Optical imaging system and biochemical substance detection system using the optical imaging system

Abstract

An optical imaging system (1) for photographing and imaging a sample. The optical imaging system (1) includes an illumination module (11) and an imaging module (15). The illumination module (11) is configured to output excitation light, and the excitation light is used to excite the sample to generate excited light. The imaging module (15) includes a time delay integration linear array camera (151), and the time delay linear array camera (151) is configured to record the excited light. A biochemical substance detection system applying the optical imaging system (1) is also provided, which can improve the detection throughput.

Description

Technical Field

[0001] The present invention relates to the field of detection, and in particular to an optical imaging system and a biochemical substance detection system using the optical imaging system. Background Art

[0002] In the field of biochemical substance analysis, imaging analysis instruments such as gene sequencers are mostly designed based on high-sensitivity scientific-grade area array cameras. Since the area of the region to be measured on the sequencing chip is usually much larger than the visible area of the objective lens of the optical imaging system at a single time, it is necessary to use a row-by-row sequential scanning method to complete the photographing and imaging of the entire region to be measured on the sequencing chip. And then splicing is performed in the data analysis stage.

[0003] When traditional scientific-grade area array cameras perform row-by-row sequential scanning, they usually use a design scheme based on platform stepping. That is to say, the sequencing chip is carried by the platform and moved to meet the requirements of photographing different positions. When the platform moves to a certain photographing position, the platform needs to first decelerate to a standstill before taking a photo, otherwise ghosting will occur in the photo. Such a requirement means that the platform must have the ability to quickly come to a standstill after high-speed movement and then resume high-speed movement after taking the photo. In the prior art, however, both the acceleration and deceleration of the platform take a considerable amount of time, which has become one of the bottlenecks in high-throughput optical sequencing.

[0004] In addition, for the key component of the optical imaging system, the microscopic objective lens, existing objective lenses usually cannot have both a large field of view and a large numerical aperture, and are not suitable for high-throughput optical imaging systems. Summary of the Invention

[0005] In order to solve some or all of the above problems of the prior art and other potential problems, it is necessary to provide an optical imaging system and a biochemical substance detection system using the optical imaging system.

[0006] In a first aspect, an optical imaging system is provided for photographing and imaging a sample. The optical imaging system includes an illumination module and an imaging module. The illumination module is configured to output excitation light, and the excitation light is used to excite the sample to generate excited light. The imaging module includes a time delay integration line array camera, and the time delay line array camera is configured to record the excited light.

[0007] In a second aspect, a biochemical substance detection system is provided. The biochemical substance detection system includes the above-mentioned optical imaging system.

[0008] The optical imaging system provided in the embodiments of the present invention and the biochemical substance detection system using the optical imaging system have the following beneficial effects: 1. An industrial-grade or scientific-grade TDI camera is used to collect the excited light, reducing the photographing time for each sample and improving the detection throughput; 2. A filter system composed of a spectroscope and a filter device is adopted. On the one hand, it can split the excited light into multiple channels for imaging. On the other hand, it prevents the excitation light and other lights, such as the detection light, from interfering with the imaging of the excited light, improving the imaging quality; 3. The output end face of the light source is rectangular, or further elongated rectangular. At the same time, the excitation light shaping unit is used to shape the excitation light output by the light source into an illumination spot adapted to the photosensitive surface of the TDI camera, making the most of the light source energy and improving the uniformity of the illumination spot; 4. An objective lens with a special structure is adopted, enabling the objective lens to meet the requirements of a large field of view and a large numerical aperture, while reducing distortion and flat-field achromatism; 5. A focusing system is adopted. The focusing system adjusts the distance between the objective lens and the sample carrier in real time, keeping the sample carrier on the focal plane of the objective lens, compensating for the distance change between the sample carrier and the objective lens caused by environmental temperature changes, mechanical vibrations, sample bending or other reasons, and ensuring the imaging quality; 6. The focusing system calculates the distance between the sample carrier and the objective lens by a specific method, effectively eliminating the influence of signal noise and the change in the brightness of the detection light source on the detection result. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0010] Figure 1 is a schematic diagram of the composition of the optical imaging system in an embodiment of the present invention.

[0011] Figure 2 is a schematic diagram comparing the photographing time per row of TDI camera imaging and traditional area array camera imaging.

[0012] Figure 3 is a schematic diagram of the optical structure of the objective lens in an embodiment of the present invention.

[0013] Figure 4 is Figure 3 the full-field and full-band MTF curve graph of the shown objective lens.

[0014] Figure 5 is Figure 3 the distortion curve graph of the shown objective lens.

[0015] Figure 6Yes Figure 3 Envelope energy diagram of the objective lens shown

[0016] Figure 7 Is the combination of the tube lens and the Figure 3 Schematic optical structure diagram of the objective lens shown

[0017] Figures 8A - 8D Is Figure 7 Wavefront aberration curve diagram of the combination of the objective lens and the tube lens shown in imaging channels 1-4

[0018] Figure 9 Is Figure 7 Distortion curve diagram of the combination of the objective lens and the tube lens shown

[0019] Figure 10 Schematic diagram of the output end face of the light source in an embodiment of the present invention

[0020] Figure 11 Is the combination of the excitation light shaping unit and the Figure 3 Schematic optical structure diagram of the objective lens shown

[0021] Figure 12 Is the combination of the excitation light shaping unit and the Figure 3 Schematic optical structure diagram of the objective lens shown in another embodiment of the present invention

[0022] Figure 13 Schematic diagram of the photosensitive surface of the TDI camera in an embodiment of the present invention

[0023] Figure 14 Image plane illuminance diagram obtained by simulation

[0024] Figure 15 Is Figure 1 Schematic control principle diagram of the optical imaging system shown

[0025] Figure 16 Is Figure 1 Schematic principle diagram of the focusing module of the optical imaging system shown performing focusing

[0026] Figure 17 Is Figure 1 Schematic optical path principle diagram of the focusing module of the optical imaging system shown performing focusing

[0027] Figures 18A - 18C Is Figure 17 Schematic diagram of the sensor of the focusing module sensing the detected light spot reflected back

[0028] Figure 19 Is Figure 1 Signal spectra measured during focusing of the optical imaging system shown

[0029] Figure 20 It is a schematic diagram of the composition of a biochemical substance detection system in an embodiment of the present invention.

