Patent Description:
A small spectrometer may be easily carried around due to its compact size. Such spectrometer can be applied to various devices, e.g., biosensors and portable gas sensors. However, it is difficult to use a spectroscopic method based on a grating structure in the case of the small spectrometer. Document <CIT> is directed to a cuvette and spacer therefore as well as method of producing the spacer. The cuvette has two opposing windows made of a material, which is transparent to the light of the waveband used for the analysis, said windows defining a limited light path of a light beam passing through a cavity inside the cuvette. The window surfaces forming the cuvette cavity are non parallel, thereby ensuring that the intemal distances between opposed areas of the windows surfaces will vary across the transparent windows.

The invention is described in the claims. The invention provides a spectrometer according to claim <NUM>. Preferred embodiments are described in the dependent claims. The embodiments which do not fall within the scope of the claims are to be interpreted as examples useful for a better understanding of the invention. Provided are spectrometers including light filters.

Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the embodiments of the disclosure.

According to an aspect of the disclosure, there is provided a light filter comprising: at least one filter, wherein the at least one filter comprises a liquid spectrum modulation layer having different transmittance spectra according to different positions on the at least one filter.

The liquid spectrum modulation layer has different thicknesses according to the different positions on the at least one filter. The thickness of the liquid spectrum modulation layer can be easily adjusted.

The at least one filter further comprises a filter frame comprising an inner space filled with the liquid spectrum modulation layer, wherein the filter frame is formed of an optically transparent material.

The filter frame may comprise glass, quartz, or polymer.

The inner space of the filter frame may comprise a triangular, trapezoidal, or lens shaped cross section.

The liquid spectrum modulation layer comprises a solution comprising a light absorption modulation material. Therefore, the liquid spectrum modulation layer may not reflect light or cause scattering.

The light absorption modulation material may comprise at least one of quantum dots (QDs), inorganic materials, or polymers.

The different transmittance spectra may have a non-linear relation.

The light filter may further comprising an anti-reflection layer provided on at least one of an upper surface and a lower surface of the at least one filter.

The at least one filter may further comprise a plurality of filters, wherein each of the plurality of filters may comprise a respective liquid spectrum modulation layer, and wherein the plurality of filters maybe arranged in an array on a same plane.

The respective liquid spectrum modulation layers of the plurality of filters may have different types of light absorption modulation materials or different sizes of light absorption modulation materials.

The at least one filter may further comprise a plurality of filters, wherein each of the plurality of filters may comprise a respective liquid spectrum modulation layer, and wherein the plurality of filters maybe arranged in a vertically overlapping form.

Ratios of the light absorption modulation materials at the different positions of the light filter maybe different according a characteristic of overlapping filters, among the plurality of overlapping filters, at the different positions of the light filter.

The at least one filter may further comprise a plurality of filters, wherein each of the plurality of filters may comprise a respective liquid spectrum modulation layer, and wherein the plurality of filters maybe arranged in an array on a same plane and are arranged in a vertically overlapping form.

According to the claimed invention, there is provided a spectrometer comprising: a light filter comprising at least one filter; and a sensor configured to receive light transmitted through the light filter, wherein the at least one filter comprises a liquid spectrum modulation layer having different transmittance spectra according to different positions on the at least one filter.

The liquid spectrum modulation layer has different thicknesses according to the different positions on the at least one filter.

The filter frame may comprises glass, quartz, or polymer.

The liquid spectrum modulation layer comprises a solution comprising a light absorption modulation material.

The light filter may further comprise an anti-reflection layer provided on at least one of an upper surface and a lower surface of the at least one filter.

The at least one filter further comprises a plurality of filters, wherein each of the plurality of filters may comprise a respective liquid spectrum modulation layer, and wherein the plurality of filters maybe arranged in an array on a same plane.

The at least one filter may further comprises a plurality of filters, wherein each of the plurality of filters may comprise a respective liquid spectrum modulation layer, and wherein the plurality of filters maybe arranged in a vertically overlapping form.

The spectrometer may have a resolution less than or equal to <NUM>.

According to another aspect of the disclosure, there is provided a light filter comprising: a filter frame; and a liquid spectrum modulation layer provided inside a cavity of the filter frame, wherein the filter frame has a first thickness at a first position on the filter frame and a second thickness at a second position on the filter frame according to different transmittance spectra.

The filter frame may comprise: a bottom portion and a top portion that form the cavity, wherein a distance between the bottom portion and the top portion may gradually changes according to different transmittance spectra.

One of the bottom portion and the top portion maybe inclined with respect to the other of the bottom portion and the top portion.

One of the bottom portion and the top portion maybe a concave shape or convex shape.

Reference will now be made in detail to embodiments, which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. Also, the size of each layer illustrated in the drawings may be exaggerated for convenience of explanation and clarity. In this regard, the embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein.

In the following description, when a constituent element is disposed "above" or "on" to another constituent element, the constituent element may be only directly on the other constituent element or above the other constituent elements in a non-contact manner. It will be further understood that the terms "comprises" and/or "comprising" used herein specify the presence of stated features or components, but do not preclude the presence or addition of one or more other features or components.

