Spectrophotometer optical system

Abstract

The invention relates to a spectrophotometer optical system, which comprises a first convergence part, an incident part, a first concave reflector, a light splitting reflection grating, a second concave reflector, an exit slit, a second convergence part, a detection pool, a convergent lens and a detection part, and is characterized in that the first convergence part comprises a first lens and a second lens which are sequentially arranged along a light path; the first converging part comprises a first concave reflecting mirror and a second concave reflecting mirror, the first concave reflecting mirror and the second concave reflecting mirror are off-axis concave reflecting mirrors, the second converging part comprises a first lens and a second lens, and light beams converged by the converging lens pass through the detection pool, pass through the converging lens after passing through the detection pool and are finally detected by the detection part. The spectrophotometer optical system provided by the invention can realize material optical analysis or test in a wide spectral range, and has the advantages of miniaturization and light weight.

Description

Technical Field

[0001] The invention relates to the field of spectrum analysis systems, and in particular to a spectrophotometer optical system. Background Art

[0002] Spectrophotometer is an important spectral analysis instrument, widely used in many fields such as chemistry, biology, material science and printing. Its main principle is that different substances absorb light of a specific wavelength differently. The composite wavelength light is separated into a single wavelength light by a monochromator, and the absorption degree of the substance to the wavelength light is measured, thereby calculating its composition or concentration. In the field of printing, spectrophotometer not only improves the color quality and production efficiency of printed products, but also provides strong support for the sustainable development of the industry.

[0003] Traditional spectrophotometers usually achieve light separation and accurate wavelength measurement through optical systems. However, in the prior art, most spectrophotometers have limited spectral ranges, usually only covering the ultraviolet spectrum or the visible spectrum. In applications that require simultaneous detection of ultraviolet, visible, and near-infrared spectra, multiple devices or complex optical systems are often required to complete the task. This approach not only increases the size and weight of the equipment, but also reduces the flexibility of the system, making it difficult to meet the needs of modern applications for miniaturization and portability. Summary of the invention

[0004] In view of the above technical problems, the present invention proposes a spectrophotometer optical system, which can cover a wide spectral range of 200nm to 1100nm, that is, it can simultaneously detect wavelengths in the 200nm-380nm ultraviolet spectral region, the 380nm-780nm visible light spectral region, and the 780nm-1100nm near-infrared spectral region; and through optimized design, a miniaturized and lightweight structure is achieved, which greatly improves the flexibility of the spectrophotometer system.

[0005] The present invention specifically relates to a spectrophotometer optical system, comprising: a first converging portion (1) composed of a first lens (11) and a second lens (12) arranged in sequence along an optical path, an incident slit (2), a first concave reflector (3), a spectroscopic reflective grating (4), a second concave reflector (5), an exit slit (6), a second concave reflector (7) comprising a third lens (71) and a fourth lens (72), a detection cell (8), a converging lens (9), and a detection portion (10); the first lens (11), the second lens (12), the third lens (71), and the fourth lens (72) are all spherical mirrors, the first concave reflector (3) and the second concave reflector (5) are off-axis concave reflectors; an incident light beam enters the converging portion (1), passes through the first lens (11) and the second lens (12) are converged in sequence, and the path is limited by the incident slit (2) and reflected by the first concave reflector (3) into a parallel light beam, the direction of the parallel light beam intersects with the direction of the incident light beam, and the parallel light beam is split by the splitting reflection grating (4) and reflected to the second concave reflector (5), and then reflected by the second concave reflector (5) to form a spectrum and projected onto the exit part (6) for exit, wherein a slit is provided on the exit part, and the converging lens group (7) comprises a first lens and a second lens, and the converged light beam passes through the detection cell (8), passes through the converging lens (9) after passing through the detection cell, and is finally detected by the detection part (10); wherein the optical focal length of the spectrophotometer optical system is Φ, the optical focal length of the first converging part (1) is Φ1, and the optical focal length of the first lens is Φ 11 , the focal power of the second lens (12) is Φ 12 , which satisfies the following relationship: 0.24≤Φ 11 / Φ≤0.29,0.31≤Φ 12 / Φ≤0.35, 0.13≤Φ 11 +Φ 12 ≤0.2, 0.3≤Φ1 / Φ≤0.41, and the distance from the incident slit (2) to the object plane of the first lens (11) is smaller than the distance from the incident slit (2) to the first concave reflecting mirror (3).

