CN113670824B

CN113670824B - Non-contact type micro photoacoustic imaging head and imaging device thereof

Info

Publication number: CN113670824B
Application number: CN202110942449.XA
Authority: CN
Inventors: 陈松良; 周加胜
Original assignee: Shanghai Jiaotong University
Current assignee: Shanghai Jiaotong University
Priority date: 2021-08-17
Filing date: 2021-08-17
Publication date: 2022-08-19
Anticipated expiration: 2041-08-17
Also published as: CN113670824A

Abstract

The application provides a miniature photoacoustic imaging head of non-contact, including optic fibre and lens, optic fibre and the coaxial alignment setting of lens. The non-contact photoacoustic imaging device comprises a non-contact miniature photoacoustic imaging head, an excitation light source, a detection light source, a beam splitter, a photoelectric detector, a beam expanding and shaping module, a wavelength division multiplexer, an optical fiber circulator and a collection card. According to the application, in non-contact photoacoustic microscopic imaging based on photoacoustic remote sensing, the miniaturization of an imaging head, the simplification of the construction and the convenience of use of an imaging system and the simplification of the imaging system in multi-mode imaging development are realized.

Description

Non-contact type micro photoacoustic imaging head and imaging device thereof

Technical Field

The application relates to the field of photoacoustic imaging, in particular to a non-contact type micro photoacoustic imaging head and an imaging device thereof.

Background

Photoacoustic imaging technology has gradually become a powerful tool in the biomedical field. In this technique, a pulsed laser having a pulse width of nanosecond order is generally used as excitation light to irradiate a sample. When the photon energy of the laser is absorbed by the sample, the photon energy is converted into heat, which causes instantaneous thermal expansion inside the sample. This thermal expansion causes a pressure change inside the sample and propagates in the form of an acoustic wave to the outside of the sample, which is detected by an ultrasonic probe placed around the sample, and the resulting signal is a so-called photoacoustic signal. Since the ultrasonic waves are strongly attenuated in air, it is necessary to use an ultrasonic couplant (such as water or a medical ultrasonic couplant) between the sample and the ultrasonic probe or immerse the sample in water if a photoacoustic signal of sufficient intensity is to be obtained. It can be seen that this contact detection method is undesirable in certain application scenarios. For example:

(1) for photoacoustic imaging of cerebrovascular or capillary vessels in burned skin, which have strict requirements on hygiene, the contact detection method may cause pollution.

(2) The use of these ultrasound coupling agents in imaging the blood vessels of the eye, such as the retina, can cause discomfort to the patient and even risk blindness to the critically ill.

(3) In such conventional photoacoustic imaging at present, an ultrasonic probe made of a piezoelectric material is generally used to detect ultrasound. When this type of ultrasonic probe is used in a photoacoustic endoscope, the sensitivity of ultrasonic detection is not high due to the characteristics of the piezoelectric material because of its small size, and the quality of the resulting photoacoustic image is not high. Meanwhile, due to the opaque characteristic of the ultrasonic probe, excitation light in the photoacoustic endoscope can be shielded, so that the design of the traditional photoacoustic endoscope is complex, and the further popularization of the photoacoustic imaging technology in the endoscopic imaging field is not facilitated. The above-mentioned shortcomings of conventional photoacoustic have prompted researchers to move photoacoustic imaging technology toward non-contact photoacoustic signal detection.

Photoacoustic remote sensing (PARS) microscopic imaging is a novel photoacoustic imaging method with non-contact characteristics proposed by Haji Reza et al in 2017. In this method, instead of using a conventional piezoelectric ultrasound probe to capture ultrasound signals, a probe light, which is confocal with the excitation light, is used to detect photoacoustic signals of the object. As mentioned above, after the sample absorbs the energy of the excitation light, a transient thermal expansion occurs inside the sample, and thus a pressure change occurs. According to the photoelastic effect, the change of the pressure can cause the refractive index of the sample to change instantaneously, so that the reflection intensity of the detection light changes, the change of the reflection light intensity can be captured by a photoelectric detector, and the obtained signal is a photoacoustic signal. Because the magnitude of the photoacoustic signal is proportional to the absorption of the excitation light and the intensity of the detection light, under the condition of keeping the intensity of the detection light irradiating the sample unchanged, the magnitude of the photoacoustic signal at different positions of the sample can be obtained according to the instantaneous change intensity of the detected reflected light at different positions of the sample, and therefore the scanning imaging of the sample is realized. It can be seen that in the method, the photoacoustic signal of the sample can be measured only by using one beam of probe light, and an ultrasonic couplant is not needed, so that the purpose of non-contact scanning imaging is achieved. Compared with other non-contact photoacoustic signal detection methods, in the photoacoustic remote sensing microscopic imaging technology, only the reflectivity change of the probe beam needs to be monitored, and the change is independent of the phase of the probe light. Therefore, the photoacoustic remote sensing microscopic imaging technology is insensitive to phase noise and artifacts caused by the probe beam, the sample and the propagation medium, so the photoacoustic remote sensing microscopic imaging has high stability in performance. At present, the prior art reports that photoacoustic remote sensing microscopic imaging has good application potential in the fields of pathological assessment, intraoperative histology, ophthalmic imaging and the like.

