A spectrophotometer optical system based on offner configuration

Abstract

The present application relates to a kind of spectrophotometer optical systems based on Offner structure, the spectrophotometer optical system includes the first converging portion of first lens and second lens, incident slit, concave mirror, convex reflection grating, exit slit, collimating lens, beam splitter, reference cell, plane mirror, the second converging portion of third lens and fourth lens, sample cell and the third converging portion of fifth lens and sixth lens.It can realize the material optical analysis or test of wide spectral range, and has the advantages of eliminating systematic errors such as light source fluctuation, environmental temperature change, solvent absorption, improving data reliability, when light source intensity decays or fluctuates with time, reference light path is compensated synchronously, avoid the problem that single-beam instrument needs frequent calibration.

Description

TECHNICAL FIELD

[0001] The present application relates to optical lens systems, in particular to a spectrophotometer optical system based on Offner structure. BACKGROUND

[0002] With the continuous improvement of the requirements of modern industry on precision detection and quality control, the application of spectrophotometer in the fields of printing, semiconductor manufacturing, biomedical analysis and the like is increasingly widespread. In the prior art, the monochromator, which is a core component of the spectrophotometer, usually adopts the Czerny-Turner spectrometer structure, and there are some deficiencies and problems, such as limited spectral range, insufficient imaging quality optimization, etc. Due to the complexity of the components, the cost is often high. The volume is bulky. In long time or high frequency use, it is difficult for some spectrometers to maintain high detection efficiency and system stability. SUMMARY

[0003] In view of the above technical problems, the present application provides a spectrophotometer optical system based on Offner structure, which can eliminate systematic errors such as light source fluctuation, environmental temperature change, solvent absorption, improve data reliability, and when the light source intensity decays or fluctuates with time, the reference light path is compensated synchronously, avoiding the problem that the single-beam instrument needs to be frequently calibrated.

[0004] The present application relates to a kind of spectrophotometer optical systems based on Offner structure, it includes: by the first lens (101) and the second lens (102) sequentially arranged along optical path and is composed of first convergence part (1), incident slit (2), concave mirror (3), convex reflective grating (4), exit slit (5), collimating lens (6), beam splitter (7), reference cell (8), plane mirror (9), by third lens (1001) and fourth lens (1002) and is composed of second convergence part (10), sample cell (11) and by fifth lens (1201) and sixth lens (1202) and is composed of third convergence part (12);Wherein, the optical axis (30) of the concave mirror is parallel with the incident optical axis, the convex reflective grating (4) is coaxial with the concave mirror (3), and the concave mirror (3) and the convex reflective grating (4) form offner structure;The first lens (101), the second lens (102), the third lens (1001) and the fourth lens (1002), the fifth lens (1201) and the sixth lens (1202) are all spherical mirrors;Incident light beam enters first convergence part (1), is sequentially converged after the first lens (101) and the second lens (102), is reflected to the convex reflective grating (4) by the concave mirror (3) after being limited path by the incident slit (2), is again reflected to the concave mirror (3) after being reflected by the convex reflective grating (4), is again reflected by the concave mirror (3) to form spectrum, and is projected on the exit slit (5), the exit light beam is collimated again after collimating lens (6), the light beam is split by beam splitter (7), passes through reference cell (8) and sample cell (11) respectively, the light path is turned over again by plane mirror (9), and finally, the two light paths are converged and detected by second convergence part (10) and third convergence part (12) respectively;The focal power of the first lens (101) is Φ 101 , the focal power of the second lens (102) is Φ 102 , and the following relationship is satisfied: 0.1≤Φ 101 =Φ 102 ≤0.25, the focal power of the spectrophotometer optical system is Φ, and the focal power of the first convergence part is Φ 1 / 0.2≤Φ 12 Φ≤0.3.

[0005] Further, the distance from the incident slit (2) to the image plane of the second lens (102) is D 12 , the distance from the incident slit (2) to the concave mirror (3) is D 23 , and the distance from the incident slit (2) to the convex reflective grating (4) is D 24，The concave reflector (3) has a radius of curvature of R1, and the convex reflective grating (4) has a radius of curvature of R2, satisfying the following relationship: 0.2≤D 12 / D 23 ≤0.5, 0.4≤D 12 / D 24 ≤0.8, 0.5≤|R1| / |R2|≤0.75.

[0006] Furthermore, the radius of curvature of the concave reflector is R1, which satisfies the following relationship: -0.02≤R1≤-0.01.

