Narrowband optical filter with multiple channels and multispectral image output equipment

Abstract

The utility model provides a narrow-band optical filter with multiple channels, which comprises a first narrow-band filtering channel, a second narrow-band filtering channel and a third narrow-band filtering channel, and the wave band ranges of the first narrow-band filtering channel, the second narrow-band filtering channel and the third narrow-band filtering channel are respectively from 400 nm to 500 nm, 500 nm to 600 nm and 600 nm to 700 nm. In the first narrowband filtering channel, the second narrowband filtering channel and the third narrowband filtering channel, there is one narrowband filtering channel, and the spectral response of the narrowband filtering channel to any color channel of the image sensor is significantly higher than that of the other two narrowband filtering channels. The utility model further provides a multispectral image output device which comprises the narrow-band filter with the multiple channels, an image sensor and a circuit board, the narrow-band filter is arranged on the image sensor, and the image sensor is arranged on the circuit board. According to the invention, multi-spectral image output meeting requirements can be realized without a complex process, the structure is simple, and the cost is low.

Description

Technical Field

[0001] This utility model relates to the technical field of hyperspectral imaging, and particularly to a narrowband filter with multiple channels and a multispectral image output device. Background Technology

[0002] In the field of multispectral image output, conventional RGB image sensors have significant limitations. Their R, G, and B channel response ranges are wide, making it difficult to directly output narrow-bandgap images, thus failing to meet the growing demand for high-precision, multispectral imaging. Currently, to address this issue, the industry has explored three main methods.

[0003] The first method uses a single-wavelength light source to sequentially image at different wavelengths. While this method can acquire narrow-band images, it has significant drawbacks. The need for a dedicated light source system results in bulky equipment that is extremely inconvenient to carry and use. Furthermore, the need to switch light source wavelengths for each image capture slows down the imaging process, severely limiting its real-time applications. For example, this method is insufficient for multispectral imaging scenarios requiring rapid capture of dynamic scenes.

[0004] The second method uses a rotating filter wheel. With each rotation, filters of different wavelengths on the wheel work sequentially to output an image of one wavelength. However, this method also faces a speed bottleneck. The mechanical movement of the rotating filter wheel is time-consuming, which cannot meet the application scenarios with high imaging speed requirements. For example, in the multispectral monitoring of high-speed moving targets, it is impossible to capture the dynamic changes of the target in a timely manner.

[0005] The third method employs a coated mosaic filter-type multispectral imaging device. This device achieves multispectral imaging by coating different wavelengths of filters onto different pixels. However, this method faces numerous challenges. To ensure precise pixel alignment, the filter film must be directly applied to the image sensor surface. This not only limits the device's flexibility but also places extremely high demands on the coating process, making it difficult and costly to implement. Furthermore, the filter film coverage reduces the spatial resolution of the image sensor, affecting image clarity and detail. In fields such as scientific research and medical imaging, where image accuracy is critical, it is difficult to achieve ideal imaging results. Utility Model Content

[0006] In order to solve the above-mentioned technical problems in the prior art, this utility model proposes an output device with a multi-channel narrowband filter and multispectral image, so as to realize the fast and low-cost output of narrowband images in multiple bands.

[0007] According to a first aspect of this invention, a multi-channel narrowband filter is proposed. The narrowband filter includes a first narrowband filtering channel, a second narrowband filtering channel, and a third narrowband filtering channel. The wavelength ranges of the first, second, and third narrowband filtering channels are respectively taken from 400–500 nm, 500–600 nm, and 600–700 nm. Among the first, second, and third narrowband filtering channels, one narrowband filtering channel exhibits a significantly higher spectral response to any color channel of the Bayer array image sensor than the other two narrowband filtering channels. This multi-channel narrowband filter enhances the capture of light signals in specific wavelength bands, improves the resolution capability of the Bayer array image sensor for different wavelength bands, provides more accurate raw data for subsequent generation of high-quality multispectral images, and meets the application scenarios with high requirements for multispectral image detail and accuracy.

[0008] In some specific embodiments, the Bayer array image sensor is an RGB image sensor, and the color channels include a blue channel (B), a green channel (G), and a red channel (R).

