CN107607197B

CN107607197B - Spectrometer and manufacturing method thereof

Info

Publication number: CN107607197B
Application number: CN201610546301.3A
Authority: CN
Inventors: 洪健翔
Original assignee: Taiwan Superfine Optical Co ltd
Current assignee: Taiwan Superfine Optical Co ltd
Priority date: 2016-07-12
Filing date: 2016-07-12
Publication date: 2021-08-31
Anticipated expiration: 2036-07-12
Also published as: CN107607197A

Abstract

The invention discloses a spectrometer which comprises an input part, a diffraction grating, an image sensor and a waveguide device. The input portion is used for receiving an optical signal. The diffraction grating is used for separating the optical signal into a plurality of spectral components. The image sensor is configured on at least part of the transmission paths of the spectral components. The waveguide device includes a first reflective surface and a second reflective surface. A waveguide space is formed between the first reflection surface and the second reflection surface, and the optical signal is transmitted from the input portion to the diffraction grating through the waveguide space. At least a portion of these spectral components are spatially transferred from the waveguide to the image sensor. The waveguide device is formed with at least one opening, and the opening is substantially parallel to at least one of the first reflecting surface and the second reflecting surface. A method for fabricating a spectrometer is also provided.

Description

Spectrometer and manufacturing method thereof

Technical Field

The present disclosure relates to optical devices, and particularly to a spectrometer and a method for fabricating the same.

Background

A spectrometer is a non-destructive testing instrument that may be used, for example, to identify the composition and characteristics of a substance's components. After the light is applied to the material, the spectrometer receives the light reflected from the material or the light penetrating through the material and shows a corresponding spectrum by utilizing the principle of light reflection or penetration and the difference of reflection, absorption or penetration of the light in different frequency bands by the composition structure in the material. Since different materials will exhibit spectra with individual characteristics, the composition and characteristics of the materials can be identified.

To reduce light loss, spectrometers typically include waveguide devices to guide light traveling in the internal channel so that the spectrum generated by the diffraction grating can be sensed by the image sensor of the spectrometer. In conventional designs, the image sensor is placed in close proximity to the waveguide assembly, which minimizes light loss. However, the inventors have found that the design of the image sensor in close proximity to the waveguide device can cause a decrease in spectral resolution due to smearing, and even cause the measured spectral data (e.g., intensity and wavelength) to be incorrect.

The "tailing effect" is caused by "Astigmatism" (Astigmatism) generated by the grating. This phenomenon is mentioned on page 90, first paragraph and page 94, fig. 7-3 and page 111, third paragraph and page 112, fig. 8-1b of the sixth edition of the Handbook of Diffraction gratings (the authors are Christopher Palmer from Newport Corporation, the authors of the first edition are Erwin Loewen) and their description. In detail, when the concave grating is a "cylindrical" grating, it can only focus the light beam in the radial plane (i.e. the meridian plane, which is substantially the horizontal plane), but cannot focus the light beam in the vertical plane (i.e. the Sagittal plane). Additionally, when light is obliquely incident on the grating, a meridional image (Tangential focus) projected from the waveguide will appear as a "meniscus". This meniscus image phenomenon is referred to as the "smearing" effect. Since the meniscus image is not a point focus, a reduction in spectral resolution results. In addition, the meniscus image is sensed by other pixels around the pixel of the image sensor corresponding to the wavelength of the meniscus image, which may also cause the measured spectral data (e.g., intensity and wavelength) to be incorrect.

Disclosure of Invention

The invention provides a spectrometer which can improve low resolution caused by astigmatism generated by a diffraction grating.

The invention provides a manufacturing method of a spectrometer, which can manufacture the spectrometer.

An embodiment of the invention provides a spectrometer, which includes an input portion, a diffraction grating, an image sensor, and a waveguide device. The input portion is used for receiving an optical signal. The diffraction grating is disposed on a transmission path of the optical signal from the input portion and is used for separating the optical signal into a plurality of spectral components. The image sensor is configured on at least part of the transmission paths of the spectral components. The waveguide device includes a first reflective surface and a second reflective surface. A waveguide space is formed between the first reflection surface and the second reflection surface, and the optical signal is transmitted from the input portion to the diffraction grating through the waveguide space. At least a portion of these spectral components are spatially transferred to the image sensor via the waveguide. The waveguide device is formed with at least one opening, the opening is substantially parallel to at least one of the first reflecting surface and the second reflecting surface, and at least one of the spectral components in the sagittal direction and the optical signals is partially emitted from the opening to the outside of the waveguide space without being incident on the image sensor.