[0030] Figure 21 It is a schematic diagram of the composition of a biochemical substance detection system in another embodiment of the present invention.

[0031] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings.

[0032] Description of main component symbols

[0033] Optical imaging system 1 Illumination module 11

[0034] Focusing module 13 Imaging module 15

[0035] Objective lens 16 Light sources 111, 1301

[0036] Excitation light shaping unit 113 Sample carrier 2

[0037] TDI camera 151 Tube lens 152, 1303

[0038] Cut-off filter 153, 116 Spectroscopic device 154

[0039] Dichroic mirrors A, B, C, Plane mirror 115

[0040] D, E

[0041] Photographing times t1, t2 First group of lenses 161

[0042] Second group of lenses 162 Third group of lenses 163

[0043] Fourth group of lenses 164 Fifth group of lenses 165

[0044] Sixth group of lenses 166 Seventh group of lenses 167

[0045] First lens L1 Second lens L2

[0046] Third lens L3 Fourth lens L4

[0047] Fifth lens L5 Sixth lens L6

[0048] Seventh lens L7 Eighth lens L8

[0049] Ninth lens L9 Tenth lens L10

[0050] Eleventh lens L11 Twelfth lens L12

[0051] The thirteenth lens L13, the fourteenth lens L14

[0052] The output end face 1112 of the multimode optical fiber 1111

[0053] The first shaping unit 113a, the second shaping unit 113b

[0054] The cylindrical lenses C1, C2, C3, C4, the photosensitive surface 1511

[0055] C3, C4

[0056] The control device 17, the movable platform 18

[0057] The computer device 19, the detection optical path 130

[0058] The sensing unit 131, the control unit 132

[0059] The sensor 1311, the mirror 1305

[0060] The PD sensor 1312, the sensing areas 1312a, 1312b

[0061] The curves O, P, Q, the intersection point S

[0062] R

[0063] The horizontal line H Specific embodiments

[0064] Hereinafter, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0065] It should be noted that when a component is referred to as being "fixed to" or "installed on" another component, it can be directly on the other component or there may also be an intermediate component. When a component is considered to be "disposed on" another component, it can be directly disposed on the other component or there may be an intermediate component at the same time. The term "and / or" used herein includes all and any combinations of one or more of the related listed items.

[0066] Please refer to Figure 1As shown in the figure, it is a schematic diagram of the composition of an optical imaging system in an embodiment of the present invention. The optical imaging system 1 includes an illumination module 11, a focusing module 13, and an imaging module 15. Among them, the imaging module 15 uses a TDI (time delay integration) line array camera (hereinafter simply referred to as a TDI camera) for imaging. Further, the TDI camera is an industrial-grade or scientific-grade TDI camera. The illumination module 11, the focusing module 13, and the imaging module 15 share some optical path guiding components and an objective lens 16. The illumination module 11 includes a light source 111 and an excitation light shaping unit 113. The excitation light emitted from the light source 111 is shaped by the excitation light shaping unit 113 into a linear illumination spot adapted to the photosensitive surface of the TDI camera. The linear illumination spot is guided to the objective lens 16 by the optical path guiding components, and is emitted from the objective lens 16 to the sample carried on the sample carrier 2. The sample is excited by the excitation light to generate fluorescence, and the fluorescence enters the imaging module 15 through the objective lens and is recorded by the TDI camera in the imaging module 15. The focusing module 13 emits a detection light, and the detection light is guided by the optical path guiding components into the objective lens 16 and is emitted from the objective lens 16 to the sample carrier 2. The detection light will not excite the sample to generate fluorescence, and will only be reflected back into the objective lens 16 by the sample carrier 2, enter the focusing module 13 through the objective lens 16 and the optical path guiding components, analyze and determine the positional relationship between the sample carrier 2 and the objective lens 16 by the focusing module 13, and adjust the position of the objective lens 16 relative to the sample carrier 2 according to the determined positional relationship between the sample carrier 2 and the objective lens 16, so that the sample carrier 2 is always located on the focal plane of the objective lens 16.

