CN115078266A - Optical system and design method thereof - Google Patents

Abstract

Disclosed are an optical system and a design method thereof, which includes: a spectroscopic chip and an optical component held in a sensing path of the spectroscopic chip. The spectrum chip comprises a photoelectric detection layer and a light modulation layer positioned on a sensing path of the photoelectric detection layer, wherein the photoelectric detection layer obtains a light signal modulated by the modulation layer from an incident light signal. The optical assembly is configured to receive an optical signal from a subject and guide the optical signal to the spectrum chip, wherein the optical assembly enables the optical signal guided to each position of the spectrum chip to have a main ray included angle with a fixed angle and a light receiving cone angle with a preset angle, and the preset angle is less than or equal to 45 degrees. Therefore, the optical assembly with the specific structural configuration controls the main light angle of each pixel point of the spectrum chip to be fixed, the light receiving cone angle to be fixed and to be within a preset range, and the spectrum recovery error of the spectrum chip is reduced.

Description

Optical system and design method thereof

Technical Field

The present application relates to spectroscopy chips, and more particularly, to optical systems including spectroscopy chips and methods of designing the same.

Background

The interaction of light with substances, such as absorption, scattering, fluorescence, raman, etc., produces a specific spectrum, and the spectrum of each substance is unique. Thus, the spectral information can be said to be a "fingerprint" of everything.

The spectrometer can directly detect the spectral information of a substance to obtain the existence condition and the substance composition of a detected target, and is one of important test instruments in the fields of material characterization, chemical analysis and the like. From the technical development, micro spectrometers can be divided into four categories: dispersive, narrowband filtered, fourier transformed, and computationally reconstructed.

A dispersive spectrometer generally comprises one or more diffraction gratings, an optical path, and a photodetector array, wherein a light signal from a target to be measured is collimated and irradiated onto the diffraction gratings through an entrance slit, the diffraction gratings disperse spectral components in different directions, and finally, a concave mirror focuses the dispersed spectral components onto the photodetector array to obtain a spectral distribution. The spectrometer has ultrahigh resolution, wide spectral range and mature technology, but the dispersive spectrometer depends on a bulky dispersive element, a long optical path and the like, and the size is difficult to compress.

The narrow-band filtering type spectrometer can selectively transmit light with a specific wavelength, realizes detection of a spectrum, is planar in devices, does not need a long optical path, and has some advantages in terms of system miniaturization. In the narrow band filtering type spectrometer, the filter for wavelength selection is a band pass filter. The higher the spectral resolution, the narrower and more filters of the passband must be used, which increases the bulk and complexity of the overall system. Meanwhile, when the spectral response curve is narrowed, the luminous flux is decreased, resulting in a decrease in the signal-to-noise ratio.

The Fourier transform spectrometer is usually used for measuring infrared absorption or emission spectrum, and the spectrum to be measured is obtained by carrying out Fourier transform on an interferogram obtained by a detector, so that the Fourier transform spectrometer has the advantages of high signal-to-noise ratio, small size and low cost. However, the fourier transform spectrometer is not suitable for further miniaturization, since it requires an external camera to perform scattering imaging on an interference pattern.

With the development of computer technology, a new spectrometer type has emerged in recent years: a computational reconstruction type spectrometer that computationally approximates or even reconstructs the spectrum of incident light. The calculation reconfiguration spectrometer can solve the problem of detection performance reduction caused by miniaturization relatively better.

Since the calculation of the reconfigured spectrometer or the calculation of the reconfigured spectrum imaging device belongs to the emerging technology, in the practical application, the calculation of the reconfigured light source instrument or the calculation of the reconfigured spectrum imaging device has many technical problems. The discovery and the solution of the technical problems are necessary ways to promote the maturity of the calculation reconstruction type spectrometer and the spectral imaging device.

Disclosure of Invention

An advantage of the present application is to provide an optical system and a design method thereof, wherein the optical system includes a spectrum chip and an optical component held on a sensing path of the spectrum chip, wherein the optical component has a structural configuration such that a main light angle of a light signal directed to each position of the spectrum chip is a fixed value and a light receiving cone angle of each position is a predetermined value, so that the light receiving cone angle of each pixel point of the spectrum chip is controlled to be the predetermined value and within a preset range and/or the main light angle of each pixel point is the fixed value by the optical component having a specific structural configuration to reduce a spectrum recovery error of the spectrum chip.

Other advantages and features of the present application will become apparent from the following description and may be realized by means of the instrumentalities and combinations particularly pointed out in the appended claims.

To achieve at least one of the above advantages, the present application provides an optical system including:

a spectroscopic chip comprising a photodetection layer and a light modulation layer located on a sensing path of the photodetection layer, the photodetection layer configured to obtain a light signal modulated by the light modulation layer from an incident light signal; and

an optical assembly held on a sensing path of the spectroscopy chip, the optical assembly configured to receive an optical signal from a subject and direct the optical signal to the spectroscopy chip;

wherein the optical assembly is configured such that a principal light angle of the optical signal directed to each location of the spectroscopic chip is a fixed value and a received light cone angle of each location is a predetermined value.

In an optical system according to the present application, the predetermined value is 45 ° or less.

In an optical system according to the present application, the predetermined value is 35 ° or less.

In an optical system according to the present application, the predetermined value is 10 ° or less.

In an optical system according to the present application, the optical assembly includes a lens group having an F-number of 1.8 or more.

In an optical system according to the present application, an F-number of the lens group is 2.5 or more.