An embodiment of the present invention provides a method for manufacturing a spectrometer, including: determining a plurality of parameters of an input part, a diffraction grating, an image sensor and a waveguide device of a spectrometer by using a simulation program; and configuring the input portion, the diffraction grating, the waveguide device and the image sensor according to these parameters. The input portion is used for receiving an optical signal, and the diffraction grating is configured on a transmission path of the optical signal from the input portion and is used for separating the optical signal into a plurality of spectral components. The image sensor is configured on at least part of the transmission paths of the spectral components. The waveguide device comprises a first reflecting surface and a second reflecting surface, a waveguide space is formed between the first reflecting surface and the second reflecting surface, and the optical signal is transmitted to the diffraction grating from the input part through the waveguide space. At least a portion of these spectral components are spatially transferred to the image sensor via the waveguide. The waveguide device is formed with at least one opening, the opening is substantially parallel to at least one of the first reflecting surface and the second reflecting surface, and at least one of the spectral components and the optical signals is partially emitted from the opening to the outside of the waveguide space without being incident on the image sensor. The parameters determined by the simulation program include the width of the opening in the direction of light wave propagation.

In the spectrometer and the manufacturing method thereof according to the embodiments of the invention, since the waveguide device is formed with the at least one opening, a portion of at least one of the spectral component and the optical signal having a large divergence angle diverges from the opening to a location outside the image sensor, and thus a portion of the spectral component that causes the smearing effect may diverge from the opening in a direction less transmitting to the image sensor. Therefore, the spectrum sensed by the spectrometer is more correct and the spectrum resolution is higher.

The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical means of the present invention more clearly understood, the present invention may be implemented in accordance with the content of the description, and in order to make the above and other objects, features, and advantages of the present invention more clearly understood, the following specific examples are described in detail with reference to the accompanying drawings.

Drawings

FIG. 1 shows a top view of a spectrometer according to an embodiment of the invention.

FIG. 2A shows a perspective view of a spectrometer according to an embodiment of the invention.

Fig. 2B is a top view of the waveguide device and the image sensor of fig. 2A.

FIGS. 2C and 2D are cross-sectional views illustrating the light incident and light exiting states of a spectrometer according to an embodiment of the invention.

Figures 3A-3C show the distribution of simulated diffraction images on the sensing surface on the sensor.

Fig. 4A to 4D show four other variations of the opening of fig. 2B.

FIG. 5 is a cross-sectional view of the light incident state of a spectrometer according to another embodiment of the present invention.

FIG. 6 is a flow chart of a method of fabricating a spectrometer according to an embodiment of the invention.

Detailed Description

Fig. 1 shows a top view of a spectrometer according to an embodiment of the invention, and fig. 2A shows a perspective view of the spectrometer 1 according to an embodiment of the invention. Referring to fig. 1 and 2A, the spectrometer 1 includes an input portion 20, a diffraction grating 30, an image sensor 40, and a waveguide device 50.

In the present embodiment, the input portion 20, the diffraction grating 30, the image sensor 40 and the waveguide device 50 are all disposed in one body 10, and the input portion 20, the diffraction grating 30 and the image sensor 40 are disposed on the rowland circle RC, as shown in fig. 1. The main body 10 is, for example, a housing (housing) of the spectrometer 1, or a frame (frame) for mounting the input unit 20, the diffraction grating 30, the image sensor 40, and the waveguide device 50.

The diffraction grating 30 has two ends F and H, and the wavelength distribution plane of the diffraction grating 30 is defined as a meridian plane (tangential plane) MP. The input portion 20 at point a and the image sensor 40 at point B are located on the same plane MP. The concave surface of the diffraction grating 30 is shaped as a cylindrical surface, and the notches (groves) are distributed on the concave surface. The diameter of the Rowland circle RC is also equal to the radius of curvature of the concave surface of the diffraction grating 30. Points O and N are also located on the rowland circle RC, which is the horizontal divergence angle of the incident beam.

The input portion 20 generally includes a slit (slit) and is mounted to the body 10. The input portion 20 is used for receiving an optical signal S1. The optical signal S1 is labeled as optical signal S2 after passing through the slits of the input portion 20, and the optical signal S2 travels along a first optical path OP 1. The optical signal S1 is, for example, light from an optical fiber, the external environment, reflected by the object to be tested, or transmitted through the object to be tested.

The diffraction grating 30 having the height hh is mounted on the body 10 and disposed on the transmission path of the optical signal S2 from the input portion 20. The diffraction grating 30 is used for receiving the optical signal S2 and separating the optical signal S2 into a plurality of spectral components S3. The image sensor 40 is disposed on a transmission path of at least a portion of the spectral components S3. In the present embodiment, the spectral components S3 include at least one specific spectral component and respectively travel along a plurality of second optical paths OP 2. In the present embodiment, the diffraction grating 30 is a reflective concave grating, and focuses at least a portion of the spectral components S3 on the sensing surface 40S of the image sensor 40 (as shown in fig. 2B).

The spectral component S3 detected by the image sensor 40 in this embodiment is, for example, diffracted light of negative third order, but the invention is not limited thereto. In other embodiments, the spectral components detected by the image sensor 40 may be diffracted light of other orders.

