89 results about "Beam polarization" patented technology

The invention provides a self-adaptive polarization modulation-based inter-satellite laser communication and signal scheduling method, which relates to the field of laser communication, and comprises the following steps of: acquiring polarization state information of emitted and received light beams, calculating a mismatch degree, generating a compensation parameter, constructing a polarization state prediction model by using a deep learning neural network for pre-correction, and calculating the mismatch degree; a polarization modulator is adopted to perform real-time modulation and establish a link quality evaluation model, carrier synchronization and channel compensation are realized based on an adaptive optical carrier recovery technology of coherent detection, a link state is monitored in real time, and a training data set is updated.

The invention provides an optical cross system based on silicon-based liquid crystal and a control method, and relates to the field of optical elements, and the optical cross system comprises an optical fiber array, a micro lens array, a collimating lens, a polarization conversion module, a dispersion element, a focus lens group and a liquid crystal spatial light modulator. Optical signals are coupled through the micro-lens array, a divergence angle is compressed, and parallel light beams are formed through the double-agglutination collimating lens; the polarization conversion module separates the light beam into P / S polarized light and unifies the polarization state; the dispersion element separates light beams according to wavelength space, and the focus lens group forms an elliptical Gaussian light spot on the liquid crystal spatial light modulator; the liquid crystal spatial light modulator divides a light spot into a plurality of independent control areas in the long-axis direction, and single-wavelength multi-port output, power proportion regulation and control and monitoring signal extraction are achieved by dynamically modulating the reflection phase of each area. The control method comprises the steps of optical path processing, regionalized phase modulation and real-time monitoring feedback. According to the invention, flexible routing, power balance and lossless monitoring of wavelength channels can be realized.

The embodiment of the invention provides an optical system and 3D measuring equipment, and relates to the technical field of machine vision, the optical system comprises a polarization regulation and control module and a polarization module, the polarization module is used for reflecting a light beam in a first polarization direction and transmitting a light beam in a second polarization direction, and the polarization regulation and control module is used for regulating the polarization direction. The polarization direction adjusting module is used for adjusting the polarization direction of the laser beam from a first polarization direction to a second polarization direction; a light beam in a first polarization direction of the incident system is reflected by the module to enter the polarization regulation and control module along a first direction, is reflected by the polarization regulation and control module to enter the polarization module along a second direction, and is transmitted from the polarization module. Through the embodiment of the invention, light path folding is realized, the size of the optical system is reduced, the working size of the 3D measurement equipment is further reduced, the 3D measurement equipment can be more suitable for a narrow and compact space, ambient light interference is reduced, and the application scene is expanded.

A multi-unit wavelength selective switch (WSS) is disclosed. The WSS includes a plurality of WSS units, each WSS unit comprising a waveguide array for providing a light beam for propagation in the multi-unit WSS, and for receiving, in a wavelength-selective manner, the light beam propagated in the multi-unit WSS. A polarizing collimator splits each light beam into polarized collimated first and second sub-beams propagating in the multi-unit WSS along separate optical sub-paths. The polarized sub-beams of each light beam may be redirected by separate redirector arrays, e.g. liquid crystal on silicon (LCoS) arrays of a redirector array assembly specific to each light beam launched into the multi-unit WSS. Using separate redirector arrays to handle polarization sub-beams provides for a greater flexibility of optical configuration, allowing the use of inexpensive, off-the-shelf redirector arrays.

The present disclosure relates to an optical detection device, a particle analysis system, and a particle analysis method, the optical detection device comprising: a light source assembly configured to generate a detection light beam; the polarization separation assembly and the light source assembly are oppositely arranged relative to the working plane; the polarization separation assembly is configured to divide an imaging light beam generated by interaction of the detection light beam and the sample to be detected into a first imaging light beam transmitted along a first light path and a second imaging light beam which is transmitted along a second light path and has a second polarization direction; the first light detector is arranged on the first light path, and the first light detector is configured to generate a first imaging image based on the first imaging light beam; and the second light detector is arranged on the second light path, and the second light detector is configured to generate a second imaging image based on the second imaging light beam.