[0067] In this embodiment, the light source 111 is a laser light source, and the excitation light is a laser. The optical imaging system 1 is a sequencing photographing imaging system for photographing a DNA sample to analyze the base sequence of the DNA sample. The DNA sample is carried on the sample carrier 2, and the four bases A, T, G, and C of the DNA sample are respectively labeled with different fluorescent dyes. The laser emitted from the objective lens 16 excites the DNA sample to emit four kinds of fluorescence with different wavelengths. The imaging module 15 includes four TDI cameras 151. The arrangement of the four TDI cameras 151 enables the optical imaging system 1 to have four imaging channels. A tube lens 152 and a cut-off filter 153 are arranged in front of each TDI camera 151. Each cut-off filter 153 only allows fluorescence within a certain wavelength range to enter the corresponding TDI camera 151, so that the corresponding TDI camera 151 only records the fluorescence signal emitted by one of the bases A, T, G, and C. The imaging module 15 further includes a plurality of beam splitting devices 154. The beam splitting devices 154 guide light within different wavelength ranges into different imaging channels by reflecting light within one wavelength range and transmitting light within another wavelength range, so as to be recorded by different TDI cameras 151. In this embodiment, the beam splitting device 154 is a dichroic mirror, and the imaging module 15 includes dichroic mirrors A, B, C, and D. Among them, the dichroic mirror A is arranged corresponding to the objective lens 16 and forms an angle of 45° with the optical axis of the objective lens 16, and is used for transmitting the laser-excited light and reflecting the excitation light and the detection light; the dichroic mirror B is arranged behind the dichroic mirror A and is arranged parallel to the dichroic mirror A, and is used for guiding the laser-excited light with different wavelengths to the dichroic mirrors C and D respectively by means of transmission and reflection. The dichroic mirrors C and D further guide the laser-excited light with different wavelengths to different cut-off filters 153 respectively through transmission and reflection, and enter the corresponding TDI cameras 151 through the tube lenses 152.

[0068] In this embodiment, the illumination module 11 and the focusing module 13 share the dichroic mirror A of the imaging module 15. In addition, the illumination module 11 and the focusing module 13 also share the dichroic mirror E. The dichroic mirror E guides the excitation light and the detection light incident from different angles to the dichroic mirror A, and then is guided by the dichroic mirror A into the objective lens 16. The illumination module 11 further includes a plane mirror 115, and the plane mirror 115 reflects the excitation light shaped by the excitation light shaping unit 113 to the dichroic mirror E.

[0069] In this embodiment, the TDI camera 151 is adopted. The multiple rows of pixels of the photosensitive chip of the TDI camera 151 can perform row-by-row charge transfer to perform multiple exposure imaging on the same target. By synchronizing the TDI camera 151 and the sample carrier 2, the photographing time for each sample can be significantly reduced, and the detection throughput can be improved. As Figure 2 shown, it is a comparison of the photographing time for each row when the TDI camera 151 and the traditional area array camera are imaging. Among them Figure 2Among them, t1 represents the exposure time per row of the TDI camera 151, and t2 represents the exposure time per row of the traditional area array camera. When scanning each row of the sample, the detection platform carrying the sample carrier 2 can be controlled to move at a constant speed, so that the TDI camera 151 continuously scans the same row of the sample to collect the image information of that row. In this way, compared with the traditional sequencing method where the area array camera needs to accelerate and decelerate the detection platform for each field of view when scanning each row, when using the TDI camera 151, only one acceleration and deceleration of the detection platform is required when changing rows, which improves the time utilization rate of the optical imaging system 1. Therefore, it also improves the detection throughput of the biochemical substance detection device applying the optical imaging system 1, and at the same time avoids the risks brought by the frequent acceleration and deceleration of the detection platform.

[0070] In this embodiment, on the one hand, the objective lens 16 homogenizes the rectangular line light spot of the illumination module 11 and irradiates it onto the sample carrier 2, and at the same time guides the detection light of the focusing module 13 onto the sample carrier 2. On the other hand, the objective lens 16 collects the excited light, and the collected excited light obtains the DNA fluorescence images of each channel on each TDI camera 151 through the relay lens 152.

[0071] Since the distance between the sample sites on the sample carrier 2 is in the order of hundreds of nanometers, according to the Rayleigh Criterion, the numerical aperture NA of the objective lens 16 is required to be > 0.8. In addition, for a high-throughput imaging system, the effective imaging field of view is a long and narrow rectangular area with a large aspect ratio, so the TDI camera 151 requires a large linear field of view. For example, for a sequencing throughput requirement of 6T / day, the object-side diameter field of view of the objective lens 16 is required to be more than 1.5 mm. Furthermore, to achieve ultra-high throughput, the objective lens 16 needs to have a large numerical aperture and a large field of view at the same time. However, for current commercial microscopes, generally, low-magnification objective lenses have a large field of view but a small numerical aperture, while high-magnification objective lenses have a large numerical aperture but a small field of view, and usually the product of the two is less than 0.8, making it difficult to achieve ultra-high throughput.

[0072] Therefore, the objective lens 16 provided in this embodiment generally meets the following specifications:

[0073] Numerical aperture NA ≥ 0.7;

[0074] Effective working distance > 1.2 mm;

[0075] Focal length = 12.5 mm;

[0076] Achromatism for light waves with wavelengths from 500 nm to 800 nm < 0.4 μm;

[0077] Field curvature < 0.4 μm;

[0078]

[0079] Combined distortion with the relay lens < 1%.

[0080] Generally speaking, the objective lens 16 provided in this embodiment is a flat-field apochromatic objective lens with a large field of view, a large numerical aperture, and small distortion, and is applicable to a 0.25 mm cover glass and a 0.05 mm water layer.

[0081] Please refer to Figure 3 As shown, it is a schematic diagram of the specific optical structure of the objective lens 16 provided in this embodiment.