[0007] Furthermore, the radius of curvature of the convex reflective grating is R2, which satisfies the following relationship: -0.04≤R2≤-0.02.

[0008] Furthermore, the grating constant of the convex reflective grating is d, which satisfies the following relationship: 2μm≤d≤10μm.

[0009] Furthermore, the optical power Φ6 of the collimating lens (6) satisfies 0.05≤Φ6≤0.1, and the optical power Φ of the spectrophotometer optical system satisfies 0.1≤Φ6 / Φ≤0.15.

[0010] Furthermore, the beam splitter (7) is coated with a semi-transparent and semi-reflective film with a transmission and reflection ratio of 50%:50%.

[0011] Furthermore, the optical power Φ of the third lens (1001) in the second converging portion (10) 1001 The optical power Φ of the fourth lens (1002) 1002 Satisfying 0.1≤Φ 1001 =Φ 1002 ≤0.25, and the optical power Φ of the second converging part (10) 10 And the optical power Φ of the spectrophotometer optical system, satisfying 0.2≤Φ 10 / Φ≤0.3.

[0012] Furthermore, the optical power Φ of the fifth lens (1201) in the third converging section (12) is... 1201 The optical power Φ of the sixth lens (1202) 1202 Satisfying 0.1≤Φ 1201 =Φ 1202 ≤0.25, and the optical power Φ of the third converging part (12) 12 And the optical power Φ of the spectrophotometer optical system, satisfying 0.2≤Φ 12 / Φ≤0.3.

[0013] The spectrophotometer optical system provided by the application is based on an offner structure, has high system stability after optimization of component design, can eliminate systematic errors such as light source fluctuation, environmental temperature change, solvent absorption, and improve data reliability through synchronous measurement of double light paths, and when light source intensity decays or fluctuates with time, the reference light path is compensated synchronously, thereby avoiding the problem that a single-beam instrument needs to be frequently calibrated.

[0014] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0015] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate an embodiment consistent with the present application and, together with the description, serve to explain the principles of the application.

[0016] Figure 1 A structure and an optical path schematic diagram of a spectrophotometer optical system according to one embodiment of the application are shown;

[0017] Figure 2 A display schematic diagram of a diffraction spot corresponding to the spectrophotometer optical system according to one embodiment of the application is shown;

[0018] Figure 3 A curve schematic diagram of a modulation transfer function corresponding to the spectrophotometer optical system according to one embodiment of the application is shown.

[0019] Reference signs: 1-first converging part, 101-first lens, 102-second lens, 2-incoming slit, 3-concave mirror, 30-optical axis of the concave mirror, 4-convex reflection grating, 5-outgoing slit, 6-collimating lens, 7-beam splitter, 8-reference cell, 9-flat mirror, 10-second converging part, 1001-third lens, 1002-fourth lens, 11-sample cell, 12-third converging part, 1201-fifth lens, 1202-sixth lens. DETAILED DESCRIPTION

[0020] The application will be further described in detail below in combination with the drawings: the described embodiments are only some of the embodiments of the application, but not all, the following embodiments are only for more clearly illustrating the technical solutions of the application, and cannot be used to limit the protection scope of the application.

[0021] It should be stated that the unit of optical power in the application is mm, the unit of curvature radius is mm, and the unit of eccentricity is mm.

[0022] In the disclosed embodiments, the Offner structure-based spectrophotometer optical system comprises, in order along the optical path: a first converging portion 1 composed of a first lens 101 and a second lens 102, an entrance slit 2, a concave mirror 3, a convex reflective grating 4, an exit slit 5, a collimating lens 6, a beam splitter 7, a reference cell 8, a plane mirror 9, a second converging portion 10 composed of a third lens 1001 and a fourth lens 1002, a sample cell 11, and a third converging portion 12 composed of a fifth lens 1201 and a sixth lens 1202.

[0023] The first converging portion 1 can converge the incident light beam; the entrance slit 2 is arranged on the converging side of the first converging portion 1 and is located on the extension of the incident optical axis, thereby defining the path of the incident light beam and ensuring that the light beam can accurately enter the subsequent part of the optical system, reducing optical path deviation and stray light interference; the concave mirror 3 is arranged towards the entrance slit 2 and can reflect the incident light beam; the convex reflective grating 4 is arranged towards the concave mirror 3 and can separate and reflect the incident light beam back to the concave mirror 3; and the detection portion 5 is arranged towards the concave mirror 3 and can receive the light signal and form an image.