In an optical system according to the present application, the optical assembly further comprises a stop for adjusting an F-number of the lens group.

In an optical system according to the present application, the lens group has a field angle θ, an image height h, wherein the optical system satisfies the following relation:

l/h tan (θ/2) ═ X/2)/Y, where X denotes a side length of a detection range of the optical system, Y denotes a distance between the optical system and a subject, and L is a side length of a sensing effective region of the spectrum chip.

In the optical system according to the present application, X is equal to or less than 6cm, and Y is equal to or less than 10cm, wherein when X is equal to or less than 6cm, and Y is equal to or less than 10cm, the spectrum chip is adapted to be configured to collect optical frequency information in an optical signal from a subject.

In an optical system according to the application, the optical assembly includes a light uniformizing module and a collimating unit located on a light exit path of the light uniformizing module, the light uniformizing module is configured to uniformize a light signal from a subject, and the collimating unit is configured to collimate the uniformized light signal.

In an optical system according to the application, the dodging module comprises a light scattering element and a diaphragm positioned on a light outlet path of the light scattering element, wherein the diaphragm is provided with a light through hole, and the size of the light through hole is 1mm to 10 mm.

In an optical system according to the application, the light homogenizing module comprises an integrating sphere, the integrating sphere is provided with a light inlet and a light outlet, and the size of the light outlet is smaller than that of the light inlet.

In an optical system according to the application, the dodging module comprises a diaphragm, a scattering element positioned on a light outlet path of the diaphragm, and a dodging rod positioned on a light outlet path of the scattering element.

In an optical system according to the present application, the dodging module further includes at least one optical lens located on the light entrance path of the diaphragm.

In an optical system according to the present application, the optical assembly includes a telecentric lens.

According to another aspect of the present application, there is also provided a method of designing an optical system, including:

acquiring a conversion matrix of a photodetection layer of a spectroscopic chip, the photodetection layer obtaining a detected optical signal from an incident optical signal based on the conversion matrix, wherein the spectroscopic chip further comprises a light modulation layer located on a sensing path of the photodetection layer; and

and determining a structural configuration of an optical component based on the numerical value change of the conversion matrix, wherein the structural configuration is used for enabling a main light angle of the optical signal guided to each position of the spectrum chip to be a fixed value and a light receiving cone angle of each position to be a preset value, and the optical component is kept on a sensing path of the spectrum chip and used for receiving the optical signal from the object to be shot and guiding the optical signal to the spectrum chip.

In the design method of an optical system according to the present application, the predetermined value is 45 ° or less.

In the design method of an optical system according to the present application, the predetermined value is 35 ° or less.

In the design method of an optical system according to the present application, the predetermined value is 10 ° or less.

In a design method of an optical system according to the present application, the optical assembly includes a lens group having an F-number of 1.8 or more.

In a design method of an optical system according to the present application, an F-number of the lens group is 2.5 or more.

In a design method of an optical system according to the present application, the lens group has a field angle θ, an image height h, wherein the optical system satisfies the following relation:

l/h tan (θ/2) ═ X/2)/Y, where X denotes a side length of a detection range of the optical system, Y denotes a distance between the optical system and a subject, and L is a side length of a sensing effective region of the spectrum chip.

Further objects and advantages of the present application will become apparent from an understanding of the ensuing description and drawings.

These and other objects, features and advantages of the present application will become more fully apparent from the following detailed description, the accompanying drawings and the claims.

Drawings

The above and other objects, features and advantages of the present application will become more apparent by describing in more detail embodiments of the present application with reference to the attached drawings. The accompanying drawings are included to provide a further understanding of the embodiments of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings, like reference numbers generally represent like parts or steps.

FIG. 1 illustrates a schematic diagram of a spectrum chip for a computational reconstruction spectrometer according to an embodiment of the present application.

FIG. 2A illustrates one of the performance curve diagrams of the spectroscopy chip according to an embodiment of the application.

Fig. 2B illustrates a second performance curve diagram of the spectrum chip according to the embodiment of the present application.

Fig. 2C illustrates a third exemplary performance curve of the spectrum chip according to the embodiment of the present application.

FIG. 2D illustrates a fourth exemplary performance curve of the spectroscopy chip in accordance with an embodiment of the application.

FIG. 2E illustrates five of the performance curves of the spectroscopy chip according to an embodiment of the application.

Fig. 2F illustrates six performance curve diagrams of the spectroscopy chip according to an embodiment of the application.

Fig. 2G illustrates a seventh performance curve diagram of the spectroscopy chip according to an embodiment of the application.

Fig. 2H illustrates an eighth performance curve diagram of the spectroscopy chip according to an embodiment of the present application.

Fig. 2I illustrates nine of performance curve diagrams of the spectroscopy chip according to an embodiment of the present application.

FIG. 3 illustrates a schematic diagram of an optical system according to an embodiment of the present application.

Fig. 4 illustrates a schematic diagram of optical components of the optical system implemented as a lens group according to an embodiment of the present application.

Fig. 5 illustrates a schematic view of an optical assembly of the optical system according to an embodiment of the present application implemented as a light unifying assembly.

Fig. 6 illustrates another schematic view of an optical assembly of the optical system according to an embodiment of the present application implemented as a dodging assembly.

Fig. 7 illustrates yet another schematic view of an optical assembly of the optical system according to an embodiment of the present application implemented as a dodging assembly.

Fig. 8A illustrates a schematic diagram in which optical components of the optical system according to an embodiment of the present application are implemented as telecentric lenses.