The use of the terms "a" and "an" and "the" and similar referents in the context of describing the disclosure (especially in the context of the following claims) are to be construed to cover both the singular and the plural. Also, the steps of all methods described herein may be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The disclosure is not limited to the described order of the steps. The use of any and all examples, or language (e.g., "such as") provided herein, is intended merely to better illuminate the disclosure and does not pose a limitation on the scope of the disclosure unless otherwise claimed.

A small spectrometer may be implemented by forming spectrum modulation layers having different transmittance spectra by adjusting a thickness of a light absorption modulation material such as quantum dots (QDs) or by adjusting a mixing ratio of different light absorption modulation materials may be used. In this case, to realize high resolution, it is necessary to form a precise and uniform spectrum modulation layer.

Generally, to form a solid spectrum modulation layer, a method of coating a solution including a light absorption modulation material for each pixel by using, for example, spin coating, dip coating, spray coating, inkjet printing, etc., and then drying the solution may be used.

However, methods such as spin coating, dip coating, spray coating and the like are not suitable for forming spectrum modulation layers of different thicknesses with only one coating. Specifically, to form spectrum modulation layers having thickness differences for each pixel, it is necessary to perform repetitive patterning several times. It is difficult to form spectrum modulation layers having precise thickness differences by such repetitive patterning.

In addition, the ink jet fritting method may form spectrum modulation layers of different thicknesses by dropping different amounts of ink droplets for each pixel. Here, the ink droplets include light absorption modulation materials. However, it is technically difficult to drop a precisely controlled amount of ink droplets to an exact position in a pixel having a micrometer size, and it is difficult to control the spectrum modulation layer to have a uniform thickness when the ink droplets are dried.

<FIG> is a perspective view showing a spectrometer <NUM> according to an embodiment. <FIG> is a cross-sectional view of the spectrometer <NUM> shown in <FIG>. <FIG> is an enlarged view of a spectrum modulation layer <NUM> of the spectrometer <NUM> shown in <FIG>.

Referring to <FIG>, the spectrometer <NUM> includes a sensing unit <NUM> and a light filter provided on the sensing unit <NUM>. Here, the light filter includes a filter unit <NUM> having different transmittance spectra according to different positions on the light filter. Specifically, the filter unit <NUM> includes a filter frame <NUM> and the liquid spectrum modulation layer <NUM> provided inside the filter frame <NUM>.

The filter frame <NUM> includes an optically transparent material. The filter frame <NUM> may include, for example, glass, quartz or, a polymer. Here, the polymer may include polydimethylsiloxane (PDMS), polycarbonate (PC), and the like, but is not limited thereto. The materials stated above are merely examples and the filter frame <NUM> may include various other materials. The filter frame <NUM> may have an optically flat surface such that no scattering occurs.

The filter frame <NUM> includes an inner space 121a filled with the liquid spectrum modulation layer <NUM>. Here, the inner space 121a of the filter frame <NUM> may be formed at different heights according to positions on the light filter. For example, the inner space 121a of the filter frame <NUM> may have a triangular cross-section whose height gradually increases in a +y direction, as shown in <FIG>.

The liquid spectrum modulation layer <NUM> is filled in the inner space 121a of the filter frame <NUM>. Here, the liquid spectrum modulation layer <NUM> includes a solution in which a light absorption modulation material 122a is dispersed in a predetermined solvent. Here, the light absorption modulation material 122a refers to a material capable of forming a spectrum modulated by absorbing light. Such a light absorption modulation material 122a may include at least one of, for example, QDs, inorganic materials, and polymers.

The QDs may be semiconductor particles having a size of about several nanometers, and may include, for example, CdSe, CdS, PbSe, PbS, InAs, InP, or CdSeS, but this is merely an example. The QDs may include other various semiconductor materials. The QDs may have, for example, a core-shell structure, but is not limited thereto. The polymers may include, for example, poly (<NUM>-methoxy-<NUM>-(<NUM>-ethylhexyloxy)-<NUM>,<NUM>-phenylenevinylene) (MEH-PPV) or poly(<NUM>-hexylthiophene) (P3HT), but this is merely an example. The polymers may include other various organic materials. The inorganic materials may include, for example, a Group VI semiconductor material, a Group III-V compound semiconductor material, or a Group II-VI compound semiconductor material, but this is merely an example. The inorganic materials may include various other materials.

The liquid spectrum modulation layer <NUM> has a shape corresponding to the inner space 121a of the filter frame <NUM>. Thus, the liquid spectrum modulation layer <NUM> has different thickness according to different positions on the light filter. For example, the liquid spectrum modulation layer <NUM> may have a triangular cross-sectional shape whose thickness gradually increases in the +y direction, as shown in <FIG>.

Referring to <FIG>, different N measurement positions P1, P2, P3,. , PN may be set in the liquid spectrum modulation layer <NUM>. Here, the N measurement positions P1, P2, P3,. , PN may include first, second, third,. , Nth measurement positions P1, P2, P3,. , PN respectively that are arranged at a regular distance d in a direction (i.e., the +y direction) in which the thickness of the spectrum modulation layer <NUM> increases.

As described above, the thickness of the spectrum modulation layer <NUM> may vary according to the measurement positions P1, P2, P3,. , PN, and a thickness change of the spectrum modulation layer <NUM> may form different transmittance spectra. For example, as shown in <FIG>, since the N measurement positions P1, P2, P3,. , PN are set in the spectrum modulation layer <NUM>, different N transmittance spectrums may be formed. These different transmittance spectra may have, for example, a non-linear relation.

