然有15％左右的能量利用率。
实施例2
本例中主要以分光片在激光共轴测距仪的应用为例进行详细描述，如图7所示，一种激光共轴测距仪，包括激光器1和检测器5，还包括沿激光器1光轴方向依次设置的第二透镜2、分光片3和第一透镜4，其中分光片3采用实施例1的任意一种结构，分光片3上设有半透半反区(或偏振分光区)和反射区，激光器1发出的光束经第二透镜2聚焦成细光束后，穿过半透半反区(或偏振分光区)，经第一透镜4后形成平行光束照射至待测物体6，待测物体6反射光束经第一透镜4聚拢并由反射区反射至检测器5进行检测。本例中激光器1为激光二极管，其他实施例中可以为类似激光发射装置。第一透镜4，第二透镜2为准直透镜，所述分光片3相对于光轴倾斜设置。
激光器1、第二透镜2、分光片3和透镜4构成发射系统。而待测物体6、第一透镜4、分光片3和检测器5构成检测光路接收系统。
为了在使接受到的物体反射光信号有较高的信噪比，分光片3的分光、反射区如图3所示，在分光片3的反射面是实现激光反射光轴和接收光轴共轴的关键部件，为了实现共轴，将分光面分成半透半反区(或偏振分光区)和反射区两个区域，参照图1，在分光片3的外部区域，图中区域B，要求将尽量多的反射光反射，因此镀制成高反射区。分光片3的内部区域A为半透半反区(或偏振分光区)，由于分光片3是倾斜使用，它的形状可选择为以光轴为中心的椭圆，半透半反区的透射率/反射率比为0.2-9，为了使尽量多的激光能量透过分光片3照射物体，同时使物体反射的光能尽量多的达到检测器5，本例中一般大于1，如7/3，甚至9/1都可。为了利用激光二极管发出的光能量，分光片3中半透半反区的大小与准直透 镜出射的光束在分光片3上照射的区域匹配。
在发射系统中，为了充分利用激光二极管发出的光能量，同时具有较小的体积，准直透镜的焦距一般都很短，这样从准直透镜出射的光束直径很小，使得分光片3中半透半反区的尺度可以更小，有利于提高检测信号的信噪比。为了用准直光束照明测量物体，激光二极管的发光面处在透镜4和准直透镜构成系统的焦点附近。
为了检测从远处物体返回的激光，接收系统透镜4经分光片3反射将光聚焦在检测器5的靶面上，因此，检测器5的靶面应处在接收系统的焦点位置。
在进行测量时，激光二极管发出的发散激光经准直透镜被压缩到一个小角度，同时用很细的光束过分光片3的半透半反区域，使得绝大部分激光能量达到第一透镜4后成为一根细的强平行光束，照射在待测物体6上，从待测物体6返回的激光经第一透镜4汇聚并经分光片3反射，将物体返回的激光聚焦在检测器5的靶面上。为了实现接收光路和激光发射光路共轴，分光片3采用倾斜放置，其倾斜角度一般采用45度，根据需要，也用采用其他30-60度的角度放置，只要使检测器5的靶面处在被分光片3反射面偏折的第一透镜4的焦点附近即可，通过确定接收到的返回信号与激光二极管发射的光波之间的关系(时间关系或相位关系)，就可测量出物体的距离。
实施例3
如图8所示，本例中相对于实施例2中去掉了第二透镜2，而激光器1发出的光通过遮挡物的小孔光栏7聚拢后射到分光片3上，该结构同样能够解决检测盲点的问题。其余结构和原理均与实施例2相同。
本发明布置可用于激光相位测距仪器，也可用于激光脉冲时间测距仪器，这种共轴方式不但能实现远距离、弱反射物体的检测，而且，有效的避免了镜面反射物体的盲点问题。
本发明的分光片可以应用于光学测量和观察领域，所述分光片包括半透半反区和反射区，所述光束源发出的光束经半透半反区照射至待测物，待测物反射光经反射区和半透半反区反射至检测器或观察者。可以用于光学频谱仪、落射显微镜、激光打孔机等。
实施例4