[0006] Furthermore, the optical focal length of the second converging portion (7) is Φ7, which satisfies the following relationship: 0.22≤Φ7 / Φ≤0.35.

[0007] Furthermore, the focal power Φ of the third lens (71) is 71 The optical power Φ of the fourth lens (72) is 72 Satisfy 0.01≤Φ 71 =Φ 72 ≤0.067.

[0008] Furthermore, the first concave reflecting mirror has a curvature radius of R1, an inclination angle of θ1, and an eccentricity of Y1, which satisfy the following relationship: -0.01≤R1≤-0.006, -13°≤θ1≤-9°, 6≤Y1≤10.

[0009] Furthermore, the curvature radius of the second concave reflecting mirror is R2, the inclination angle is θ2, and the eccentricity is Y2, which satisfies the following relationship: -0.02≤R2≤-0.005, -20°≤θ2≤-16°, 4≤Y2≤10.

[0010] Furthermore, the grating constant of the light-splitting reflection grating is d, and the tilt angle is θ3, which satisfies the following relationship: 2μm≤d≤10μm, 14°≤θ3≤25°.

[0011] Furthermore, the light-splitting reflection grating (4) is a blazed grating, the blazing wavelength is λ, and satisfies the following relationship: 450nm≤λ≤625nm.

[0012] Furthermore, the detection unit (6) comprises a receiving plane for directly receiving the optical signal, and the inclination angle of the receiving plane is θ4, satisfying the following relationship: 10°≤θ4≤15°.

[0013] Furthermore, the focal power Φ9 of the converging lens (9) satisfies 0.01≤Φ9≤0.074, and 0.1≤Φ9 / Φ≤0.23.

[0014] The spectrophotometer optical system provided by the present invention has the advantages of miniaturization and light weight, which greatly improves the flexibility of the spectrophotometer system; the spectrophotometer function is excellent, the separation of different colors of light at different object surfaces is clear, the size of the diffuse spot is close to that of the Airy disk, the spectrum is stable, and it can cover a wide spectral range of 200nm to 1100nm in detection, that is, wavelength detection for the 200nm-380nm ultraviolet spectrum region, the 380nm-780nm visible light spectrum region, and the 780nm-1100nm near-infrared spectrum region; the MTF (Modulation Transfer Function) of the full field of view at a spatial frequency of 100lp / mm is greater than 0.2, and the overall length is less than 160mm. In addition, the detection optical path of the present invention adopts a single-beam optical path without beam splitting throughout the entire process, and the light energy utilization rate is higher. In the detection of low-concentration or weakly absorbing samples, a single beam may show a better signal-to-noise ratio, and the simplified optical path makes the instrument smaller, which is suitable for rapid detection in laboratories or on-site with limited space.

[0015] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0017] Figure 1 A schematic diagram of an optical system of a spectrophotometer according to an embodiment of the present invention is shown; Figure 2 A schematic diagram of a diffuse spot corresponding to an optical system of a spectrophotometer according to an embodiment of the present invention is shown; Figure 3 A schematic diagram of a curve of a modulation transfer function corresponding to an optical system of a spectrophotometer according to an embodiment of the present invention is shown.

[0018] Figure numerals: 1-first converging portion, 11-first lens, 12-second lens, 2-incident slit, 3-first concave reflector, 4-spectrometric reflective grating, 5-second concave reflector, 6-detection portion, 7-second converging portion, 71-third lens, 72-fourth lens, 8-detection cell, 9-converging lens, 10-detection portion DETAILED DESCRIPTION

[0019] The present invention is further described in detail below in conjunction with the accompanying drawings: the described embodiments are only part of the embodiments of the present invention, not all of them. The following embodiments are only for more clearly illustrating the technical solutions of the present invention and cannot be used to limit the scope of protection of the present invention.

[0020] Before introducing the embodiments of the present invention in detail, the spectrophotometer optical system involved in the present invention is first introduced. It should be noted that the units of the focal power, the radius of curvature and the eccentricity in the present invention are all mm, mm and mm, respectively.

[0021] In the embodiment disclosed in the present invention, in the order of the optical path, the spectrophotometer optical system includes: a first converging portion 1 composed of a first lens 11 and a second lens 12 arranged in sequence along the optical path, an incident slit 2, a first concave reflector 3, a spectroscopic reflection grating 4, a second concave reflector 5, an exit slit 6, a second converging portion 7 including a third lens 71 and a fourth lens 72, a detection cell 8, a converging lens 9, and a detection portion 10.