Fig. 8B illustrates another schematic diagram in which optical components of the optical system are implemented as telecentric lenses according to embodiments of the present application.

Fig. 8C illustrates yet another schematic diagram in which optical components of the optical system according to an embodiment of the present application are implemented as telecentric lenses.

Detailed Description

Hereinafter, example embodiments according to the present application will be described in detail with reference to the accompanying drawings. It should be understood that the described embodiments are only some embodiments of the present application and not all embodiments of the present application, and that the present application is not limited by the example embodiments described herein.

Summary of the application

As described above, the spectrometer can directly detect the spectral information of a substance to obtain the existence condition and the substance composition of a target to be detected, and is one of important test instruments in the fields of material characterization, chemical analysis, and the like. From the technical development, micro spectrometers can be divided into four categories: dispersive, narrowband filtering, fourier transform, and computational reconstruction.

A calculation reconstruction type spectrometer (hereinafter, referred to as a calculation spectrometer) or a calculation reconstruction type spectral imaging device is a novel spectrometer or a spectral imaging device which appears along with the development of computer technology in recent years. Most of the embodiments below are described by taking a spectrometer as an example, and a computationally reconfigured spectrometer can solve the problem of detection performance degradation due to miniaturization relatively well.

However, since the calculation reconstruction type spectrometer belongs to a new technology, in practical application, the calculation reconstruction type light source instrument has many technical problems. The discovery and the solution of the technical problems are the necessary way to promote the maturation of the calculation reconstruction type spectrometer.

More specifically, existing computational spectrometers typically operate as follows: firstly, a spectrum chip is adopted to obtain an optical signal from a measured target, and then data processing is carried out on the obtained optical information based on a specific algorithm so as to obtain the spectrum information of the measured target. By way of example and not limitation, in this process, the spectrum chip can capture information in an optical signal of a measured object in an optical frequency domain to be measured, and the implementation manner includes: the method includes the steps of using a light detector array with a light modulation structure, or combining a filter element array with the light detector array, wherein the filter element array can perform broadband filtering processing on light information on a frequency domain or a wavelength domain.

In comparison to conventional spectrometers (e.g., narrow band filter type spectrometers), the use of a wide spectrum filter for at least one of the filter elements in the computing spectrometer makes the data detected by the computing spectrometer system appear quite different from the original spectrum. However, by applying a computational reconstruction algorithm, the original spectrum can be recovered by computation. Since the broadband filter passes more light than the narrowband filter, the computing spectrometer can detect spectra from darker scenes, such as night scenes. Furthermore, according to the compressive sensing theory, the spectral curves of the filter elements can be properly designed to recover the sparse spectrum with high probability, and the number of the filter elements is much smaller than the desired number of spectral channels (recovering a higher-dimensional vector from a lower-dimensional vector), which is certainly very advantageous for miniaturization. On the other hand, by using a larger number of filter elements, a regularization algorithm (lower dimensional vectors after noise reduction are obtained from higher dimensional vectors) can be used to reduce noise, which increases the signal-to-noise ratio and makes the overall system more robust.

In contrast, when a conventional spectrometer is designed, a filter (the effect of which is also equal to that of the optical modulation structure of the spectrum chip) needs to be designed according to a required wavelength, so that light with a specific wavelength can be transmitted (generally, the conventional spectrometer is designed to enhance the projection of incident light with the specific wavelength, but incident light with a non-specific wavelength band cannot be projected, the resonance condition can be controlled by changing the period and the diameter of the structure such as a nano disc, and the central wavelength of the incident light capable of enhancing the projection is changed, so that the filtering characteristic is realized). That is, the conventional spectrometer needs to control the size and position accuracy of the light modulation structure during the design process, and needs to improve the transmittance of a specific wavelength. For computational spectrometers, however, it is desirable to be able to receive light over a wide range of wavelength bands (e.g., 350nm to 900nm), and therefore, to focus more on the refractive index at the time of design.

FIG. 1 illustrates a schematic diagram of a spectrum chip for a computational reconstruction spectrometer according to an embodiment of the present application. As shown in fig. 1, the spectrum chip is a spectrum chip disclosed in chinese patent CN201921223201.2 by the inventor of the present application, and based on the content of the chinese patent CN201921223201.2, the spectrum chip 100 includes a photodetection layer 110 and a light modulation layer 120 held on a sensing path of the photodetection layer 110. Specifically, the optical modulation layer 120 includes at least one modulation unit 121, each modulation unit 121 corresponds to at least one sensing unit 111 of the photodetection layer 110, wherein the spectrum chip 100 modulates an optical signal from a detected object by using the modulation unit 121 of the optical modulation layer 120 to obtain a modulated optical frequency signal, receives the modulated optical frequency signal by using the photodetection layer 110 and provides a differential response thereto, and then reconstructs the differential response by using the signal circuit processing layer of the spectrum chip 100 to obtain original spectrum information of the detected object. In some specific examples, the light modulation layer 120 includes at least one modulation unit 121 and at least one non-modulation unit, and each modulation unit 121 and each non-modulation unit respectively correspond to at least one sensing unit 111 of the photodetection layer 110, that is, the modulation unit 121 and the sensing unit 111 may be disposed in a one-to-one correspondence manner, or in a one-to-many correspondence manner, or even in a many-to-one correspondence manner, or in a one-to-many correspondence manner, or even in a many-to-one correspondence manner.