The sensing unit <NUM> receives light transmitted through the filter unit <NUM>, which is a light filter and may convert the light into an electrical signal. Light incident on the filter unit <NUM> may be transmitted through the liquid spectrum modulation layer <NUM> having different thicknesses according to measurement positions and reach pixels (not shown) of the sensing unit <NUM>. The sensing unit <NUM> may convert light incident on the pixels into an electrical signal. The sensing unit <NUM> includes an image sensor such as a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) image sensor.

A spectrum input to the spectrometer <NUM> may be reconstructed using transmittance spectra of the liquid spectrum modulation layer <NUM> according to the measurement positions P1, P2, P3,. , PN and signals of the sensing unit <NUM>.

Specifically, the relationship between the transmittance spectra of the spectrum modulation layer <NUM> according to the measurement positions P1, P2, P3,. , PN and signals of the sensing unit <NUM> may be defined by Equation <NUM>. <MAT>
where r denotes the signals of the sensing unit <NUM>, H denotes a transmittance spectrum matrix of the spectrum modulation layer <NUM>, s denotes a reconstructed input spectrum, and n denotes a noise value. According to an embodiment, r, H, S, and n may be defined in a matrix form as shown below. Herein, the transmittance spectrum matrix H may show transmittances based on wavelengths in the transmittance spectra of the measurement positions P1, P2, P3,. , PN of the spectrum modulation layer <NUM> in a matrix form and may include values measured in a test. The transmittance spectrum matrix H may be calculated using known values of the input spectrum s based on wavelengths and the measured signals r. <MAT>
(where λ denotes a wavelength, N denotes the number of measurement positions, and M denotes the number of signals.

When a parameter of the transmittance spectrum matrix H is determined in an initial test, the input spectrum s may be calculated using an inverse matrix of the transmittance spectrum matrix H of the spectrum modulation layer <NUM> and the signals r of the sensing unit <NUM>. The value of the noise n may refer to dark noise caused in the sensing unit <NUM> and may be a small value that is normally negligible. To increase calculation accuracy, if necessary, a dark noise value measured in a darkroom environment may be used.

According to the embodiment, different transmittance spectra may be formed using the liquid spectrum modulation layer <NUM> having thicknesses varying according to the measurement positions P1, P2, P3,. , PN, and an input spectrum may be calculated using the transmittance spectra. Meanwhile, the different transmittance spectra of the spectrum modulation layer <NUM> may increase the accuracy of the calculated input spectrum. For example, the different transmittance spectra may have a non-linear relation.

As described above, according to the embodiment, different transmittance spectra are formed using the liquid spectrum modulation layer <NUM> having thicknesses varying according to positions. For example, when <NUM> or more different transmittance spectra are generated within a wavelength range of about <NUM>, a spectrometer having a high resolution equal to or lower than about <NUM> may be implemented.

Also, the thickness of the spectrum modulation layer <NUM> may be easily adjusted by manufacturing the light filter using the filter frame <NUM> and the liquid spectrum modulation layer <NUM>. Also, the thickness of the liquid spectrum modulation layer <NUM> may be precisely adjusted according to different positions on the light filter, and thus precisely modulated transmittance spectra may be obtained. Also, the filter frame <NUM> may have the optically flat surface that does not cause scattering, and the liquid spectrum modulation layer <NUM> may include the solvent that causes no scattering, and thus the spectrometer <NUM> having optically excellent characteristics may be implemented.

<FIG> illustrates an example of an experimental model of a light filter. <FIG> is a simulation result showing transmittance spectra of the light filter shown in <FIG>.

Referring to <FIG>, the liquid spectrum modulation layer <NUM> whose thickness varies according to different positions on the light filter is provided in an inner space of the filter frame <NUM>. Here, the liquid spectrum modulation layer <NUM> may include a cyclohexane solution including a light absorption modulation material 122a' having a concentration of <NUM> wt% (weight percent). According to an embodiment, the light absorption modulation material 122a' maybe a QD having a maximum absorption wavelength of <NUM>. Such a liquid spectrum modulation layer <NUM> may have a triangular cross section whose thickness gradually increases in a D direction. In the spectrum modulation layer <NUM>, the measurement positions P1, P2, P3,. , P31 may be set at a regular distance in the D direction.

<FIG> shows <NUM> different transmittance spectra S1, S2, S3,. S31 measured at the <NUM> measurement positions P1, P2, P3,. P31 set at the regular distance along the D direction in the spectrum modulation layer <NUM> of <FIG>. In <FIG>, S1, S2 and S3 denote examples of the first, second and third measured positions S1, S2 and S3 measured at the first, second, and third measurement positions P1, P2, and P3 of <FIG> respectively among the <NUM> transmittance spectra S1, S2, S3,. Referring to <FIG>, the <NUM> transmittance spectrums S1, S2, S3,. may be differently formed from <NUM> to <NUM>. These different transmittance spectra S1, S2, S3,. may have a non-linear relation.

<FIG> illustrates another example of an experimental model of a light filter. <FIG> is a simulation result showing transmittance spectra of the light filter shown in <FIG>.

