Portable real-time digital holographic microscopy device and use method

Abstract

The invention relates to a portable real-time digital holographic microscopy device and a use method. According to the technical scheme, a laser diode, a beam splitter prism and a reflector are sequentially arranged on a light path, a microscope objective and an imaging device are sequentially and concentrically arranged on the beam splitter prism, the imaging device is connected with a mobile phone, and a sample is arranged below the beam splitter prism; according to the device, an objective lens with a long working distance is adopted to perform optical microscopic amplification on a sample, a small Michelson interferometer, an imaging device or a mobile phone camera is constructed to record an off-axis hologram by adding a beam splitter prism between the objective lens and the sample, and a mobile phone is used for reconstructing an interferogram and displaying a reconstruction result. The method is simple and fast to operate, and can realize reflection-type real-time quantitative phase measurement. The device is small in size and convenient to carry and measure.

Description

Technical Field

[0001] The invention relates to a portable real-time digital holographic microscope device and a use method thereof. Technical Background

[0002] Quantitative phase imaging is a novel imaging technique that can quantitatively obtain phase information of a sample. Digital holographic microscopy is an effective method for achieving quantitative phase imaging. Due to its advantages of full-field, non-contact, and label-free imaging, digital holographic microscopy has been widely used for quantitative phase measurement in biological cells, micro- and nanostructures, and microfluidics.

[0003] Lee et al. (Lab Chip, 2014, 14, 3056–3063) proposed a low-cost digital holographic microscopy system that implements a microscopy imaging solution based on a smartphone platform. However, this solution can only achieve ordinary microscopy imaging and cannot achieve quantitative phase imaging. Traditional digital holographic microscopy systems require multiple optical, mechanical, and electronic control components, often containing complex mechanical and optical structures, and are relatively large in size. To obtain stable interference fringes, traditional digital holographic microscopes need to be used in a relatively stable environment such as an optical laboratory. To process and display data, traditional digital holographic microscopes require necessary supporting equipment such as computers. In addition, a stable, high-power power supply is required for the supporting computers and lasers to operate properly. The application number is "202010353949.5", and the patent name is "A point diffraction digital holographic microscopy device and method based on polarization grating". It discloses a laser, a light intensity control unit, a microscope objective, a first thin lens, a reflector, a grating, a second thin lens, a pinhole filter, a polarizer and a CMOS camera. It also discloses a point diffraction digital holographic microscopy method based on a polarization grating. The point diffraction digital holographic microscopy device and method have the advantages of high stability and real-time amplitude / phase imaging, and can be widely used in biomedical imaging, industrial detection and other fields. The problem is that the device structure is complex. In order to realize pinhole filtering, the device requires a precise mechanical adjustment device and uses many parts, which not only increases the system cost, but also has the problem of complex and cumbersome optical adjustment. In addition, a computer for data processing and display and a matching high-power stable power supply are required. The overall device is inconvenient to carry and can only be used in a laboratory environment. Summary of the Invention

[0004] In light of this, the present invention provides a real-time digital holographic microscope device based on a portable camera and its use method. This device has the advantages of simple structure, compact size, and portability, making it suitable for real-time observation and research of samples, and can directly record holograms using a camera or mobile phone.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a portable real-time digital holographic microscope device, characterized in that a laser diode, a dichroic prism and a reflector are arranged in sequence on the optical path of the microscope device, a microscope objective lens and an imaging device are concentrically arranged on the dichroic prism in sequence, the imaging device is connected to a mobile phone, and a sample is arranged under the dichroic prism.

[0006] Furthermore, the imaging device is a CMOS camera or a microscope eyepiece.

[0007] Furthermore, the laser diode is powered by a mobile power supply.

[0008] Furthermore, the laser diode, the beam splitter prism and the reflector are arranged concentrically and at equal heights.

[0009] Furthermore, the distances from the beam splitter to the mirror and sample are equal.

[0010] Furthermore, the photosensitive surface of the CMOS camera or the dry light surface of the mobile phone camera is placed on the image plane or the Fresnel diffraction plane of the sample (5); and the microscope eyepiece is arranged in front of the mobile phone camera.