A 3D printing device includes a light control module, a light source module, and a receiving slot. The light source module provides a light beam to the light control module. The receiving slot receives a photo-curing material. The light control module is between the light source module and the receiving slot. The photo-curing material is cured by the light beam. The light control module includes first and second substrates, a dielectric layer, and a polarizing element. The first substrate has outer and inner surfaces opposite to each other. The second substrate is opposite to the first substrate. The dielectric layer is between the inner surface of the first substrate and the second substrate. The polarizing element is on the outer surface of the first substrate. A polarization degree of the polarizing element for a light beam having a wavelength range of 375 nm to 405 nm is 98% to 100%.

A light detection and ranging (LIDAR) system for a vehicle includes a laser source, a polarization grating, a first scanner, and a second scanner. The laser source is configured to output a beam. The polarization grating is configured to direct the beam, based on a polarization of the beam, along either a first path as a first output beam or a second path as a second output beam. The first scanner is configured to receive the first output beam from the first path and output the first output beam as a first scan beam. The second scanner is configured to receive the second output beam from the second path and output the second output beam as a second scan beam.

The invention relates to the technical field of microscopic imaging, and particularly provides a stimulated Raman scattering microscopic imaging system capable of simultaneously scanning double Raman frequency shift spectrums, which comprises a laser light source driving and modulating unit and a signal detecting and data processing unit, the laser light source driving and modulating unit comprises a dual-channel laser synchronous excitation module, a light beam polarization regulation and power distribution module, a pulse broadening and spectrum focusing module, a dual-channel dual-phase modulation module, a common-path different-time dual-frequency difference module and a laser scanning and telecentric focusing module; and the signal detection and data processing unit comprises a dual-channel orthogonal demodulation module and a scanning driving and signal synchronous acquisition module. Compared with the prior art, the dual-Raman frequency shift spectrum scanning stimulated Raman microimaging device has the advantages that dual-Raman frequency shift spectrum scanning stimulated Raman microimaging with higher acquisition speed, high resolution and wide spectrum coverage range is realized, and the problem of long time consumption for acquiring the complete spectrum of the to-be-tested sample by the traditional single-frequency resonance spectrum scanning stimulated Raman microimaging is solved.

The present invention provides a laser radar, comprising a light emitting device, a polarization splitting device, a beam adjusting device, a scanning device, and a light receiving device. The light emitting device is adapted to emit a probe beam for detecting a target; the polarization splitting device is adapted to reflect the probe beam and transmit an echo beam that has undergone polarization state adjustment and focusing processing by the beam adjusting device; the beam adjusting device is adapted to perform focusing processing and polarization state adjustment on the probe beam reflected by the polarization splitting device and the echo beam reflected by the scanning device; the scanning device is adapted to reflect the probe beam that has undergone focus processing and polarization state adjustment by the beam adjusting device to scan a target and reflect the echo beam reflected by the target; and the light receiving device is adapted to receive the echo beam transmitted by the polarization splitting device. The laser radar provided by the present invention can reduce costs and size while ensuring the required detection accuracy and detection range of the laser radar.

The application belongs to the technical field of optical switching, and particularly relates to an LCOS-based OCS optical switch, which comprises a collimating and polarizing module, a first LCOS, an achromatic Fourier transform lens group and a second LCOS. The collimating and polarizing module collimates, separates and converts a first light beam to obtain a first group of P light beams containing two P light beams. The first LCOS modulates and deflects the first group of P light beams to obtain a second group of P light beams containing a plurality of P light beams emitted at different deflection angles. The achromatic Fourier transform lens group deflects and transforms the waist of the second group of P light beams to obtain a third group of P light beams. The second LCOS modulates and deflects the third group of P light beams to obtain a fourth group of P light beams containing a plurality of P light beams emitted at the same deflection angle. The polarizing and focusing module converts, combines and focuses the fourth group of P light beams into a second light beam composed of S light and P light. The first light beam enters the OCS input port, and the second light beam is output from the OCS output port, so as to realize an optical switching technical scheme which is less affected by external vibration, has good stability and low implementation cost.

This application provides a radar system and a target detection method. The radar system provided includes a beam transmission control component, a polarization angle modulator, an antenna array with adjustable linear polarization, a signal receiving and processing unit, and a computer. The beam transmission control component generates a transmitted signal. The polarization angle modulator modulates the transmitted signal according to the beam polarization angle indicated by the computer. The computer determines the beam polarization angle for each modulation cycle, and based on the beam polarization angle corresponding to each modulation cycle and the processing information corresponding to that modulation cycle, determines the polarization response characteristics of the target, and detects the target based on the target polarization response characteristics during target detection and tracking. The radar system and target detection method provided in this application can improve the signal-to-noise ratio, identification capability, and anti-interference ability of the radar system for detecting small, slow-moving targets.