At present, all photoacoustic remote sensing microscopic imaging devices in the prior art are built based on free space light, which brings great inconvenience to the application and clinical popularization of the technology.

(1) The current photoacoustic remote sensing microscopic imaging apparatus is not suitable for imaging of large volume or large weight samples. Because the position of an optical component needs to be kept constant in a system based on free space light, when imaging is carried out, a sample is mainly fixed on an electric control displacement platform, the electric control displacement platform is controlled to move the sample, point-by-point scanning is completed, and the volume or the weight of the scanned sample is usually small. However, when the sample volume is too large and the weight is heavy, for example, when some parts of a human or other large animals are subjected to photoacoustic remote sensing microscopic imaging, the common electrically-controlled displacement platform cannot meet the requirement. Meanwhile, when a large-volume or heavy sample is moved, the sample is easy to shake, and for a photoacoustic remote sensing micro-imaging device with the resolution of micron level, an image obtained by scanning is blurred, and even scanning cannot be finished.

(2) The large volume of the photoacoustic remote sensing micro-imaging device based on free space light makes it difficult to use in certain scenarios, such as photoacoustic scanning inside the oral cavity and inside the digestive tract.

(3) Systems based on free-space light are complex to build. In a photoacoustic remote sensing imaging device based on free space light, a plurality of optical components are required, and it is difficult to ensure confocal of excitation light and detection light. In addition, when combined with other optical methods, such as fluorescence imaging or optical coherence tomography, the whole imaging device is especially complex, which greatly increases the difficulty of constructing the optical system, and is not favorable for further development of photoacoustic remote sensing microscopic imaging technology.

(4) The optical imaging device built based on free space light is not high in stability. Because the imaging device is built based on the optical component, the position or the posture of the optical component may be changed in the moving process of the imaging device, and the imaging level of the whole system is further influenced, so that the robustness of the photoacoustic remote sensing system based on the free space light is poor.

Although there is already prior art that uses fiber optics (e.g. fiber optic circulator) to simplify photoacoustic remote sensing microscopic imaging apparatus. However, the imaging head is still based on free space light, including dichroic mirrors, scanning galvanometers, etc., and many of the above disadvantages still exist. Therefore, further development is still needed to construct the miniaturization of the photoacoustic remote sensing microscopic imaging device based on the optical fiber and the imaging head thereof.

Therefore, it is desirable for those skilled in the art to develop a non-contact micro photoacoustic imaging head and an imaging apparatus thereof, which are used to solve the above technical problems in the prior art.

Disclosure of Invention

In order to solve the above technical problem, an object of the present application is to provide a non-contact micro photoacoustic imaging head, which includes an optical fiber and a lens, wherein the optical fiber is coaxially aligned with the lens.

Further, the optical fiber and the lens are coaxially fixed in alignment by a glass tube.

Further, the glass tube comprises an inner glass tube and an outer glass tube, and the outer glass tube is sleeved outside the inner glass tube.

Further, the optical fiber is a single mode optical fiber, and the end face of the single mode optical fiber is cut at an 8-degree inclination angle.

Further, the single mode optical fiber is used for simultaneously transmitting the excitation light, the detection light and the reflected light from the object to be measured.