[0082] The objective lens 16 includes seven groups of lenses 161-167. The first group of lenses 161 to the seventh group of lenses 167 are arranged in sequence from the object side to the image side. Among them, the first three groups of lenses 161-163 bear negative optical power, and the last four groups of lenses 164-167 bear positive optical power. The first group of lenses 161 includes a first lens L1. The first lens L1 is a thick meniscus lens with positive optical power, forms an aplanatic lens, and generates positive field curvature; the second group of lenses 162 includes a second lens L2. The second lens L2 is a meniscus lens with positive optical power and bears positive decentration with the first lens L1 together; the third group of lenses 163 includes a third lens L3, a fourth lens L4 and a fifth lens L5. The third lens L3, the fourth lens L4 and the fifth lens L5 are sequentially cemented to form a triple cemented lens group with positive optical power, which is mainly used to correct coma and chromatic aberration; the fourth group of lenses 164 includes a sixth lens L6. The sixth lens L6 is a thin meniscus lens with positive optical power; the fifth group of lenses 165 includes a seventh lens L7 and an eighth lens L8. The seventh lens L7 and the eighth lens L8 are cemented to form a double cemented lens group with positive optical power; the sixth group of lenses 166 includes a ninth lens L9 and a tenth lens L10. The ninth lens L9 and the tenth lens L10 are cemented to form a double cemented lens group with negative optical power. The seventh group of lenses 167 includes an eleventh lens L11 and a twelfth lens L12. The eleventh lens L11 and the twelfth lens L12 are cemented to form a double cemented meniscus negative lens group with negative optical power. Among them, the sixth group of lenses 166 and the seventh group of lenses 167 are used to control field curvature and distortion. Among them, the three types of lenses, namely the thick meniscus lens, the meniscus lens, and the thin meniscus lens, referred to in this embodiment gradually decrease in thickness along the optical axis direction, that is, the thickness of the thick meniscus lens along the optical axis direction is greater than the thickness of the meniscus lens in this direction, and the thickness of the meniscus lens along the optical axis direction is greater than the thickness of the thin meniscus lens in this direction. The "thick" and "thin" used in this embodiment are only relative concepts used to describe the thickness of an object.

[0083] The first group of lenses 161 satisfies: 9.2 < f1 / fobj < 9.7;

[0084] The second group of lenses 162 satisfies: 4.7 < f2 / fobj < 5.5;

[0085] The third group of lenses 163 satisfies: 4.6 < f3 / fobj < 5.6;

[0086] The fourth group of lenses 164 satisfies: 3.25 < f4 / fobj < 3.88;

[0087] The fifth group of lenses 165 satisfies: 5.71 < f5 / fobj < 6.11;

[0088] The sixth group of lenses 166 satisfies: -4.76 < f6 / fobj < -3;

[0089] The seventh group of lenses 167 satisfies: -23.9 < f7 / fobj < -19.5.

[0090] Wherein, f1 is the focal length of the first group of lenses 161, f2 is the focal length of the second group of lenses 162, f3 is the focal length of the third group of lenses 163, f4 is the focal length of the fourth group of lenses 164, f5 is the focal length of the fifth group of lenses 165, f6 is the focal length of the sixth group of lenses 166, f7 is the focal length of the seventh group of lenses 167, and fobj is the focal length of the objective lens 16.

[0091] Please refer to Figures 4 to 6 as shown, wherein Figure 4 is the MTF (Modulation Transfer Function) curve of the full field of view and full wavelength band of the objective lens 16 obtained by simulation, Figure 5 is the distortion curve of the objective lens 16 obtained by simulation, Figure 6 is the envelope energy diagram of the objective lens 16 obtained by simulation. It can be seen from the above simulation result diagrams that the objective lens 16 is close to the diffraction limit in the imaging result, its normalized field of view distortion is less than 1% and the resolution ability is high.

[0092] Please refer to Figure 7 as shown, which is the schematic optical structure diagram of the combination of the objective lens 16 and the barrel lens 152 provided in this embodiment. In this embodiment, the barrel lens 152 includes four lenses, and the four lenses are glued to form two doublet lenses, hereinafter referred to as the thirteenth lens L13 and the fourteenth lens L14. The focal length of the barrel lens 152 is 150 mm - 250 mm. Specifically, in specific applications, the specific focal length value of the barrel lens 152 is also set according to the focal length of the objective lens 16, the pixel size and number of the TDI camera 151, and the magnification and resolution required by the optical imaging system 1. The combination of the barrel lens 152 and the objective lens 16 needs to meet the imaging limitation requirements such as distortion and field curvature, and the barrel lens 152 compensates for the residual aberration of the objective lens 16.

[0093] Please refer to Figures 8A - 8D and Figure 9 as shown, Figures 8A to 8DThey are the wave aberration curves of the combination of the objective lens 16 and the tube lens 152 obtained by simulation in imaging channels 1-4 respectively. Figure 9 It is the distortion curve of the combination of the objective lens 16 and the tube lens 152 obtained by simulation. Among them, Figures 8A - 8D The horizontal line H in represents the diffraction limit. The wave aberration of the combination of the objective lens 16 and the tube lens 152 in imaging channels 1-4 is lower than the horizontal line H, which proves that the design of the combination of the objective lens 16 and the tube lens 152 has reached the limit of the resolution requirement. From Figure 9 it can be seen that the normalized field distortion of the combination of the objective lens 16 and the tube lens 152 is less than 1%.

[0094] In this embodiment, the objective lens 16 is an infinity-corrected objective lens. The objective lens 16 changes the laser light emitted from the sample into parallel light or quasi-parallel light. In this way, it is convenient to add a beam splitting device 154 between the objective lens 16 and the tube lens 152 as needed.

[0095] Please refer to Figure 10 shown, which is a schematic diagram of the output end face of the light source 111 in this embodiment. In this embodiment, the light source 111 is a laser light source that emits red and green lasers. The light source includes a fiber optic coupler (not shown in the figure) and a multimode optical fiber 1111. The red and green lasers are coupled to the multimode optical fiber 1111 through the fiber optic coupler and output. The multimode optical fiber 1111 has an output end face 1112, and the output end face 1112 is the output end face of the light source 111. In this embodiment, the output end face 1112 is rectangular to match the long strip-shaped photosensitive surface of the TDI camera 151. Therefore, compared with the commonly used circular output end face in the prior art, the rectangular output end face of the light source 111 can be adapted to the TDI camera 151 and can improve the utilization rate of the excitation light.