[0024] The incident light beam enters the first converging portion 1, is sequentially converged by the first lens 101 and the second lens 102, is reflected by the concave mirror 3 to the convex reflective grating 4 through the entrance slit 2, is reflected by the convex reflective grating 4 to the concave mirror 3, is again reflected by the concave mirror 3 to form a spectrum, and is projected on the exit slit 5; the exit light beam is collimated by the collimating lens 6, is split by the beam splitter 7, passes through the reference cell 8 and the sample cell 11, is turned by the plane mirror 9, and is finally converged by the second converging portion 10 and the third converging portion 12 to be detected.

[0025] For the first converging portion 1, the entrance slit 2, the exit slit 5, the second converging portion 10, and the third converging portion 12, the description of “object side” or “image side” or “incident side” or “converging side” can be referred to the light ray direction in Figure 1 The above “towards” means “there can be an optical path connection” but is not equal to “directly opposite”. The combination design of the concave mirror 3 and the convex reflective grating 4 reduces the aberration and optical path interference in the system through optical optimization, thereby improving the imaging quality and enabling the detection portion to obtain high-precision spectral imaging. The spectrophotometer optical system can cover a wide spectral range (200 nm-1100 nm) from ultraviolet to visible light and near-infrared regions and has high resolution and good imaging quality.

[0026] In one embodiment, the optical axis of the concave reflector 3 is parallel to the incident optical axis, the convex reflective grating 4 is coaxial with the concave reflector 3, and the concave reflector 3 and the convex reflective grating 4 form an offner structure; the first lens 101, the second lens 102, the third lens 1001, the fourth lens 1002, the fifth lens 1201, and the sixth lens 1202 are all spherical mirrors.

[0027] In a preferred embodiment, such as Figure 1 As shown, the optical power of the first lens 101 is Φ. 101 The optical power of the second lens 102 is Φ 102 It satisfies the following relationship: 0.1≤Φ 101 =Φ 102 The optical power Φ of the spectrophotometer optical system, and the optical power Φ1 of the first converging section, satisfy 0.2 ≤ Φ. 1 / Φ≤0.3.

[0028] In a preferred embodiment, such as Figure 1 As shown, the distance from the entrance slit 2 to the image plane of the second lens 102 is D. 12 The distance from the incident slit 2 to the concave mirror 3 is D. 23 The distance from the incident slit 2 to the convex reflecting grating 4 is D. 24 The concave mirror 3 has a radius of curvature of R1, and the convex grating 4 has a radius of curvature of R2, satisfying the following relationship: 0.2 ≤ D 12 / D 23 ≤0.5, 0.1≤D 12 / D 24 ≤0.25, 0.5≤|R1| / |R2|≤0.75.

[0029] The present invention uses a combination of two lenses as a first converging part 1, a second converging part 10, and a third converging part 12, which can better handle optical power, reduce the sensitivity of lens processing, and help eliminate aberrations.

[0030] In a preferred embodiment, such as Figure 1 As shown, the radius of curvature of the concave mirror 3 is R1, which satisfies the following relationship: 0.01≤R1≤0.02.

[0031] In a preferred embodiment, such as Figure 1 As shown, the radius of curvature of the convex reflective grating 4 is R2, which satisfies the following relationship: -0.04≤R2≤-0.02.

[0032] In a preferred embodiment, such as Figure 1 As shown, the grating constant of the convex reflective grating 4 is d, which satisfies the following relationship: 2μm≤d≤10μm.

[0033] In a preferred embodiment, such as Figure 1 As shown, the convex reflective grating 4 is a blazed grating. The blazed wavelength λ of the blazed grating satisfies 450nm≤λ≤550nm, which improves the spectral efficiency and wavelength resolution, enabling the spectral detection range to cover a wide wavelength range of 200nm-1100nm.

[0034] In a preferred embodiment, such as Figure 1 As shown, the optical power Φ6 of the collimating lens 6 satisfies 0.05≤Φ6≤0.1, and the optical power Φ of the spectrophotometer optical system satisfies 0.1≤Φ6 / Φ≤0.15.

[0035] In a preferred embodiment, the beam splitter 7 is coated with a semi-transparent and semi-reflective film with a transmission and reflection ratio of 50%:50%.

[0036] In a preferred embodiment, such as Figure 1 As shown, the optical power Φ of the third lens 1001 in the second converging section 10 is... 1001 Optical power Φ of the fourth lens 1002 1002 Satisfying 0.1≤Φ 1001 =Φ 1002 ≤0.25, and the optical power Φ of the second converging part 10 10 And the optical power Φ of the spectrophotometer optical system, satisfying 0.2≤Φ 10 / Φ≤0.3.