[0022] The incident light beam enters the first converging portion 1, is converged by the first lens 11 and the second lens 12 in sequence, and is reflected by the first concave reflector 3 as a parallel light beam after the path is limited by the incident slit 2. The direction of the parallel light beam intersects with the direction of the incident light beam. After the parallel light beam is split by the splitting reflection grating 4 and reflected to the second concave reflector 5, it is reflected by the second concave reflector 5 to form a spectrum and is projected onto the exit slit 6 for emission. The exiting light is converged by the second converging portion 7. The converged light beam passes through the detection cell 8 and the converging lens 9, and finally forms a spectrum and is projected onto the detection portion 10 for imaging.

[0023] The incident slit 2 is arranged on the converging side of the first converging portion, and is a slit that intersects and is perpendicular to the extension line of the first converging portion, and is used to limit the path of the incident light beam; the first concave reflector 3 is arranged toward the incident slit 2, the spectroscopic reflection grating 4 is arranged toward the first concave reflector 3, the second concave reflector 5 is arranged toward the spectroscopic reflection grating 4, and the exit slit 6 is arranged toward the second converging portion 7, and is used to limit the path of the exiting light beam; the second converging portion 7 is arranged on the exiting light path and converges the exiting light; the converged light beam passes through the detection cell 8, and the substance in the detection cell 8 has different absorption rates for light of different wavelengths.

[0024] Due to the design of multiple reflections and the reasonable setting of the optical parameters and position parameters of each part, this embodiment effectively controls the optical distortion and realizes the miniaturization and lightness of the optical system of the spectrophotometer. For the description of the first converging part, the second converging part, the incident slit 2, and the exit slit 6, please refer to Figure 1 The direction of light in the spectrum. The above-mentioned "direction" means "can be connected by the optical path" but is not equivalent to "directly facing". The spectrophotometer optical system can realize its functions with only six optical units and one detector. Its structure has the advantages of miniaturization and lightness, which greatly improves the flexibility of the spectrophotometer system.

[0025] In a preferred embodiment, Figure 1 As shown, the first lens 11, the second lens 12, the third lens 71 and the fourth lens 72 are all spherical lenses. The present invention uses a lens combination of two lenses as the first converging portion and the second converging portion, which can better bear the optical focal length, reduce the sensitivity of lens processing, and help eliminate aberrations.

[0026] In a preferred embodiment, the first concave reflecting mirror 3 and the second concave reflecting mirror 5 are off-axis concave reflecting mirrors.

[0027] In a preferred embodiment, Figure 1As shown, the focal power of the spectrophotometer optical system is Φ, the focal power of the first converging portion (1) is Φ1, and the focal power of the first lens 11 is Φ 11 , the focal length of the second lens 12 is Φ 12 , which satisfies the following relationship: 0.24≤Φ 11 / Φ≤0.29,0.31≤Φ 12 / Φ≤0.35, 0.13≤Φ 11 +Φ 12 ≤0.2, 0.3≤Φ1 / Φ≤0.41, and the distance from the incident slit 2 to the object plane of the first lens (11) is smaller than the distance from the incident slit (2) to the first concave reflector (3), which helps to ensure clear separation of different colors of light at different object planes, close sizes of the diffuse spot and the Airy disk, and stable spectrum within a wide spectral range of 200nm to 1100nm.

[0028] In some embodiments, Figure 1 As shown, the central axis (or equivalent central axis) of the first concave reflector 3, the beam splitting reflective grating 4, the second concave reflector 5 and the detection part 6 are all inclined relative to the incident light axis. Figure 1 ,exist Figure 1 The tilt angle θ of any component in the plane shown is defined as the angle between the central axis and the extended line of the incident light axis, with the counterclockwise direction being positive.

[0029] In a preferred embodiment, Figure 1 As shown, the first concave reflecting mirror has a curvature radius of R1, an inclination angle of θ1, and an eccentricity of Y1, satisfying the following relationship: -0.01≤R1≤-0.006, -13°≤θ1≤-9°, 6≤Y1≤10.

[0030] In a preferred embodiment, Figure 1 As shown, the radius of curvature of the second concave reflecting mirror is R2, the inclination angle is θ2, and the eccentricity is Y2, satisfying the following relationship: -0.02≤R2≤-0.005, -20°≤θ2≤-16°, 4≤Y2≤10.