[0096] Please refer to Figure 11 shown, which is a schematic diagram of the optical structure of the combination of the excitation light shaping unit 113 and the objective lens 16 in an embodiment. The excitation light shaping unit 113 includes a first shaping unit 113a and a second shaping unit 113b. The first shaping unit 113a and the second shaping unit 113b are arranged in sequence from the image side to the object side. Among them, the first shaping unit 113a is used to shape the rectangular light spot emitted by the light source 111 in the first direction, and the second shaping unit 113b is used to shape the illumination light spot emitted by the light source 111 in the second direction. Among them, the first direction and the second direction are perpendicular to each other. After the illumination light spot is shaped by the first shaping unit 113a and the second shaping unit 113b, a linear light spot with the aspect ratio required for imaging and scanning of the TDI camera 151 is formed. In this embodiment, the first shaping unit 113a and the second shaping unit 113b are cylindrical lenses C1 and C2 respectively. The cylindrical lens C1 magnifies the illumination light spot in the Figure 1 X direction shown, and the cylindrical lens C2 magnifies the illumination light spot in the Figure 1The reduction in the Y direction as shown makes the illumination spot finally form the aspect ratio required for the imaging scan of the TDI camera 151. By reasonably selecting the focal lengths of the cylindrical lenses C1 and C2, the aspect ratio of the illumination spot output by the illumination module 11 can be adjusted. In this embodiment, the cylindrical lenses C1 and C2 can achieve the shaping of the aspect ratio of the illumination spot to 10:1, and the rectangular output end face 1112 of the cascaded optical fiber 1111, so the aspect ratio of the illumination spot output by the illumination module 11 can reach about 20:1. In this embodiment, two cylindrical lenses C1 and C2 are used to shape the illumination spot. On the one hand, since fewer shaping elements are used, the structure of the excitation light shaping unit 113 is simple and easy to assemble and adjust; on the other hand, it can reduce the deviation of the illumination spot caused by the element itself and the assembly tolerance. In addition, critical illumination is adopted in this embodiment to strictly control the line uniformity of illumination, while maximizing the utilization of the energy of the light source 111, providing uniform illumination for exciting the laser.

[0097] Please refer to Figure 12 As shown, it is a schematic optical structure diagram of the combination of the excitation light shaping unit 113 and the objective lens 16 in another embodiment. Different from the previous embodiment, in this embodiment, the first shaping unit 113a and the second shaping unit 113b are respectively the cylindrical lenses C3 and C4. The cylindrical lens C3 reduces the illumination spot in the Figure 1 Y direction as shown, and the cylindrical lens C4 magnifies the illumination spot in the Figure 1 X direction as shown, so that the illumination spot finally forms the aspect ratio required for the imaging scan of the TDI camera 151.

[0098] Please refer to Figure 13 And Figure 14 As shown, Figure 13 This is a schematic diagram of the photosensitive surface of the TDI camera 151 in this embodiment. The photosensitive surface 1511 of the TDI camera 151 is a rectangular surface or, further, a long strip. Figure 14 This is the image plane illuminance diagram obtained by simulation. Specifically, Figure 14 This is the illuminance diagram of the image plane obtained by simulating the optical imaging system 1 using non-sequential simulation software. Among them, in the simulation, the input power of the light source 111 is normalized to 1W, the dichroic mirrors A-E are simplified to beam splitters with a reflection / transmission ratio of 50 / 50, and the transmittance of all lenses is assumed to be 100%. It can be seen from the image plane illuminance diagram that the illuminance uniformity in the image space is greater than 85%.

[0099] In other embodiments, the first shaping unit 113a and the second shaping unit 113b can also be respectively a prism, a microlens or a diffractive optical element, etc.

[0100] Please refer to again Figure 1As shown, in this embodiment, a cut-off filter 153 is provided before each barrel lens 152. Additionally, a cut-off filter 116 is also provided between the light source 111 and the excitation light shaping unit 113 to filter out stray light outside the excitation wavelength. The cut-off filters 153 and 116, together with dichroic mirrors A - E, form a filter system that enables the four generated stimulated emission lights to be imaged through four channels respectively and collected by four TDI cameras 151. On the one hand, this filter system realizes the imaging of the stimulated emission light through each channel; on the other hand, it also filters out the excitation light and detection light outside the TDI cameras 151. In this embodiment, the cut-off degree of the cut-off filter 153 is 8.

[0101] Please refer to Figure 15 As shown, it is the control schematic diagram of the optical imaging system 1 in this embodiment. The optical imaging system 1 further includes a control device 17. The control device 17 is used to control the moving speed of the detection platform (which is the movable platform 17 in this embodiment) to match and keep synchronized with the frequency of the TDI camera 151. At the same time, the control device 17 is also used to control the turning on of the light source 111 to be synchronized with the photographing of the TDI camera 151. Specifically, in this embodiment, to achieve the above purposes, the control device 17 is communicatively connected to the movable platform 18 on which the sample carrier 2 is placed. When the movable platform 18 reaches the designated position, the control device 17 simultaneously triggers the light source 111 and the TDI camera 151 to synchronize the sample, the light source 111, and the TDI camera 151. At the same time, the frequency of the TDI camera 151 automatically matches the moving speed of the movable platform 18 to ensure that the generated image is not deformed. Please also refer to Figure 1 As shown, the movable platform 18 can be controlled to move in the illustrated X direction and in the Y direction perpendicular to X, and can also be controlled to rotate within the plane formed by the X direction and the Y direction, so that the movable platform 18 can be moved or positioned to a preset position. The objective lens 16 can be controlled to move in the illustrated Z direction, and the Z direction is perpendicular to both the X direction and the Y direction.

