Spectrometer and imaging device

A spectrometer that includes: a first diffraction grating configured to spectroscopically process provided light; a first detection unit configured to condense light spectroscopically processed by the first diffraction grating and to output an electrical signal corresponding to condensed light; a second diffraction grating configured to spectroscopically process 0th order light provided by the first diffraction grating; and a second detection unit configured to condense light spectroscopically processed by the second diffraction grating and to output an electrical signal corresponding to condensed light.

FIELD OF THE INVENTION

The present technology relates to a spectrometer and an imaging device.

BACKGROUND OF THE INVENTION

A spectrometer refers to a device that decomposes light, that is, electromagnetic waves, absorbed or emitted by a target material into different wavelengths and measures an intensity distribution for each wavelength. The spectrometer may use a diffraction grating, a prism, an interferometer, a filter, or the like to disperse electromagnetic waves for each wavelength.

A conventional spectrometer is designed and configured to output a light of a specific order having the strongest intensity with respect to input light.

The conventional spectrometer is designed and manufactured so that an intensity of the light of a predetermined specific order is large, so that the light of another undesired order is not spectroscopically processed, nor is subject to perform other processing.

SUMMARY OF THE INVENTION

Technical Problem

Accordingly, the present disclosure has been made keeping in mind the above problems occurring in the related art. Specifically, in a conventional spectrometer, a ratio of light discarded without being spectroscopically processed is high, and when it is necessary to perform processing in various ways with provided light, a processing procedure needs to be performed several times, which is cumbersome and takes a long time.

The present embodiment is intended to solve the above-described disadvantages of the related art and to provide a spectrometer capable of performing a plurality of processing cases with the same light. In addition, the present embodiment is intended to provide an imaging device capable of performing imaging simultaneously with spectroscopic processing with the same light.

Technical Solution

In order to accomplish the above objective, there may be provided a spectrometer according to a present embodiment, the spectrometer including: a first diffraction grating configured to spectroscopically process provided light; a first detection unit configured to condense light spectroscopically processed by the first diffraction grating and to output an electrical signal corresponding to condensed light; a second diffraction grating configured to spectroscopically process 0thorder light provided by the first diffraction grating; and a second detection unit configured to condense light spectroscopically processed by the second diffraction grating and to output an electrical signal corresponding to condensed light.

In one aspect of a present spectrometer embodiment, the first detection unit may include: a first condenser configured to condense light spectroscopically processed by the first diffraction grating; and a first detector configured to detect light condensed and provided by the first condenser and to output an electrical signal corresponding to detected light, and the second detection unit may include: a second condenser configured to condense the light spectroscopically processed by the second diffraction grating; and a second detector configured to detect light condensed and provided by the second condenser and to output an electrical signal corresponding to detected light.

In one aspect of the present spectrometer embodiment, the first detector and the second detector may be different from each other in at least one of characteristics in sensitivity, a detection wavelength band, and resolution.

In one aspect of the present spectrometer embodiment, the first detector and the second detector may have the same characteristics as each other in sensitivity, a detection wavelength band, and resolution.

In one aspect of the present spectrometer embodiment, the spectrometer may further include: a housing; and a slit configured to provide light into the housing.

In one aspect of the present spectrometer embodiment, the spectrometer may further include a collimator configured to form the light provided from the slit into parallel light and to provide the parallel light to the first diffraction grating.

In one aspect of the present spectrometer embodiment, the spectrometer may further include a light delivery unit configured to provide light provided from a target T to the slit, wherein the light delivery unit may include: an objective lens configured to condense the light provided from the target T; and a focusing lens configured to provide light condensed by the objective lens to the slit.

In one aspect of the present spectrometer embodiment, the first diffraction grating may be any one of a transmissive diffraction grating and a reflective diffraction grating, and the second diffraction grating may be any one of the transmissive diffraction grating and the reflective diffraction grating.

In one aspect of the present spectrometer embodiment, the first diffraction grating may include any one of a diffraction grating in a form of a concave mirror and a diffraction grating in a form of a convex lens.

In one aspect of the present spectrometer embodiment, the first diffraction grating and the second diffraction grating may be different from each other in resolution.

In one aspect of the present spectrometer embodiment, the first diffraction grating and the second diffraction grating may have the same resolution as each other.