[0009] In some specific embodiments, the band of the first narrowband filter channel is the peak position of the spectral response of the blue channel B. This setting optimizes the blue channel's ability to capture light in this band.

[0010] In some specific embodiments, the band of the second narrowband filter channel is the peak position of the spectral response of the green channel G, or the intersection position of the spectral responses of the blue channel B and the red channel R. This setting helps to better distinguish and utilize the information of different color channels in this band. When it is the intersection position of the blue and red channels, the response of the blue and red channels in this band can be balanced, avoiding the information of one channel being too strong or too weak, so that the color representation of the multispectral image in this band is more accurate, which is beneficial to subsequent image processing and analysis.

[0011] In some specific embodiments, the band of the third narrowband filter channel is the peak position of the red channel R spectral response, or the peak and valley positions of the green channel G spectral response. This setting can enhance the display of red-related substances or features in the image; or further highlight the differences between the red and green channels in this band.

[0012] In some specific embodiments, a fourth narrowband filter channel is also included, the wavelength of which is taken from the range of 700 to 1000 nm. This configuration broadens the wavelength coverage of the narrowband filter, covering the near-infrared region, and enables the acquisition of more spectral information.

[0013] In some specific embodiments, the Bayer array image sensor is an RGBIR image sensor, and the blue channel (B), green channel (G), red channel (R), and infrared channel (IR) of the RGBIR image sensor have the same spectral response values ​​in the band of the fourth narrowband filter channel of the narrowband filter. This setting helps to unify the information of different channels in this band, facilitating subsequent fusion processing of multispectral images.

[0014] According to a first aspect of this invention, a multispectral image output device is proposed, comprising a multi-channel narrowband filter as described above, a Bayer array image sensor, and a circuit board. The narrowband filter is disposed on the Bayer array image sensor, and the Bayer array image sensor is mounted on the circuit board. This multispectral image output device structural design ensures that the device can effectively acquire optical signals of different wavelengths and convert the optical signals into electrical signals for transmission and processing, thereby realizing the output of a multispectral image.

[0015] In some specific embodiments, a filter holder is also included, which has a groove for accommodating the narrowband filter. The narrowband filter is tightly embedded in the groove, and the filter holder is mounted on the circuit board so that the narrowband filter covers the photosensitive surface of the Bayer array image sensor. This arrangement ensures accurate relative positioning between the narrowband filter and the Bayer array image sensor, guaranteeing that the optical signal can accurately pass through the narrowband filter and be received by the Bayer array image sensor, improving the stability and reliability of the device, and also facilitating the assembly and maintenance of the device.

[0016] In some specific embodiments, an image processor is also provided on the circuit board, and the image processor is electrically connected to the Bayer array image sensor.

[0017] This invention presents a multi-channel narrowband filter. By setting three narrowband filtering channels within specific wavelength ranges (400-500nm, 500-600nm, and 600-700nm), the narrowband filter can selectively filter light of different wavelengths. It also ensures that at least one channel has a significantly higher spectral response to any color channel of the image sensor than the other two channels. This helps enhance the capture of light signals in specific wavelength ranges and improves the image sensor's ability to resolve different wavelengths of light. Furthermore, a multispectral image output device is proposed. Through the reasonable combination of the filter and the RGB image sensor, it can achieve the required multispectral image output without requiring demixing algorithms or complex processes, resulting in a simple structure and low cost. Attached Figure Description

[0018] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and, together with the description, serve to explain the principles of the present invention. Other embodiments and many anticipated advantages of the embodiments will be readily recognized as they become better understood through reference to the following detailed description. Elements in the drawings are not necessarily to scale. The same reference numerals refer to corresponding similar parts.

[0019] Figure 1 This is a cross-sectional schematic diagram of a multispectral image output device according to one embodiment;

[0020] Figure 2 This is a diagram illustrating the effect of three narrowband image outputs from a specific embodiment of a narrowband filter with multiple channels;

[0021] Figure 3 This is a diagram illustrating the effect of four narrowband image outputs from a specific embodiment of a multi-channel narrowband filter. Detailed Implementation