[0102] In this embodiment, the focusing module 13 is used to detect the positional relationship between the sample carrier 2 and the objective lens 16 by emitting detection light, and control the movement of the objective lens 16 in the Z direction according to the detection result to adjust the distance between the objective lens 16 and the sample carrier 2, so that the sample carrier 2 is always in the focal plane of the objective lens 16. Therefore, by using the focusing module 13, the distance change between the objective lens 16 and the sample carrier 2 caused by environmental temperature changes, mechanical vibrations, bending of the sample carrier 2, surface undulations of the sample carrier 2, and thickness changes of the sample carrier 2 can be compensated for.

[0103] Please refer to Figure 16As shown, it is a schematic diagram of the focusing module 13 performing focusing in this embodiment. In this embodiment, the detection light emitted by the focusing module 13 passes through the objective lens 16 and irradiates on the sample carrier 2, and is reflected back to the objective lens 16 by the sample carrier 2. Then, it returns to the focusing module 13 along the original optical path through the objective lens 16. The focusing module 13 determines whether the sample carrier 2 is located on the focal plane of the objective lens 16 according to the returned detection light. If the sample carrier 2 is not on the focal plane of the objective lens 16, the focusing module 13 sends a signal to the driving unit 161 that drives the objective lens 16 to move, and controls the driving unit 161 to drive the objective lens 16 to move closer to or farther away from the sample carrier 2, so that the sample carrier 2 is repositioned on the focal plane of the objective lens 16.

[0104] Specifically, in this embodiment, the imaging data of each TDI camera 151 is transmitted to a computer device 19. The computer device 19 comprehensively evaluates the imaging quality of all TDI cameras 151 according to a preset rule, and determines the standard position of the objective lens 16 (that is, when the sample carrier 2 is located on the focal plane of the objective lens 16, the position of the objective lens 16 in the Z direction) based on the principle of optimal quality, that is, obtains a standard value representing the standard position of the objective lens 16. The standard value is provided to the focusing module 13. The focusing module 13 includes a detection optical path 130, a sensing unit 131, and a control unit 132. The sensing unit 131 senses the returned detection light and outputs an electrical signal. The control unit 132 obtains a detection value according to the electrical signal output by the sensing unit 131, compares the detection value with the standard value, and obtains a control signal for controlling the driving unit 161, so as to control the driving unit 161 to drive the objective lens 16 to move closer to or farther away from the sample carrier 2.

[0105] Please also refer to Figure 17 and Figure 18A -C shown, Figure 17 which is the optical path schematic diagram of the focusing module 13 performing focusing in this embodiment. Figures 18A - 18C It is a schematic diagram of the sensing unit 131 of the focusing module 13 in this embodiment sensing whether the sample carrier 2 is on the focal plane of the objective lens 16. The detection optical path includes a light source 1301 and a tube lens 1303. The sensing unit 131 includes a sensor 1311. The detection light emitted by the light source 1301 passes through the tube lens 1303 and the objective lens 16 (in this embodiment, it enters the tube lens 1303 after being reflected by a reflecting mirror 1305), irradiates on the sample carrier 2 and is reflected by the sample carrier 2. The reflected detection light irradiates on the sensor 1311 after passing through the objective lens 16 and the tube lens 1303. In this embodiment, the sensor 1311 uses a photoelectric sensor, specifically a PD (Photodiode) sensor 1312. Two sensing regions 1312a and 1312b are provided on the PD sensor 1312. The positions where the detection light irradiates on the sensing regions 1312a and 1312b can determine the position between the sample carrier 2 and the objective lens 16. As Figure 18AAs shown, the light spot G of the detection light is biased towards the sensing area 1312a, indicating that the sample carrier 2 is above the focal plane of the objective lens 16; as Figure 18B shown, the area where the light spot G of the detection light falls on the sensing area 1312a is the same as the area falling on the sensing area 1312b or the difference between the two is within a preset range, indicating that the sample carrier 2 is on the focal plane of the objective lens 16; as Figure 18C shown, the light spot of the detection light is biased towards the sensing area 1312b, indicating that the sample carrier 2 is below the focal plane of the objective lens 16. The sensing area 1312a converts the received optical signal into an electrical signal PD1 for output, and the sensing area 1312b converts the received optical signal into an electrical signal PD2 for output. The control unit 132 determines the defocus direction and defocus amount corresponding to the sample carrier 2 according to the two received electrical signals PD1 and PD2, and then controls the driving unit 161 to drive the objective lens 16 to move closer to or away from the sample carrier 2 by a corresponding distance.

[0106] In this embodiment, the difference between the electrical signals PD1 and PD2 is divided by their sum to generate a control signal DIV for controlling the driving unit 161. Therefore, signal noise can be effectively filtered, and at the same time, the influence of the brightness fluctuation of the light source 1301 on the focusing accuracy is avoided. The calculation formula for generating the control signal DIV is as follows:

[0107] DIV = α(DIFF / SUM + β)

[0108] where α is the signal amplification factor, the difference signal DIFF = PD1 - PD2, the sum signal SUM = PD1 + PD2, and β is the preset voltage offset.