The working principle can be understood as follows: the incident light signal is set to be a vector X ═ X1, X2, … … XN ] T, and the signal received by the sensing unit of the photodetecting layer is a vector Y ═ Y1, Y2, … … YM ] T, and accordingly, Y ═ DX + W, where the transformation matrix D is determined by the light modulation layer and the vector W is noise. In the practical application of the spectrum chip, the spectrum chip is calibrated to obtain the transformation matrix D, and then the spectrum chip after calibration is used to measure the spectrum information of the target to be measured, that is, the known transformation matrix D and the vector Y obtained by the sensing unit are used to solve the spectrum signal X of the target to be measured.

However, the inventors of the present application found that: the calculation spectrum chip working based on the principle has some problems in practical application, and the problems can influence the spectrum detection performance of the spectrum chip.

First, the present inventors found that in practical applications, a computing spectrum chip is sensitive to a main light angle of an incident light signal, and a change in the main light angle of the incident light signal greatly affects accuracy of spectrum recovery under practical use conditions. Here, a chief ray angle of any one specific position of the spectrum chip represents an angle between a chief ray of an optical signal directed to the spectrum chip, which indicates a line between a point of emitting the optical signal from the object and a point of reaching a corresponding light sensing unit of the spectrum chip, and a normal line, which indicates a line perpendicular to a light sensing surface of the spectrum chip. Specifically, for the spectrum chip, the angles of the main light angles of different sensing units allow a large difference, but the light rays incident on the same sensing unit need to maintain a small angle difference.

Secondly, the inventor of the present application also finds that, in practical application, the calculation of the light receiving cone angle of the spectrum chip is sensitive to the incident light signal reaching each position of the spectrum chip. In practical applications, if the light receiving cone angle of the incident light signal is changed greatly, the accuracy of spectrum recovery will be greatly affected.

Specifically, when an incident optical signal reaches a certain sensing unit of the spectrum chip, if an incident angle of the optical signal to the sensing unit of the spectrum chip (for the sensing unit, the incident angle may also be defined as a light receiving cone angle of the sensing unit) changes, a parameter value of a corresponding position in the transformation matrix D also changes correspondingly, thereby affecting accuracy of spectrum recovery.

That is, due to the angular sensitivity of the light modulation layer, the transformation matrix D may be influenced by the chief ray angle and/or the acceptance cone angle of the incident light signal during the computational reconstruction. Under an actual use environment, the distribution condition of light to be measured in a space and the angular distribution of light rays have uncertainty, so that the main light angle and the light receiving cone angle of different sensing units incident to the spectrum chip also have uncertainty, and a large error of spectrum measurement is caused.

Through the verification of test data, the inventor of the application finds that: in practical applications, the transformation matrix D of the spectrum chip is not constant, and is influenced by the main light angle and the light-receiving cone angle. Further, when the light receiving cone angle of the incident light signal is large, which is equivalent to the superposition of the incident collimated light transmission spectrums at a plurality of angles, the randomness and complexity of the spectrum transmitted by the light modulation layer are reduced, and the correlation among different light modulation units is improved, so that the spectrum recovery effect is reduced; conversely, the smaller the angle of the light acceptance cone angle, the better the spectrum recovery effect.

Secondly, in the above technology, the information collected at different positions of the spectrum chip (e.g. different sensing units on the photodetector layer) is assumed to originate from a certain point of the object to be measured, and then data processing is performed to obtain the spectrum information of the object to be measured. In practical application scenarios, the complexity of the environment and the object to be measured may cause the above assumptions to deviate, thereby causing a large error in the spectral measurement effect.

In view of the first problem, the inventors of the present application propose a solution. In particular, when using and calibrating the spectroscopic chip, it is ensured that the angle of the chief ray angle of the incident light signal to each sensing unit of the spectroscopic chip remains consistent, i.e. the chief ray angle of the light signal directed to each position of the spectroscopic chip is a fixed value. Here, the fact that the angle value of the main light angle is a fixed value does not mean that the main light angle of each of the light sensing units is completely equal in different operations, but the value of the main light angle is maintained within a predetermined range, for example, a range of ± 5 ° in different operations. Further, in order to optimize the spectrum recovery performance of the spectrum chip, it is also necessary to ensure that the acceptance cone angle of the incident optical signal directed to each position of the spectrum chip is a predetermined value, and the predetermined value is 45 ° or less. Here, the predetermined value of the acceptance cone angle of the incident light signal directed to each position of the spectrum chip does not mean that the values of the acceptance cone angles of each of the photosensitive cells during different operations are completely equal, but that the value of the acceptance cone angle of each position is maintained within a predetermined range, for example, within a range of ± 5 ° during different operations. For example, when the imaging system has a focusing, zooming or virtual focusing function, since the focus or focal length of the optical system is changed to a certain extent, the main light angle and the light-receiving cone angle will be changed to a certain extent, but the change will be within a predetermined range and will not affect the system performance, so it can also be understood that the main light angle corresponding to the system is a fixed value and the light-receiving cone angle is a predetermined value.

Further, when the spectral chip is used in conjunction with an optical assembly, the optical assembly has a particular structural configuration such that optical signals directed to the spectral chip have a fixed principal optical angle and a predetermined angular acceptance cone of light. Through testing, the range of the preset angle is less than or equal to 45 degrees, preferably less than or equal to 35 degrees, and preferably the preset angle is 10-15 degrees in some scenes with longer back focal lengths; the predetermined angle may also be 35-40 in some scenes with larger field angles. It is worth mentioning that the acceptance cone angle has a certain tolerance, but is generally controlled within ± 5 °. That is, the main light angle and the acceptance cone angle of each sensing unit of the spectrum chip are controlled by the optical assembly having a specific structural configuration, generally, the main light angle is a fixed value, the acceptance cone angle is a predetermined angle, and the predetermined angle is 45 ° or less. To reduce spectral recovery errors of the spectral chip.