The application discloses a phase screen-based array photonic orbital angular momentum beam quantum control system, and belongs to the technical field of quantum control.The application is used for solving the problem of mutual overlapping and interference among sub-beams of an array photonic orbital angular momentum beam.The application comprises a laser, a beam shaping unit, a polarization control unit and a quantum state control unit;the beam shaping unit is used for spatially filtering and expanding a laser beam generated by the laser to generate parallel light beams;the polarization control unit is used for performing polarization control on the parallel light beams output by the beam shaping unit to generate linearly polarized light beams with horizontal polarization states;the quantum state control unit is used for performing array photonic orbital angular momentum control on the linearly polarized light beams to obtain array photonic orbital angular momentum light beams, and each sub-beam in the array is independent;and the application can be used for generating array photonic orbital angular momentum light beams with independent sub-beams through a compact optical path.

The invention provides a method for testing the optical density of an absorption type laser goggles, and relates to the technical field of laser detection. The method for testing the optical density of the absorption type laser protective goggles comprises the following specific steps: S1, placing equipment: sequentially placing a laser light source, an attenuator, a polarization beam splitter prism, an aperture diaphragm I, a semi-transparent and semi-reflective prism, a photoelectric detector I, an aperture diaphragm II and a photoelectric detector II, other parts are arranged on the same straight line; s2, setting a light source: turning on a laser light source and preheating; and S3, releasing the light source: opening the aperture diaphragm I, and enabling the emergent light beam of the laser light source to enter the polarization beam splitter prism through the attenuator. A device for generating linear polarized light and monitoring the polarization state of a light beam entering the surface of the protective glass is introduced into a test light path, so that laser energy before and after a to-be-detected product is added does not generate large fluctuation, and the accuracy of an optical density detection result is further improved.

The present application discloses an optical touch module, an optical touch method, and a touch terminal. The optical touch module includes: a linearly polarized light source for emitting a linearly polarized light beam to a touch area; a polarization photosensitive component including N polarization photosensitive units arranged in an array, each of the polarization photosensitive units having a polarization angle, wherein at least three of the polarization photosensitive units are staggered and have different polarization directions from each other, and each of the polarization photosensitive units is configured to receive a reflected light beam corresponding to the linearly polarized light beam reflected by an occluder in the touch area and output a corresponding detection value; and a processor connected to the polarization photosensitive component for receiving the detection value and determining a movement state of the occluder in the touch area according to the detection value.

The invention discloses a blue light coherent tuning locking narrow linewidth output system, and belongs to the technical field of blue light semiconductor laser. The output system comprises a space beam combining module and a double-external-cavity tuning locking module. The space beam combining module outputs a blue light beam; the double-external-cavity tuning locking module comprises an adjustable wave plate, a polarization splitting prism, a first external cavity and a second external cavity; the adjustable wave plate changes the polarization state of the blue light beam, and the proportion of the mixed polarized light beam is adjustable; the polarization splitting prism separates P polarized light and S polarized light in the mixed polarized light beam; the first outer cavity processes the S polarized light and then returns the S polarized light to the space beam combining module according to an original light path, so that the wavelength is locked and the line width is compressed; the second outer cavity outputs one part of the P polarized light, and the other part of the P polarized light returns to the space beam combining module according to an original light path after being processed; the receiver receives P polarized light fed back in the second outer cavity and transmits the P polarized light to the upper computer, and spectral parameters of feedback light beams are obtained. And relatively high beam quality and laser power are realized.

The present invention discloses a three-port reflective optical circulator based on a birefringent crystal, belonging to the field of optical communications. The three-port reflective optical circulator comprises a first birefringent crystal, a half-wave plate assembly, a roof prism, a Faraday rotator crystal, a second birefringent crystal, a quarter-wave plate, and a reflector, which are arranged in sequence. The first port, the second port, and the third port are respectively located on a side of the first birefringent crystal away from the half-wave plate assembly. The birefringent crystal performs light splitting to split a light beam into two sub-beams, o-polarized light and e-polarized light, with mutually perpendicular polarization directions. The polarization directions of the sub-beams are controlled by the half-wave plate, the quarter-wave plate, and the Faraday rotator crystal. Finally, the birefringent crystal performs light combining, thus realizing the functions of the optical circulator with input at the first port and output at the second port, and with input at the second port and output at the third port. The three ports are located on the same side of the optical circulator, making it easier to arrange other components and miniaturizing the optical circulator.