Referring to <FIG>, the liquid spectrum modulation layer <NUM> whose thickness varies according to different positions on the light filter is provided in an inner space of the filter frame <NUM>. Here, a cyclohexane solution including a light absorption modulation material 122a" having a concentration of <NUM> wt% (weight percent) was used as the liquid spectrum modulation layer <NUM>, and a quantum dot having a maximum absorption wavelength of <NUM> was used as the light absorption modulation material 122a". Such a liquid spectrum modulation layer <NUM> may have a triangular cross section whose thickness gradually increases along a D direction. In the spectrum modulation layer <NUM>, the measurement positions P1, P2, P3,. , P31 may be set at a regular distance along the D direction.

<FIG> shows the <NUM> different transmittance spectra S1, S2, S3,. , S31 measured at the <NUM> measurement positions P1, P2, P3,. , P31 set at the regular distance along the D direction in the spectrum modulation layer <NUM> of <FIG>. In <FIG>, S1, S2 and S3 denote examples of the first, second and third measured positions S1, S2 and S3 measured at the first, second, and third measurement positions P1, P2, and P3 of <FIG>, respectively, among the <NUM> transmittance spectra S1, S2, S3,. Referring to <FIG>, the <NUM> transmittance spectrums S1, S2, S3,. may be differently formed from <NUM> to <NUM>. These different transmittance spectra S1, S2, S3,. may have a non-linear relation.

<FIG> is a cross-sectional view illustrating a spectrometer <NUM> according to another embodiment. The spectrometer <NUM> shown in <FIG> is the same as the spectrometer <NUM> shown in <FIG> except that an anti-reflection layer <NUM> is formed on a surface of the filter unit <NUM>. Hereinafter, differences between the embodiment and the above-described embodiment will be mainly described.

Referring to <FIG>, the spectrometer <NUM> includes the sensing unit <NUM> and a light filter provided on the sensing unit <NUM>. The light filter includes the filter unit <NUM> and may include the anti-reflection layer <NUM> provided on the filter unit <NUM>. The filter unit <NUM> includes the filter frame <NUM> and the liquid spectrum modulation layer <NUM> provided inside the filter frame <NUM>. Here, the liquid spectrum modulation layer <NUM> has different thickness according to positions as described above.

The anti-reflection layer <NUM> may be provided on a lower surface and an upper surface of the filter frame <NUM>. Here, the anti-reflection layer <NUM> provided on the upper surface of the filter frame <NUM> may prevent external light from being reflected from the upper surface of the filter frame <NUM>. The anti-reflection layer <NUM> provided on the lower surface of the filter frame <NUM> may prevent light transmitted through the spectrum modulation layer <NUM> from being reflected from the lower surface of the filter frame <NUM>. The anti-reflection layer <NUM> may be provided as a film or may be formed by processing the surface of the filter frame <NUM>. Although <FIG> shows the case where the anti-reflection layer <NUM> is provided on the upper and lower surfaces of the filter frame <NUM>, the anti-reflection layer <NUM> may be provided only on one of the upper and lower surfaces of the filter frame <NUM>.

<FIG> is a cross-sectional view showing a light filter of a spectrometer according to another embodiment. Hereinafter, differences between the embodiment described in <FIG> and the above-described embodiments will be mainly described.

Referring to <FIG>, the light filter includes a filter unit <NUM> having different transmittance spectra according to different positions on the light filter. The filter unit <NUM> includes a filter frame <NUM> and a liquid spectrum modulation layer <NUM> provided inside the filter frame <NUM>.

The filter frame <NUM> includes an optically transparent material and may have an optically flat surface such that scattering does not occur. An inner space 131a of the filter frame <NUM> may be formed at different heights according to positions. Specifically, the inner space 131a of the filter frame <NUM> may have a trapezoidal cross section having a height gradually increasing in one direction.

The inner space 131a of the filter frame <NUM> is filled with the liquid spectrum modulation layer <NUM>. Therefore, the liquid spectrum modulation layer <NUM> has a shape corresponding to the inner space 131a of the filter frame <NUM>, that is, a trapezoidal cross section having a height gradually increasing in one direction.

<FIG> and <FIG> are a plan view and a cross-sectional view respectively showing a light filter of a spectrometer according to another embodiment. Hereinafter, differences between the embodiment in <FIG> and <FIG> and the above-described embodiments will be mainly described.

Referring to <FIG> and <FIG>, the light filter includes a filter unit <NUM> having different transmittance spectra according to positions. The filter unit <NUM> includes a filter frame <NUM> and a liquid spectrum modulation layer <NUM> provided inside the filter frame <NUM>.

The filter frame <NUM> may include a base frame <NUM>" formed with an inner space 141a and a cover frame <NUM>' provided to cover the inner space 141a. The filter frame <NUM> includes an optically transparent material and may have an optically flat surface such that no scattering occurs. The inner space 141a of the filter frame <NUM> may be formed at different heights according to positions. Specifically, the inner space 141a of the filter frame <NUM> may have a lens-shaped cross section whose height gradually increases in one direction and then decreases again. The lens-shaped cross section may be a concave or convex shape.

The liquid spectrum modulation layer <NUM> is filled in the inner space 141a of the filter frame <NUM>. Therefore, the liquid spectrum modulation layer <NUM> may have a lens-shaped cross section corresponding to the inner space 141a of the filter frame <NUM>. The cross-sectional shapes of the spectrum modulation layers <NUM>, <NUM>, and <NUM> described above are merely examples, and the spectrum modulation layers <NUM>, <NUM>, and <NUM> may have various other cross-sectional shapes having thicknesses varying according to positions.