[0011] Furthermore, the microscope objective lens is a microscope objective lens with a long working distance.

[0012] A method for using a portable real-time digital holographic microscope device, comprising the following steps:

[0013] 1) The laser diode emits a wavelength λ laser beam which is split into two beams after passing through a beam splitter prism. One beam of light passes through the beam splitter prism to illuminate the reflector and serves as the reference light; the other beam of light is reflected and then illuminates the reflective sample and serves as the object light wave.

[0014] 2) After being reflected by the reflector and the sample respectively, the reference light and the object light return along the optical path, are combined by the beam splitter (3), and then propagate upward along the optical axis.

[0015] 3) The object light and reference light respectively pass through the long working distance microscope objective lens and reach the photosensitive surface of the CMOS camera. The two interfere with each other to form an off-axis hologram, which is transmitted to the mobile phone via wired or wireless means, reconstructed on the mobile phone, and then displayed on the mobile phone in real time.

[0016] A method for using a portable real-time digital holographic microscope device, comprising the following steps:

[0017] 1) The laser diode emits a wavelength λ laser beam which is split into two beams after passing through a beam splitter prism. One beam of light passes through the beam splitter prism to illuminate the reflector and serves as the reference light; the other beam of light is reflected and then illuminates the reflective sample and serves as the object light wave.

[0018] 2) After being reflected by the reflector and the sample respectively, the reference light and the object light return along the optical path, are combined by the beam splitter, and then propagate upward along the optical axis.

[0019] 3) The object light and reference light pass through the long working distance microscope objective lens and the microscope eyepiece respectively, and reach the photosensitive surface of the mobile phone camera. The two interfere with each other to form an off-axis hologram, which is reconstructed on the mobile phone and the result is displayed on the mobile phone in real time.

[0020] Furthermore, in step 3), the density and direction of the interference fringes in the off-axis hologram are adjusted by adjusting the angle of the reflector.

[0021] Compared with the prior art, the advantages of the present invention are as follows:

[0022] 1) The device presented here is compact and portable. It uses a long-working-distance objective lens for optical microscopy of samples. By inserting a beamsplitting prism between the objective lens and the sample, a compact, off-axis Michelson interferometer is constructed. The system only requires a mobile power supply for the laser diode, enhancing overall portability and facilitating field operation.

[0023] 2) The device of the present invention uses a CMOS camera or a mobile phone to directly record the hologram, and the camera transmits the data to the mobile phone through a USB interface or wireless transmission. The hologram reconstruction and result display are completed on the mobile phone platform. The entire system does not require a matching computer and corresponding power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a structural diagram of Example 1.

[0025] Figure 2 This is a structural diagram of Example 2.

[0026] Figure 3 This is the digital hologram of the micro-nano sample recorded by the camera in Example 1.

[0027] Figure 4 This is the reconstructed height distribution map of the micro-nano object in Example 1.

[0028] Figure 5 This is the micro-nano chip interference pattern recorded by the mobile phone lens in Example 2.

[0029] Figure 6 This is the reconstructed height distribution map of the two-dimensional nanochip in the embodiment.