The application provides an N+1 laser interference lithography system, comprising: a light source module, which controls the exposure dose of a laser beam emitted by a laser by using an electrically controlled clock valve device, and controls the laser beam to be incident to a rotating light splitting module at 45°; the rotating light splitting module splits the amplitude of the laser beam to obtain N+1 coherent beams with similar energy, and modulates the spatial position of N edge coherent beams; a beam arm, which is used for controlling a 1 center coherent beam to be directly incident to a sample table capable of rotating by 360° and moving in three dimensions, and respectively controlling N edge coherent beams to be incident to the sample table from the same side or different sides at a specified incident angle with the 1 center coherent beam; and the sample table, which is placed with a substrate material, and a double-sided periodic or three-dimensional periodic micro-nano structure is prepared by converging the N+1 coherent beams. The system can flexibly control the light splitting ratio, the beam polarization state, the interference angle and the number of participating beams to obtain periodic structures with more parameters and pattern changes.

The invention relates to an optical device (10) for changing the polarisation (12) of a polarised light beam (14). The optical device (10) has a beam input (16) for the polarised light beam (14), which can enter the beam input (16) of the optical device (10) along a first propagation axis (18), and a beam output (20) for the polarised light beam (14), which can exit the beam output (20) of the optical device (10) along a second propagation axis (22). Furthermore, the optical device (10) has a plurality of deflecting elements (24), each of which is designed to deflect the polarised light beam (14) within the optical device (10), wherein at least one of said deflecting elements (24) is designed to change at least one polarisation component of the polarised light beam (14). The optical device (10) also has a beam path (26), which is formed within the optical device (10) by means of the deflecting elements (24) starting from the beam input (16) to the beam output (20) of the optical device (10). According to the invention, the deflecting elements (24) are arranged in such a way that they can be rotated together about an axis of rotation (28). Furthermore, according to the invention, the first propagation axis (18), the second propagation axis (22) and the axis of rotation (28) are parallel to one another.

The invention relates to the technical field of LED epitaxial wafers, in particular to an LED epitaxial wafer, a preparation method of the LED epitaxial wafer and an LED chip, and the method comprises the following steps: firstly, carrying out cleaning and hydrofluoric acid etching treatment on a sapphire substrate, and growing a Sn-doped Li5GaO8 buffer layer through pulse laser deposition; then growing an n-type GaN layer through a chemical vapor deposition method, preparing a ZnGa2O4 seed layer through pulsed laser deposition, forming an InGaN quantum dot array through strain induced phase separation, then constructing a gradient In component quantum well, depositing a BaTiO3 ferroelectric layer through magnetron sputtering, and neutralizing a built-in electric field through electron beam polarization; and finally, growing a gradient doped p-type GaN layer by adopting a circulating annealing process, and assembling a KZnPO4 nanosheet ordered array on the surface of the gradient doped p-type GaN layer by adopting a vertical pulling technology. Therefore, the problems of poor heat dissipation, low luminous efficiency, high efficiency attenuation, short service life and the like of the LED epitaxial wafer are solved.

The present disclosure relates to the technical field of holographic optical waveguide, and provides a holographic grating preparation system and a preparation method. The holographic grating preparation system comprises: a laser light source for generating a laser beam; a polarization light splitting component for splitting the laser beam into two beams and adjusting the light intensity and the beam polarization direction of the split laser beams, so that the polarization directions of the two split laser beams are perpendicular to the horizontal plane and parallel to the rotation axis of the mirror; a mirror group for mirror reflecting the split laser beams output by the polarization light splitting component to form two intersecting laser beams with a set angle, and the set angle is adjusted according to the rotation angle of the mirror group; and a recording medium for receiving the two intersecting laser beams, recording the interference fringes of the two intersecting laser beams through the refractive index and / or transmittance changes varying with the two intersecting laser beams, and forming a holographic grating.