Referring to fig. 2B to 2D, the waveguide device 50 is disposed on the body 10 and has a first reflective surface 52 and a second reflective surface 57 facing each other. The waveguide device 50 is capable of confining the first optical path OP1 and the second optical path OP2 between the first reflective surface 52 and the second reflective surface 57 to guide the optical signal S2 and the spectral component S3. A waveguide space S is formed between the first reflection surface 52 and the second reflection surface 57, and the optical signal S2 is transmitted from the input portion 20 to the diffraction grating 30 through the waveguide space S. At least one specific spectral component S3 is transmitted to the image sensor 40 through the waveguide space S. In the present embodiment, at least one specific spectral component S3 is transmitted to an end E1 of the waveguide space S through the waveguide space S and exits from the end E1.

The image sensor 40 is installed in the body 10 and is configured to receive the spectral component S3. The image sensor 40 includes at least one sensing element 44, and the sensing element 44 has a sensing surface 40S. The sensor 44 of the image sensor 40 can be disposed at the focus position of at least one of the spectral components S3, and sense the spectral component S3 (i.e. the specific spectral component), so that the sensor 44 can transmit the received specific spectral component to a computer or a processor for processing. In addition, the image sensor 40 can be disposed on a circuit board 60 and electrically connected to the circuit board 60.

In the present embodiment, at least one opening 501 is formed on the waveguide device 50, the opening 501 is substantially parallel to at least one of the first reflective surface 52 and the second reflective surface 57, and at least one of the spectral components S3 and the optical signal S2 (e.g., the spectral component S3 in the present embodiment) partially diverges from the opening 501 to the outside of the waveguide S without being incident on the image sensor 40. In the present embodiment, the waveguide device 50 further includes at least one extension 54 (two extensions 54 are illustrated in fig. 2B). The extension 54 extends from the end E1 of the waveguide space S toward the image sensor 40 to define an opening 501 between the end E1 and the image sensor 40. In the present embodiment, the extension portion 54 extends to the image sensor 40 and abuts against the image sensor 40, the opening 501 is a notch, and the width G of the opening 501 in the light wave propagation direction is the distance between the end E1 and the image sensor 40 in the present embodiment. When the opening 501 is located between the diffraction grating 30 and the image sensor 40, the "optical wave propagation direction" is the propagation direction of the optical wave of the spectral component S3 in the waveguide space S, and is defined as the direction from the center of the diffraction grating 30 to the center of the image sensor 40; when the opening 501 is located between the input portion 20 and the diffraction grating 50, the "light wave propagation direction" is the propagation direction of the light wave of the optical signal S2 in the waveguide space S, and is defined as the direction from the center of the input portion 20 to the center of the diffraction grating 50. In another embodiment, the extension 54 may also abut against a component connected to the image sensor 40, such as a base, a pad, the body 10 or the circuit board 60 connected to the image sensor 40, so as to form the opening 501 between the end E1 and the image sensor 40.

In the present embodiment, the waveguide device 50 includes a first reflector 51 and a second reflector 56. The first mirror 51 includes a waveguide portion 55 and an extension 54, wherein the extension 54 connects the waveguide portion 55. The waveguide part 55 has a light exit end E55, and the light exit end E55 extends toward the sensing surface 40S and defines a distal end E1 of the waveguide space S. The first reflecting mirror 51 has a first reflecting surface 52, and the second reflecting mirror 56 has a second reflecting surface 57, wherein the first reflecting surface 52 and the second reflecting surface 57 face each other (surface to surface).

FIGS. 2C and 2D are cross-sectional views illustrating the light incident and light exiting states of a spectrometer according to an embodiment of the invention. Referring to fig. 2C to 2D, when the number of the sensing elements 44 is plural, the sensing elements 44 may be arranged in a line (line) along a direction perpendicular to the paper surface of fig. 2D (i.e. along the horizontal direction of fig. 2B) or in an array (array). When the sensing elements 44 are aligned, they can be matched with the free-form surface diffraction grating, because the free-form surface diffraction grating can focus the spectral components S3 on a straight line. In other embodiments, diffraction grating 50 can be the grating disclosed in U.S. patent No. 9,146,155.

Referring to fig. 2D, the width G of the opening 501 is related to the width h of the sensing surface 40S, wherein the width h may be substantially perpendicular to the first reflecting surface 52 and the second reflecting surface 57.

The magnitude of the width G can be derived theoretically and/or obtained by software simulation. The following will illustrate how the width G is determined by software simulation.

The soft TracePro can be used to manipulate the diffraction efficiency provided by the user to process the beam diffracted by the Grating by simulating the ray tracing of a Slab-Waveguide Micro-grading (SWMG) system using the soft TracePro. A strict diffraction efficiency calculation of the grating can be performed by using the software PCGrate.