<FIG> is a perspective view showing a spectrometer <NUM> according to another embodiment. <FIG> is a cross-sectional view of the spectrometer <NUM> shown in <FIG>.

Referring to <FIG> and <FIG>, the spectrometer <NUM> may include a sensing unit <NUM> and a light filter provided on the sensing unit <NUM>. Here, the light filter may include a first filter unit <NUM> and a second filter unit <NUM> that are vertically stacked.

The first filter unit <NUM> may be provided on an upper surface of the sensing unit <NUM> and may have different transmittance spectra according to positions. The first filter unit <NUM> may include a first filter frame <NUM> and a liquid first spectrum modulation layer <NUM> provided inside the first filter frame <NUM>. The second filter unit <NUM> may be provided on an upper surface of the first filter unit <NUM> and may have different transmittance spectra according to positions. The second filter unit <NUM> may include a second filter frame <NUM> and a liquid second spectrum modulation layer <NUM> provided inside the second filter frame <NUM>.

The first and second filter frames <NUM> and <NUM> may include an optically transparent material. The first and second filter frames <NUM> and <NUM> may include, for example, glass, quartz, or polymer. The first and second filter frames <NUM> and <NUM> may have an optically flat surface such that no scattering occurs.

The first filter frame <NUM> may include an inner space 321a filled with the liquid first spectrum modulation layer <NUM>. Here, the inner space 321a of the first filter frame <NUM> may be formed at different heights according to positions. For example, as shown in <FIG>, the inner space 321a of the first filter frame <NUM> may have a triangular cross section whose height increases in the +y direction.

The liquid first spectrum modulation layer <NUM> may be filled in the inner space 321a of the first filter frame <NUM>. Here, the liquid first spectrum modulation layer <NUM> may include a solution in which a first light absorption modulation material 322a is dispersed in a predetermined solvent. The first light absorption modulation material 322a may include at least one of, for example, QDs, inorganic materials, and polymers.

The liquid first spectrum modulation layer <NUM> may have a shape corresponding to the inner space 321a of the first filter frame <NUM>. Therefore, the liquid first spectrum modulation layer <NUM> may have different thicknesses according to positions. For example, as shown in <FIG>, the liquid first spectrum modulation layer <NUM> may have a triangular cross-sectional shape having thickness increasing along the +y direction.

The second filter frame <NUM> may include an inner space 361a in which the liquid second spectrum modulation layer <NUM> is filled. Here, the inner space 361a of the second filter frame <NUM> may be formed at different heights according to positions. For example, the internal space 361a of the second filter frame <NUM> may have a triangular cross section whose height gradually decreases along the +y direction.

The liquid second spectrum modulation layer <NUM> may be filled in the inner space 361a of the second filter frame <NUM>. Here, the liquid second spectrum modulation layer <NUM> may include a solution in which a second light absorption modulation material 362a is dispersed in a predetermined solvent. The second light absorption modulation material 362a may be a material different from the first light absorption modulation material 322a. For instance, a type of the second light absorption modulation material 362a may be different from that of the first light absorption modulation material 322a or a size of the second light absorption modulation material 362a may be different from that of the first light absorption modulation material 322a. Such a second light absorption modulation material 362a may include at least one of, for example, QDs, inorganic materials, and polymers.

The liquid second spectrum modulation layer <NUM> may have a shape corresponding to the inner space 361a of the second filter frame <NUM>. Therefore, the liquid second spectrum modulation layer <NUM> may have different thicknesses according to positions. For example, as shown in <FIG>, the liquid second spectrum modulation layer <NUM> may have a triangular cross-sectional shape whose thickness gradually decreases along the +y direction.

In the embodiment, as described above, the light filter may include the first and second filter units <NUM> and <NUM> vertically stacked on the sensing unit <NUM>. In the light filter including the vertically stacked first and second filter units <NUM> and <NUM>, ratios of the first and second light absorption modulation materials 322a and 362a may be different according to the measurement positions P1, P2, P3,. In <FIG>, P1, P2, and P3 respectively denote the first, second, and third measurement positions set at a predetermined distance along the +y direction in the light filter.

In <FIG>, the first spectrum modulation layer <NUM> may have the triangular cross section whose thickness increases along the +y direction, and the second spectrum modulation layer <NUM> may have the triangular cross section whose thickness decreases along the +y direction. In this case, when the measurement positions P1, P2, P3,. of the light filter move in the +y direction, an amount of the first light absorption modulation material 322a may increase and an amount of the second light absorption modulation material 362a may increase. Therefore, the ratios of the first and second light absorption modulation materials 322a and 362a may be different according to the measurement positions P1, P2, P3,. of the light filter.

On the other hand, in the light filter including the vertically stacked first and second filter units <NUM> and <NUM>, the sum of the thicknesses of the first and second spectrum modulation layers <NUM> and <NUM> may be the same or different according to the measurement positions P1, P2, P3,. For example, as shown in <FIG>, when the thickness of the first spectrum modulation layer <NUM> increases along the +y direction and the thickness of the second spectrum modulation layer <NUM> decreases along the +y direction, the sum of the thicknesses of the first and second spectrum modulation layers <NUM> and <NUM> may be the same or different according to the measurement positions P1, P2, P3,. of the light filter.