In one aspect of the present spectrometer embodiment, the spectrometer may be configured to allow a position of the first detection unit to be adjusted with respect to the first diffraction grating.

In one aspect of the present spectrometer embodiment, the spectrometer may be configured to allow a position of the second detection unit to be adjusted with respect to the second diffraction grating.

There may be provided a spectrometer according to another embodiment, the spectrometer including: a diffraction grating configured to spectroscopically process provided light; a first detection unit configured to condense light spectroscopically processed by the diffraction grating and to output an electrical signal corresponding to condensed light; a reflection mirror configured to reflect 0thorder light output from the diffraction grating, back to the diffraction grating; and a second detection unit, wherein the diffraction grating may be configured to spectroscopically process light reflected by the reflection mirror and to provide spectroscopically processed light to the second detection unit.

In one aspect of the present spectrometer embodiment, the first detection unit may include: a first condenser configured to condense light spectroscopically processed by the diffraction grating; and a first detector configured to detect light condensed by the first condenser and to output detected light in an electrical signal, and the second detection unit may include: a second condenser configured to condense light, which is the reflected 0thorder light spectroscopically processed by the diffraction grating; and a second detector configured to detect light condensed by the second condenser and to output detected light in an electrical signal.

In one aspect of the present spectrometer embodiment, the first detector and the second detector may have the same characteristics as each other in sensitivity, a detection wavelength band, and resolution.

In one aspect of the present spectrometer embodiment, the first detector and second detector may be different from each other in any one of sensitivity, a detection wavelength band, and resolution.

In one aspect of the present spectrometer embodiment, the spectrometer may further include: a housing; a slit configured to provide light into the housing; and a collimator configured to modify the light provided from the slit into parallel light.

In one aspect of the present spectrometer embodiment, the spectrometer further comprises a light delivery unit configured to provide light provided from a target T to the slit, wherein the light delivery unit may further include: an objective lens configured to condense the light provided from the target T; and a focusing lens configured to provide light condensed by the objective lens to the slit.

In one aspect of the present spectrometer embodiment, the diffraction grating may be any one of a transmissive diffraction grating and a reflective diffraction grating

In one aspect of the present spectrometer embodiment, the diffraction grating may include any one of a diffraction grating in a form of a concave mirror and a diffraction grating in a form of a convex lens.

In one aspect of the present spectrometer embodiment, the spectrometer may be configured to allow at least any one of a position, of the first detection unit, and a position, of the second diffraction grating, to be adjusted with respect to the diffraction grating.

There may be provided an imaging device according to a present embodiment, the imaging device including: a diffraction grating configured to spectroscopically process provided light; a detection unit configured to condense light spectroscopically processed by the diffraction grating and to output condensed light in an electrical signal; and an imaging unit configured to image 0thorder light output from the diffraction grating, wherein the imaging unit may include a focusing lens configured to focus the 0thorder light.

In one aspect of a present imaging device embodiment, the detection unit may include: a condenser configured to condense light spectroscopically processed by the diffraction grating; and a detector configured to detect light condensed by the condenser and to output detected light in an electrical signal.

In one aspect of a present imaging device embodiment, the spectrometer may further include: a housing; a slit configured to provide light into the housing; and a collimator configured to modify the light provided from the slit into parallel light.

In one aspect of a present imaging device embodiment, the diffraction grating may include any one of a diffraction grating in a form of a concave mirror and a diffraction grating in a form of a convex lens.

In one aspect of a present imaging device embodiment, the diffraction grating may be any one of a transmissive diffraction grating and a reflective diffraction grating.

In one aspect of a present imaging device embodiment, the imaging device may further include a light delivery unit configured to provide light provided from a target T to the slit, wherein the light delivery unit may include: an objective lens configured to condense the light provided from the target T; and a focusing lens configured to provide light condensed by the objective lens to the slit.

Advantageous Effects

As described above, according to a present embodiment, a spectrometer capable of performing two or more spectroscopic analyses with the same light is provided. In addition, according to the present embodiment, an imaging device capable of performing a spectroscopic analysis and imaging with the same light is provided.