The invention relates to the technical field of optical detection, in particular to a light beam polarization dynamic analysis device based on a metasurface. The device comprises a polarization analysis function unit array, and each function unit is composed of four subunits: a left-handed rotation light detection unit, a right-handed rotation light detection unit, a vertical line polarization detection unit and a horizontal line polarization detection unit. Synchronous detection of a pair of orthogonal circular polarized light and a pair of orthogonal line polarized light is realized based on a chiral sub-wavelength micro-nano structure and a sub-wavelength cuboid structure respectively. The device can be pasted or directly processed on a camera target surface, and global polarization analysis is realized through area array arrangement. The invention solves the problems of complex system and poor environmental adaptability of the existing polarization phase-shifting interference measurement technology, has the advantages of simplified structure, high detection precision, strong environmental robustness and the like, and is suitable for dynamic optical surface shape detection application.

The application provides a method and system for simultaneously measuring transverse vibration and angular jitter of a Hermite-Gaussian beam, comprising: expanding a Gaussian light source, and modulating a phase diagram corresponding to the Hermite-Gaussian beam on a spatial light modulator; passing the Hermite-Gaussian beam through a pre-selection, separating horizontal polarization components and vertical polarization components of the beam, perceiving vibration and jitter of a perception unit, and converting the transverse vibration and jitter, and passing the polarization state of the beam through a post-selection; and making the beam incident on the spatial light modulator, modulating a phase diagram corresponding to a projection measurement base for transverse vibration signals and angular jitter signals, converting the projection measurement transverse vibration and angular jitter signals into light intensity information, measuring the light intensity and converting it into a voltage signal, and inputting the voltage signal into a spectrum analyzer to demodulate amplitudes and frequencies of the transverse vibration signals and the angular jitter signals.

The invention provides an (N + 1)-beam laser interference photoetching system, which comprises a light source module for controlling the exposure dose of a laser beam emitted by a laser by using an electric control clock valve device and controlling the exposure dose to enter a rotary light splitting module at 45 degrees; the rotary light splitting module is used for carrying out amplitude division light splitting on the laser beams to obtain N + 1 coherent light beams with similar energy, and modulating the spatial positions of the N edge coherent light beams; the light beam arm is used for controlling one central coherent light beam to directly enter a sample table which can rotate by 360 degrees and move in a three-dimensional manner; and respectively controlling the N edge coherent light beams and the central coherent light beam to be incident to the sample table from the same side or different sides at a specified incident angle, a substrate material is placed on the sample table, and the N + 1 coherent light beams are converged, so that the double-sided periodic or three-dimensional periodic micro-nano three-dimensional structure is prepared. The system can flexibly regulate and control the splitting ratio, the light beam polarization state, the interference angle and the number of participating light beams so as to obtain a periodic structure with more parameters and pattern changes.

The invention provides a reflective bidirectional light-passing magneto-optical switch, which relates to the technical field of optical communication and comprises an optical fiber collimation coupling unit, a polarization beam splitting and combining unit, a polarization state regulation and control unit, a reflection unit and a magnetic field generation and control unit which are sequentially arranged along an optical path. The 45-degree half-wave plate and the Faraday optical rotation crystal are configured to regulate and control light beam polarization, and it is ensured that optical signals are accurately guided to the output end after passing through the birefringent crystal. According to the design, the input port and the output port are integrated on the same side, compared with a transmission type structure, the magneto-optical switch has the advantages of being small in size, high in material utilization rate and compact in layout, the flexibility and adaptability of the magneto-optical switch are remarkably improved, bidirectional reversible transmission of an optical path is achieved, and the application requirement for bidirectional information interaction between channels is met.

The application provides a kind of classical entanglement-based optical beam axial rotation measurement method and system, comprising: after single-frequency laser light source is expanded, the phase diagram corresponding to Hermite-Gaussian light beam is modulated, and higher purity Hermite-Gaussian light source is generated after filtering system;The horizontal component and vertical component of the polarization state of the light beam are introduced by pre-selection, and the axial rotation in opposite directions is introduced, and then the polarization state of the light beam is passed through post-selection, so that the optical beam axial rotation parameter is carried by spatial mode entanglement state;The phase diagram corresponding to the mode entanglement state carrying parameter of the light beam after post-selection is modulated, Fourier lens is passed through, and fiber tail fiber is used for receiving;Projection measurement converts optical beam axial rotation parameter into light intensity information, measures the light intensity obtained by projection measurement, converts into electrical signal and inputs into spectrum analyzer, and demodulates the size of optical beam axial rotation.The application has higher measurement accuracy compared with the existing optical beam axial rotation measurement scheme.