[0030] In the figure: 1-mobile power supply, 2-laser diode, 3-beam splitter prism, 4-reflector, 5-sample, 6-microscope objective lens, 7-imaging device, 8-mobile phone. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and the accompanying drawings. Here, the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0032] The principle of the present invention is to use a long working distance objective lens to perform optical microscopic magnification on the sample, and to form a compact Michelson interference optical path by adding a dichroic prism between the sample and the long working distance microscope objective lens. The light emitted by the light source is divided into two beams by the dichroic prism, one beam of light illuminates the reflector as a reference light, and the other beam of light illuminates the object to be measured as the object light; the reflected object light and the reference light are combined by the dichroic prism and propagate upward along the optical axis. After passing through the long working distance microscope objective lens, they interfere on the photosensitive surface of the imaging device to form an off-axis hologram. By adjusting the angle of the reflector, the fringe spacing and direction can be adjusted. The off-axis interference pattern is collected by the imaging device and transmitted to the mobile phone or directly photographed by the mobile phone camera, and the hologram is displayed and reconstructed in the mobile phone. Since it is an off-axis interference pattern, its frequency spectra at each level are separated from each other in the frequency domain, so the Fourier transform method can be used to complete the reconstruction. The +1 level spectrum is filtered out on its spectrum diagram, and after moving to the center of the spectrum and performing an inverse Fourier transform, the corresponding wrapped phase is obtained. After unwrapping the wrapped phase, the phase distortion is eliminated to obtain the true phase Φ. Finally, based on the relationship between phase and height, the reconstructed sample height distribution map can be obtained and displayed in real time on the mobile phone.

[0033]

[0034] Because the miniature Michelson interferometer is located between the objective lens and the sample, the object and reference beams travel through nearly identical paths, resulting in a quasi-common-path interferometer. This common-path structure improves the system's anti-interference capabilities and creates a stable and compact digital holographic microscopy system.

[0035] Example 1:

[0036] The imaging device uses a CMOS camera, such as Figure 1 As shown, the present invention provides a portable real-time digital holographic microscope device, which includes a mobile power supply 1, a laser diode 2, a beam splitter prism 3, a reflector 4, a sample 5, a microscope objective lens 6, a CMOS camera and a mobile phone 8.

[0037] The laser diode 2, beam splitter prism 3, and reflector 4 are placed concentrically in this order. A mobile power supply 1 supplies power to the small laser diode 2 via a USB cable, ensuring its normal operation in the field. The small laser diode 2 is secured using a mechanical structure such as a cage plate, with the laser diode 2, beam splitter prism 3, and reflector 4 at the same height. The distance from the reflector 4 to the beam splitter prism 3 is equal to the distance from the sample 5 to the beam splitter prism 3. The reflector 4 is placed after the beam splitter prism 3, with its distance from the front end of the long working distance microscope objective 6 equal to the microscope's working distance. The reflector 4 can be adjusted to change the propagation direction of the reference light.

[0038] The above-mentioned sample 5, long working distance objective lens 6 and CMOS camera are placed concentrically along the optical axis in sequence, the sample 5 is placed under the dichroic prism 3, the CMOS camera is placed on the objective lens 6, and the CMOS camera is connected to the mobile phone 8 by wired or wireless means; the photosensitive surface of the CMOS camera is placed on the image plane or Fresnel diffraction plane of the sample 5; the optical axes of the CMOS camera and the long working distance objective lens 6 are collinear; ensure that the center position of the CMOS camera is at the center of the field of view of the objective lens.

[0039] The working distance of the long working distance microscope objective lens 6 is greater than the length of the beam splitter prism 3 .

[0040] The steps of using the above-mentioned portable real-time digital holographic microscope device are as follows:

[0041] During measurement, the sample 5 is placed at the working distance of the long working distance microscope objective 6 .

[0042] 1) Power is supplied to the laser diode 2 via a mobile power supply 1. The laser light of wavelength λ emitted by the laser diode 2 is split into two beams after passing through a beam splitter prism 3. One beam of light passes through the beam splitter prism 3 to illuminate the reflector 4 and serves as the reference light. The other beam of light is reflected and then illuminates the reflective sample 5 and serves as the object light wave.

[0043] 2) After being reflected by the reflector 4 and the sample 5 respectively, the reference light and the object light return along the optical path, are combined by the beam splitter prism 3, and then propagate upward along the optical axis;

[0044] 3) The object light and reference light respectively pass through the long working distance microscope objective lens 6 and reach the photosensitive surface of the CMOS camera 7. The two interfere with each other to form an off-axis hologram (the density and direction of the off-axis hologram interference fringes are adjusted by adjusting the angle of the reflector 4). The off-axis hologram is transmitted to the mobile phone 8 via wired or wireless means. On the mobile phone, the off-axis hologram is numerically reconstructed. The steps include Fourier transform, frequency domain filtering, inverse Fourier transform and unwrapping. Finally, the reconstruction result of the sample is displayed on the mobile phone.