[0037] In a preferred embodiment, such as Figure 1 As shown, the optical power Φ of the fifth lens 1201 in the third converging section 12 is... 1201 Optical power Φ of the sixth lens 1202 1202 Satisfying 0.1≤Φ 1201 =Φ 1202 ≤0.25, and the optical power Φ of the third converging part 12 12 And the optical power Φ of the spectrophotometer optical system, satisfying 0.2≤Φ 12 / Φ≤0.3.

[0038] In a preferred embodiment, the distance from the convex reflective grating 4 to the concave reflective mirror 3 is D. 34 The distance from the exit slit 5 to the concave mirror 3 is D. 35 The following relationship is satisfied: D 23 / D 34 ≥2, D 35 / D 34 ≥2; more preferably, satisfying the following relationship: 0.9≤D 23 / D 35≤1.1. It should be noted that the convex grating and concentric optical design can reduce aberration. The high line density and uniform dispersion characteristics of the convex grating ensure accurate focusing of different wavelengths, reduce spectral line broadening, and thus improve resolution.

[0039] The distance and length are defined in the direction of the incident optical axis or parallel to the incident optical axis, and the direction of the height is perpendicular to the direction of the length in the plane shown. Figure 1 The above arrangement helps the dispersion spot of the spectrophotometer optical system to be concentrated.

[0040] The following provides a specific embodiment of the present application and its performance effects for auxiliary explanation:

[0041] Referring to Figure 1 , in the spectrophotometer optical system, the first converging part 1 is composed of the first lens 101 and the second lens 102 along the incident optical axis, the optical power Φ 101 of the first lens 101 is 0.15, and the optical power Φ 102 of the second lens 102 is 0.15; the length (in the direction of the incident optical axis) of the entire converging part 1 (including the first lens 101, the second lens 102, and the assembly for fixedly connecting the first lens 101 and the second lens 102) is 48 mm. This design reduces the aberration of the system and obtains a total weight that is lighter than that of using a single converging lens.

[0042] The converging part 1 is connected with the incident slit 2 by a light shielding assembly, the body of the incident slit 2 intersects the extension line of the incident optical axis, and a slit intersecting and perpendicular to the extension line of the incident optical axis is formed on the body, only the light rays converged by the converging part 1 can pass through, and the length of the slit is 2.2 mm and the width is 0.3 mm to accommodate the light in the wavelength range of 200 nm-1100 nm to pass through after being converged by the converging part 1.

[0043] The concave mirror 3 improves the correction ability of the system to the off-axis aberration, and only the concave mirror 3 provides the function of twice reflection for the incident light, the mechanical degree of freedom of the system is reduced, not only the compactness of the system is improved, but also the probability of damage in use is reduced; the curvature radius of the concave mirror is -0.01, the optical axis 30 of the concave mirror is parallel to the incident optical axis, and the distance (in the direction of the incident optical axis) from the curvature center of the concave mirror to the incident slit 2 is 22 mm.

[0044] The curvature radius of the convex reflection grating 4 is -0.02, the grating constant is 6 μm, the optical axis coincides with the optical axis of the concave mirror, and the size of the concave mirror 3 can be as small as possible; the curvature center of the convex reflection grating 4 is located on the same side as the concave mirror 3 to further eliminate aberration; the blaze wavelength is 500 nm, and the transverse distance (i.e. in the direction parallel to the incident optical axis) from the grating center to the curvature center of the concave mirror 3 is 26 mm.

[0045] The exit slit 5 is located on the other side of the entrance slit 2 relative to the convex reflection grating 4, has a transverse distance of 21mm from the curvature center of the concave mirror 3, and has a slit intersecting the extension of the incident light axis and being perpendicular to the incident light axis, only allowing the light reflected by the concave mirror 3 to pass through, and the length of the slit is 4.5mm and the width is 0.1mm to allow the light in the wavelength range of 200nm-1100nm to pass through.

[0046] The collimating lens 6 has an optical power Φ1 of 0.1, and the optical axis thereof coincides with the exit light axis of the exit slit 5 to collimate the light exiting from the exit slit 5 to facilitate subsequent light splitting by the beam splitter 7.