In some examples, only the main light angle or only the light receiving cone angle may be controlled separately, that is, one of the main light angle and the light receiving cone angle is a predetermined value, which is not limited by the present application.

In response to the second problem, the inventors of the present application found that: in the process of spectrum recovery through the spectrum chip, in order to achieve a good effect, randomness and complexity of a transmission spectrum of the light modulation layer and low correlation degree of the transmission spectrum among different modulation units need to be ensured, wherein the randomness and the complexity can be characterized as the degree of rapid spectrum change in a specific frequency domain range.

Through experimental tests, as shown in fig. 2A to 2I, the test charts of the projection performance curves of the spectrum chip corresponding to the incidence angles of 20 °, 15 °, 10 °, 5 °, 0 °, -5 °, -10 °, -15 °, and-20 ° are respectively shown, wherein the horizontal axis is the wavelength, the unit is micrometer, and the vertical axis is the absolute value of the light intensity. Note that due to the angular sensitivity of the spectroscopic chip, i.e., the transmission spectrum of the light modulating layer varies greatly when light signals of different angles are incident. It can be concluded that, when the light-receiving cone angle is large, the randomness and complexity of the transmission spectrum of the light modulation layer are reduced, and the correlation between different modulation units is improved, thereby causing a reduction in the spectrum recovery effect; when the light receiving cone angle is smaller, the randomness and the complexity of the transmission spectrum of the light modulation layer are improved, and the correlation among different modulation units is reduced, so that the spectrum recovery effect is improved.

Through further experiments, the inventors of the present application found that: when the light-receiving cone angle of each sensing unit of the spectrum chip is less than or equal to 45 degrees, the spectrum recovery effect is better, namely, the randomness and complexity of the projection spectrum are relatively higher, and the correlation among different modulation units is lower. According to experimental tests, the smaller the light receiving cone angle is, the better the effect is, and preferably, the light receiving cone angle is less than or equal to 10 degrees.

Based on this, the present application provides an optical system comprising: a spectroscopic chip and an optical component held in a sensing path of the spectroscopic chip. The spectrum chip comprises a photoelectric detection layer and a light modulation layer positioned on a sensing path of the photoelectric detection layer. The optical assembly is configured to receive an optical signal from a subject and guide the optical signal to the spectrum chip, wherein the optical assembly is configured such that a main light angle of the optical signal guided to each position of the spectrum chip is a fixed value and a light receiving cone angle of each position is a predetermined value, the predetermined value being 45 ° or less. That is, by the optical component having a specific structural configuration, the light receiving cone angle of each pixel point of the spectrum chip is controlled to be a predetermined value and the predetermined value is within a predetermined range, and the main light angle of the optical signal corresponding to each pixel point is a fixed value, so as to reduce the spectrum recovery error of the spectrum chip.

Having described the general principles of the present application, various non-limiting embodiments of the functionality of the present application will now be described with particular reference to the accompanying drawings.

Exemplary optical System

As shown in fig. 3, an optical system according to an embodiment of the present application is illustrated, which includes: a spectroscopic chip 100 and an optical assembly 200 held in a sensing path of the spectroscopic chip 100.

In a specific example of the present application, the spectrum chip 100 includes a photodetection layer 110 and a light modulation layer 120 located on a sensing path of the photodetection layer 110, the light modulation layer 120 includes at least one modulation unit 121 and at least one non-modulation unit, and the modulation unit 121 is used for modulating a light signal from a target under test. The light modulation layer 120 may be a structure or a material having a light filtering characteristic, such as a super surface, a photonic crystal, a nano-pillar, a multi-layer film, a dye, a quantum dot, a MEMS, a FP etalon, a cavity layer, a waveguide layer, or a diffusion element.

In order to solve the two technical problems found in the summary section of the application, in particular, in the embodiment of the present application, the optical component 200 is configured such that the main light angle of the light signal directed to each position of the spectrum chip 100 is a fixed value and the light-receiving cone angle of each position is a predetermined value, the predetermined value is 45 ° or less. That is, in the embodiment of the present application, the optical component 200 has a structural configuration such that the main light angle of the optical signal directed to each position of the spectrum chip 100 is a fixed value and the light receiving cone angle of each position is a predetermined value, wherein the predetermined value is equal to or less than 45 °. In this way, the light receiving cone angle of each pixel point of the spectrum chip 100 is controlled to be a predetermined value and within a preset range and/or the main light angle of each pixel point of the spectrum chip 100 is controlled to be a fixed value, so as to reduce the spectrum recovery error of the spectrum chip 100.

It should be particularly noted that, in the embodiment of the present application, the smaller the predetermined value of the light-receiving cone angle is, the better the spectrum recovery effect of the spectrum chip 100 is. Preferably, in the embodiment of the present application, the predetermined value is 35 ° or less, and more preferably, the predetermined value is 10 ° or less.