[0045] Specifically:

[0046] Power bank 1 is connected to small laser diode 2 via a USB cable to power it, ensuring its normal operation in the field environment; power bank 1 is a portable USB battery pack with an output of 5VDC and 2A, providing a capacity of 10,000mAh; small laser diode 2 has a housing size of φ11.0mm×60.2mm, an operating wavelength of 635nm, an output power of 4.5mW, and emits 635nm laser; beam splitter 3 has a size of 12.7mm×12.7mm×12.7mm, a wavelength range of 400nm-700nm, and a transmission-reflection ratio of 50:50; beam splitter 3 splits the laser emitted by light source 2 into two parts, one part illuminates the object to be measured as the object light wave, and the other part illuminates reflector 4 as the reference light; reflector 4 has a size of 10mm×10mm; sample to be measured 5 is a micro-nanostructure chip with a depth of 200nm. The object light reflected from the sample under test and the reference light are combined by the beam splitter prism 3, propagated upward along the optical axis, and after passing through the long working distance microscope objective lens 6, they reach the photosensitive surface of the CMOS camera and interfere to form a digital hologram. The long working distance objective lens 6 has a numerical aperture NA = 0.28, a magnification of 10×, a focal length of 20mm, a working distance of 33.5mm, and an operating wavelength range of 436-656nm; the CMOS camera has a photosensitive surface size of 1 / 2.7 inches, a resolution of 1280×720 pixels, and a pixel size of 3μm×3μm. When the photosensitive surface of the CMOS camera and the plane where the object 5 is located meet the object-image conjugate relationship, what is recorded is an image plane hologram, such as Figure 3 The figure shows an example of an image plane hologram. The recorded image plane hologram can be displayed on the mobile phone 8 and numerical reproduction can be completed. The reconstructed result can be displayed on the mobile phone screen or transmitted to the computer through the network for display. Figure 4 Shown is a schematic diagram of the reconstruction results.

[0047] Example 2:

[0048] This embodiment provides a portable real-time digital holographic microscopy device and method, which has the same overall structure as the first embodiment, except that the imaging device uses a microscope eyepiece, the mobile phone 8 is placed at the rear end of the optical path, the optical axis of the rear camera of the mobile phone 8 is collinear with the optical axis of the microscope eyepiece, and the mobile phone 8 directly records the digital hologram; ensure that the field of view is in the center of the mobile phone screen, and place the sample 5 at the working distance of the long working distance microscope objective 6.

[0049] Structure such as Figure 2 shown.

[0050] Specifically:

[0051] Power bank 1 is connected to a small laser diode 2 via a USB cable to power it, ensuring power supply in outdoor environments. Power bank 1 is a portable USB battery pack with an output of 5VDC and 2A and a capacity of 10,000mAh. Small laser diode 2 has an operating voltage of 5VDC, a housing size of φ11.0mm×60.2mm, an operating wavelength of 635nm, an output power of 4.5mW, and emits laser light with a wavelength of 635nm. The laser light passes through a beam splitter prism 3, which has dimensions of 12.7mm×12.7mm×12.7mm, a wavelength range of 400nm-700nm, and a transmittance-reflection ratio of 50:50. The laser light emitted by the light source is divided into two parts: one part is the object light that illuminates the object to be measured, and the other part is the reference light. The reference light illuminates a reflector 4, which has dimensions of 10mm×10mm. The sample to be measured 5 is a micro-nanostructure chip with a depth of 100nm. The object light reflected by the sample and the reference light meet and combine for the second time at the beam splitter prism 3, propagate upward along the optical axis, and pass through the long working distance microscope objective 6 (NA = 0.28, magnification of 10×, focal length of 20mm, working distance of 33.5mm) and the microscope eyepiece 7 (Huygens eyepiece with WF25× and magnification of 25×) in sequence; the reference light and the object light finally overlap and interfere at the photosensitive surface of the camera of the mobile phone 8, forming an off-axis interference fringe pattern (see Figure 5 ) and was captured by the mobile phone 8; the hologram was recorded using the rear camera of the mobile phone (iPhone SE2) (resolution 4032×3024 pixels, pixel size 1.22μm×1.22μm). The recorded off-axis interferogram was reconstructed on the mobile phone, and then the reconstructed height distribution map of the micro-nano chip was reconstructed through the phase and height relationship (see Figure 6 ) to complete the display.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention.