[0047] The beam splitter 7 is located on the same exit light axis as the exit slit 5 and the collimating lens 6, and splits the exiting light into two beams which pass through the reference cell 8 and the sample cell 11, respectively. By splitting the exiting light into two beams for synchronous detection, systematic errors such as light source fluctuation, environmental temperature change, and solvent absorption can be eliminated, and data reliability can be improved.

[0048] The reference cell 8 can be filled with a blank solution (solvent or reference material). When the light source intensity decays or fluctuates over time, synchronous compensation can be performed by setting a reference light path to avoid the problem of frequent calibration of single-beam instruments, and further eliminate systematic errors such as light source fluctuation, environmental temperature change, and solvent absorption to improve data reliability.

[0049] The plane mirror 9 converts the exiting light passing through the reference cell 8 into output light perpendicular to the exit light axis.

[0050] The second converging part 10 is composed of a third lens 1001 and a fourth lens 1002, the optical power Φ 1001 of the third lens 1001 is 0.12, the optical power Φ 1002 of the fourth lens 1002 is 0.12, and the length (in the direction of the incident light axis) of the entire second converging part 10 (including the third lens 1001 and the fourth lens 1002 and the components for fixedly connecting the third lens 1001 and the fourth lens 1002) is 20mm.

[0051] The sample cell 11 is filled with a sample to be measured.

[0052] The third converging part 12 is composed of a fifth lens 1201 and a sixth lens 1202, the optical power Φ 1201 of the fifth lens 1201 is 0.12, and the optical power Φ 1202The value of the ratio of the length of the third converging portion 12 to the length of the first converging portion 11 is 0.12, and the length (in the direction of the incident optical axis) of the entire third converging portion 12 (including the fifth lens 1201 and the sixth lens 1202 and the assembly for fixedly connecting the fifth lens 1201 and the sixth lens 1202) is 20 mm.

[0053] The imaging effect of this embodiment is described below with reference to Figure 2 , Figure 2 The diffraction spot corresponding to the spectrophotometer optical system in this embodiment is shown: under different object plane transverse positions (0 mm, ±3 mm, ±5 mm) and corresponding image plane positions, the light spots of wavelengths of 200 nm (ultraviolet), 425 nm (approximately blue light), 650 nm (approximately red light), 875 nm (near-infrared), and 1100 nm (near-infrared) are respectively imaged from bottom to top in the corresponding image planes, and in the transverse dimension, the distribution of each light spot is relatively concentrated, and the distribution of the light spot of each wavelength on the image plane is concentrated in the middle part of the image; the position and size of the diffraction spot slightly change under different angles, but there is no obvious diffusion; the diffraction spot distribution is highly concentrated in the range from short wave to long wave; it is shown that the spectrophotometer optical system has high imaging accuracy and good aberration control effect for light rays of different wavelengths, and has high imaging stability and good imaging quality in a wide spectral range.

[0054] Figure 3 The curve diagram of the modulation transfer function of the spectrophotometer optical system of the present application is shown, and the uppermost point line in the diagram represents the diffraction limit, which is the theoretical maximum resolution capability of the lens assembly, and the other curves are the curve diagrams of the modulation transfer functions of the spectrophotometer optical system of the present application under 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 diagram that the MTF of the spectrophotometer optical system of the present application at a spatial frequency of 120 lp / mm in the full field of view is greater than 0.3, and has high resolution capability.

[0055] Therefore, the spectrophotometer optical system of the embodiment of the present application realizes synchronous measurement through double light paths, wherein the reference light path passes through the blank solution, the sample light path passes through the sample to be measured, and the two beams of light of the reference light path and the sample light path alternately or synchronously reach the detector; if there are errors such as fluctuation of the light source in the light path, change of the ambient temperature, and solvent absorption, the double light paths can calculate the absorbance A = -log10 (I sample / I reference) in real time, so the errors can be offset by the ratio (I sample / I reference), thereby improving the data reliability. In addition, the optical system can realize miniaturization and high-quality imaging in a spectral range of 200 nm-1100 nm, i.e., simultaneously for the spectral ranges of 200 nm-380 nm ultraviolet spectral region, 380 nm-780 nm visible spectral region, and 780 nm-1100 nm near-infrared spectral region.

[0056] Although the specific values of the various parameters are shown in the above embodiment, it should be noted that each part of the optical system of the spectrophotometer is electrically connected to the controller, and the angles and distances can be fine-tuned to adapt to 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 application, and the imaging performance of the spectrophotometer can also be approximately Figure 2 The specific parameters above are not limited by the interval, and the protection scope of the present application is not limited by the above specific parameters.