In the embodiment of the present application, the angular sensitivity of the spectrum chip 100 can be expressed by the change of the angle of the main light and the change of the angle of the receiving light cone. In order to ensure the above technical effects, experiments show that, in the embodiment of the present application, the variation of the main light angle is less than or equal to 5 °, that is, for each pixel point of the spectrum chip 100, the variation of the main light angle corresponding to the pixel point in different working processes is less than or equal to 5 °, and preferably less than or equal to 1 °. Moreover, the variation of the light receiving cone angle is less than or equal to 1 °, that is, for each pixel point of the spectrum chip 100, the variation of the light receiving cone angle corresponding to the pixel point in different working processes is less than or equal to 1 °. Thus, the light modulation layer 120 of the spectrum chip 100 has a relatively better modulation effect, so as to obtain a relatively more spectrum recovery effect. In addition, in the working process, the light receiving cone angle of each pixel point of the spectrum chip 100 needs to be kept at a predetermined value, and the smaller the predetermined value is, the more favorable the spectrum recovery of the spectrum chip 100 is.

The optical system according to the embodiments of the present application can be applied as a spectrometer or a spectral imaging device or other image sensing devices based on different application scenarios and application requirements.

In particular, when the optical system is applied as a spectrometer, in a specific example of the present application, the optical component 200 is implemented as a lens group 210A, and the lens group 210A includes at least one optical lens for converging an incident optical signal, as shown in fig. 4.

For convenience of explanation, in the present application, the size of the measured object is defined as Xcm × Xcm, and the measurement distance is defined as Y, wherein, preferably, X is equal to or less than 6cm, and Y is equal to or less than 10 cm. That is, when X is 6cm or less and Y is 10cm or less, the spectrum chip 100 is adapted to be configured to collect optical frequency information in an optical signal from a subject.

Further, setting the lens group 210A to have the field angle θ and the image height h, the optical system applied as a spectrometer satisfies the following relation: l/h tan (θ/2) ═ X/2)/Y, where X denotes a side length of a detection range of the optical system, Y denotes a distance between the optical system and a subject, and L is a side length of a sensing effective region of the spectrum chip 100.

In a specific example of this example, the side length of the sensing effective region of the spectrum chip 100 is 1.2mm, the field angle θ of the lens group 210A is 23.5 °, the image height h is 10mm, the working distance is 60mm, and the size of the measured object is 3mm × 3 mm.

It is worth mentioning that in this example, the F-number of the lens group 210A is greater than or equal to 1.8, preferably greater than or equal to 2.5, in order to match the size and range of the object to be measured, and on the other hand also to improve the measurement accuracy. It is also worth mentioning that in some variant embodiments of this example, in order to control the F-number, the lens group 210A further comprises a stop for adjusting the F-number of the lens group 210A.

It is also worth mentioning that the optical system provided in this example may be applied to other terminal devices, such as smart phones, etc., where the size of the optical system may be required, especially in the height direction. For example, taking the requirement of the height direction as an example, the height dimension of the optical system can be designed to be less than or equal to 10mm, for example, the optical system is configured as a periscopic optical system, that is, the optical system further includes a light turning element (not shown) for turning the incident light signal, for example, 90 °, so as to reduce the overall height dimension of the optical system.

Further, the optical system as illustrated in fig. 4 may also be applied as a spectral imaging apparatus, that is, when the optical assembly 200 is implemented as the lens group 210A, the optical system may also be applied as a spectral imaging apparatus.

Unlike the above-described spectrometer, when the optical system is applied as a spectral imaging apparatus, a photographing range does not need to be set, that is, the photographing range of a target to be measured does not need to be limited. In addition, the lens group 210A forms a conjugate plane between the target to be measured and the spectrum chip 100, thereby significantly reducing the influence of different light-emitting positions reaching the same pixel point of the spectrum chip 100.

Further, when the optical system is applied as a spectrometer, the optical assembly 200 may also be implemented as other optical structures.

As shown in fig. 5, in this example, the optical assembly 200 of the optical system is implemented as a light uniformizing assembly 210B, wherein the light uniformizing assembly 210B is configured to homogenize and collimate light signals at different angles, so that the light receiving cone angle of the light signal finally reaching each position of the spectrum chip 100 is a predetermined value and within a predetermined angle range (e.g., 45 ° or less) and the light receiving cone angle of the light signal at each position is a fixed value. It should be noted that, ideally, the light receiving cone angle and the main light angle of the collimated light signal reaching the spectrum chip 100 are 0 °, but in practice, since there is no perfect collimation system, there is a certain angle between the light signal and the normal, but regardless of the existence of the angle, the main light angle and the light receiving cone angle of the incident light in the optical system can be understood to meet the design requirements of the above parameters, that is, the main light angle is a fixed angle, and the light receiving cone angle is a predetermined value and is within a preset range.

In this example, the dodging assembly 210B includes a dodging module 211B and a collimating unit 212B located on an outgoing light path of the dodging module 211B, the dodging module 211B is configured to homogenize a light signal from a subject, and the collimating unit 212B is configured to collimate the homogenized light signal. In the example illustrated in fig. 5, the dodging module 211B includes a dodging element 2111B and a diaphragm 2112B located on a light exit path of the dodging element 2111B. In particular, the diaphragm 2112B has a light-passing hole having a size of 1mm to 10mm, preferably 2mm to 5mm, that is, the diaphragm 2112B has a light-passing hole of a relatively small size to intercept a small portion of incident light. After passing through the collimating unit 212B, the incident light signal becomes approximately parallel light such that the acceptance cone angle of the spectrum chip 100 is close to 0 °.

Fig. 6 illustrates another schematic diagram of the optical assembly 200 of the optical system according to an embodiment of the present application implemented as a dodging assembly 210B. As shown in fig. 6, in this modified implementation, the dodging assembly 210B includes a dodging module 211B and a collimating unit 212B located on the light exit path of the dodging module 211B, the dodging module 211B is configured to homogenize the light signal from the object to be photographed, and the collimating unit 212B is configured to collimate the homogenized light signal. In particular, the light homogenizing module 211B includes an integrating sphere 2113B, and the integrating sphere 2113B has a light inlet and a light outlet, and the size of the light outlet is smaller than that of the light inlet.