As described above, in the light filter in which the first and second filter units <NUM> and <NUM> are vertically stacked, different transmittance spectra may be obtained by varying the ratios of the first and second light absorption modulation materials 322a and 362a or by varying the thicknesses of the first and second spectrum modulation layers <NUM> and <NUM>.

The first and second spectrum modulation layers <NUM> and <NUM> have been exemplarily described as having the triangular cross section above, but the disclosure is not limited thereto. The first and second spectrum modulation layers <NUM> and <NUM> may have a trapezoidal or lens type cross section or may have various other types of cross sections. The thickness of the first spectrum modulation layer <NUM> has been exemplarily described as increasing along the +y direction and the thickness of the second spectrum modulation layer <NUM> has been exemplarily described as decreasing along the +y direction, but the disclosure is not limited thereto. The thicknesses of the first and second spectrum modulation layers <NUM> and <NUM> may vary in various directions. The two first and second filter units <NUM> and <NUM> have been exemplarily described as being vertically stacked on the sensing unit <NUM> above, but the disclosure is not limited thereto. Three or more filter units may be vertically stacked on the sensing unit <NUM>.

<FIG> illustrate examples of an experimental model of a light filter. <FIG> and <FIG> are simulation results showing transmittance spectra of the light filter shown in <FIG>.

<FIG> shows a plan view of the light filter. <FIG> is a cross-sectional view taken along line B-B' of <FIG>. <FIG> is a cross-sectional view taken along line C-C' of <FIG>.

Referring to <FIG>, the light filter may include first and second vertically stacked filter units <NUM> and <NUM>. Here, the first filter unit <NUM> may include a first filter frame <NUM> and a liquid first spectrum modulation layer <NUM> filled in an inner space of the first filter frame <NUM>. As the first spectrum modulation layer <NUM>, a cyclohexane solution including a first light absorption modulation material 422a of a concentration of <NUM> wt% was used. As the first light absorption modulation material 422a, QDs having a maximum absorption wavelength of <NUM> were used. The first filter unit <NUM> and the first spectrum modulation layer <NUM> may have a cross-sectional shape having thickness increasing along a +x direction.

The second filter unit <NUM> may include a second filter frame <NUM> and a liquid second spectrum modulation layer <NUM> filled in an inner space of the second filter frame <NUM>. Here, a cyclohexane solution including a second absorption modulation material 462a of a concentration of <NUM> wt% was used as the second spectrum modulation layer <NUM>, and QDs having a maximum absorption wavelength of <NUM> were used as the second absorption modulation material 462a. The second filter unit <NUM> and the second spectrum modulation layer <NUM> may have a cross-sectional shape having thickness increasing in a -y direction.

A part of the first filter unit <NUM> and a part of the second filter unit <NUM> may overlap each other. Specifically, a thin part of the first filter unit <NUM> and a thin part of the second filter unit <NUM> may overlap each other.

<FIG> shows a simulation result showing the transmittance spectra of the light filter shown in <FIG> in a wavelength range of <NUM> to <NUM>. Specifically, <FIG> shows the transmittance spectra measured at <NUM> measurement positions set at a regular distance in a direction D1 in a region where the thin part of the first filter unit <NUM> and the thin part of the second filter unit <NUM> overlap each other. <FIG> shows the transmittance spectra by enlarging a wavelength range of <NUM> to <NUM> in <FIG>. Referring to <FIG> and <FIG>, it may be seen that <NUM> transmittance spectrums are formed differently from each other. These different transmittance spectra may have a non-linear relation.

<FIG> illustrate other examples of an experimental model of a light filter. <FIG> and <FIG> are simulation results showing transmittance spectra of the light filter shown in <FIG>.

<FIG> shows a plan view of the light filter. <FIG> is a cross-sectional view taken along line D-D' in <FIG>. <FIG> is a cross-sectional view taken along line E-E' in <FIG>.

Referring to <FIG>, the light filter may include first and second vertically stacked filter units <NUM> and <NUM>. The first and second filter units <NUM> and <NUM> may be the same as the first and second filter units <NUM> and <NUM> shown in <FIG>. Here, the first filter unit <NUM> and the first spectrum modulation layer <NUM> may have a cross-sectional shape having a thickness increasing along the +x direction, and the second filter unit <NUM> and the second spectrum modulation layer <NUM> may have a cross-sectional shape having a thickness increasing along the +y direction. A part of the first filter unit <NUM> and a part of the second filter unit <NUM> may overlap each other. Specifically, a thick part of the first filter unit <NUM> and a thick part of the second filter unit <NUM> may overlap each other.

<FIG> shows the simulation result showing the transmittance spectra of the light filter shown in <FIG> in a wavelength range of <NUM> to <NUM>. Specifically, <FIG> shows the transmittance spectrum measured at <NUM> measurement positions set at a regular distance in a direction D2 in a region where the thick part of the first filter unit <NUM> and the thick part of the second filter unit <NUM> overlap each other. <FIG> is an enlarged view of the transmittance spectra by enlarging a wavelength range of <NUM> to <NUM> in <FIG>. Referring to <FIG> and <FIG>, it may be seen that <NUM> transmittance spectrums are formed differently from each other. These different transmittance spectra may have a non-linear relation.

