阅读说明：本技术 一种双通道成像光谱物镜及成像光谱仪装置 (Double-channel imaging spectrum objective lens and imaging spectrometer device ) 是由 许晨 张垚 陈丰农 于 2020-07-17 设计创作，主要内容包括：本发明公开了一种双通道成像光谱物镜及成像光谱仪装置。本发明包括前组镜头、分光狭缝和后组镜头。经过前置镜组后的光通过倾斜放置的分光狭缝,一部分光束透射通过分光狭缝,其余成像光束在所述分光狭缝前表面发生反射。所述在分光狭缝上透射穿过的光束路径为所述光谱通道；所述在分光狭缝的前表面上发生反射的光束路径为图像通道。本发明使得光谱获取和图像拍摄具有相同的视点并且同时进行,有益于光谱数据对应空间位置的标定,即在无人机飞行拍摄或使用者手持拍摄过程中,无须按照特定要求进行平扫,而是可以任意方式扫描覆盖后,根据图像拼接进行光谱数据的空间位置对准。(The invention discloses a dual-channel imaging spectrum objective lens and an imaging spectrometer device. The invention comprises a front group lens, a light splitting slit and a rear group lens. The light passing through the front lens group passes through the obliquely arranged light splitting slit, one part of light beams are transmitted through the light splitting slit, and the rest imaging light beams are reflected on the front surface of the light splitting slit. The light beam path transmitted through the light splitting slit is the spectrum channel; the beam path reflected on the front surface of the light-splitting slit is an image channel. The invention enables the spectrum acquisition and the image shooting to have the same viewpoint and be carried out simultaneously, which is beneficial to the calibration of the spatial position corresponding to the spectrum data, namely, in the process of the flight shooting of the unmanned aerial vehicle or the handheld shooting of a user, the flat scanning is not required to be carried out according to the specific requirements, and the spatial position alignment of the spectrum data is carried out according to the image splicing after the scanning and covering can be carried out in any mode.)

1. A dual-channel imaging spectrum objective lens is characterized by comprising a front group lens, a light splitting slit and a rear group lens;

the front group of lenses collects imaging light beams of an external scene and forms an intermediate image surface;

the light splitting slit is positioned between the front group of lenses and the rear group of lenses, light is transmitted in a central strip-shaped area, the light is totally reflected in the rest areas, and a certain included angle is formed between the normal direction of the light splitting slit and the optical axis of the front group of lenses;

the rear group of lenses receives the imaging light beams reflected and emitted from the light splitting slits and forms an image surface.

2. The dual-channel imaging spectrum objective lens of claim 1, wherein a ratio F of a focal length and an entrance pupil diameter of the front group lens satisfies the following expression: 2.4< F < 3.3.

3. The dual channel imaging spectral objective of claim 1, wherein the change in the capture distance is achieved by axial movement of the front set of lenses such that the capture distance ranges between 300mm and infinity.

4. The objective lens of claim 1, wherein the direction of the long side of the elongated region on the slit is perpendicular to the normal direction of the slit and the optical axis of the front group lens, and the incident positions of the central rays of the central field of view and the center of the elongated region on the slit coincide.

5. The objective lens of claim 1, wherein the center of the strip-shaped region on the beam-splitting slit and the center of the intermediate image plane formed by the front group lens are coincident in the optical axis direction of the front group lens.

6. The dual channel imaging spectroscopy objective of claim 1 wherein the front set of lenses comprises a stop, the front side of the stop providing positive power and the rear side of the stop having three optical elements with powers negative, positive and positive, respectively.

7. The dual-channel imaging spectroscopy objective of claim 1 wherein the rear set of lenses comprises six optical elements having powers of positive, negative, positive, and positive, respectively.

8. The dual-channel imaging spectral objective of claim 1, wherein the power Beta of the rear lens group satisfies the following expression: 0.98< Beta < 1.24.

9. An imaging spectrometer arrangement employing the dual channel imaging spectroscopy objective of claim 1, wherein: the light beam penetrating through the light splitting slit reaches a spectrum detector after passing through a light splitting light path, and the light beam reflected by the light splitting slit reaches an image detector after passing through a rear group of lenses.

Technical Field

The invention relates to the technical field of optics, in particular to a dual-channel imaging spectrum objective lens.

Background

The imaging spectrometer can acquire spectral information of a target object and is increasingly applied to different fields. For example, in the field of agricultural remote sensing, the spectrum of ground crops is acquired by using an unmanned aerial vehicle mounted imaging spectrometer, so that the growth of the crops is monitored.

Most of the current imaging spectrometers adopt a flat scanning structure, namely: the spectral information of one line region of the target surface is acquired at the same time, and the movement or rotation of the imaging spectrometer is required to obtain spectral data of different positions of the target surface. In use, alignment of the spatial position of the target surface needs to be achieved, so that the spectral data of one line region acquired each time is spliced into the data of a surface region.

In addition, the flat-scan imaging spectrometer is difficult to accurately focus a shooting target, and particularly, when a near object is subjected to spectral imaging, the defect of difficult focusing is obviously revealed. If there is a method to acquire an image scene of a target in an imaging spectrometer system, (1) focusing can be effectively performed, so that the imaging spectrometer can be used for both a near target and a far target, and (2) the position corresponding to the acquired spectrum can be conveniently determined through image information.

Disclosure of Invention

In view of the above, the present invention provides a dual-channel imaging spectrum objective lens and an imaging spectrometer device.

The invention is realized by the following technical scheme.