Fig. 7 illustrates yet another schematic diagram of the optical assembly 200 of the optical system according to an embodiment of the present application implemented as a dodging assembly 210B. As shown in fig. 7, in this modified implementation, the dodging assembly 210B includes a dodging module 211B and a collimating unit 212B located on the light exit path of the dodging module 211B, the dodging module 211B is configured to homogenize the light signal from the object to be photographed, and the collimating unit 212B is configured to collimate the homogenized light signal. In particular, the dodging module 211B includes a diaphragm 2112B, a scattering element 2114B located on an outgoing light path of the diaphragm 2112B, and a dodging rod 2115B located on an outgoing light path of the scattering element 2114B (in some examples, the dodging rod 2115B may be replaced by an optical fiber), wherein one end of the dodging rod 2115B is located near a focal plane of the collimating unit 212B. It should be noted that, in the diaphragm 2112 of the present invention, the inner surface is inclined and extends outward from the optical axis from the object side to the image side, and further at least a portion of the inner surface is a reflection surface to increase the light intensity, so as to reflect a portion of the light beam, so that the light beam can enter the collimating unit 212B, thereby increasing the light intensity entering the spectrum chip 100, and further improving the accuracy.

Optionally, in the example illustrated in fig. 7, optionally, the dodging module 211B further includes at least one optical lens 2116B, for example, a convex lens, located on the light path of the stop 2112B.

In particular, in another embodiment of the present application, the optical assembly 200 is implemented as a telecentric lens 210C. That is, in some embodiments, telecentric lens 210C is used as optical assembly 200, which may be particularly advantageous in certain application scenarios. It will be appreciated by those skilled in the art that telecentric lens system 210C is a special lens system characterized by placing a stop with a small clear aperture at the image (or object) focal plane of the lens so that only light passing through the focal point is transmitted, where the incident (or outgoing) light from the object (or image) is approximately parallel to the principal optical axis. As shown in fig. 8A-8C, there are an object-side telecentric lens 210C, an image-side telecentric lens 210C, and two telecentric lenses 210C. The stop corresponding to the object-side (image-side) telecentric lens 210C is located on the image-side (object-side) focal plane, and the incident (emergent) light rays of the object-side (image-side) are approximately parallel light parallel to the main optical axis. The two lenses are combined to form the two telecentric lenses 210C, and the effects of the object space telecentric lens 210C on the image space are superposed.

In the optical system, the image-side telecentric lens 210C is adopted, so that the main light angle incident to any specific position on the spectrum chip 100 can be ensured to be fixed, and the light receiving cone angle is a small preset value. If the object-side telecentric lens 210C is adopted, the requirement of the type of the light source to be measured can be reduced. If the two-side telecentric lens 210C is adopted, the two advantages are achieved. In practical application, the factors such as the aperture size and the length of the optical system need to be comprehensively considered.

In summary, an optical system according to an embodiment of the present application is illustrated, wherein the optical system includes a spectrum chip 100 and an optical component 200 held on a sensing path of the spectrum chip 100, wherein the optical component 200 has a structural configuration such that a main light angle of a light signal directed to each position of the spectrum chip 100 is a fixed value and a light acceptance light cone angle of each position is a predetermined value, such that, by the optical component 200 having a specific structural configuration, the light acceptance light cone angle of each pixel point of the spectrum chip 100 is controlled to be a predetermined value and within a preset range and/or the main light angle of each pixel point is a fixed value, to reduce a spectrum recovery error of the spectrum chip 100

Design method of exemplary optical system

Accordingly, according to another aspect of the present application, there is also provided a design method of an optical system, including: s110, acquiring a conversion matrix of a photoelectric detection layer of a spectrum chip, wherein the photoelectric detection layer acquires a detected optical signal from an incident optical signal based on the conversion matrix, and the spectrum chip further comprises a light modulation layer positioned on a sensing path of the photoelectric detection layer; and S120, determining the structural configuration of an optical component based on the numerical value change of the conversion matrix, wherein the structural configuration is used for enabling the main light angle of the optical signal guided to each position of the spectrum chip to be a fixed value and the light receiving cone angle of each position to be a preset value, and the optical component is kept on the sensing path of the spectrum chip and used for receiving the optical signal from the object to be shot and guiding the optical signal to the spectrum chip.

In step S110, the spectrum chip is sensitive to the angle of the incident light signal, and the sensitivity can be quantitatively characterized by the main light angle and the acceptance cone angle of the incident light signal. Specifically, when an incident optical signal reaches a certain sensing unit of the spectrum chip, if an incident angle (for the sensing unit, the incident angle may also be defined as a light receiving cone angle of the sensing unit) and a main light angle of the sensing unit of the spectrum chip from the optical signal change, a parameter value of a corresponding position in the conversion matrix D may also change correspondingly, thereby affecting accuracy of spectrum recovery.

Accordingly, a transformation matrix of the photodetecting layer of the spectroscopic chip may be obtained by a computing device. And further adjusting the values of the main light angle and the light receiving light cone angle, and observing the change of the values of all positions in the conversion matrix and the final spectrum recovery effect of the spectrum chip. Therefore, through simulation experiments and practical application requirements, the parameter selection of the main light angle and the light receiving cone angle can be determined.