如图9所示，为了使分光片3的像散与光束源(激光器1)之间的像散部分或完全抵消，提高激光测距系统性能；本例中在实施例8的基础上进行了改进，其中，光束源为半导体激光器或发光二极管等，光束源的快轴位于子午面内，慢轴位于弧矢面内，由于分光片3倾斜设置也会产生像散。通过选择分光片3的折射率n和厚度t以及分光片3的装配角度I，使得分光片3与光束源产生的像散至少部分地抵消，从而提高入射光的质量，最优选的是分光 片3与光束源的像散全部抵消。光束源的入射光轴O2与第一透镜4的光轴O1平行，且光束源的入射光轴O2相对于第一透镜4的光轴O1在子午面内偏移，偏移方向为靠近分光片3法线的一侧，即在制造测距系统时，可先确定第一透镜4的光轴O1位置，然后以第一透镜4的光轴O1为参考将光束源的安装位置沿分光片3法线所在的一方偏移，具体偏移的距离可以根据测距系统能够接受的精度范围确定，使得入射光穿过分光片后尽量向第一透镜的光轴靠拢，当然最佳是与第一透镜光轴重合。
采用上述结构，由于半导体激光器本身就具有固有像散，让分光片3产生的像散和半导体激光器的像散互相抵消，从而使得激光通过第一透镜4后，得到很好的平行光，从而使这种激光测距仪得到很好的性能。
使分光片3产生的像散与激光二极管固有像散互相抵消的原理是，由于激光二极管的像散是由其波导结构引起，快轴由于发光区域小，发散角大，其发光位置一般处在激光输出面上，而慢轴由于发光输出面大发散角小，其发光位置在激光输出面的后面，它们二者的距离差就是像散，不同厂家，不同激光器的像散值一般不同，其值一般在几微米到几百微米范围，要想充分利用激光，就必须考虑像散值对测距系统的影响。
当分光片3处在汇聚光束中，将使理想的汇聚光产生像差，虽然分光片3对光学系统的各种像差都有影响，但对于平行薄板，主要是像散，这个像散使子午面的光线汇聚位置与弧矢面光线汇聚位置不再重合，其分离距离就是倾斜板引起的像散。
分光片3的像散大小与分光片3的厚度、倾斜角度和折射率有关，如分光片3的厚度为t，倾角为I，折射率为n，则分光片3产生的像散值l为：
Figure PCTCN2016099212-appb-000003
因此，可以通过改变分光片3的折射率、倾角(入射角)、厚度等参数，来匹配光束源的本征像散，使分光片3的像散与光束源的本征像散相等并完全抵消；具体数值可以根据测距系统能接受的程度存在一定偏离，如分光片3的像散抵消大部分光束源的像散也可。从该关系可看出，在材料一定的情况下，即折射率不变，如果选择适当的厚度或倾角，使分光片3的像散等于激光二极管或激光器1的固有像散，并使激光二极管或激光器1的快轴处在子午面内，即图中纸面；而慢轴在弧矢面内，则这个系统的像散将为0，这样可以得到很平行的照明光，从而得到高性能的激光测距系统。
本例中，具有本征像散的激光二极管发出的激光经倾斜45度放置的厚度为t的半透半反分光后板像散被抵消，使得激光束通过第一透镜4后形成平行光束照明物体，由于分光片3 有一定厚度，为了实现激光二极管本征像散与倾斜45半透半反分光片3在汇聚光中产生出的像散抵消。激光二极管的入射光轴O2相对于第一透镜4的光轴O1在子午面内平移一个距离D，其距离值D与分光片3的倾斜角度I、折射率n和厚度t满足如下关系：
Figure PCTCN2016099212-appb-000004
在计算像散l和偏移距离D时，需要知道分光片的折射率n和分光片厚度t，对于单层材料，直接材料分光膜的厚度和折射率进行计算；对于多层材料，要综合考虑分光膜33和分光片本体31基材(如光学玻璃34)的折射率，通常可采用取两者中间值的方式计算；分光片的厚度t，则是分光膜33和分光片本体31基材(如光学玻璃34)叠加的总厚度。
实施例5
本例中与实施例4不同之处在于，将带小孔的遮挡物替换成了第二透镜2，并且本例中分光片3的倾斜角度发生变化，不再是45°，这种情况下，由于改变了倾角，物体散射光的轴线经分光片3反射后不再与第一透镜4光轴垂直，如图10，为了得到更好的效果，不但检测器5的位置应在焦点处，而且检测器5靶面应与散射光的反射光轴垂直，其余均与实施例4相同。