The invention provides a double-channel imaging spectrometer objective lens, wherein light passing through a front lens group passes through a light splitting slit which is obliquely arranged, a part of light beams are transmitted through the light splitting slit, and the rest of imaging light beams are reflected on the front surface of the light splitting slit. The light beam path transmitted through the light splitting slit is the spectrum channel; the beam path reflected on the front surface of the light-splitting slit is an image channel.

The light beams in the spectrum channel leave the two-channel imaging spectrum objective lens after passing through the light splitting slit, and the light beams in the image channel reach the image detector after being reflected by the light splitting slit and passing through the rear lens group.

When the dual-channel imaging spectrum objective lens is in a working state, external light beams emitted from an external target penetrate through the front group of lenses and then reach the light splitting slit.

The light splitting slit is a flat glass element, a strip-shaped area is arranged on the front surface of the element, a reflecting film is plated in other areas except the area, a reflecting film is not plated in the area or an antireflection film with a specific wave band is plated in the area, so that light beams reaching the inside of the strip-shaped area can penetrate through the strip-shaped area and are emitted from the rear side of the light splitting slit, and the light beams reaching the outer side of the strip-shaped area are reflected on the front surface of the light splitting slit.

The direction of the long edge of the strip-shaped area on the light splitting slit is perpendicular to the normal direction of the light splitting slit and perpendicular to the optical axis of the front group lens, and the incident positions of the central light of the central view field and the center of the strip-shaped area on the light splitting slit are overlapped. Although the light splitting slit is placed with an inclination angle of 45 ° in the embodiment provided by the present invention, the change of the inclination angle of the light splitting slit does not introduce additional aberration, and thus can be changed, and only the condition of avoiding the conflict of the spatial positions of the front group lens and the rear group lens is required to be satisfied.

In the structure of the front group of lenses, the focal power of the front side of the diaphragm is positive, and the back side of the diaphragm is provided with a lens with negative focal power and a lens with positive focal power.

The light beams in the image channel reach the rear group of lenses after being reflected by the light splitting slit, and reach the image detector after sequentially passing through each lens in the rear group of lenses.

The focusing process of the dual-channel imaging spectrum objective lens is realized by the axial movement of the front lens group. In the above-described focusing operation, the focusing process is stopped when the picture on the image plane is clearest, at which time the focusing of the dual-channel imaging spectral objective lens is completed.

Preferably, the front group of lenses of the objective lens of the two-channel imaging spectrometer has image-side telecentric characteristics, so that the central rays of the light beams emitted from the light splitting slits in the spectral channels are all parallel to the optical axis as much as possible.

The invention has the beneficial effects that:

the invention enables the spectrum acquisition and the image shooting to have the same viewpoint and be carried out simultaneously, which is beneficial to the calibration of the spatial position corresponding to the spectrum data, namely, in the process of the flight shooting of the unmanned aerial vehicle or the handheld shooting of a user, the flat scanning is not required to be carried out according to the specific requirements, and the spatial position alignment of the spectrum data is carried out according to the image splicing after the scanning and covering can be carried out in any mode. In addition, when acquiring the spectral information of a near or far target, the position of the front group lens can be axially adjusted by means of the image definition degree so as to realize accurate focusing.

Drawings

Fig. 1 is a schematic structural diagram of an optical system according to a first embodiment of the present invention;

FIG. 2 is a front view of a light-splitting slit according to a first embodiment of the present invention;

fig. 3 is an MTF curve of the front group lens at the light splitting slit according to the first embodiment of the present invention;

FIG. 4 is an MTF curve of the image plane position of the first embodiment of the present invention;

FIG. 5 is a schematic structural diagram of an optical system according to a second embodiment of the present invention;

FIG. 6 is a front view of a light-splitting slit according to a first embodiment of the present invention;

fig. 7 is an MTF curve of a front group lens at a light splitting slit according to a second embodiment of the present invention;

FIG. 8 is an MTF curve at an image plane position for the second embodiment of the present invention;

FIG. 9 is a schematic diagram of an imaging spectrometer apparatus of the present invention.

Detailed Description

The invention is described in detail below by way of example with reference to the accompanying drawings.

The invention comprises a front group lens, a light splitting slit and a rear group lens; the front group of lenses collects imaging light beams of an external scene and forms an intermediate image surface; the light splitting slit is positioned between the front group of lenses and the rear group of lenses, light is transmitted in a central strip-shaped area, the light is totally reflected in the rest areas, and a certain included angle is formed between the normal direction of the light splitting slit and the optical axis of the front group of lenses; the rear group of lenses receives the imaging light beams reflected and emitted from the light splitting slits and forms an image surface.

Wherein a ratio F of the focal length to the entrance pupil diameter of the front group lens satisfies the following expression: f is more than 2.4 and less than 3.3, and the shooting distance is changed by the axial movement of the front group lens, so that the shooting distance ranges from 300mm to infinity.

The direction of the long side of the strip-shaped area on the light splitting slit is vertical to the normal direction of the light splitting slit and is vertical to the optical axis of the front group lens, and the incident positions of the central light of the strip-shaped area and the central light of the central view field on the light splitting slit are overlapped. The center of the strip-shaped area on the light splitting slit is superposed with the center of a middle image plane formed by the front group of lenses in the optical axis direction of the front group of lenses.

Wherein the front group of lenses comprises a diaphragm, the front side of the diaphragm provides positive optical power and the rear side of the diaphragm is provided with three optical elements, and the optical powers of the three optical elements are respectively negative, positive and positive. The rear group lens comprises six optical elements, and the focal powers of the six optical elements are respectively positive, negative, positive and positive. The magnification Beta of the rear group lens meets the following expression: beta is more than 0.98 and less than 1.24.