Multispectral camera optical system based on three-color prism

Abstract

The utility model belongs to the technical field of optical systems of spectral cameras, and discloses a multispectral camera optical system based on a three-color prism, which is characterized in that light passes through an L1 common-aperture telescopic system to be in a convergent state, and is split through an L2 spectral imaging system, an L3 spectral imaging system and an L4 spectral imaging system which comprise prisms; the light beams are respectively focused on the corresponding detectors; wherein in the L2 spectral band imaging system, the 400-570 nm spectral band light in the light is sequentially transmitted, reflected, totally reflected and transmitted in the first prism; in the L3 spectral band imaging system, the 570nm-740nm spectral band light in the light is sequentially transmitted and transmitted in the first prism, and is sequentially transmitted, reflected, totally reflected and transmitted in the second prism; in the spectrum imaging system, the light of the L4 with the spectrum of 740nm-900nm in the light is sequentially transmitted and transmitted in the first prism, is sequentially transmitted and transmitted in the second prism, and is sequentially transmitted and transmitted in the third prism.

Description

Technical Field

[0001] The utility model relates to the technical field of spectral camera optical systems, in particular to a multi-spectral camera optical system based on a trichromatic prism. Background Art

[0002] A multispectral camera is a device that can simultaneously acquire spectral information in multiple discrete bands. Compared with traditional full-spectrum cameras, multispectral cameras usually have more limited bands, but have higher spectral resolution in these bands. Its optical system mainly includes lenses, prisms and detector systems, and is widely used in agriculture, environmental monitoring, earth observation, medical imaging and other fields.

[0003] Traditional multispectral cameras achieve spectral separation of different bands by using multiple filters or beam splitters. These filters or beam splitters allow light of a specific wavelength range to pass through while blocking light of other wavelengths, thereby achieving selective detection of different bands. One of the simplest forms of traditional multispectral cameras uses multiple filters, each of which allows light of a specific band to pass through. These filters are usually arranged in front of a detector, such as a CCD or CMOS sensor, and each filter corresponds to a band required by the camera. After the light passes through the sample, the spectral information on each filter is captured and forms an image corresponding to the corresponding band. Another common way of splitting light in traditional multispectral cameras is to use a beam splitter or prism to separate the light into different bands. These beam splitters usually divide the light into multiple paths, each path corresponding to a band in the camera. Appropriate optical elements, such as lenses, may be included on each path to ensure a clear image on the detector.

[0004] Traditional multi-spectral cameras use a combination of a beam splitter prism and a filter. The beam splitter prism is mostly semi-reflective and semi-transparent. While splitting the light, the energy is also separated in proportion, so that very little energy reaches the image surface. Therefore, a three-color prism is needed to replace the traditional beam splitter prism, which can not only split the spectrum, but also ensure that each spectrum segment still has a high transmittance. Utility Model Content

[0005] In view of this, the utility model provides a multi-spectral camera optical system based on a trichromatic prism. The utility model adopts a combined trichromatic prism to complete the light splitting of three spectral bands.

[0006] A multi-spectral camera optical system based on a trichromatic prism, comprising:

[0007] The light passes through the L1 common aperture telescope system in a convergent state and is split by three L2 spectral imaging systems, L3 spectral imaging systems and L4 spectral imaging systems including prisms, and is focused on corresponding detectors respectively;

[0008] Among them, in the L2 spectral imaging system, the 400nm-570nm spectral light in the light is transmitted, reflected, totally reflected and transmitted in prism No. 1 in sequence;

[0009] In the L3 spectral imaging system, the 570nm-740nm spectral light in the light is sequentially transmitted, transmitted, transmitted, transmitted, reflected, totally reflected, and transmitted in the No. 2 prism in sequence;

[0010] In the L4 spectral imaging system, the 740nm-900nm spectral light in the light is transmitted, transmitted, transmitted in prism No. 1, transmitted, transmitted in prism No. 2, and transmitted and transmitted in prism No. 3 in sequence.

[0011] Preferably, the L1 common-aperture telescopic system includes lens No. 1, lens No. 2, lens No. 3, lens No. 4, a reflector and lens No. 5, which are arranged in sequence along the optical axis.

[0012] Preferably, the No. 1 lens is a positive lens with a focal length of 90 to 95 mm; the No. 2 lens is a negative lens glued together with a negative lens, with a total focal length of -135 to -140 mm; the No. 3 lens is a positive lens with a focal length of 230 to 235 mm, the No. 4 lens is a negative lens with a focal length of -110 to -115 mm, and the No. 5 lens is a negative lens glued together with a positive lens, with a total focal length of -110 to -115 mm.

[0013] Preferably, the L2 spectral band imaging system comprises: a prism No. 1 and a lens No. 6 which are sequentially arranged along the optical axis.

[0014] Preferably, the No. 6 lens is a positive lens with a focal length of 120-125 mm.

