CN203163728U - Multi-spectral light field camera - Google Patents

Abstract

The utility model provides a multi-spectral light field camera. The multi-spectral light field camera comprises an optical filter array, an imaging main lens, a micro-lens array, a combinational auxiliary lens, a detector and a signal processing system, which are sequentially arranged along the direction of a light path; and an imaging method comprises the following steps of firstly placing the optical filter array on a pupil plane of the imaging main lens, and adopting an aperture segmentation method to introduce the information of each spectral section of a target; utilizing the micro-lens array on an image surface of the main imaging main lens to separate the multi-spectral information in space; introducing the combinational auxiliary lens to secondarily transfer a focal plane of the micro-lens to a photosensitive surface of the detector; and finally calculating the data obtained by the detector through the signal processing system, and extracting different waveband optical images. By adopting the multi-spectral light field camera, the multi-spectral information of each pixel in the total view field range can be obtained simultaneously, the dynamic multi-spectral imaging can be realized, and the system structure is firm.

Description

Multispectral Light Field Camera

technical field

The utility model relates to the technical field of spectral imaging, in particular to a multi-spectral light field camera.

Background technique

Multispectral imaging technology has been developed since the early 1970s, and has developed with the needs of earth observation, space exploration, military and civil affairs. Since the concept of the imaging spectrometer was proposed by the Jet Propulsion Laboratory of the California Institute of Technology, contemporary multispectral remote sensing technology has developed rapidly. In 2000, Zhang Chunmin, Xiang Libin and Zhao Baochang proposed the space-time mixed modulation polarization interference imaging spectroscopy technology, proposed the steady state polarization interference imaging spectrometer based on Savart polarizer and the steady state large field of view polarization interference imaging spectrometer related technologies, and carried out Through theoretical research, as well as the development of experimental devices and prototypes, in addition to the two-dimensional spatial information and one-dimensional spectral information of the target, the polarization information of the target can also be obtained.

Gershun proposed the concept of light field in 1936, and defined it as the propagation of light radiation in all directions in various positions in space; in the 1960s and 1970s, scholars such as Okoshi and Dudnikov continuously improved IP technology, microlens array The role in imaging has also been highlighted; in 1995, Berthon placed a color filter on the pupil plane, and placed a microlens array on the focal plane, and successfully obtained a color image; in 1996, Marc Levoy, Pat Hanrahan and others introduced In 2005, Ng, Levoy et al. proposed a typical representative of light field camera—plenoptic camera; after that, Ren Ng, Marc Levoy et al. put forward a new idea, placing each camera directly on the pupil plane of the camera An optical filter allows the modulation of spectrum, polarization state and light intensity to be achieved simultaneously after one exposure.

However, the existing multi-spectral cameras mostly adopt the method of time-sharing detection, using rotating filters, adjusting liquid crystal modulators or acousto-optic modulators, and sequentially collecting image information of multiple spectral segments within a period of time. The disadvantage is that the instrument needs external intervention to adjust the internal moving parts to change its working spectrum during the working process. Its delay makes it impossible to detect in real time, and it is impossible to perform dynamic video detection on moving targets, and the mechanical structure of the instrument is complex and reliable. and lower stability.

Utility model content

The purpose of the utility model is to provide a multi-spectral light field camera capable of real-time multi-spectral detection and multi-spectral video detection of detection targets.

The technical solution to realize the purpose of this utility model is: a multi-spectral light field camera, including a filter array, an imaging main lens, a microlens array, a combined secondary lens, a detector and a signal processing system arranged in sequence along the optical path direction , wherein the combination sub-lens includes a first lens and a second lens arranged in sequence along the optical path direction, the combination sub-lens transfers the rear focal plane of the microlens array to the target surface of the detector twice; the filter array is located at At the aperture stop of the imaging main lens, the microlens array is located on the image plane of the imaging main lens, the back focal plane of the microlens array coincides with the front focal plane of the first lens, and the detector is located on the back focal plane of the second lens, The signal processing system is connected to the detector; all optical elements are coaxially and equally high relative to the substrate, ie relative to the optical table or the instrument base. The filter array 1 is composed of M×N coplanar filters of different wavelength bands, all the filters have the same size, and M and N are both positive integers.