[0057] It should be emphasized that the embodiments described in the present application are exemplary rather than limiting, and therefore the present application is not limited to the embodiments described in the specific embodiments, and any other embodiments derived from the technical solutions of the present application by those skilled in the art also belong to the protection scope of the present application.

Claims

1. An Offner-structure-based spectrophotometer optical system, characterized by, The spectrophotometer optical system comprises: a first converging part (1) composed of a first lens (101) and a second lens (102) arranged in sequence along an optical path, an incident slit (2), a concave mirror (3), a convex reflection grating (4), an exit slit (5), a collimating lens (6), a beam splitter (7), a reference cell (8), a plane mirror (9), a second converging part (10) composed of a third lens (1001) and a fourth lens (1002), a sample cell (11), and a third converging part (12) composed of a fifth lens (1201) and a sixth lens (1202); wherein an optical axis (30) of the concave mirror is parallel to an incident optical axis, the convex reflection grating (4) is coaxial with the concave mirror (3), and the concave mirror (3) and the convex reflection grating (4) form an offner structure; the first lens (101), the second lens (102), the third lens (1001), the fourth lens (1002), the fifth lens (1201), and the sixth lens (1202) are all spherical mirrors; an incident light beam enters the first converging part (1), is sequentially converged by the first lens (101) and the second lens (102), is reflected by the concave mirror (3) to the convex reflection grating (4) through the incident slit (2) for path limitation, is reflected by the convex reflection grating (4) to the concave mirror (3) again, is reflected by the concave mirror (3) again to form a spectrum, and is projected on the exit slit (5), and the exit light beam is collimated by the collimating lens (6) again, is split by the beam splitter (7), passes through the reference cell (8) and the sample cell (11) respectively, is turned by the plane mirror (9), and is finally converged by the second converging part (10) and the third converging part (12) for detection; The optical power of the first lens (101) is Φ 101 , the optical power of the second lens (102) is Φ 102 , and the following relationship is satisfied: 0.1 ≤ Φ 101 = Φ 102 ≤ 0.25, the optical power of the spectrophotometer optical system is Φ, and the optical power of the first converging portion is Φ1, which satisfies 0.2 ≤ Φ1 / Φ ≤ 0.

3. The distance from the incident slit (2) to the second lens (102) image plane is D 12 The distance from the incident slit (2) to the concave mirror (3) is D 23 The distance from the incident slit (2) to the convex reflection grating (4) is D 24， The radius of curvature of the concave mirror (3) is R1, and the radius of curvature of the convex reflection grating (4) is R2, satisfying the following relationship: 0.2≤D 12 / D 23 ≤0.5, 0.4≤D 12 / D 24 ≤0.8, 0.5≤|R1| / |R2|≤0.75; a radius of curvature of the concave mirror (3) is R1, and the following relationship is satisfied: -0.02≤R1≤-0.01; a radius of curvature of the convex reflection grating (4) is R2, and the following relationship is satisfied: -0.04≤R2≤-0.

02.

2. The spectrophotometer optical system of claim 1, wherein, a grating constant of the convex reflection grating (4) is d, and the following relationship is satisfied: 2μm≤d≤10μm.

3. The spectrophotometer optical system of claim 1, wherein, a refractive power Φ6 of the collimating lens (6) satisfies 0.05≤Φ6≤0.1, and a refractive power Φ of the spectrophotometer optical system satisfies 0.1≤Φ6 / Φ≤0.

15.

4. The spectrophotometer optical system of claim 1, wherein, The beam splitter (7) is coated with a semi-transparent half-reflection film, and the transmission and reflection ratio is 50%:50%.

5. The spectrophotometer optical system of any one of claims 1-4, wherein, power Φ of the third lens (1001) in the second converging portion (10) 1001 power Φ of the fourth lens (1002) 1002 satisfies 0.1 ≤ Φ 1001 = Φ 1002 ≤ 0.25, and the power Φ of the second converging portion (10) 10 and the power Φ of the spectrophotometer optical system satisfies 0.2 ≤ Φ 10 / Φ ≤ 0.

3.

6. The spectrophotometer optical system of claim 5, wherein, power Φ of the fifth lens (1201) in the third converging portion (12) 1201 power Φ of the sixth lens (1202) 1202 satisfies 0.1 ≤ Φ 1201 = Φ 1202 ≤ 0.25, and the power Φ of the third converging portion (12) 12 and the power Φ of the spectrophotometer optical system satisfies 0.2 ≤ Φ 12 / Φ ≤ 0.3.

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