[0109] Please refer to Figure 19 shown, which is a schematic diagram of the changes in various signals obtained during focusing. Among them, the abscissa represents the relative distance between the objective lens 16 and the sample carrier 2 on the Z axis, with the unit of mm. The curve O represents the difference signal DIFF, the curve Q represents the sum signal SUM, the curve P represents the control signal DIV, and the curve R represents the relative coordinate position between the driving unit 161 and the sample carrier 2 in the Z direction. Among them, Figure 19 the intersection point S of the curve R and the curve P represents the focal plane of the objective lens 16, and the value of the curve P (DIV value) at the intersection point S is the standard value representing the standard position of the objective lens 16.

[0110] Please refer to Figure 20 shown, which is a schematic diagram of a biochemical substance detection system provided by an embodiment of the present invention. The biochemical substance detection system 5 includes an optical imaging system 51, and the optical imaging system 51 can be the optical imaging system 1 introduced in the above embodiment.

[0111] Please refer to Figure 21As shown in the figure, it is a schematic diagram of a biochemical substance detection system provided by another embodiment of the present invention. The biochemical substance detection system 6 includes an optical imaging system 61 and a detection platform 62. The optical imaging system 61 may be the optical imaging system 1 introduced in the above embodiment, and the detection platform 62 is used to carry a sample carrier. The detection platform 62 is a movable platform, and the control device 611 of the optical imaging system 61 is used to control and coordinate the optical imaging system 61 and the detection platform 62. For example, the control device 611 is used to control the moving speed of the detection platform 62 to match and synchronize with the frequency of the TDI camera 613 of the optical imaging system 61. At the same time, the control device 63 is also used to control the turning on of the light source 615 of the optical imaging system 61 to synchronize with the photographing of the TDI camera 613. When the detection platform 62 reaches the specified position, the control device 611 simultaneously triggers the light source 615 and the TDI camera 613, so that the sample (not shown in the figure) carried on the detection platform 62, the light source 615, and the TDI camera 613 are synchronized. At the same time, the frequency of the TDI camera 613 automatically matches the moving speed of the detection platform 62 to ensure that the generated image is not distorted.

[0112] In summary, for the optical imaging system and the biochemical substance detection system provided in the above embodiments: 1. An industrial-grade or scientific-grade TDI camera is used to collect the excited light, reducing the photographing time for each sample and improving the detection throughput; 2. A filter system composed of a beam splitting device and a filter device is adopted. On the one hand, it can divide the excited light into multiple channels for imaging. On the other hand, it prevents the excitation light and other lights, such as the detection light, from interfering with the imaging of the excited light, improving the imaging quality; 3. The output end face of the light source is rectangular, or further elongated rectangular. At the same time, the excitation light shaping unit is used to shape the excitation light output by the light source into an illumination spot adapted to the photosensitive surface of the TDI camera, making full use of the light source energy to the greatest extent and improving the uniformity of the illumination spot; 4. An objective lens with a special structure is adopted, enabling the objective lens to meet the requirements of a large field of view and a large numerical aperture, while reducing distortion and flat-field achromatism; 5. A focusing system is adopted, which adjusts the distance between the objective lens and the sample carrier in real time to keep the sample carrier on the focal plane of the objective lens, compensating for the distance change between the sample carrier and the objective lens caused by environmental temperature changes, mechanical vibrations, sample bending, or other reasons, ensuring the imaging quality; 6. The focusing system calculates the distance between the sample carrier and the objective lens by a specific method, effectively eliminating the influence of signal noise and the change in the brightness of the detection light source on the detection result.

[0113] It should be noted that the above description only describes one or two specific embodiments. However, it is not difficult for those of ordinary skill in the art to understand that more embodiments can be derived from the above specific embodiments. For example, the first shaping unit and the second shaping unit of the excitation light shaping unit may not be limited to one lens, but may be composed of multiple lenses; the lenses constituting the first shaping unit and the second shaping unit may not be limited to cylindrical lenses and aspherical mirrors, but may also be spherical mirrors or Fresnel lenses. Again, for example, the number of TDI cameras and corresponding imaging channels is not limited to four, but may also be one or other plural numbers; the respective band-pass and cut-off bands of the filter system may also be adjusted accordingly according to specific circumstances; the design of the tube lens is not limited to the structure of two doublet lenses, but may be deformed in other ways according to the focal length or imaging requirements, such as using more lenses or one lens.

[0114] It can be understood that the optical imaging system provided by the embodiments of the present invention can be applied not only to biochemical substance detection systems, but also to any other devices that use excitation light to excite the laser to be detected and image the laser to be detected, so as to achieve fast imaging of the device.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. An optical imaging system for photographing and imaging a DNA sample, characterized in that, The optical imaging system includes an illumination module, an imaging module, an objective lens, and a focusing module. The illumination module is used to output excitation light, which is used to excite the DNA sample to generate stimulated light. The objective lens serves as the channel for the optical imaging system to output the excitation light and collect the stimulated light. The imaging module includes four time-delay integration linear array cameras, and each time-delay integration linear array camera is used to record the stimulated light emitted by one of the bases A, T, G, and C of the DNA sample. The objective lens meets the following conditions: the numerical aperture is greater than or equal to 0.7, the effective working distance is greater than 1.2 mm, the focal length is 12.5 mm, the apochromatism for light waves with wavelengths in the range of 500 nm to 800 nm is less than 0.4 μm, the field curvature is less than 0.4 μm, and the object space field of view range is greater than φ1.2 mm. The objective lens includes a total of seven groups of lenses, namely the first group, the second group, the third group, the fourth group, the fifth group, the sixth group, and the seventh group. The first group to the seventh group of lenses are arranged in sequence from the object side to the image side. The first group of lenses has a positive focal power and is used to generate positive field curvature. The second group of lenses has a positive focal power and is used to bear the positive decentration together with the first group of lenses. The third group of lenses has a positive focal power and is used to correct coma and chromatic aberration. The fourth group of lenses has a positive focal power. The fifth group of lenses has a positive focal power. The sixth group of lenses has a negative focal power. The seventh group of lenses has a negative focal power. The sixth group of lenses and the seventh group of lenses are jointly used to control field curvature and distortion. The first group of lenses satisfies: 9.2 < f1 / fobj < 9.7; the second group of lenses satisfies: 4.7 < f2 / fobj < 5.5; the third group of lenses satisfies: 4.6 < f3 / fobj < 5.6; the fourth group of lenses satisfies: 3.25 < f4 / fobj < 3.88; the fifth group of lenses satisfies: 5.71 < f5 / fobj < 6.11; the sixth group of lenses satisfies: -4.76 < f6 / fobj < -3; the seventh group of lenses satisfies: -23.9 < f7 / fobj < -19.