After determining the parameter selections of the main light angle and the acceptance cone angle, the structural configuration of the optical assembly may be further determined, which is also the content of step S120.

In the design method of an optical system according to the present application, in one example, the predetermined value is 45 ° or less.

In the design method of an optical system according to the present application, in one example, the predetermined value is 35 ° or less.

In the design method of an optical system according to the present application, in one example, the predetermined value is 10 ° or less.

In a design method of an optical system according to the present application, in one example, the optical component includes a lens group having an F-number of 1.8 or more.

In a design method of an optical system according to the present application, in one example, an F-number of the lens group is 2.5 or more.

In a design method of an optical system according to the present application, in one example, the lens group has a field angle θ, an image height h, wherein the optical system satisfies the following relation:

l/h tan (θ/2) ═ X/2)/Y, where X denotes a side length of a detection range of the optical system, Y denotes a distance between the optical system and a subject, and L is a side length of a sensing effective region of the spectrum chip.

It will be appreciated by persons skilled in the art that the embodiments of the invention described above and shown in the drawings are given by way of example only and are not limiting of the invention. The objects of the invention have been fully and effectively accomplished. The functional and structural principles of the present invention have been shown and described in the examples, and any variations or modifications of the embodiments of the present invention may be made without departing from the principles.

Claims (22)

1. An optical system, comprising:

a spectroscopic chip comprising a photodetection layer and a light modulation layer located on a sensing path of the photodetection layer, the photodetection layer configured to obtain a light signal modulated by the light modulation layer; and

an optical assembly held on a sensing path of the spectroscopy chip, the optical assembly configured to receive an optical signal from a subject and direct the optical signal to the spectroscopy chip;

wherein the optical assembly is configured such that a principal light angle of the optical signal directed to each location of the spectroscopic chip is a fixed value and a received light cone angle of each location is a predetermined value.

2. The optical system according to claim 1, wherein the predetermined value is 45 ° or less.

3. The optical system according to claim 2, wherein the predetermined value is 35 ° or less.

4. The optical system according to claim 3, wherein the predetermined value is 10 ° or less.

5. The optical system of claim 2, wherein the optical assembly comprises a lens group having an F-number of 1.8 or greater.

6. The optical system according to claim 5, wherein an F-number of said lens group is 2.5 or more.

7. The optical system of claim 5, wherein the optical assembly further comprises a stop for adjusting the F-number of the lens group.

8. The optical system according to claim 5, wherein the lens group has a field angle θ, an image height h, wherein the optical system satisfies the following relation:

l/h tan (θ/2) ═ X/2)/Y, where X denotes a side length of a detection range of the optical system, Y denotes a distance between the optical system and a subject, and L is a side length of a sensing effective region of the spectrum chip.

9. The optical system according to claim 8, wherein X is equal to or less than 6cm and Y is equal to or less than 10cm, wherein when X is equal to or less than 6cm and Y is equal to or less than 10cm, the spectrum chip is adapted and configured to collect optical frequency information in an optical signal from the object.

10. The optical system of claim 4, wherein the optical assembly comprises a dodging module configured to homogenize the optical signal from the subject and a collimating unit located in an exit path of the dodging module, the collimating unit configured to collimate the homogenized optical signal.

11. The optical system according to claim 10, wherein the dodging module comprises a light scattering element and a diaphragm located on a light exit path of the light scattering element, the diaphragm having a light through hole with a size of 1mm to 10 mm.

12. The optical system of claim 10, wherein the light homogenizing module comprises an integrating sphere having a light entrance and a light exit, the light exit having a size smaller than the light entrance.

13. The optical system of claim 10, wherein the dodging module comprises a diaphragm, a scattering element located on an exit path of the diaphragm, a dodging rod located on an exit path of the scattering element.

14. The optical system of claim 13, wherein the dodging module further comprises at least one optical lens positioned in the light entrance path of the stop.

15. The optical system of claim 2, wherein the optical assembly comprises a telecentric lens.

16. A method of designing an optical system, comprising:

acquiring a conversion matrix of a photodetection layer of a spectroscopic chip, the photodetection layer obtaining a detected optical signal from an incident optical signal based on the conversion matrix, wherein the spectroscopic chip further comprises a light modulation layer located on a sensing path of the photodetection layer; and

and determining the structural configuration of an optical component based on the numerical value change of the conversion matrix, wherein the structural configuration is used for enabling the main light angle of the optical signal guided to each position of the spectrum chip to be a fixed value and the light receiving cone angle of each position to be a preset value, and the optical component is kept on the sensing path of the spectrum chip and used for receiving the optical signal from the object to be shot and guiding the optical signal to the spectrum chip.

17. The method of designing an optical system according to claim 16, wherein the predetermined value is 45 ° or less.

18. The method of designing an optical system according to claim 17, wherein the predetermined value is 35 ° or less.

19. The method of designing an optical system according to claim 18, wherein the predetermined value is 10 ° or less.

20. The method of designing an optical system according to claim 16, wherein the optical component includes a lens group having an F-number of 1.8 or more.

21. The method of designing an optical system according to claim 20, wherein an F-number of said lens group is 2.5 or more.

22. The method of designing an optical system according to claim 21, wherein said lens group has a field angle θ, an image height h, wherein said optical system satisfies the following relation:

l/h tan (θ/2) ═ X/2)/Y, where X denotes a side length of a detection range of the optical system, Y denotes a distance between the optical system and a subject, and L is a side length of a sensing effective region of the spectrum chip.

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