The sensing surface 40S of the image sensor 40 is positioned so that its center is at the focus point of the diffracted light on the Rowland circle RC and its surface is perpendicular to the main beam from the point O, as shown in FIG. 1. That is, the sensing surface 40S of the image sensor 40 is located on the focal plane. In this example, a sensor of 1.50mm (horizontal dimension) by 0.90mm (vertical dimension) was used for the simulation. In particular, in using software for simulation, the width G can be changed, and the divergence half-angle of the normal (in sagittal plane SP of FIG. 2A) of the incident beam will also change, but the position of the image sensor 40 is fixed. In all simulations, the horizontal (in the meridian plane) half angle of divergence of the incident beam was maintained at 12 °.

Fig. 3A to 3C show the distribution of simulated diffraction images on the sensing surface on the image sensor, which correspond to widths G of 1, 3 and 5mm, respectively. Referring to FIGS. 3A-3C, the diffracted light image is divided into two tails to form a meniscus. With respect to the widest width (G ═ 5mm) in the simulation, the intensity distribution in the y direction is actually larger than the width h of the simulated sensing surface 40S. Thus, the distribution shown in FIG. 3C is truncated in the y-direction and is not captured into the image sensor 40 exactly as shown in FIGS. 3A and 3B. As shown in fig. 3A to 3C, the larger the width G, the more the meniscus image is not bent, and the more the image sensor 40 can detect no two tails of the meniscus image, so that the spectrum detected by the image sensor 40 is less affected by the tailing effect (i.e. the effect caused by astigmatism). However, as the width G is larger, the meniscus image is less curved, and thus less light energy (apparent from comparing FIG. 3A with FIG. 3C) enters the sensing surface 40S (i.e., in the h-range), resulting in a weaker spectral signal. Therefore, the value of the width G can be selected according to the actual use requirement.

The vertical pixel dimension denoted by h in FIGS. 3A-3C (i.e., the width h of the sensing surface 40S), which is, for example, 200 μm, is the width h of the sensing surface 40S of a commercially available image sensor 40, and other commercially available image sensors 40 have vertical pixel dimensions of 50 μm, 500 μm, or other dimensions. In order to collect more light signals on the linear image sensor 40, a larger vertical pixel size may be used. However, larger vertical pixel sizes include more of the meniscus image tail (see fig. 3A-3C) and result in incorrect wavelength readings. Therefore, in addition to selecting a suitable value of the width G according to actual requirements, a suitable value of the width h may also be selected.

In an embodiment of the present invention, a procedure for removing smearing from spectral data has been devised cleverly by: (1) firstly, simulating results generated when different widths G are adopted by adopting a software; and (2) selecting an appropriate vertical pixel size (i.e., width h) of the linear image sensor. By allowing some gap between the sensor plane and the waveguide edge, the resultant focal point pattern expands into a meniscus profile at the detector plane (see fig. 3A-3C). The linear image sensor captures only the central portion of the meniscus image distribution with the vertical pixel height (i.e., width h) (see fig. 3A to 3C) set at y-0. Using this G-h adjustment mechanism, the tailing effect problem can be completely solved by the embodiments of the present invention.

Thus, the designer can easily obtain or adjust the width G according to the parameters of the image sensor to effectively eliminate the adverse effect caused by the tailing effect. The design criteria for conventional spectrometers are that the planar waveguide must be placed close to the image sensor in order to reduce light loss. The inverse embodiment of the present invention completely breaks away from the design specifications of the conventional spectrometer, so that the image sensor can obtain good spectral data.

It should be noted that although the embodiments of the present invention are described with reference to a rowland circle and a diffraction grating with a fixed pitch d, since the rowland circle and the diffraction grating with the fixed pitch d are the basis of the diffraction theory, the embodiments of the present invention are also applicable to non-rowland circles and non-fixed pitch diffraction gratings, and the profile of the diffraction grating may include a straight line, a circular arc or other curved surfaces, so that the input portion 20 and the image sensor 40 may not be necessarily located on the rowland circle RC.

In the spectrometer 1 of the present embodiment, since the opening 501 exists between the end E1 and the image sensor 40, the portion (portion with a larger divergence angle) of the spectral component S3 that causes the tailing effect may diverge from the end E1 of the waveguide space S to a direction that is less transmitted to the sensing surface 40S. Thus, the spectrum sensed by the spectrometer 1 is less affected by the tailing effect.

In the present embodiment, the opening 501 formed by the extension 54 and the light exit end E55 is a light dissipation gap, and the opening 501 is located at a position where the light transmission path (e.g. the second optical path OP2 in fig. 1) is orthographically projected to the extension surface of the first reflection surface 52 of the first reflection mirror 51. In fig. 2B, the number of the extension sections 54 is two as an example. However, in other embodiments, if the width G can be maintained, there may be only one extension 54, such as only the extension 54 at the right of fig. 2B.