[0031] In a preferred embodiment, Figure 1 As shown, the grating constant of the spectroscopic reflection grating is d, and the tilt angle is θ4, which satisfies the following relationship: 2μm≤d≤10μm, 14°≤θ4≤25°.

[0032] In a preferred embodiment, Figure 1 As shown, the spectroscopic reflection grating 4 is a blazed grating, and the blazing wavelength is λ, which satisfies the following relationship: 450 nm≤λ≤625 nm.

[0033] In a preferred embodiment, Figure 1As shown, the exit slit 6 includes a receiving plane for directly receiving the optical signal, and the inclination angle of the receiving plane is θ6, which satisfies the following relationship: 10°≤θ6≤15°.

[0034] In the embodiment disclosed in the present invention, the overall length of the spectrophotometer optical system is less than 210 mm, and the overall height is less than 90 mm; the length of the first converging portion is less than 60 mm.

[0035] In a preferred embodiment, the distance from the incident slit 2 to the image plane of the second lens 12 is less than one third of the distance from the incident slit 2 to the first concave reflecting mirror 3 .

[0036] In a preferred embodiment, the distance from the beam splitting reflection grating 4 to the first concave reflection mirror 3 is D 34 , the distance from the beam splitting reflection grating 4 to the second concave reflection mirror 5 is D 45 , satisfying the following relationship: D 34 <D 45 More preferably, the following relationship is satisfied: 0.6≤D 34 / D 45 ≤0.85.

[0037] In a preferred embodiment, the distance from the beam splitting reflection grating 4 to the second concave reflection mirror 5 is D 45 , the distance from the detection plane of the exit slit 6 to the second concave reflector 5 is D 56 , satisfying the following relationship: 0.74≤D 45 / D 56 ≤0.92.

[0038] In a preferred embodiment, Figure 1 As shown, the optical power of the second converging portion 7 is Φ7, which satisfies the following relationship: 0.22≤Φ7 / Φ≤0.35.

[0039] In a preferred embodiment, Figure 1 As shown, the focal length of the third lens 71 is Φ 71 The refractive power Φ of the fourth lens 72 72 Satisfy 0.01≤Φ 71 =Φ 72 ≤0.067.

[0040] In a preferred embodiment, Figure 1 As shown, the focal power Φ9 of the converging lens 9 satisfies 0.01≤Φ9≤0.074, and 0.1≤Φ9 / Φ≤0.23.

[0041] The above distances and lengths are defined in the direction of the incident light axis or parallel to it, while the height direction is defined in Figure 1The above arrangement helps the optical system of the spectrophotometer to keep the diffuse spots of each color light focused.

[0042] A specific embodiment of the present invention and its technical effects are provided below for auxiliary explanation: See also Figure 1 In the optical system of the spectrophotometer, the first converging portion is composed of a first lens 11 and a second lens 12 along the incident optical axis, the optical focal power Φ1 of the first lens 11 is 0.02, the optical focal power Φ2 of the second lens 12 is 0.015, and the sum of the two focal powers satisfies 0.02≤Φ1+Φ2≤0.05; the length (along the direction of the incident optical axis) of the entire first converging portion (including the first lens 11, the second lens 12 and the component for fixing the first lens 11 and the second lens 12) is 50 mm.

[0043] The first converging portion is connected to the incident slit 2 by a shading component. The incident slit 2 intersects and is perpendicular to the extension line of the incident light axis, allowing only the light converged by the first converging portion to pass through. The length of the slit is 5.5 mm and the width is 0.2 mm to accommodate light in the wavelength range of 200 nm-1100 nm that passes through after being converged by the first converging portion.

[0044] The first concave reflecting mirror 3 improves the correction capability of the system's off-axis aberration and increases the field of view of the system; its radius of curvature is -0.005, the tilt angle is -13°, the eccentricity is 6.5, and the distance from its center of curvature to the incident slit 2 (along the direction of the incident light axis) is 62 mm.

[0045] The blazed reflection grating serving as the spectroscopic reflection grating 4 has a grating constant of 3 μm, a tilt angle of 22°, a blazing wavelength of 500 nm, and a lateral distance (i.e., a direction parallel to the incident light axis) between the grating center and the curvature center of the first concave reflection mirror 3 of 46 mm.

[0046] The second concave reflecting mirror 5 further improves the correction capability of the system off-axis aberration; its radius of curvature is -0.004, the tilt angle is -13°, the eccentricity is 6, and the lateral distance from the center of curvature to the beam splitting reflection grating 4 is 60 mm.