[0022] In the following detailed description, reference is made to the accompanying drawings, which form part of the detailed description and illustrate illustrative specific embodiments in which the present invention may be practiced. In this regard, directional terms such as “top,” “bottom,” “left,” “right,” “up,” “down,” etc., are used with reference to the orientation of the described figures. Because components of the embodiments can be positioned in several different orientations, directional terms are used for illustrative purposes and are by no means limiting. It should be understood that other embodiments may be utilized or logical changes may be made without departing from the scope of the present invention. Therefore, the following detailed description should not be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

[0023] In one aspect of this application, a narrowband filter with multiple channels is proposed, such as... Figure 1As shown, it can be placed in the target optical path, such as above the image sensor 3, passing through the narrowband filter 1 before incident on the photosensitive surface of the image sensor 3 for imaging. Specifically, the narrowband filter 1 includes a first narrowband filter channel, a second narrowband filter channel, and a third narrowband filter channel. The wavelength ranges of the first, second, and third narrowband filter channels are taken from 400–500 nm, 500–600 nm, and 600–700 nm, respectively. Among the first, second, and third narrowband filter channels, there is always one channel whose spectral response to any color channel of the image sensor is significantly higher than the other two channels (the spectral response of this channel is 6 times or more than the spectral response of the other narrowband channels). This multi-channel narrowband filter enhances the capture of light signals in specific wavelength bands, improves the image sensor's ability to resolve different wavelength bands of light, provides more accurate raw data for the subsequent generation of high-quality multispectral images, and meets the application scenarios with high requirements for multispectral image detail and accuracy. The following is combined with Figure 1 A cross-sectional structural diagram of the multispectral image output device is provided to illustrate the narrowband filter 1 in detail:

[0024] like Figure 1 As shown, the multispectral image output device includes a narrowband filter 1, an image sensor 3, and a circuit board 4. The narrowband filter 1 is positioned above the image sensor 3 via a filter holder 2. Its function is to filter the incident light, splitting it into narrowbands of different wavelengths, enabling the image sensor 3 to receive light signals of specific wavelengths to meet the requirements of multispectral imaging. The image sensor 3, mounted above the circuit board 4, is the core component for acquiring image information. It converts light signals into electrical signals based on responses to different wavelengths, providing raw data for the subsequent generation of the multispectral image. The circuit board 4 houses the circuitry, responsible for transmitting the electrical signals generated by the image sensor to the image processor. The processor then performs a series of operations on these signals, including noise filtering, enhancement processing, and feature extraction, ultimately generating the multispectral image.

[0025] In one specific embodiment, the filter holder 2 is provided with a groove for accommodating the narrowband filter 1. The narrowband filter 1 is tightly embedded in the groove. The filter holder 2 is mounted on the circuit board 4, ensuring that the narrowband filter 1 covers the photosensitive surface of the image sensor 3. The arrangement of the filter holder 2 ensures the accurate relative position between the narrowband filter 1 and the image sensor 3, guaranteeing that the light signal can accurately pass through the narrowband filter 1 and be received by the image sensor 3. This improves the stability and reliability of the device and also facilitates the assembly and maintenance of the device.

[0026] In a specific embodiment, image sensor 3 employs a Bayer array image sensor, whose color channels include a blue channel (B), a green channel (G), and a red channel (R). This sensor is mature and low-cost, and can be widely used in various imaging devices. Leveraging its existing color filter array structure and working principle, it can efficiently perceive color and convert signals from light passing through a narrowband filter. In conjunction with the narrowband filter 1, it can reduce equipment costs while maintaining a certain level of image quality, making multispectral image output devices more competitive in the market and suitable for cost-sensitive applications with certain multispectral imaging requirements.