In the present embodiment, the width G of the opening 501 affects the meniscus distribution of at least some of the spectral components S3, the width h of the sensing surface 40S in the direction parallel to the normal of the first reflective surface 52 affects the integration range of the image sensor 40, and the divergence half-angle of the optical signal S2 incident from the input portion 20 into the waveguide space S in the direction parallel to the normal of the first reflective surface 52 (the divergence half-angle of the light beam in the sagittal plane) affects the meniscus expansion. The simulation procedure matches the width G of the opening 501 in the direction of light wave propagation, the divergence half-angle and the width h of the sensing surface 40S in the direction parallel to the normal of the first reflecting surface 52, and the width G of the opening 501 allows some of the spectral components to diverge in the direction parallel to the normal of the first reflecting surface 52, so that the two tails of the meniscus distribution derived from the divergence half-angle do not substantially fall within the integration range of the image sensor 40.

In this embodiment, the width G of the opening 501 is greater than or equal to 1 millimeter. In one embodiment, the width G of the opening 501 is in a range from 1 mm to 5 mm.

In the present embodiment, the first reflector 51 has an extension 54 abutting against the image sensor 40, and the second reflector 56 does not abut against the image sensor 40. However, in other embodiments, the second reflector 56 may have a light-emitting end (e.g., the light-emitting end E55) and an extension (e.g., the extension 54) abutting against the image sensor 40, and the first reflector 51 does not abut against the image sensor 40 and does not have the extension 54. Alternatively, in other embodiments, the first reflector 51 and the second reflector 56 may have the light-emitting end E55 and the extension section 54 abutting against the image sensor 40, respectively. In addition, in the present embodiment, the first reflecting mirror 51 has the opening 501, and the second reflecting mirror 56 does not have the opening 501. However, in other embodiments, the second reflector 56 may have the opening 501 and the first reflector 51 may not have the opening 501, or both the first reflector 51 and the second reflector 56 may have the opening 501.

In the present embodiment, the spectrometer 1 further includes a light trapping structure 12 (as shown in fig. 2D) disposed outside the waveguide space S and configured to absorb light emitted from the opening 501. The light trapping structure 12 may be a serrated surface structure or other suitable non-planar surface structure provided on the body 10 (i.e., the housing of the spectrometer 1), which may be plated with a light absorbing layer. When light emitted from the opening 501 enters the light trapping structure 12, the light is continuously reflected by the sawtooth-shaped surface structure toward the bottom of the sawtooth-shaped recess, and the light absorbing layer absorbs light once more for each reflection. Therefore, the light capture structure 12 can effectively absorb the light emitted from the opening 501, so as to effectively reduce the chance that the light becomes stray light incident on the image sensor 40. In another embodiment, the inner surface of the body 10 may be coated with a light absorbing layer that absorbs light emitted from the opening 501, rather than absorbing light with the light trapping structure 12.

Fig. 4A to 4D show four other variations of the opening of fig. 2B. Referring to fig. 4A, distances from different positions on the light-emitting end E551 of the waveguide 551 to the image sensor 40 (i.e., widths G of the opening 501 at different positions) are not completely the same. In the present embodiment, the edge of the light exit end E551 is inclined with respect to the sensing surface 40S to define an end E11 of the waveguide space inclined with respect to the sensing surface 40S. In another embodiment, the edge of the light exit end E551 may also be an uneven edge, such as a saw-toothed edge, a stepped edge, or an edge with a step difference, which is not limited in the disclosure. In addition, different widths G can be designed at different positions of the opening 501 according to different focusing positions of light with different wavelengths.

However, in other embodiments, as shown in fig. 4B, the edge of the light-emitting end E552 of the waveguide portion 552 may be an arc-shaped edge to define the end E12 of the arc-shaped waveguide space. The design of the end E11 and the end E12 can be determined to make the position of the end E11 corresponding to the wavelength close to the sensing surface 40S to increase the light sensing intensity or far away from the sensing surface 40S to increase the resolution according to the different resolving effects of different wavelengths on the sensing surface 40S.

In general, the resolution of the short wavelength light is better, so the position on the end E11 corresponding to the short wavelength can be designed to be closer to the sensing surface 40S. Conversely, the position on the end E11 corresponding to the long wavelength may be designed to be farther from the sensing surface 40S. In addition, in other embodiments, the value of the width G may be designed differently according to the wavelength to be detected.

Referring to fig. 4C, the first reflector 51 may include a plurality of openings 501 (e.g.,

openings

501a and 501b), wherein the openings 501a are closed openings and are located between the diffraction grating 30 and the image sensor 40. The extending segment 543 and the light-emitting end E553 of the waveguide portion 55 may also form an opening 501b, and in this case, the end E13 of the waveguide space is defined by the light-emitting end E553. In the present embodiment, the width G1 of the opening 501a in the direction of optical wave propagation and the width G2 of the opening 501b in the direction of optical wave propagation may be the same or different. When the widths G1, G2 are larger, light of a smaller divergence angle can be made to diverge from the opening 501. For example, width G2 is greater than width G1, light with a divergence angle of 70 to 90 degrees may diverge from opening 501a, and light with a divergence angle of 60 to 90 degrees may diverge from opening 501 b. In other embodiments, there may be a plurality of closed openings 501a arranged in the light wave propagation direction. In another embodiment, the opening 501 (e.g., the opening 501a) is inclined with respect to the sensing surface 40S of the image sensor 40 in a direction parallel to the extending direction of at least one of the first reflecting surface 52 and the second reflecting surface 57.