Another objective of the present application is to provide a non-contact photoacoustic imaging apparatus, including the above-mentioned non-contact miniature photoacoustic imaging head, which is characterized in that it further includes an excitation light source, a detection light source, a beam splitter, a photodetector, an expanded beam shaping module, a wavelength division multiplexer, an optical fiber circulator and a collection card, the excitation light source is connected to the incident end of the beam splitter, the first emergent end of the beam splitter is connected to the incident end of the expanded beam shaping module, the emergent end of the expanded beam shaping module is connected to the first port of the wavelength division multiplexer, and the third port of the wavelength division multiplexer is connected to the non-contact miniature photoacoustic imaging head; a second emergent end of the beam splitter is connected with an optical port of a first photoelectric detector, and an electrical port of the first photoelectric detector is connected with the acquisition card; the detection light source is connected with a first port of the optical fiber circulator, and a second port of the optical fiber circulator is connected with a second port of the wavelength division multiplexer; and a third port of the optical fiber circulator is connected with an optical port of a second photoelectric detector, and an electrical port of the second photoelectric detector is connected with the acquisition card.

Further, excitation light is emitted from the excitation light source, sequentially passes through the beam splitter, the beam expanding and shaping module and the wavelength division multiplexer, and is emitted from the non-contact type micro photoacoustic imaging head to an object to be measured; the detection light is emitted from the detection light source, passes through the optical fiber circulator and the wavelength division multiplexer in sequence, and is emitted to the object to be detected from the non-contact type micro photoacoustic imaging head; after the exciting light passes through the beam splitter, a part of the exciting light reaches a first photoelectric detector; and the light reflected from the object to be detected sequentially passes through the non-contact type micro photoacoustic imaging head, the wavelength division multiplexer and the optical fiber circulator and reaches the second photoelectric detector.

Furthermore, the beam expanding and shaping module is connected with the first port of the wavelength division multiplexer, the third port of the wavelength division multiplexer is connected with the non-contact micro photoacoustic imaging head, the detection light source is connected with the first port of the optical fiber circulator, the second port of the optical fiber circulator is connected with the second port of the wavelength division multiplexer, and the third port of the optical fiber circulator is connected with the second photodetector through single mode optical fibers.

Further, the beam splitting ratio of the beam splitter is 10: 90.

further, the beam expanding and shaping module comprises a lens and an adjustable pinhole.

Compared with the prior art, the technical scheme provided by the application at least has the following beneficial technical effects:

1. the problem of large imaging head volume of the photoacoustic remote sensing microscopic imaging device is solved. (the diameter of the non-contact micro photoacoustic imaging head 8 of the present application is only 3 mm, and the head can be developed into a handheld imaging head or an endoscopic imaging head in the future.)

2. The photoacoustic remote sensing microscopic imaging device based on the optical fiber improves the problems that the building is not easy, the use is inconvenient and the system stability is poor.

3. As the non-contact type micro photoacoustic imaging head only needs to use a glass tube to coaxially align and fix the single-mode optical fiber and the focusing lens, the difficulty of free-space optical confocal alignment can be avoided, and the system is easier to set up.

4. This application can fix the miniature optoacoustic imaging head of non-contact on two-dimentional automatically controlled displacement platform, removes this imaging head and scans, and need not remove the sample for it is more convenient to use, especially to the live body animal experiment.

5. Since the whole optical path is guided by the optical fiber, the whole imaging device is more stable.

6. When the photoacoustic imaging device based on the optical fiber is combined with other non-contact optical imaging methods (such as fluorescence imaging and optical coherence tomography), the purpose can be achieved only by welding different optical fiber devices, the system can be built simply, and the further development of the imaging method in multi-mode imaging is facilitated.

Drawings

FIG. 1 is a schematic view of a non-contact photoacoustic imaging system according to one embodiment of the present application;

FIG. 2 is a schematic structural diagram of a non-contact micro photoacoustic imaging head used in one embodiment of the present application;

FIG. 3 is a graph illustrating performance measurements of a non-contact photoacoustic imaging system (including a non-contact micro photoacoustic imaging head) according to one embodiment of the present application;

FIG. 4 is a schematic illustration of imaging effects of an embodiment of the present application;

FIG. 5 is a schematic illustration of imaging effects of an embodiment of the present application.