[0027] In a specific embodiment, among the first, second, and third narrowband filter channels, there is always one channel whose spectral response to any color channel of the image sensor is significantly higher than that of the other two channels. Specifically, this is manifested in the fact that the ratio of the spectral response value of any channel in the peak band of the narrowband filter to its spectral response value in other bands of the narrowband filter is greater than a preset value, which is not less than 6. In a specific example: the ratio of the spectral response value QBw1 of the blue channel B in the first narrowband filter channel of the narrowband filter 1 in band W1 to the spectral response value QBw2 in the second narrowband filter channel in band W2 is greater than 7; the ratio of the spectral response value QBw1 of the blue channel B in the first narrowband filter channel in band W1 to the spectral response value QBw3 in the third narrowband filter channel in band W3 is greater than 7; the ratio of the spectral response value QGw2 of the green channel G in the second narrowband filter channel in band W2 to the spectral response value QGw2 in the first narrowband filter channel in band W1 is greater than 7. The ratio of QGw1 is greater than 7; the ratio of the spectral response value QGw2 of the green channel G in band W2 of the second narrowband filter channel to the spectral response value QGw3 in band W3 of the third narrowband filter channel is greater than 7; the ratio of the spectral response value QRw3 of the red channel R in band W3 of the third narrowband filter channel to the spectral response value QRw1 in band W1 of the first narrowband filter channel is greater than 7; the ratio of the spectral response value QRw3 of the red channel R in band W3 of the third narrowband filter channel to the spectral response value QRw2 in band W2 of the second narrowband filter channel is greater than 7.

[0028] In a specific embodiment, the band W1 of the first narrowband filter channel is the peak position of the spectral response of the blue channel B, thus optimizing the ability of the blue channel B to capture light in this band.

[0029] In a specific embodiment, the band W2 of the second narrowband filter channel is the peak position of the spectral response of the green channel G, or the intersection position of the spectral responses of the blue channel G and the red channel R. This helps to better distinguish and utilize the information of different color channels in this band. When it is the intersection position of the blue and red channels, it can balance the response of the blue and red channels in this band, avoid the information of one channel being too strong or too weak, and make the color representation of the multispectral image in this band more accurate. This is beneficial to subsequent image processing and analysis, such as improving accuracy in color image fusion and target recognition.

[0030] In a specific embodiment, band W3 of the third narrowband filter channel represents the peak position of the red channel R spectral response or the peak-valley position of the green channel G spectral response. As the peak position of the red channel R spectral response, band W3 enhances the display of red-related substances or features in the image; as the peak-valley position of the green channel G spectral response, it further highlights the difference between the red and green channels in this band, enabling clearer differentiation of red and green related objects or regions in multispectral images, thus improving image contrast and recognizability.

[0031] In a specific example, taking the output of three narrowband images as an example, the narrowband channels of the narrowband filter 1 are W1, W2, and W3, respectively, and the spectral responses of the RGB image sensor 3 are QB, QG, and QR, respectively, and satisfying that the ratios of QBw1 / QBw2, QBw1 / QBw3, QGw2 / QGw1, QGw2 / QGw3, QRw3 / QRw1, and QRw3 / QRw1 are greater than T, where T is set to 7. Figure 2 The diagram illustrates the effect of three narrowband image outputs from a specific embodiment of a multi-channel narrowband filter, as shown below. Figure 2 As shown in the figure, the blue, green, and red curves represent the spectral response curves of the blue, green, and red channels in image sensor 3, respectively. The horizontal axis represents wavelength, and the vertical axis may represent spectral response intensity. The pink rectangles in the figure represent the band range of the narrowband filter, corresponding to bands W1, W2, and W3, respectively. This visually presents the position and approximate range of different bands on the wavelength axis, demonstrating the selective transmission characteristics of the narrowband filter 1 for different bands of light. In this embodiment, W1 = 460; W2 = 545; W3 = 655; and the values ​​of QBw1 / QBw2, QBw1 / QBw3, QGw2 / QGw1, QGw2 / QGw3, QRw3 / QRw1, and QRw3 / QRw2 are 11.2524, 29.1558, 8.1932, 14.8391, 21.1695, and 18.8232, respectively.

[0032] In a specific embodiment, a fourth narrowband filter channel is also included, with the band W4 of the fourth narrowband filter channel located in the range of 700–1000 nm. The fourth narrowband filter channel broadens the spectral coverage of the narrowband filter, encompassing the near-infrared region and enabling the acquisition of more dimensional spectral information. Furthermore, when the image sensor is an RGBIR image sensor, the spectral response values ​​of the blue, green, red, and infrared channels of the RGBIR image sensor are the same (or substantially the same) in the band of the fourth narrowband filter channel of the narrowband filter.