Referring to fig. 4D again, compared to fig. 4C, in the present embodiment, the first reflector 51 has only the closed opening 501a, but not the open opening 501b as shown in fig. 4D, and the end E13 of the waveguide space S is defined by the light-emitting end E553, and the end E13 directly abuts against the image sensor 40.

FIG. 5 is a cross-sectional view of the light incident state of a spectrometer according to another embodiment of the present invention. Referring to fig. 5, in the present embodiment, the opening 501 of the waveguide device 50 is located between the input portion 20 and the diffraction grating 30, which can make the optical signal S2 with a large divergence angle diverge from the opening 501, so that the light causing the tailing effect is less transmitted to the image sensor 40. In the present embodiment, the first mirror 51 and the second mirror 56 both have an opening 501. However, in other embodiments, one of the first reflector 51 and the second reflector 56 may have the opening 501. In another embodiment, the waveguide device 50 may have an opening 501 between the input portion 20 and the diffraction grating 30 and between the diffraction grating 30 and the image sensor 40, and the width G of the opening 501 in the light wave propagation direction allows the optical signal S2 and the spectral component S3 to partially diverge in a direction parallel to the normal of the first reflecting surface 52 or the second reflecting surface 57. In other embodiments, the opening 501 may also be located at an end of the waveguide device 50 facing the input portion 20, that is, the waveguide device 50 is formed with an extension 54 similar to that shown in fig. 2B at an end facing the input portion 20 to form the open opening 501.

FIG. 6 is a flow chart of a method of fabricating a spectrometer according to an embodiment of the invention. Referring to fig. 1, fig. 2A to fig. 2D and fig. 6, the method for manufacturing a spectrometer of the present embodiment can be used to manufacture the spectrometer 1 of fig. 2A to fig. 2D or the spectrometer of other embodiments, and the manufacturing of the spectrometer 1 of fig. 2A to fig. 2D is taken as an example. The manufacturing method of the spectrometer of the present embodiment includes the following steps. First, in step S110, a plurality of parameters of the input unit 20 of the spectrometer 1, the diffraction grating 30, the image sensor 40, and the waveguide device 50 are determined by the simulation program. Then, step S120 is executed to configure the input unit 20, the diffraction grating 30, the waveguide device 50 and the image sensor 40 according to the parameters, for example, to make the input unit 20, the diffraction grating 30 and the image sensor 40 directly or indirectly support on the waveguide device 50 according to the parameters. Details of the structures that can be employed, the relative positions in the optical path, the images produced by the light, and the achievable effects of the input section 20, the diffraction grating 30, the image sensor 40, and the waveguide device 50 are as described above and will not be repeated here. In addition, when the image sensor 40 is indirectly supported on the waveguide device 50, a gasket is firstly used to support the waveguide device 50, the image sensor 40 is supported on the gasket, and after the waveguide device 50 and the image sensor 40 are fixed, the gasket is pulled away, so that the distance between the image sensor 40 and the waveguide device 50 is kept. In other embodiments, the waveguide device 50 may be fixed to the housing, or the image sensor 40 may be fixed to the housing.

In addition, the parameters determined by the simulation program include the width G of the opening 501 in the direction of light wave propagation. In one embodiment, these parameters further include the distance between the first reflective surface 52 and the second reflective surface 57, and the meniscus image is more gradual (i.e., less curved) as the distance is greater.

In the present embodiment, the input portion 20 and the diffraction grating 30 are respectively supported by two positioning sides (for example, two positioning sides of the first mirror 51) of the waveguide device 50, and the two positioning sides, the opening 501 and the extension section 54 are formed by, for example, a mems process. The mems process can be used to make precise and small-error positioning sides, openings 501 and extensions 54, suitable for small-scale waveguide devices 50, and can be used to make closed openings for the first mirror 51 and the second mirror 56, and the manufacturing cost is low. However, in other embodiments, the positioning sides and the extension 54 can be machined by a Computer Numerical Control (CNC) machine.

Since the mems process can produce a precise profile, the two positioning sides and the extension 54 can be precisely and smoothly produced. In this way, when the input portion 20, the diffraction grating 30 and the image sensor 40 abut against the waveguide device 50, the relative positions of the input portion 20, the diffraction grating 30 and the image sensor 40 can be accurately determined. Therefore, the optical quality and the accuracy of the spectrometer can be effectively improved.