[0015] Preferably, the L3 spectral band imaging system includes: prism No. 1, prism No. 2 and lens No. 7 arranged sequentially along the optical axis.

[0016] Preferably, the No. 7 lens is a positive lens with a focal length of 125-130 mm.

[0017] Preferably, the L4 spectral band imaging system includes: prism No. 1, prism No. 2, prism No. 3 and lens No. 8 arranged in sequence along the optical axis.

[0018] Preferably, the No. 8 lens is a positive lens with a focal length of 125-130 mm.

[0019] Preferably, the No. 1 prism, the No. 2 prism and the No. 3 prism are located in one place;

[0020] The two sides of the No. 2 prism are respectively adjacent to the No. 1 prism and the No. 3 prism;

[0021] And the incident surface of the No. 1 prism is parallel to the output surface of the No. 3 prism.

[0022] Through the above technical solutions, it can be known that compared with the prior art, the utility model discloses a multi-spectral camera optical system based on a trichromatic prism. In the utility model, a trichromatic prism is used to complete the light splitting of three spectral bands, and the prism is coated with a filter film so that each spectral band still has a high transmittance after light splitting, ensuring that the detector receives more energy. Adding a reflector makes the optical system compact and minimizes the volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0024] Figure 1 The accompanying drawing is a schematic diagram of the overall structure of the optical system of the multi-spectral camera based on the trichromatic prism of the utility model;

[0025] Figure 2 The accompanying drawing is a modulation transfer function diagram of the imaging of the 400nm-570nm spectrum band in the multi-spectral camera optical system based on the trichromatic prism of the utility model;

[0026] Figure 3 The accompanying drawing is a modulation transfer function diagram of the imaging of the 570nm-740nm spectrum band in the multi-spectral camera optical system based on the trichromatic prism of the utility model;

[0027] Figure 4 The attached drawing is a modulation transfer function diagram of the imaging of the 740nm-900nm spectrum band in the trichromatic prism-based multi-spectral camera optical system of the present invention.

[0028] In the figure: lens No. 1-1, lens No. 2-2, lens No. 3-3, lens No. 4-4, M-reflector, lens No. 5-5, lens No. 6-6, lens No. 7-7, lens No. 8-8, prism No. P1-1, prism No. P2-2, prism No. P3-3. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Embodiment 1:

[0031] The utility model embodiment discloses a multi-spectral camera optical system based on a trichromatic prism, comprising:

[0032] The light is converged through the L1 common aperture telescope system and split by three prism-containing L2 spectral imaging systems, L3 spectral imaging systems and L4 spectral imaging systems, and is focused on the corresponding detectors respectively;

[0033] Among them, in the L2 spectrum imaging system, the 400nm-570nm spectrum light in the light is transmitted, reflected, totally reflected and transmitted in the prism P1 No. 1 in sequence;

[0034] In the L3 spectral imaging system, the 570nm-740nm spectral light in the light is transmitted, transmitted, transmitted, transmitted, reflected, totally reflected, and transmitted in prism No. 2 P2 in sequence in prism No. 1 P1;

[0035] In the L4 spectral imaging system, the 740nm-900nm spectral light in the light is transmitted, transmitted, in turn in prism No. 1 P1, transmitted, transmitted, in turn in prism No. 2 P2, and transmitted and transmitted, in turn in prism No. 3 P3.

[0036] Specifically:

[0037] The L1 common aperture telescope system includes lens No. 1 1, lens No. 2 2, lens No. 3 3, lens No. 4 4, a reflector M and lens No. 5 5 which are arranged in sequence along the optical axis.

[0038] Among them, lens 1 No. 1 is a positive lens with a focal length of 90~95mm; lens 2 No. 2 is a negative lens glued together with a negative lens, with a total focal length of -135~-140mm; lens 3 No. 3 is a positive lens with a focal length of 230~235mm, lens 4 No. 4 is a negative lens with a focal length of -110~-115mm, and lens 5 No. 5 is a negative lens glued together with a positive lens, with a total focal length of -110~-115mm.

[0039] In this embodiment, the L2 spectrum imaging system includes: a prism No. 1 P1 and a lens No. 6 6 arranged in sequence along the optical axis. The lens No. 6 6 is a positive lens with a focal length of 120-125 mm.

[0040] In this embodiment, the L3 spectrum imaging system includes: a prism No. 1 P1, a prism No. 2 P2 and a lens No. 7 7 arranged in sequence along the optical axis. Among them, the lens No. 7 7 is a positive lens with a focal length of 125-130 mm.

[0041] In this embodiment, the L4 spectrum imaging system includes: a prism No. 1 P1, a prism No. 2 P2, a prism No. 3 P3 and a lens No. 8 8 arranged in sequence along the optical axis. Among them, the lens No. 8 8 is a positive lens with a focal length of 125-130 mm.