[0047] The inclination angle of the receiving plane of the exit slit 6 is 12°, and the lateral distance between the center of the receiving plane and the center of curvature of the second concave reflector 5 is 78 mm; the position and angle of the receiving screen can be controlled and adjusted through the communication connection to correspond to different object planes.

[0048] The second converging part is composed of a third lens 71 and a second lens 72 along the exit optical axis. The focal length of the third lens 71 is Φ 71 is 0.05, and the focal length Φ of the second lens 72 72is 0.05, and the focal length satisfies 0.01≤Φ 71 =Φ 72 ≤0.067; the length (along the direction of the incident optical axis) of the entire first converging portion (including the third lens 71 and the second lens 72 and the component for fixing and connecting the first lens 11 and the second lens 12) is 30 mm.

[0049] The detection pool is a focused light beam passing through the detection pool (8). The substance in the detection pool has different absorption rates for light of different wavelengths. The detection pool serves as a core carrier for the interaction between light and the sample, providing a closed space to accommodate liquid, gas or solid samples to avoid external contamination or volatilization.

[0050] The focal power Φ9 of the converging lens 9 is 0.06, and its focal power satisfies 0.01≤Φ9≤0.074, and 0.1≤Φ9 / Φ≤0.23. Its function is to converge light of different wavelengths for detection by the detector.

[0051] The length (along the incident light axis) of the part of the spectrophotometer optical system excluding the first converging part and the second converging part is 102 mm, and the height (in the direction perpendicular to the incident light axis) is 75 mm; the overall length of the spectrophotometer optical system is about 210 mm, which obviously has the advantages of miniaturization and lightweight, realizes the application of a wide spectral range (200nm-1100nm), well controls optical distortion, and greatly improves the flexibility and practicality of the system.

[0052] The imaging effect of this specific embodiment can be seen in Figure 2 , Figure 2 The diffuse spots corresponding to the spectrophotometer optical system in this embodiment are shown: at different object plane inclination angles (-0.300°, 0.000°, 0.300°), the light spots with wavelengths of 200nm (ultraviolet), 425nm (approximately blue light), 650nm (approximately red light), 875nm (near infrared), and 1100nm (near infrared) are gathered and imaged from top to bottom according to the wavelength at the corresponding image planes (-9.754mm, -6.241mm, -2.746mm). On the horizontal scale, the distribution of each light spot is relatively concentrated, and the diffuse spot is nearly circular with the whole; at different angles, the position of the diffuse spot changes slightly, but there is no obvious diffusion; from short wave to long wave, the distribution of the diffuse spot is highly concentrated. Therefore, the imaging stability of the spectrophotometer optical system is high, the aberration control effect of the spectrophotometer optical system is good, it has a strong correction ability for off-axis asymmetric coma and astigmatism, and has good imaging quality in a wide spectrum range.

[0053] Figure 3A schematic diagram of the modulation transfer function curve of the spectrophotometer optical system of the present invention is shown. The dotted dashed line at the top of the figure and close to the straight line represents the diffraction limit, which is the theoretical maximum resolution capability of the lens assembly. The other curves are schematic diagrams of the modulation transfer function curves of the spectrophotometer optical system of the present invention at multiple field angles. It can be seen that the curves of these modulation transfer functions are close to the diffraction limit, and the closer to the diffraction limit, the higher the resolution capability of the lens. It can be seen from the figure that the spectrophotometer optical system proposed by the present invention has excellent resolution capability.

[0054] Although the specific values ​​of various parameters are shown in this embodiment, it should be noted that the various parts of the spectrophotometer optical system are electrically connected to the controller, and their angles and distances can be fine-tuned to meet the imaging requirements of different object distances; the performance parameters of each optical unit can also be adjusted within the range shown in the present invention, and the approximate Figure 2 That is, the above non-interval-limited specific parameters are only examples and do not limit the protection scope of the present invention.

[0055] In a specific embodiment of the present invention, see Figure 1 In the spectrophotometer optical system, the slit lengths of the incident slit 2 and the exit slit 6 are 5.5 mm and the widths are 0.2 mm; the blazed reflection grating serving as the spectroscopic reflection grating 4 has a grating constant of 4 μm, an inclination angle of 22°, and a blazing wavelength of 625 nm.

[0056] In a preferred embodiment, the first converging portion 1 and / or the second converging portion 7 are detachably and telescopically arranged relative to the entire system, so as to facilitate assembly in different application scenarios.