In the present embodiment, in the simulation process, the width G of the opening 501 held between the end E1 and the image sensor 40 is determined by performing simulation with a plurality of different widths when the image sensor 40 is set at the focal length, and the width G of the opening 501 held between the end E1 and the image sensor 40 is determined. In other words, the position of the image sensor 40 is fixed, and the end E1 is retracted to generate different widths G of the opening 501, or at least one of the first mirror 51 and the second mirror 56 is formed with the opening 501 (as shown in fig. 4C, 4D, and 5).

In addition, the parameters determined by the simulation program further include a width h of the sensing surface 40S in a direction parallel to the normal of the first reflective surface 52, which is determined by performing the simulation with a plurality of different widths of the sensing surface 40S in the direction parallel to the normal of the first reflective surface 52 under the condition that the image sensor is set at the focal length in the simulation program. That is, through the simulation method, the appropriate width G and width h can be determined, and the detailed process can refer to the above embodiment.

The parameters determined by the simulation program may also include the relative positions of the various components, the pitch of the grating lines, the relative angles of the optical axes or optical paths, the shape of the end E1 of the waveguide space S, etc., as shown in fig. 1. Thus, the method for manufacturing a spectrometer of the present embodiment can manufacture a spectrometer with high accuracy and high optical efficiency without being affected by the tailing effect.

Referring to fig. 2A to 2D, the extension 54 of the present embodiment or the extensions of the other embodiments can be fabricated by using a mems process, so as to precisely abut against the image sensor 40. In addition, the light exit end E55 of the first reflector 51 can also be fabricated by mems process to define the end E1 of the waveguide space S with precise position. .

In summary, in the spectrometer and the manufacturing method thereof according to the embodiments of the invention, since the waveguide device is formed with at least one opening, the sagittal light beam with a large divergence angle in at least one of the spectral component and the optical signal is diverged from the opening to a position outside the image sensor, so that a portion of the spectral component causing the tailing effect is diverged from the opening to a direction less transmitting to the image sensor. In other words, if the opening is replaced by a reflective surface, the sagittal beam with a large divergence angle enters the image sensor, and the smearing effect is worsened.

Although the present invention has been described with reference to the above embodiments, it should be understood that the invention is not limited to the above embodiments, and that various changes and modifications can be made by those skilled in the art without departing from the scope of the invention.

Claims

1. A spectrometer, comprising:

an input portion for receiving an optical signal;

a diffraction grating disposed on a transmission path of the optical signal from the input portion for separating the optical signal into a plurality of spectral components;

an image sensor disposed on at least a portion of the transmission path of the spectral components; and

a waveguide device, comprising:

a first reflecting surface; and

a second reflecting surface, wherein a waveguide space is formed between the first reflecting surface and the second reflecting surface, the optical signal is transmitted from the input portion to the diffraction grating through the waveguide space, and the at least part of the spectral components is transmitted to the image sensor through the waveguide space;

the waveguide device is provided with at least one opening, the opening is positioned between the diffraction grating and the image sensor and positioned at the position of the orthographic projection of the transmission path of the spectral components to the first reflecting surface, the opening is substantially parallel to at least one of the first reflecting surface and the second reflecting surface, and part of the spectral components are dispersed out of the waveguide space from the opening and do not enter the image sensor.

2. The spectrometer of claim 1, wherein the waveguide further comprises at least one extension extending from an end of the waveguide space toward the image sensor to define the opening between the end and the image sensor.

3. A spectrometer as claimed in claim 2, wherein the waveguide means comprises:

a first reflector having the first reflective surface and including a waveguide portion and the extended portion connected to the waveguide portion, wherein the waveguide portion defines the end of the waveguide space toward the light-emitting end of the sensing surface of the image sensor; and

and the second reflector is provided with the second reflecting surface, wherein the first reflecting surface faces the second reflector, and the second reflecting surface faces the first reflector.

4. A spectrometer as in claim 3, wherein the distances from the plurality of different locations on the light exit end to the image sensor are not all the same.

5. A spectrometer as in claim 2, wherein the extension abuts the image sensor such that the opening is formed between the end and the image sensor.

6. A spectrometer as in claim 2, wherein the extension abuts a component connected to the image sensor such that the opening is formed between the end and the image sensor.

7. The spectrometer of claim 1, wherein the opening is tilted with respect to a sensing surface of the image sensor in a direction parallel to an extension direction of at least one of the first reflecting surface and the second reflecting surface.

8. A spectrometer as in claim 1, wherein the waveguide device further defines another opening between the input and the diffraction grating, wherein the waveguide device comprises at least one extension extending from an end of the waveguide space toward the input to define the another opening between the end and the input.

9. The spectrometer of claim 1, wherein the diffraction grating is a concave grating and focuses the at least some of the spectral components onto a sensing surface of the image sensor.