5. Wherein, f1 is the focal length of the first group of lenses, f2 is the focal length of the second group of lenses, f3 is the focal length of the third group of lenses, f4 is the focal length of the fourth group of lenses, f5 is the focal length of the fifth group of lenses, f6 is the focal length of the sixth group of lenses, f7 is the focal length of the seventh group of lenses, and fobj is the focal length of the objective lens. The focusing module includes a light source for outputting detection light to irradiate a sample carrier on which the DNA sample is mounted, a sensing unit for sensing the detection light reflected back from the sample carrier, and a control unit. The sensing unit includes a photoelectric sensor, and two sensing regions are provided on the photoelectric sensor. Each sensing region converts the received detection light into an electrical signal. The control unit determines the defocus direction and defocus amount of the sample carrier deviating from the focal plane of the objective lens in a manner that the difference between the electrical signals output by the two sensing regions is divided by the sum of the electrical signals output by the two sensing regions. The control unit is used to control the objective lens to approach or move away from the sample carrier by a corresponding distance so that the sample carrier is repositioned on the focal plane of the objective lens. The control unit calculates a control signal for controlling the movement of the objective lens according to the calculation formula: DIV = α(DIFF / SUM + β), where DIV is the control signal, α is a signal amplification factor, DIFF is the difference signal of the electrical signals output by the two sensing regions, SUM is the sum signal of the electrical signals output by the two sensing regions, and β is a preset voltage offset; The illumination module includes a light source, and the output end face of the light source for outputting the excitation light is rectangular.

2. The optical imaging system according to claim 1, wherein The third lens group includes three lenses, and the three lenses are glued together to form a triplet lens group; and / or, the fifth lens group includes two lenses, and the two lenses of the fifth lens group are glued together to form a doublet lens group; and / or, the sixth lens group includes two lenses, and the two lenses of the sixth lens group are glued together to form a doublet lens group; and / or, the seventh lens group includes two lenses, and the two lenses of the seventh lens group are glued together to form a doublet lens group.

3. The optical imaging system according to claim 1, wherein It further includes a filter system disposed between the objective lens and the time delay integration linear array camera, and the filter system blocks light outside a specific wavelength from entering the time delay integration linear array camera.

4. The optical imaging system according to claim 3, wherein It further includes a relay lens disposed between the filter system and the time delay integration linear array camera, and the distortion of the combination of the relay lens and the objective lens is <1%.

5. The optical imaging system according to claim 4, wherein The focal length of the relay lens is 150 mm - 250 mm; and / or, the relay lens includes four lenses, and the four lenses are glued together to form two doublet lenses.

6. The optical imaging system according to claim 3, characterized in that, The filter system includes a beam splitter and a filter. The beam splitter guides the excited light to different imaging channels to be recorded by different time delay integration linear array cameras, and the filter is used to block light outside a specific wavelength from entering each time delay integration linear array camera.

7. The optical imaging system according to claim 1, characterized in that, The illumination module further includes an excitation light shaping unit. The excitation light shaping unit is configured to magnify the spot of the excitation light in a first direction and shrink the spot of the excitation light in a second direction perpendicular to the first direction, so that the shape of the spot of the excitation light is adapted to the shape of the photosensitive surface of the time delay integration linear array camera. The excitation light shaping unit includes a first shaping unit and a second shaping unit. The first shaping unit is configured to magnify the spot of the excitation light in the first direction, and the second shaping unit is configured to shrink the spot of the excitation light in the second direction perpendicular to the first direction. The excitation light shaping unit includes two cylindrical lenses, one of the two cylindrical lenses is configured to magnify the spot of the excitation light in the first direction, and the other is configured to shrink the spot of the excitation light in the second direction perpendicular to the first direction.

8. The optical imaging system according to claim 7, wherein The aspect ratio of the spot of the excitation light after being shaped by the excitation light shaping unit is greater than or equal to 20.

9. The optical imaging system according to claim 1, wherein It further includes a control device. The control device is configured to control the moving speed of the sample to match and be synchronized with the frequency of the time delay integration linear array camera, and to control the turning on of the light source to be synchronized with the photographing of the time delay integration linear array camera.

10. A biochemical substance detection system, characterized in that, It includes the optical imaging system according to any one of claims 1-9.

11. The biochemical substance detection system according to claim 10, wherein, It further includes a detection platform for carrying the sample.

12. The biochemical substance detection system according to claim 11, wherein The optical imaging system further includes a control device. The control device is configured to communicate with the detection platform to control the synchronization between the optical imaging system and the detection platform.

13. The biochemical substance detection system according to claim 12, wherein The control device is configured to control the moving speed of the detection platform to match and be synchronized with the frequency of the time delay integration linear array camera, and to control the turning on of the illumination module to be synchronized with the photographing of the time delay integration linear array camera.

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