DETAILED DESCRIPTION OF THE DRAWINGS

First Embodiment

Hereinafter, a spectrometer1according to the first embodiment will be described with reference to the accompanying drawings.FIG.1is a block diagram showing an outline of a spectrometer according to a first embodiment. With reference toFIG.1, the spectrometer1according to the present embodiment includes: a first diffraction grating130configured to spectroscopically process provided light; a first detection unit150configured to condense light spectroscopically processed by the first diffraction grating130and to output an electrical signal corresponding to condensed light; a second diffraction grating140configured to spectroscopically process 0thorder light provided by the first diffraction grating; and a second detection unit160configured to condense light spectroscopically processed by the second diffraction grating140and to output an electrical signal corresponding to condensed light.

In one embodiment, the spectrometer1according to the present embodiment may further include a housing, wherein for example, the housing may have a light-blocking structure and thus shield an inner side thereof. In addition, the housing may include a slit110through which light to be spectroscopically processed is provided.

In the one embodiment, the first detection unit150includes: a first condenser152configured to condense light spectroscopically processed by the first diffraction grating130; and a first detector154configured to be provided with light condensed by the first condenser and to detect provided light in order to output the detected light in an electrical signal corresponding to the detected light. In addition, the second detector160includes: a second condenser162configured to condense light spectroscopically processed by the second diffraction grating140; and a second detector164configured to detect light condensed and provided by the second condenser162and to output an electrical signal corresponding to detected light.

FIG.2is a view showing an outline of a light delivery unit180according to the present embodiment. With reference toFIG.2, the spectrometer1according to the present embodiment may further include a light delivery unit180configured to condense the light reflected from a target T and to provide the condensed light to the slit110. Here, the light delivery unit180may include at least any one of an objective lens182configured to condense the light provided from the target T and a focusing lens184configured to provide light condensed by the objective lens182to the slit110.

With reference again toFIG.1, in the embodiment illustrated inFIG.1, the spectrometer1includes a collimator120. The light provided to the housing through the slit110is diffused by being diffracted or is diffused after being incident on the slit by being condensed, so the collimator120forms diffused light into parallel light to be provided to the first diffraction grating130. According to an embodiment not shown, the spectrometer1may not include the collimator120, and the light provided to the housing through the slit110may be condensed and spectroscopically processed by a reflective diffraction grating in a form of a concave mirror or a transmissive diffraction grating in a form of a convex lens.

FIG.3Ais a view explaining an outline of an operation of a diffraction grating,FIG.3Bis a view showing an outline explaining a reflective diffraction grating, andFIG.3Cis a view showing an outline explaining a transmissive diffraction grating. The diffraction grating may be divided into the transmissive type and the reflective type, and the diffraction grating illustrated inFIG.3Ais the reflective type. In a reflective diffraction grating, the light of various diffraction orders is formed by being reflected from the diffraction grating. When a difference between two adjacent diffracted light rays is an odd multiple of λ/2, destructive interference occurs and the diffracted light amplitude becomes the minimum, and when a difference between two adjacent diffracted light rays is an even multiple of λ/2, constructive interference occurs and the diffracted light amplitude becomes the maximum. Conditions in which the maximum diffracted light is generated, when generalized, may be expressed as following Equation 1.
mλ=d(sin θi−sin θm)  [Equation 1]

where d is a distance between the diffraction gratings, λ is a wavelength of incident light, θiis an angle of the incident light with respect to a diffraction grating plane, θmis an angle between the diffracted light and a vertical vector of the diffraction grating, and m is an integer value representing the order of the diffracted light.

FIG.3Bis a view showing an outline explaining a reflective diffraction grating, andFIG.3Cis a view showing an outline explaining a transmissive diffraction grating. With reference toFIG.3B, in the reflective diffraction grating, 0thorder light is equal to reflection made on a mirror surface. That is, the reflection angle θmof the 0thorder light is equal to the incidence angle θiof the incident light. However, as the order increases, such as the first order light, the second order light, the third order light, and the like, the angle θmmade by the light with respect to a normal line of the reflective surface increases. In addition, there may be (−) first order light, (−) second order light, and the like, and absolute values of the angles made by such light with respect to the normal line of the reflective surface equal to the values made by the first order light, second order light, third order light, and the like, respectively, but signs of the values of such angles are opposite, so such light is formed in an opposite direction with respect to the light having positive values with the incident light as a reference.