<FIG> is a cross-sectional view of a spectrometer <NUM> according to another embodiment. The spectrometer <NUM> shown in <FIG> is the same as the spectrometer <NUM> shown in <FIG> except that anti-reflection layers <NUM> are formed on the vertically stacked first and second filter units <NUM> and <NUM>. Hereinafter, differences between the embodiment and the above-described embodiment will be mainly described.

Referring to <FIG>, the spectrometer <NUM> may include a sensing unit <NUM> and a light filter provided on the sensing unit <NUM>. The light filter may include the first and second filter units <NUM> and <NUM> vertically stacked on the sensing unit <NUM> and the plurality of anti-reflection layers <NUM> provided on the first and second filter units <NUM> and <NUM>. Here, the first and second filter units <NUM> and <NUM> may have different thicknesses according to positions as described above.

The anti-reflection layers <NUM> may be provided on a lower surface of the first filter unit <NUM>, on an upper surface of the second filter unit <NUM>, and between the first and second filter units <NUM> and <NUM>, respectively. Meanwhile, the anti-reflection layers <NUM> may be provided on at least one of the lower surface of the first filter unit <NUM>, the upper surface of the second filter unit <NUM>, and between the first and second filter units <NUM> and <NUM>.

<FIG> is a plan view showing a spectrometer <NUM> according to another embodiment.

Referring to <FIG>, the spectrometer <NUM> may include a sensing unit <NUM> and a light filter provided on the sensing unit <NUM>. Here, the light filter may include a plurality of filter units <NUM>, <NUM>, <NUM>, and <NUM> arranged in an array on the sensing unit <NUM>. Each of the filter units <NUM>, <NUM>, <NUM>, and <NUM> may have different thicknesses according to positions as described above.

<FIG> shows the example in which the four filter units <NUM>, <NUM>, <NUM>, and <NUM> are arranged in a two-dimensional (2D) array on an upper surface of the sensing unit <NUM>, but the disclosure is not limited thereto. The number of filter units arranged on the sensing unit <NUM> and an arrangement shape of the filter units may be variously modified.

Referring to <FIG>, the spectrometer <NUM> may include a sensing unit <NUM> and a light filter provided on the sensing unit <NUM>. Here, the light filter may include a plurality of filter units <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> arranged horizontally and vertically on the sensing unit <NUM>. Here, each of the filter units <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> may have different thicknesses according to positions as described above.

<FIG> shows the example in which the four filter units <NUM>, <NUM>, <NUM>, and <NUM> are arranged in a 2D array on an upper surface of the sensing unit <NUM> and the two filter units <NUM> and <NUM> are stacked on an upper portion of the four filter units <NUM>, <NUM>, <NUM>, and <NUM>, but the disclosure is not limited thereto. The number of filter units arranged on the sensing unit <NUM> and an arrangement shape of the filter units may be variously modified.

<FIG> and <FIG> show examples of an experimental model of a light filter. <FIG> is a plan view of the light filter. <FIG> is a cross-sectional view of the light filter.

Referring to <FIG> and <FIG>, the light filter may include first and second filter units <NUM> and <NUM> horizontally arranged on the same plane. Here, the first filter unit <NUM> may include a first filter frame <NUM> and a liquid first spectrum modulation layer <NUM> filled in an inner space of the first filter frame <NUM>. As the first spectrum modulation layer <NUM>, a cyclohexane solution including a first light absorption modulation material 822a of a concentration of <NUM> wt% was used. As the first light absorption modulation material 822a, QDs having a maximum absorption wavelength of <NUM> were used. The first filter unit <NUM> and the first spectrum modulation layer <NUM> may have a cross-sectional shape having thickness increasing along the +x direction.

The second filter unit <NUM> may include a second filter frame <NUM> and a liquid second spectrum modulation layer <NUM> filled in an inner space of the second filter frame <NUM>. As the second spectrum modulation layer <NUM>, a cyclohexane solution including a second light absorption modulation material 862a of a concentration of <NUM> wt% was used. As the second light absorption modulation material 862a, QDs having a maximum absorption wavelength of <NUM> were used. The second filter unit <NUM> and the second spectrum modulation layer <NUM> may have a cross-sectional shape having thickness increasing along the +x direction.

<FIG> is a simulation result showing transmittance spectrums SB and SA of a light filter shown in <FIG> and <FIG> in a wavelength range of <NUM> to <NUM>. Specifically, <FIG> shows the transmittance spectrums SB measured at <NUM> measurement positions set at a regular distance along the +x direction in the first filter unit <NUM> and the transmittance spectra SB measured at <NUM> measurement positions set at a regular distance along the +x direction in the first filter unit <NUM>. Referring to <FIG>, it may be seen that the <NUM> different transmittance spectrums SB are formed by the first filter unit <NUM>, and the <NUM> different transmittance spectrums SA are formed by the second filter unit <NUM>.

<FIG> and <FIG> show comparisons between a reconstructed input spectrum and a real input spectrum from a result shown in <FIG>. Here, the reconstructed input spectrum may be calculated using Equation (<NUM>) described above. This is also the same hereinafter.