Compared with the prior art, the utility model has significant advantages:

(1) The multi-spectral information of each pixel in the full field of view can be obtained;

(2) Spectral images of multiple bands can be acquired at the same time to realize dynamic multi-spectral imaging;

(3) There are no moving parts inside, and the system structure is stable.

Below in conjunction with accompanying drawing, the utility model is described in further detail.

Description of drawings

Fig. 1 is a schematic diagram of the optical path structure of the multi-spectral light field camera of the present invention.

Fig. 2 is a schematic diagram of spectrum extraction of the multispectral light field camera of the present invention.

Detailed ways

Further illustrate the utility model below in conjunction with accompanying drawing and specific embodiment.

In conjunction with Fig. 1, the multi-spectral light field camera of the present invention includes a filter array 1, an imaging main lens 2, a microlens array 3, a combination secondary lens 4, a detector 5 and a signal processing system 6 arranged in sequence along the optical path direction , wherein the combination sub-lens 4 includes a first lens 41 and a second lens 42 arranged in sequence along the optical path direction, the combination sub-lens 4 transfers the back focal plane of the microlens array 3 to the target surface of the detector 5 twice; Described optical filter array 1 is positioned at the aperture stop place of imaging main lens 2, and microlens array 3 is positioned at the image plane of imaging main lens 2, and the rear focal plane of microlens array 3 coincides with the front focal plane of first lens 41, The detector 5 is located on the back focal plane of the second lens 42, and the signal processing system 6 is connected to the detector 5; all optical elements are coaxially and equally high relative to the base, that is, coaxially and equally high relative to the optical platform or the instrument base.

In the multi-spectral light field camera of the utility model, the filter array 1 is composed of M×N coplanar filters of different bands, all the filters have the same size, and M and N are both positive integers.

The imaging method of the utility model multispectral light field camera comprises the following steps:

Step 1: The incident light from each point of the target passes through the filter array 1 to form light beams carrying information in different bands and passes through the imaging main lens 2, and then forms an image on the microlens array 3 at the image surface of the imaging main lens 2, forming a light beam carrying Image points of different band information, each image point is separated in the space of the rear focal plane of the microlens array 3;

Step 2: the light rays at each point of the rear focal plane of the microlens array 3 enter the first lens 41, enter the second lens 42 in the form of parallel light after passing through the first lens 41, and enter the second lens 42 at the rear focal plane of the second lens 42. Obtain target images carrying information of different bands on the target surface of the detector 5, and convert the target images carrying information of different bands into electrical signals and enter the signal processing system 6;

Step 3: The signal processing system 6 converts the received electrical signal into different band spectral data of each point of the target, calculates the obtained different band spectral data, and extracts different band spectral images to obtain multi-spectral video. The specific process is : The incident light at each point of the target is incident on the imaging main lens 2 after passing through the filter array 1, and forms an image point on a microlens of the microlens array 3 through the imaging main lens 2, and then forms an image point through the combined sub-lens 4 in the detection A pixel unit is formed on the target surface of the device 5; the image formed by the pupil of the imaging main lens 2 facing the microlens array 3 is imaged on the target surface of the detector 5 through the combined sub-lens 4, and the image received by the detector 5 The image is the superposition of the target image and the imaging of the microlens array 3, and the image formed by any microlens in the microlens array 3 on the target surface of the detector 5 is regarded as a unit, and each unit can be divided into M ×N sub-units, each sub-unit corresponds to a band, and the sub-units at the corresponding positions in each unit are composed of the spectral image of the band with the original relative positional relationship.

Example 1

Taking the 2×2 filter array 1 as an example, the present invention will be further described in detail.