The invention discloses a laser amplifier and a method for avoiding thermal depolarization of a side pump. According to an exemplary embodiment, a laser amplifier comprises: a vector polarization conversion device for converting linearly polarized light into light in a single vector polarization state; and a side pump module for amplifying the light incident on the side pump module. According to the technical scheme provided by the invention, only one vector polarization component exists in the module through the polarization conversion device, and thermal depolarization does not occur in single radial or angular vector polarization under cylindrical symmetric anisotropic refractive index distribution, so that thermal depolarization does not occur no matter whether a light beam passes through a crystal rod for one time or multiple times, and therefore, the reliability of the module is improved. Therefore, the influence of the thermal depolarization effect of the side pump module on the polarization state of the light beam is reduced, and the amplification quality of the high-energy picosecond laser and the stability of an amplification system are improved.

There are disclosed systems for generating super-polarized electromagnetic radiation comprising a source providing a source beam of electromagnetic radiation, a beam splitter having a selected transmission-reflection coefficient ratio, a rotator that provides equivalence to an orthogonal rotation of modes, a two-channel polarizer having polarization axes orthogonal to each other, and a means for directing the two beams from the beam splitter to the corresponding inputs of the two-channel polarizer, wherein the first beam polarization axis is in axial alignment with the first input polarization axis of the two-channel polarizer and orthogonal to the second input polarization axis of the polarizer, wherein the rotator is positioned in the second beam to provide equivalence to an orthogonal rotation of modes on the second beam, wherein the paths traveled by the first beam the second beam are equal, and wherein the output beams combine to form an output beam including super-polarized modes.

The invention relates to the technical field of optical measurement, and provides a cholesteric liquid crystal refractive index measurement method, device and equipment and a medium. According to the method, when a target polarization grating is in an abnormal diffraction state, incident parameters of an incident beam and emergent parameters of an emergent beam are collected; and the actual optical characteristics of the cholesteric liquid crystal are directly reflected in the measurement process. A Mueller matrix is constructed on the basis of incident parameters and emergent parameters, polarization state changes of light beams are described, the influence of cholesteric liquid crystal molecule arrangement on the light polarization state is more accurately captured, and measurement errors caused by optical property differences are reduced. Ellipsometry parameters are calculated through a Mueller matrix, and key features of light beam polarization state changes are further extracted. According to the method, the ellipsometry parameters are analyzed through the parameter fitting model, the refractive index of the target polarization grating is directly generated, measurement errors caused by structural differences in related technologies are avoided, and therefore the accuracy and reliability of measurement results are remarkably improved.

The application discloses a kind of laser pump sources, including base, and first light emitting unit, second light emitting unit, beam combination unit and coupling unit are arranged on base;First light emitting unit and / or second light emitting unit are obliquely arranged in the direction of emitting light beam, so that the light outlet of first light emitting unit and the light outlet of second light emitting unit are located at different heights, and the optical path of obliquely arranged first light emitting unit and / or second light emitting unit is provided with a pressure light reflector, and the pressure light reflector is used to press the oblique light emitted by first light emitting unit and / or second light emitting unit into horizontal light;Beam combination unit is used for polarized beam combination of light beam emitted by first light emitting unit and second light emitting unit, and coupling unit is used for coupling the light beam after polarization beam combination into optical fiber.The laser pump source of the application not only has compact structure, but also has lower spectral width.

The disclosure provides an optical device, including: a light source, used to emit a beam; a polarizing beam splitting layer, located on an optical path of the beam and splitting the beam into a first beam and a second beam, wherein the first beam passes through the polarizing beam splitting layer, the second beam is reflected by the polarizing beam splitting layer, the first beam has a first polarization direction, and the second beam has a second polarization direction perpendicular to the first polarization direction; a phase retardation element, located on an optical path of the second beam, wherein the second beam passes through the phase retardation element at least once to become a third beam with the first polarization direction; a lens, located on the optical paths of the first beam and the third beam, wherein the first beam and the third beam respectively pass through the lens.