With reference toFIG.3C, even when incident light is provided to the transmissive diffraction grating, light such as 0thorder light, first order light, and second order light, and the like are formed. The 0thorder light is the light penetrating through the transmissive diffraction grating, and the angle made by the 0thorder light with respect to the normal line of the transmissive surface of the diffraction grating is equal to the angle θiformed by the incident light with respect to the normal line of the transmissive diffraction grating surface.

Although not shown, as described above, the reflective diffraction grating may have a form of a concave mirror, and the transmissive diffraction grating may have a form of a convex lens. In this case, condensing and spectroscopic processing are possible without the collimator.

With reference toFIGS.1and3, the light provided to the first diffraction grating130is spectroscopically processed and provided to the first light condenser152. In the one embodiment, the first diffraction grating130spectroscopically processes the light provided through the slit110and provides light of a predetermined order to the first condenser152. For example, the first condenser152may be disposed so as to correspond to an angle at which light of a specific order provided by the first diffraction grating130is provided, whereby a target light of a specific order may be condensed and provided to the first detector154. An angle θmat which the light of a specific order m is provided may be expressed as Equation 2 below derived from Equation 1.

In the embodiment in which the first diffraction grating130is the transmissive diffraction grating illustrated inFIG.3Cand the first light is to be spectroscopically processed, the first detection unit150is disposed to make an angle be equal to θ1 with respect to a normal line of the transmissive surface of the first diffraction grating130, whereby a desired first light may be condensed.

The first condenser152condenses the light spectroscopically processed by the first diffraction grating130and provides same to the first detector154. The first detector154forms and outputs an electrical signal corresponding to the condensed light.

The 0thorder light from the first diffraction grating130is provided to the second diffraction grating140. The second diffraction grating140may be any one of the reflective diffraction grating and the transmissive diffraction grating illustrated inFIGS.3A to3C. In the embodiment illustrated inFIG.1, the spectrometer1may have the first diffraction grating130and the second diffraction grating140having different characteristics from each other, whereby resolution of the first and second spectroscopic processing may be different. In another embodiment, the spectrometer1may have the first diffraction grating130and the second diffraction grating140having the same characteristics as each other.

The 0thorder light provided to the second diffraction grating140is spectroscopically processed by the second diffraction grating140. The second detection unit160may be disposed to condense the light of a desired order from the second diffraction grating140. The second light condenser162included in the second detection unit provides the condensed light to the second detector164.

In the one embodiment, the first detector154and the second detector164may include elements such as a photodiode, CCD, CMOS, and the like that are configured to output an electrical signal corresponding to the light. The first detector154and the second detector164have characteristics of the resolution, a detection band, and a sensitivity, at least one of which is different from each other. Thus, it is possible to spectroscopically process the same light and to process spectroscopically processed light, thereby obtaining different features. In another embodiment, the first detector154and the second detector164have the characteristics of the resolution, detection band, and sensitivity that are the same as each other. For example, the first detector154and the second detector164may use the same detector to improve signal correction or signal-to-noise ratio.

In one embodiment, by spectroscopically processing by adjusting a position of the first detection unit150with respect to the first diffraction grating130, it is possible to adjust an analysis target wavelength region, and by adjusting a position of the second detection unit160with respect to the second diffraction grating140, it is possible to adjust an analysis target wavelength region to be spectroscopically processed. In addition, spectroscopic processing characteristics measured by each detector may be adjusted by varying measurement conditions of the first detector154and the second detector164. For example, the signal-to-noise ratio measured by each of the first detector154and the second detector164may become different by varying a signal measurement time (detection time or integration time). In addition, the first detector154uses a Si semiconductor, and the second detector164uses an InGaAs semiconductor, wherein the Si detector may detect a wavelength of 1.1 μm or less, and the InGaAs semiconductor detector may detect a wavelength of 1.1 μm or greater.

The detection material of the first detector154and the second detector164may measure different wavelengths of ultraviolet, visible, infrared, and the like, the detection material being selected from semiconductor materials such as Si, Ge, InGaAs, GaN, GaAs, InAs, InGaAsP, PbS, PbSe, PtSi, InSb, Mercury Cadmium Telluride (MCT), HgCdTe, Mercury Zinc Telluride (MZT), HgZnTe, and the like and oxides such as vanadium pentoxide and the like.