Claims

1. A portable real-time digital holographic microscope device, characterized in that: A laser diode (2), a beam splitter prism (3), and a reflector (4) are sequentially arranged on the optical path of the microscope device; a microscope objective lens (6) and an imaging device (7) are concentrically arranged on the beam splitter prism (3); the imaging device (7) is connected to a mobile phone (8); and a sample (5) is arranged under the beam splitter prism (3).

2. The portable real-time digital holographic microscopy device according to claim 1, characterized in that: The imaging device (7) is a CMOS camera or a microscope eyepiece.

3. A portable real-time digital holographic microscopy device according to claim 1 or 2, characterized in that: The laser diode (2) is powered by a mobile power supply (1).

4. The portable real-time digital holographic microscope device according to claim 3, characterized in that: The laser diode (2), the beam splitter prism (3) and the reflector (4) are arranged concentrically and at equal heights.

5. The portable real-time digital holographic microscope device according to claim 4, characterized in that: The distances from the beam splitter (3) to the reflector (4) and the sample (5) are equal.

6. The portable real-time digital holographic microscope device according to claim 2, characterized in that: The photosensitive surface of the CMOS camera or the dry light surface of the mobile phone camera is placed on the image plane or the Fresnel diffraction plane of the sample (5); the microscope eyepiece is arranged in front of the mobile phone camera.

7. The portable real-time digital holographic microscope device according to claim 6, characterized in that: The microscope objective lens (6) is a microscope objective lens with a long working distance.

8. The method for using a portable real-time digital holographic microscope according to claim 1, characterized in that: The steps are: 1) The laser light of wavelength λ emitted by the laser diode (2) is split into two beams after passing through the beam splitter prism (3). One beam of light passes through the beam splitter prism (3) to illuminate the reflector (4) and serves as the reference light. The other beam of light is reflected and then illuminates the reflective sample (5) and serves as the object light wave. 2) After being reflected by the reflector (4) and the sample (5) respectively, the reference light and the object light return along the optical path, are combined by the beam splitter (3), and then propagate upward along the optical axis. 3) The object light and the reference light pass through the long working distance microscope objective lens (6) and reach the photosensitive surface of the CMOS camera. The two interfere with each other to form an off-axis hologram, which is transmitted to the mobile phone (8) via wired or wireless means. The reconstruction is completed on the mobile phone and the result is displayed on the mobile phone in real time.

9. The method for using a portable real-time digital holographic microscope according to claim 1, characterized in that: The steps are: 1) The laser light of wavelength λ emitted by the laser diode (2) is split into two beams after passing through the beam splitter prism (3). One beam of light passes through the beam splitter prism (3) to illuminate the reflector (4) and serves as the reference light. The other beam of light is reflected and then illuminates the reflective sample (5) and serves as the object light wave. 2) After being reflected by the reflector (4) and the sample (5) respectively, the reference light and the object light return along the optical path, are combined by the beam splitter (3), and then propagate upward along the optical axis. 3) The object light and the reference light pass through the long working distance microscope objective lens (6), the microscope eyepiece, and reach the photosensitive surface of the mobile phone (8) camera. The two interfere with each other to form an off-axis hologram, which is reconstructed on the mobile phone and the result is displayed on the mobile phone in real time.

10. The method for using the portable real-time digital holographic microscope according to claim 8 or 9, characterized in that: In the step 3), the density and direction of the interference fringes in the off-axis hologram are adjusted by adjusting the angle of the reflector (4).

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