In conjunction with Fig. 1, the multi-spectral light field camera of the present invention includes a filter array 1, an imaging main lens 2, a microlens array 3, a combination secondary lens 4, a detector 5 and a signal processing system 6 arranged in sequence along the optical path direction , wherein the combination sub-lens 4 includes a first lens 41 and a second lens 42 arranged in sequence along the optical path direction, the combination sub-lens 4 transfers the back focal plane of the microlens array 3 to the target surface of the detector 5 twice; The above-mentioned filter array 1 is composed of 2×2 coplanar filters of different wavelength bands. All the filters have the same size. Starting from the upper left, along the clockwise direction, there are filters with a waveband of 400-450nm. LA, a filter LB with a waveband of 450-500nm, a filter LC with a waveband of 500-550nm, and a filter LD with a waveband of 550-600nm; the filter array 1 is located in the imaging main At the aperture stop of the lens 2, the microlens array 3 is located on the image plane of the main imaging lens 2, the back focal plane of the microlens array 3 coincides with the front focal plane of the first lens 41, and the detector 5 is located at the front focal plane of the second lens 42. On the rear focal plane, the signal processing system 6 is connected to the detector 5; all optical elements are coaxially and equally high relative to the base, that is, coaxially and equiheightly relative to the optical platform or the instrument base.

The working process of the multi-spectral light field camera is as follows: the incident light from each point of the target passes through the filter array 1 to form light beams carrying information of different bands and passes through the main imaging lens 2. Imaging on the microlens array 3 forms image points carrying information of different wavelength bands, and each image point is separated in the space of the back focal plane of the microlens array 3; the light rays at each point of the back focal plane of the microlens array 3 enter the first lens 41, After passing through the first lens 41, it enters the second lens 42 in the form of parallel light, and on the target surface of the detector 5 at the rear focal plane of the second lens 42, target images carrying information of different wavelength bands are obtained, and will carry different The target image of the band information is converted into an electrical signal and enters the signal processing system 6; the signal processing system 6 converts the received electrical signal into different band spectral data of each point of the target, calculates the obtained different band spectral data, and extracts different bands Spectral images to obtain multispectral video. Combined with Figure 2, the multi-spectral light field camera processes the image received by the detector 5 as follows, taking N=2, M=2 as an example: the image received by the detector 5 is the superposition of the target image and the microlens array imaging, if the The image formed by any microlens in the microlens array 3 on the target surface of the detector 5 is regarded as a unit, as shown in the left figure of Fig. Each unit is divided into four sub-units: A, B, C, and D: A sub-unit corresponds to the 400-450nm band, B sub-unit corresponds to the 450-500nm band, C sub-unit corresponds to the 500-550nm band, D sub-unit The unit corresponds to the 550-600nm band. Therefore, four complete spectral images can be obtained by rearranging the order of the subunits as follows: the subunit A in the first quadrant of each unit is composed of the spectral diagram of the 400-450nm band with the original relative positional relationship, The subunit B of the second quadrant forms the spectrum diagram of the 450-500nm band, the subunit C of the third quadrant forms the spectrum diagram of the 500-550nm band, and the subunit D of the fourth quadrant forms the spectrum diagram of the 550-600nm band.

Claims (2)

1. multispectral light field camera, it is characterized in that, comprise the filter arrays (1), imaging main lens (2), the microlens array (3) that arrange in turn along optical path direction, make up secondary lens (4), detector (5) and signal processing system (6), wherein make up secondary lens (4) and comprise first lens (41) and second lens (42) that arrange in turn along optical path direction, make up secondary lens (4) with the back focal plane secondary transferring of microlens array (3) to the target surface of detector (5); Described filter arrays (1) is positioned at the aperture diaphragm place of imaging main lens (2), microlens array (3) is positioned on the image planes of imaging main lens (2), the back focal plane of microlens array (3) overlaps with the front focal plane of first lens (41), detector (5) is positioned on the back focal plane of second lens (42), and signal processing system (6) links to each other with detector (5); All optical elements are coaxial contour with respect to substrate, and are namely coaxial contour with respect to optical table or instrument base.

2. multispectral light field camera according to claim 1 is characterized in that, described filter arrays (1) is made of the optical filter of M * coplanar different-waveband of N sheet, and the size of all optical filters is all identical, and M, N are positive integer.

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