[0042] Example 2

[0043] On the basis of Example 1, this embodiment further discloses a trichromatic prism applied to Example 1, the trichromatic prism comprising: a prism No. 1 P1, a prism No. 2 P2 and a prism No. 3 P3;

[0044] Specifically:

[0045] In this embodiment, prism No. 1 P1, prism No. 2 P2, and prism No. 3 P3 are located in one place;

[0046] The two sides of prism No. 2 P2 are adjacent to prism No. 1 P1 and prism No. 3 P3 respectively;

[0047] And the incident surface of prism No. 1 P1 and the output surface of prism No. 3 P3 are parallel.

[0048] Embodiment 3:

[0049] Based on Example 2, this example further discloses the following contents:

[0050] Prism No. 1 P1 and Prism No. 2 P2 are both triangular prisms;

[0051] Prism No. 3 P3 is a quadrangular prism, and the cross section of the quadrangular prism is a right-angled trapezoid;

[0052] Moreover, the surface opposite to the inclined surface of the prism No. 3 P3 is parallel to the incident surface of the prism No. 1 P1; the incident surface of the prism No. 1 P1 is an inclined surface;

[0053] The two surfaces of prism No. 2 P2 except the output surface are adjacent to the inclined surface of prism No. 3 P3 and the third surface of prism No. 1 P1 respectively;

[0054] The third surface is the remaining surface of the prism P1 except the incident surface and the output surface.

[0055] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0056] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multi-spectral camera optical system based on a trichromatic prism, characterized in that: include: The light is converged through the L1 common aperture telescope system and split by three prism-containing L2 spectral imaging systems, L3 spectral imaging systems and L4 spectral imaging systems, and is focused on the corresponding detectors respectively; Among them, in the L2 spectral imaging system, the 400nm-570nm spectral light in the light is transmitted, reflected, totally reflected and transmitted in prism No. 1 (P1) in sequence; In the L3 spectral imaging system, the 570nm-740nm spectral light in the light is sequentially transmitted, transmitted, transmitted, transmitted, reflected, totally reflected, and transmitted in the No. 2 prism (P2) in sequence in the No. 1 prism (P1); In the L4 spectral imaging system, the 740nm-900nm spectral light in the light is sequentially transmitted, transmitted in the No. 1 prism (P1), sequentially transmitted, transmitted in the No. 2 prism (P2), and sequentially transmitted and transmitted in the No. 3 prism (P3).

2. The multi-spectral camera optical system based on a trichromatic prism according to claim 1, characterized in that: The L1 common aperture telescopic system comprises a No. 1 lens (1), a No. 2 lens (2), a No. 3 lens (3), a No. 4 lens (4), a reflector (M) and a No. 5 lens (5) which are sequentially arranged along the optical axis.

3. The multi-spectral camera optical system based on a trichromatic prism according to claim 2, characterized in that: The No. 1 lens (1) is a positive lens with a focal length of 90 to 95 mm; the No. 2 lens (2) is a negative lens glued together with a negative lens, with a total focal length of -135 to -140 mm; the No. 3 lens (3) is a positive lens with a focal length of 230 to 235 mm; the No. 4 lens (4) is a negative lens with a focal length of -110 to -115 mm; the No. 5 lens (5) is a negative lens glued together with a positive lens, with a total focal length of -110 to -115 mm.

4. The multi-spectral camera optical system based on a trichromatic prism according to claim 1, characterized in that: The L2 spectrum band imaging system comprises: a No. 1 prism (P1) and a No. 6 lens (6) which are sequentially arranged along the optical axis.

5. The multi-spectral camera optical system based on a trichromatic prism according to claim 4, characterized in that: The No. 6 lens (6) is a positive lens with a focal length of 120-125 mm.

6. The multi-spectral camera optical system based on a trichromatic prism according to claim 1, characterized in that: The L3 spectrum band imaging system comprises: a No. 1 prism (P1), a No. 2 prism (P2) and a No. 7 lens (7) which are sequentially arranged along the optical axis.

7. The multi-spectral camera optical system based on a trichromatic prism according to claim 6, characterized in that: The No. 7 lens (7) is a positive lens with a focal length of 125 to 130 mm.

8. The multi-spectral camera optical system based on a trichromatic prism according to claim 1, characterized in that: The L4 spectrum band imaging system comprises: a prism No. 1 (P1), a prism No. 2 (P2), a prism No. 3 (P3) and a lens No. 8 (8) which are sequentially arranged along the optical axis.

9. The multi-spectral camera optical system based on a trichromatic prism according to claim 8, characterized in that: The No. 8 lens (8) is a positive lens with a focal length of 125 to 130 mm.

10. The multi-spectral camera optical system based on a trichromatic prism according to claim 1, characterized in that: The prism No. 1 (P1), the prism No. 2 (P2) and the prism No. 3 (P3) are located in one place; The two surfaces of the No. 2 prism (P2) are respectively adjacent to the No. 1 prism (P1) and the No. 3 prism (P3); Furthermore, the incident surface of the No. 1 prism (P1) and the output surface of the No. 3 prism (P3) are parallel.

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