[0033] In another specific example, taking the output of four narrow-band images as an example, the narrow-band channels with filter 1 are W1, W2, W3, and W4, respectively. Image sensor 3 is an RGBIR image sensor, and the spectral response curves of its different light channels are QB, QG, QR, and QIR, respectively, and satisfy QBw4=QGw4=QRw4=QIRw4. The ratios of QBw1 / QBw2, QBw1 / QBw3, QGw2 / QGw1, QGw2 / QGw3, QRw3 / QRw1, and QRw3 / QRw2 are greater than T and are taken as 7. Figure 3 The diagram illustrates the effect of four narrowband image outputs from a specific embodiment of a multi-channel narrowband filter. In this embodiment, w1 = 460; w2 = 545; w3 = 655; w4 = 830; and the values ​​of QBw1 / QBw2, QBw1 / QBw3, QGw2 / QGw1, QGw2 / QGw3, QRw3 / QRw1, and QRw3 / QRw2 are 11.2524, 29.1558, 8.1932, 14.8391, 21.1695, and 18.8232, respectively.

[0034] This application overcomes the technical challenges of spectral aliasing in the acquired spectrum due to wavelength overlap in the quantum curves of RGB image sensors, and the high difficulty of spectral calculation and purification when more than three spectral information points are extracted, through the reasonable combination of filters and RGB image sensors. It can achieve the required output of 2-4 spectral images without requiring demixing algorithms or complex processes, resulting in a simple structure and low cost.

[0035] Obviously, those skilled in the art can make various modifications and changes to the embodiments of this utility model without departing from the spirit and scope of this utility model. In this way, this utility model is also intended to cover such modifications and changes if they fall within the scope of the claims of this utility model and their equivalents. The word "comprising" does not exclude the presence of other elements or steps not listed in the claims. The simple fact that certain measures are described in mutually different dependent claims does not indicate that a combination of these measures cannot be used for profit. Any reference numerals in the claims should not be considered as limiting the scope.

Claims

1. A narrowband filter with multiple channels, characterized in that, The narrowband filter includes a first narrowband filter channel, a second narrowband filter channel, and a third narrowband filter channel. The wavelength ranges of the first, second, and third narrowband filter channels are taken from 400–500 nm, 500–600 nm, and 600–700 nm, respectively. Among the first, second, and third narrowband filter channels, there is one narrowband filter channel whose spectral response to any color channel of the Bayer array image sensor is significantly higher than that of the other two narrowband filter channels.

2. The narrowband filter with multiple channels according to claim 1, characterized in that, The Bayer array image sensor is an RGB image sensor, and the color channels include a blue channel (B), a green channel (G), and a red channel (R).

3. The narrowband filter with multiple channels according to claim 2, characterized in that, The band of the first narrowband filter channel is the peak position of the spectral response of the blue channel B.

4. The narrowband filter with multiple channels according to claim 2, characterized in that, The band of the second narrowband filter channel is the peak position of the spectral response of the green channel G, or the intersection position of the spectral responses of the blue channel B and the red channel R.

5. The narrowband filter with multiple channels according to claim 2, characterized in that, The band of the third narrowband filter channel is the peak position of the red channel R spectral response, or the peak and valley positions of the green channel G spectral response.

6. The narrowband filter with multiple channels according to claim 1, characterized in that, It also includes a fourth narrowband filter channel, the wavelength of which is taken from the range of 700 to 1000 nm.

7. The narrowband filter with multiple channels according to claim 6, characterized in that, The Bayer array image sensor is an RGBIR image sensor, and the spectral response values ​​of the blue channel B, green channel G, red channel R, and infrared channel IR of the RGBIR image sensor are basically the same in the band of the fourth narrowband filter channel of the narrowband filter.

8. A multispectral image output device, characterized in that, The device includes a narrowband filter with multiple channels as described in any one of claims 1-7, and further includes a Bayer array image sensor and a circuit board, wherein the narrowband filter is disposed on the Bayer array image sensor and the Bayer array image sensor is mounted on the circuit board.

9. The multispectral image output device according to claim 8, characterized in that, It also includes a filter holder, which has a groove for accommodating the narrowband filter. The narrowband filter is tightly embedded in the groove. The filter holder is mounted on the circuit board so that the narrowband filter covers the photosensitive surface of the Bayer array image sensor.

10. The multispectral image output device according to claim 8, characterized in that, The circuit board is also equipped with an image processor, which is electrically connected to the Bayer array image sensor.

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