The device comprises a light source 1, an excitation light source 2, a beam splitter 3, a beam expanding and shaping module 4, a photoelectric detector 5, a wavelength division multiplexer 6, an optical fiber circulator 7, a detection light source 8, a non-contact micro photoacoustic imaging head 9, a collection card 10, a computer 11, a two-dimensional electric control displacement platform 81, a single mode optical fiber 82, an inner glass tube 83, an outer glass tube 84 and a focusing lens 84.

Detailed Description

The technical contents of the preferred embodiments of the present invention will be made clear and easily understood by referring to the drawings attached to the specification. The present invention may be embodied in many different forms of embodiments and the scope of the invention is not limited to the embodiments set forth herein.

In the drawings, elements that are structurally identical are represented by like reference numerals, and elements that are structurally or functionally similar in each instance are represented by like reference numerals. The size and thickness of each component shown in the drawings are arbitrarily illustrated, and the present invention is not limited to the size and thickness of each component. The thickness of the components may be exaggerated where appropriate in the figures to improve clarity.

Fig. 1 shows a non-contact photoacoustic imaging apparatus provided in an embodiment of the present application, which includes a non-contact micro photoacoustic imaging head 8, an excitation light source 1, a detection light source 7, a beam splitter 2, a photodetector 4, a beam expanding and shaping module 3, a wavelength division multiplexer 5, a fiber circulator 6, and an acquisition card 9. As shown in fig. 1, an excitation light source 1 is connected with an incident end of a beam splitter 2, a first exit end of the beam splitter 2 is connected with an incident end of a beam expanding and shaping module 3, an exit end of the beam expanding and shaping module 3 is connected with a first port of a wavelength division multiplexer 5 through a single mode fiber, and a third port of the wavelength division multiplexer 5 is connected with a non-contact micro photoacoustic imaging head 8 through a single mode fiber; the second emergent end of the beam splitter 2 is connected with the optical port of the first photoelectric detector 4, and the electrical port of the first photoelectric detector 4 is electrically connected with the acquisition card 9; the detection light source 7 is connected with a first port of the optical fiber circulator 6 through a single mode optical fiber, and a second port of the optical fiber circulator 6 is connected with a second port of the wavelength division multiplexer 5 through a single mode optical fiber; the third port of the optical fiber circulator 6 is connected with the optical port of the second photodetector 4 through a single mode optical fiber, and the electrical port of the second photodetector 4 is electrically connected with the acquisition card 9.

In the measuring process, exciting light is emitted from an exciting light source 1, sequentially passes through a beam splitter 2, a beam expanding and shaping module 3 and a wavelength division multiplexer 5, and is emitted to an object to be measured from a non-contact type micro photoacoustic imaging head 8. The detection light is emitted from a detection light source 7, passes through an optical fiber circulator 6 and a wavelength division multiplexer 5 in sequence, and is emitted to an object to be detected from a non-contact type micro photoacoustic imaging head 8. After passing through the beam splitter 2, a part of the excitation light reaches the first photodetector 4. In the present embodiment, the beam splitter 2 preferably has a splitting ratio of 10: 90. 90% of the light enters the beam expanding and shaping module 3 from the first exit end of the beam splitter 2; 10% of the light enters the optical port of the first photodetector 4 from the second exit end of the beam splitter 2. The light reflected from the object to be measured sequentially passes through the non-contact type micro photoacoustic imaging head 8, the wavelength division multiplexer 5 and the optical fiber circulator 6 to reach the optical port of the second photoelectric detector 4.

In the present embodiment, it is preferable that the excitation light source 1 employs a nanosecond pulse laser and a nanosecond pulse laser light source with a wavelength of 1064 nm. The detection light source 7 may use a continuous laser having a wavelength of 1310 nm.

The beam expanding and shaping module 3 comprises a neutral density filter, can be used for adjusting the pulse energy of exciting light, and further comprises a lens and an adjustable pinhole 4, and is coupled with a first port of a wavelength division multiplexer 5 through the lens.

The wavelength division multiplexer 5 has to be selected according to the wavelength used. In this example, 1064nm pulsed light was used as excitation light, 1310nm continuous laser light was used as probe light, and the wavelength division multiplexer was of the type (CIR-1310-3-P-900-1-FA, Shconnet). As another example, when the excitation light wavelength is 532nm and the detection light wavelength is 670nm, a wavelength division multiplexer model (RG40A1, Thorlabs) can be selected.

In the embodiment, the photoacoustic signal is digitized by the acquisition card 9, the acquisition card 9 is electrically connected to the computer 10, and the data is processed and displayed by the computer 10.