[0057] The spectrophotometer optical system of the embodiment of the present invention can achieve miniaturization and high-quality imaging in the spectral range of 200nm-1100nm, that is, simultaneously for the ultraviolet spectral region of 200nm-380nm, the visible light spectral region of 380nm-780nm, and the near-infrared spectral region of 780nm-1100nm, and has good aberration control and wavelength consistency, which meets the design requirements of precision spectral instruments.

[0058] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive, and therefore the present invention is not limited to the embodiments described in the specific implementation manners, and any other implementation manners derived by those skilled in the art based on the technical solutions of the present invention also fall within the scope of protection of the present invention.

Claims

1. A spectrophotometer optical system, characterized in that: The spectrophotometer optical system comprises: A first converging portion (1) composed of a first lens (11) and a second lens (12) arranged in sequence along an optical path, an incident slit (2), a first concave reflector (3), a spectroscopic reflective grating (4), a second concave reflector (5), an exit slit (6), a second converging portion (7) including a third lens (71) and a fourth lens (72), a detection cell (8), a converging lens (9), and a detection portion (10); The first lens (11), the second lens (12), the third lens (71) and the fourth lens (72) are all spherical mirrors, and the first concave reflector (3) and the second concave reflector (5) are off-axis concave reflectors; An incident light beam enters the first converging portion (1), is converged by the first lens (11) and the second lens (12) in sequence, passes through a path defined by the incident slit (2), and is reflected by the first concave reflector (3) to form a parallel light beam, wherein the direction of the parallel light beam intersects with the direction of the incident light beam, and is reflected by the second concave reflector (5) after being split by the splitting reflection grating (4) to form a spectrum and projected onto the exit slit (6) for exit, and the exit light is converged by the second concave reflector (7), and the converged light beam passes through the detection cell (8), and passes through the converging lens (9), and is finally detected by the detection portion (10); The focal power of the spectrophotometer optical system is Φ, the focal power of the first converging portion (1) is Φ1, and the focal power of the first lens is Φ 11 , the focal power of the second lens (12) is Φ 12 , which satisfies the following relationship: 0.24≤Φ 11 / Φ≤0.29,0.31≤Φ 12 / Φ≤0.35, 0.13≤Φ 11 +Φ 12 ≤0.2, 0.3≤Φ1 / Φ≤0.41, and the distance from the incident slit (2) to the object plane of the first lens (11) is smaller than the distance from the incident slit (2) to the first concave reflecting mirror (3).

2. The spectrophotometer optical system according to claim 1, wherein: The optical focal length of the second converging portion (7) is Φ7, which satisfies the following relationship: 0.22≤Φ7 / Φ≤0.

35.

3. The spectrophotometer optical system according to claim 2, wherein: The focal power of the third lens (71) is Φ 71 The optical power Φ of the fourth lens (72) is 72 Satisfy 0.01≤Φ 71 =Φ 72 ≤0.

067.

4. The spectrophotometer optical system according to claim 3, characterized in that: The first concave reflecting mirror has a curvature radius of R1, an inclination angle of θ1, and an eccentricity of Y1, which satisfy the following relationship: -0.01≤R1≤-0.006, -13°≤θ1≤-9°, 6≤Y1≤10.

5. The spectrophotometer optical system according to claim 4, characterized in that: The curvature radius of the second concave reflecting mirror is R2, the inclination angle is θ2, and the eccentricity is Y2, which satisfy the following relationship: -0.02≤R2≤-0.005, -20°≤θ2≤-16°, 4≤Y2≤10.

6. The spectrophotometer optical system according to claim 5, characterized in that: The grating constant of the spectroscopic reflection grating is d, and the tilt angle is θ4, which satisfies the following relationship: 2μm≤d≤10μm, 14°≤θ4≤25°.

7. The spectrophotometer optical system according to claim 6, characterized in that: The light-splitting reflection grating (4) is a blazed grating, the blazing wavelength is λ, and satisfies the following relationship: 450nm≤λ≤625nm.

8. The spectrophotometer optical system according to claim 7, characterized in that: The exit slit (6) comprises a receiving plane for directly receiving the optical signal, and the inclination angle of the receiving plane is θ6, satisfying the following relationship: 10°≤θ6≤15°.

9. The spectrophotometer optical system according to claim 8, wherein: The focal power Φ9 of the converging lens (9) satisfies 0.01≤Φ9≤0.074, and 0.1≤Φ9 / Φ≤0.23.

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