10. The spectrometer of claim 1, wherein a width of the opening in the direction of optical propagation affects a meniscus distribution of the at least part of the spectral components, a width of a sensing surface of the image sensor in a direction parallel to a normal of the first reflecting surface affects an integration range of the image sensor, a half angle of divergence of the optical signal injected into the waveguide space by the input portion in the direction parallel to the normal of the first reflecting surface affects an expansion of the meniscus, the width of the opening in the direction of optical propagation allowing the optical signal and at least one of the spectral components to partially diverge in the direction parallel to the normal of the first reflecting surface by matching the width of the opening in the direction of optical propagation, the half angle of divergence and a width of the sensing surface in the direction parallel to the normal of the first reflecting surface, the two tails of the meniscus distribution derived from the divergence half angle do not substantially fall within the integration range of the image sensor.

11. A spectrometer as claimed in claim 10 wherein the width of the opening in the direction of optical waveguide is greater than or equal to 1 mm.

12. A spectrometer as in claim 11, wherein the width of the opening in the direction of optical waveguide falls in the range from 1 mm to 5 mm.

13. The spectrometer of claim 1, wherein the opening comprises a closed opening.

14. The spectrometer of claim 1, further comprising a light trapping structure disposed outside the waveguide space and configured to absorb light emanating from the opening.

15. A method of fabricating a spectrometer, comprising:

determining a plurality of parameters of an input part, a diffraction grating, an image sensor and a waveguide device of a spectrometer by using a simulation program; and

configuring the input portion, the diffraction grating, the waveguide device and the image sensor according to the parameters, wherein the input portion is configured to receive an optical signal, the diffraction grating is configured on a transmission path of the optical signal from the input portion and is configured to separate the optical signal into a plurality of spectral components, the image sensor is configured on a transmission path of at least part of the spectral components, the waveguide device includes a first reflection surface and a second reflection surface, a waveguide space is formed between the first reflection surface and the second reflection surface, the optical signal is transmitted from the input portion to the diffraction grating through the waveguide space, and the at least part of the spectral components is transmitted to the image sensor through the waveguide space; wherein the waveguide device is formed with at least one opening between the diffraction grating and the image sensor and at a position where the transmission path of the spectral components is orthographically projected to the first reflecting surface, the opening is substantially parallel to at least one of the first reflecting surface and the second reflecting surface, and a part of the spectral components is emitted from the opening to the outside of the waveguide space without entering the image sensor,

the parameters determined by the simulation program include the width of the opening in the direction of light wave propagation.

16. A method as claimed in claim 15 wherein the input portion and the diffraction grating are supported by two alignment sides of the waveguide respectively, and the alignment sides and the opening are formed by mems processing.

17. The method of claim 15, wherein the waveguide further comprises at least one extension extending from the end of the waveguide space toward the image sensor to define the opening between the end and the image sensor.

18. A spectrometer as in claim 17, wherein the waveguide device comprises a first reflector and a second reflector, the first reflector has the first reflective surface and comprises a waveguide portion and the extension portion connected to the waveguide portion, the light-emitting end of the waveguide portion facing the sensing surface of the image sensor defines the end of the waveguide space, the second reflector has the second reflective surface, the first reflective surface faces the second reflector, the second reflective surface faces the first reflector, and the extension portion is formed by mems process.

19. The method as claimed in claim 15, wherein the diffraction grating is a reflective concave grating and focuses the at least some of the spectral components onto a sensing surface of the image sensor.

20. A spectrometer as in claim 15, wherein in the simulation process, the width of the opening in the direction of optical wave propagation is determined by performing a simulation with a plurality of different widths with the image sensor set at the focal length.

21. The method as claimed in claim 15, wherein the parameters determined by the simulation procedure further include a width of the sensing surface of the image sensor in a direction parallel to the normal of the first reflective surface, wherein the width of the sensing surface of the image sensor determined by the simulation procedure is determined by the image sensor being set at a focal length and being simulated at a plurality of different widths of the sensing surface in the direction parallel to the normal of the first reflective surface.

22. A method as claimed in claim 15 wherein the width of the opening in the direction of optical propagation affects the meniscus distribution of the at least some of the spectral components, the width of the sensing surface of the image sensor in the direction parallel to the normal of the first reflecting surface affects the integration range of the image sensor, the half angle of divergence of the optical signal injected into the waveguiding space by the input portion in the direction parallel to the normal of the first reflecting surface affects the expansion of the meniscus, the simulation procedure matches the width of the opening in the direction of optical propagation, the half angle of divergence and the width of the sensing surface in the direction parallel to the normal of the first reflecting surface, the width of the opening in the direction of optical propagation allows the optical signal and at least one of the spectral components to partially diverge in the direction parallel to the normal of the first reflecting surface, the two tails of the meniscus distribution derived from the divergence half angle do not substantially fall within the integration range of the image sensor.

23. The method of claim 15, wherein the parameters determined by the simulation further include a distance between the first reflective surface and the second reflective surface.