In the image acquisition process, the non-contact type micro photoacoustic imaging head 8 can be fixed on the two-dimensional electric control displacement platform 11 and used for moving and scanning.

Fig. 2 is a schematic structural diagram of a non-contact micro photoacoustic imaging head 8 used in one embodiment of the present application. The non-contact micro photoacoustic imaging head 8 mainly comprises a single-mode fiber 81 and a focusing lens 84. The single-mode optical fiber 81 and the focusing lens 84 are coaxially aligned and fixed by the inner glass tube 82 and the outer glass tube 83. As shown in FIG. 2, the dashed lines are schematic representations of the propagation of the excitation and detection light within the imaging head. Wherein denser dots represent excitation light and sparser dashed lines represent probe light. The single mode optical fiber 81 is extended from the third port of the wavelength division multiplexer 5 in fig. 1. The end face of the single-mode optical fiber 81 is cut at an inclined angle of 8 degrees to eliminate reflected light from the end face of the optical fiber, thereby eliminating background noise from the reflected light. In the present embodiment, the focusing lens 84 is specifically a gradient index lens (GRIN2313A, Thorlabs) with a diameter of 1.8 mm. The single-mode optical fiber 81 and the focusing lens 84 are coaxially aligned and fixed by an inner glass tube 82 and an outer glass tube 83 (outer diameter 3 mm), so that the overall diameter of the entire non-contact micro photoacoustic imaging head 8 is only 3 mm.

According to the technical scheme, the problem that the imaging head of the photoacoustic remote sensing micro-imaging device is large in size is solved. (the diameter of the non-contact type micro photoacoustic imaging head 8 is only 3 mm, and the non-contact type micro photoacoustic imaging head can be developed into a handheld imaging head or an endoscopic imaging head in the future.) the problems of difficulty in building, inconvenience in use and poor system stability are improved through the photoacoustic remote sensing micro imaging device based on optical fiber. As the non-contact type micro photoacoustic imaging head 8 only needs to use a glass tube to coaxially align and fix the single-mode optical fiber and the focusing lens, the difficulty of free-space optical confocal alignment can be avoided, and the system is easier to build. The non-contact type micro photoacoustic imaging head 8 can be fixed on the two-dimensional electric control displacement platform 11, and the imaging head is moved to scan without moving a sample, so that the use is more convenient, and particularly, the living animal experiment is realized. Since the whole optical path is guided by the optical fiber, the whole imaging device is more stable. When the photoacoustic imaging device based on the optical fiber is combined with other non-contact optical imaging methods (such as fluorescence imaging and optical coherence tomography), the purpose can be achieved only by welding different optical fiber devices, the system can be built simply, and the further development of the imaging method in multi-mode imaging is facilitated.

Fig. 3 shows a performance parameter chart of an embodiment of the present application, wherein fig. 3a is an excitation light focusing spot measured using a beam profiler (beam profiler) with a diameter of about 6 microns. Fig. 3b is the measured axial resolution, about 123 microns. Fig. 3c shows the time-domain photoacoustic remote sensing signal obtained when a carbon fiber with the diameter of 6 microns is excited. Fig. 3d is the spectrum of fig. 3c with a-6 dB bandwidth of about 4.3 MHz. Fig. 3e is a photoacoustic image obtained by photoacoustic remote sensing microscopic imaging of some carbon fibers with the diameter of 6 micrometers by using the imaging device (including the non-contact micro photoacoustic imaging head) of the present embodiment.

Fig. 4 illustrates the imaging effect of the embodiment of the present application. Fig. 4a shows a photoacoustic image obtained by performing photoacoustic remote sensing microscopic imaging on leaf veins soaked by black ink by using the imaging device (including the non-contact micro photoacoustic imaging head) of the embodiment. Fig. 4b is a photoacoustic image (right image) obtained by performing photoacoustic remote sensing microscopic imaging on zebra fish (mainly for melanin imaging) by using the imaging device (including the non-contact micro photoacoustic imaging head) of the embodiment, and compared with a bright field image (left image), the two images have good consistency.