Referring to <FIG> and <FIG>, it may be seen that a deviation between the real input spectrum and the reconstructed input spectrum is as small as about <NUM>% such that the reconstructed input spectrum substantially coincides with the real input spectrum of a light filter. Thus, the reconstructed input spectrum with high accuracy may be obtained, and the real input spectrum may be accurately measured from the reconstructed input spectrum.

<FIG> illustrate other examples of an experimental model of a light filter. <FIG> shows a plan view of the light filter. <FIG> is a cross-sectional view taken along line B-B' of <FIG>. <FIG> is a cross-sectional view taken along line C-C' of <FIG>.

Referring to <FIG>, the light filter may include the vertically stacked first and second filter units <NUM> and <NUM>. The first and second filter units <NUM> and <NUM> are the same as the first and second filter units shown in <FIG> and <FIG>. Here, the first filter unit <NUM> and the first spectrum modulation layer <NUM> may have a cross-sectional shape having thickness increasing along the +x direction. The second filter unit <NUM> and the second spectrum modulation layer <NUM> may have a cross-sectional shape having thickness increasing along the -y direction. A part of the first filter unit <NUM> and a part of the second filter unit <NUM> may overlap each other. Specifically, a thin part of the first filter unit <NUM> and a thin part of the second filter unit <NUM> may overlap each other.

<FIG> shows a simulation result showing transmittance spectra of light filters shown in <FIG> in a wavelength range of <NUM> to <NUM>. Specifically, <FIG> shows the transmittance spectra measured at <NUM> measurement positions set at a regular distance along the direction D1 in a region where a thin part of the first filter unit <NUM> and a thin part of the second filter unit <NUM> overlap. Referring to <FIG>, it may be seen that the <NUM> transmittance spectrums are formed differently from each other.

<FIG> and <FIG> show comparisons between a reconstructed input spectrum and a real input spectrum from a result shown in <FIG>.

Referring to <FIG> and <FIG>, it may be seen that a deviation between the real input spectrum and the reconstructed input spectrum is as small as about <NUM>% such that the reconstructed input spectrum almost coincides with the real input spectrum of a light filter. Thus, the reconfigured input spectrum with high accuracy may be obtained, and the real input spectrum may be accurately measured from the reconstructed input spectrum.

<FIG> illustrate other examples of an experimental model of a light filter. <FIG> is a plan view of the light filter. <FIG> is a cross-sectional view taken along line D-D' in <FIG>. <FIG> is a cross-sectional view taken along line E-E' in <FIG>.

Referring to <FIG>, the light filter may include the first and second vertically stacked filter units <NUM> and <NUM>. The first and second filter units <NUM> and <NUM> are the same as the first and second filter units <NUM> and <NUM> shown in <FIG> and <FIG>. Here, the first filter unit <NUM> and the first spectrum modulation layer <NUM> may have a cross-sectional shape having thickness increasing along the +x direction, and the second filter unit <NUM> and the second spectrum modulation layer <NUM> may have a cross-sectional shape having thickness increasing along the +y direction. A part of the first filter unit <NUM> and a part of the second filter unit <NUM> may overlap each other. Specifically, a thick part of the first filter unit <NUM> and a thick part of the second filter unit <NUM> may overlap each other.

<FIG> shows a simulation result showing transmittance spectra of a light filter shown in <FIG> in a wavelength range of <NUM> to <NUM>. Specifically, <FIG> shows the transmittance spectra measured at <NUM> measurement positions set at a regular distance along the direction D2 in a region where the thick part of the first filter unit <NUM> and the thick part of the second filter unit <NUM> overlap. Referring to <FIG>, it may be seen that the <NUM> transmittance spectrums are formed differently.

According to the above embodiments, different transmittance spectrums may be formed by varying a thickness of a spectrum modulation layer according to positions. For example, when <NUM> or more different transmittance spectra are formed within a wavelength range of <NUM>, a spectrometer having a high resolution of about <NUM> or less may be realized.

Further, the thickness of the spectrum modulation layer may be easily adjusted by manufacturing a light filter using a filter frame and a liquid spectrum modulation layer. Also, the liquid spectrum modulation layer may precisely adjust the thickness according to positions, and thus precisely modulated transmittance spectra may be obtained. Further, since the filter frame has an optically flat surface that does not cause scattering, and a liquid spectrum modulation layer may include a solvent that does not cause scattering, a spectrometer having excellent optical characteristics may be realized.

Claim 1:
A spectrometer comprising:
a light filter; and
a sensing unit (<NUM>) configured to receive light transmitted through the light filter, wherein the sensing unit comprises an image sensor, and
wherein the light filter is provided on the sensing unit and comprises at least one filter (<NUM>), wherein the at least one filter comprises:
(a) a liquid spectrum modulation layer (<NUM>) having different transmittance spectra according to different positions on the at least one filter, wherein the liquid spectrum modulation layer has different thicknesses according to the different positions on the at least one filter, and wherein the liquid spectrum modulation layer comprises a solution comprising a light absorption modulation material (122a) dispersed in a predetermined solvent; and
(b) a filter frame (<NUM>) comprising an inner space (121a) filled with the liquid spectrum modulation layer, wherein the filter frame is formed of an optically transparent material, and wherein the liquid spectrum modulation layer has a shape corresponding to the inner space of the filter frame.