实施例6
如图11所示，与实施例5不同之处在于，本例中分光片3的倾斜方向不同，实施例5中分光片3法线N位于的光轴O1上方，本例中分光片3法线N位于第一透镜4光轴下方，对应的光束源偏移方向和检测器5位置发生变化。
任何熟悉此技术的人士皆可在不违背本发明的精神及范畴下，对上述实施例进行修饰或改变。因此，举凡所属技术领域中具有通常知识者在未脱离本发明所揭示的精神与技术思想下所完成的一切等效修饰或改变，仍应由本发明的权利要求所涵盖。

Claims (13)

  1. 一种分光片，其特征在于：包括分光片本体，所述分光片本体上具有用于反射的第一区域以及用于透光和反射的第二区域，所述第一区域为反射区，所述第二区域为半透半反区或偏振分光区，在使用时，光束源发出的光束经第二区域照射至目标物，目标物的反射光经第二区域和第一区域反射。
  2. 根据权利要求1所述的分光片，其特征在于：所述第二区域位于分光片本体的中部，所述第一区域位于分光片本体的外部；或所述第二区域位于分光片本体的外部，所述第一区域位于分光片本体的中部；或所述第一区域和第二区域分散于分光片本体上；所述半透半反区的透射率/反射率为0.2-9。
  3. 根据权利要求2所述的分光片，其特征在于：所述半透半反区的透射率/反射率大于1。
  4. 根据权利要求1所述的分光片，其特征在于：所述分光片本体包括光学玻璃，在所述光学玻璃的第一区域上镀有全反膜，在光学玻璃的第二区域上镀有半透半反膜或偏振分光膜。
  5. 一种激光共轴测距仪，其特征在于：包括权利要求1至4任意一项所述的分光片，还包括光束源、第一透镜和检测器，所述第一透镜位于分光片与目标物之间，所述光束源发出的光束经分光片的第二区域和第一透镜后形成平行光束照射至目标物，目标物反射光束经第一透镜聚拢并由第一区域和第二区域反射至检测器。
  6. 根据权利要求5所述的激光共轴测距仪，其特征在于：所述光束源与分光片之间设置有用于将发散光聚拢的第二透镜。
  7. 根据权利要求6所述的激光共轴测距仪，其特征在于：所述第一透镜为透镜，第二透镜为准直透镜。
  8. 根据权利要求5所述的激光共轴测距仪，其特征在于：所述分光片相对于光轴倾斜设置。
  9. 根据权利要求8所述的激光共轴测距仪，其特征在于：所述分光片为以光轴为中心的椭圆形，所述分光片与光轴的夹角为30-60度。
  10. 根据权利要求5至9任意一项所述的激光共轴测距仪，其特征在于：所述光束源的入射光轴与第一透镜的光轴平行，所述分光片倾斜设置，分光片的像散与光束源的本征像散部分抵消或全部抵消，且光束源被配置为入射光轴相对于第一透镜的光轴沿靠近分光片法线的一侧偏移，使得入射光穿过分光片后向第一透镜的光轴靠拢或与第一透镜光轴重合。
  11. 根据权利要求10所述的激光共轴测距仪，其特征在于：所述分光片的像散与光束源的像散相等，正负抵消，分光片的像散l与分光片的倾斜角度I、折射率n和厚度t满足如下关系：
    Figure PCTCN2016099212-appb-100001
  12. 根据权利要求10所述的激光共轴测距仪，其特征在于：所述光束源的入射光轴相对于第一透镜的光轴的偏移距离为D，D与分光片的倾斜角度I、折射率n和厚度t满足如下关系：
    Figure PCTCN2016099212-appb-100002
  13. 一种如权利要求1至4任意一项所述的分光片在光学测量系统或观察系统中的应用。
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