Fig. 5 shows the results of imaging a symmetric lithium metal battery using an example of the present application. Wherein fig. 5a is a schematic cross-sectional side wall surface view of a symmetric lithium/lithium battery, with dashed boxes representing the imaging area. Fig. 5b is a photo acoustic image of an uncharged lithium/lithium battery, where the signal of the lithium electrode can be seen. FIG. 5c is a photo-acoustic image of a lithium/lithium battery charged at a current density of 1mA/cm 2 for 15 hours, showing the deposition of lithium metal at the glass fiber membrane. The dashed lines in fig. 5b and 5c represent the interface between the lithium electrode and the glass fiber membrane in fig. 5 a.

The foregoing detailed description of the preferred embodiments of the invention has been presented. It should be understood that numerous modifications and variations could be devised by those skilled in the art in light of the present teachings without departing from the inventive concepts. Therefore, the technical solutions available to those skilled in the art through logic analysis, reasoning and limited experiments based on the prior art according to the concept of the present invention should be within the scope of protection defined by the claims.

Claims

1. The utility model provides a miniature optoacoustic imaging head of non-contact, includes optic fibre and lens, its characterized in that, optic fibre with the setting is aimed at to the lens is coaxial, optic fibre is single mode fiber, single mode fiber's terminal surface is 8 degrees angle of inclination cutting, lens are gradient index lens, lens with the terminal surface that optic fibre is relative is the inclined plane.

2. The non-contact micro photoacoustic imaging head of claim 1 wherein the optical fiber and the lens are coaxially fixed in alignment by a glass tube.

3. The non-contact micro photoacoustic imaging head of claim 2 wherein the glass tube comprises an inner glass tube and an outer glass tube, the outer glass tube being sleeved outside the inner glass tube.

4. The non-contact micro photoacoustic imaging head of claim 3 wherein the single mode fiber is used to transmit the excitation light, the probe light, and the reflected light from the object to be measured simultaneously.

5. A non-contact type micro photoacoustic imaging device, comprising the non-contact type micro photoacoustic imaging head of claim 4, further comprising an excitation light source, a detection light source, a beam splitter, a photodetector, a beam expanding and shaping module, a wavelength division multiplexer, a fiber circulator and an acquisition card, wherein the excitation light source is connected to the incident end of the beam splitter, the first exit end of the beam splitter is connected to the incident end of the beam expanding and shaping module, the exit end of the beam expanding and shaping module is connected to the first port of the wavelength division multiplexer, and the third port of the wavelength division multiplexer is connected to the non-contact type micro photoacoustic imaging head; the second emergent end of the beam splitter is connected with the optical port of a first photoelectric detector, and the electrical port of the first photoelectric detector is connected with the acquisition card; the detection light source is connected with a first port of the optical fiber circulator, and a second port of the optical fiber circulator is connected with a second port of the wavelength division multiplexer; and a third port of the optical fiber circulator is connected with an optical port of a second photoelectric detector, and an electrical port of the second photoelectric detector is connected with the acquisition card.

6. The non-contact photoacoustic imaging apparatus according to claim 5, wherein excitation light is emitted from the excitation light source, passes through the beam splitter, the beam expanding and shaping module, and the wavelength division multiplexer in sequence, and is emitted from the non-contact photoacoustic imaging head to the object to be measured; the detection light is emitted from the detection light source, passes through the optical fiber circulator and the wavelength division multiplexer in sequence, and is emitted to the object to be detected from the non-contact type micro photoacoustic imaging head; after the exciting light passes through the beam splitter, a part of the exciting light reaches the first photoelectric detector; and the light reflected from the object to be detected sequentially passes through the non-contact type micro photoacoustic imaging head, the wavelength division multiplexer and the optical fiber circulator and reaches the second photoelectric detector.

7. The non-contact photoacoustic imaging apparatus of claim 6, wherein the beam-expanding shaping module and the first port of the wavelength-division multiplexer, the third port of the wavelength-division multiplexer and the non-contact micro photoacoustic imaging head, the probe light source and the first port of the fiber-optic circulator, the second port of the fiber-optic circulator and the second port of the wavelength-division multiplexer, and the third port of the fiber-optic circulator and the second photodetector are all connected by a single-mode fiber.

8. The noncontact photoacoustic imaging apparatus of claim 6 wherein the beam splitter has a split ratio of 10: 90.

9. the non-contact photoacoustic imaging apparatus of claim 6 wherein the beam expanding shaping module comprises a lens, an adjustable pinhole.