FIG.1shows an example of using two diffraction gratings, but a configuration, in which the 0thorder light provided from the second diffraction grating is spectroscopically processed by a third diffraction grating, and the light spectroscopically processed is detected by a third detection unit, is also naturally possible. That is, when an intensity of the provided light is sufficient enough, three or more diffraction gratings and detection units may be provided, so that the spectroscopic processes and analyses may be performed with the same light a plurality of times.

In addition, the illustrated embodiment uses two diffraction gratings, so the resolution of the two detectors may be easily changed, and spectroscopic process conditions such as resolution, wavelength band, and the like may be adjusted by varying a photodiode array size or pixel pitch of the first and second detectors.

In the embodiment described above with reference to the drawings, the collimator120, the first condenser152, the second condenser162, the objective lens182, and the focusing lens184are all exemplified as convex lenses. However, such convex lenses may be used in combination with concave lenses in order to reduce an influence of non-ideal characteristics of the lens, such as chromatic aberration. In addition, the convex lens may be substituted with a concave mirror (or vice versa), and the concave lens may be substituted with a convex mirror (or vice versa).

Second Embodiment

Hereinafter, a spectrometer2according to the second embodiment will be described with reference to the accompanying drawings. For a simple and clear description, a description of elements that are the same as or similar to those described in the first embodiment may be omitted.FIG.4is a block diagram showing an outline of a spectrometer according to the second embodiment. With reference toFIG.4, the spectrometer2according to the present embodiment includes: a diffraction grating130configured to spectroscopically process provided light; a first detection unit150configured to condense light spectroscopically processed by the diffraction grating130and to output an electrical signal corresponding to condensed light; a reflection mirror170configured to reflect Oth order light output from the diffraction grating130back to the diffraction grating130; and a second detection unit160, wherein the diffraction grating130is configured to spectroscopically process light reflected by the reflection mirror170and to provide spectroscopically processed light to the second detection unit160.

In one embodiment, the spectrometer2according to the present embodiment may further include a housing, wherein for example, the housing may have a light-blocking structure and thus shield an inner side thereof. In addition, the housing may include a slit110through which the light to be spectroscopically processed is provided.

In the one embodiment, the first detection unit150includes: a first condenser152configured to condense light spectroscopically processed by the diffraction grating130; and a first detector154configured to be provided with light condensed by the first condenser and to detect condensed light to output the detected light in an electrical signal corresponding to the detected light. In addition, the second detector160includes: a second condenser162configured to condense the light, which are the reflected 0thorder light that are spectroscopically processed by the diffraction grating130; and a second detector164configured to detect light condensed and provided by the second condenser162and to output an electrical signal corresponding to detected light.

In one embodiment, the spectrometer2according to the present embodiment may further include a light delivery unit180(refer toFIG.2) configured to condense the light provided from a target T to provide condensed light to the slit110. Here, the light delivery unit180may include at least any one of an objective lens182configured to condense the light provided from the target T as described above and a condensing lens184configured to provide the light condensed by the objective lens182to the slit110.

The light provided through the slit110are diffused after being incident on the slit by being condensed or diffused by being diffracted after being incident on the slit, so the spectrometer2may further include a collimator120that converts the diffused light into parallel light. According to another embodiment described above, when the diffraction grating130in the form of a concave mirror or the diffraction grating in the form of a convex lens is used, condensing and spectroscopic processing may be performed together, so the collimator120may not be necessary.

The diffraction grating130spectroscopically processes the light provided through the slit110to provide to the first detection unit150. As described above, the first detection unit150is disposed at a position capable of detecting the light of a desired order among the light spectroscopically processed by the diffraction grating130. The light spectroscopically processed by the diffraction grating130is provided to the first condenser152, and the first detector154receives the light condensed and provided by the first condenser152and outputs an electrical signal corresponding to received light. The light provided by the diffraction grating130has angles provided according to the order, the angles being different from each other, so a position of the first detection unit150may be adjusted to receive the light of the desired order.

The 0thorder light provided by the diffraction grating130is reflected by the reflection mirror170and provided to the diffraction grating130again at a desired incident angle. The 0thorder light is incident on the diffraction grating130and is spectroscopically processed. The second detection unit160is disposed at a position capable of condensing the light of a desired order.

The first detector154and the second detector164may include elements such as CCD, CMOS, and the like that are configured to output an electrical signal corresponding to the light. The first detector154and the second detector164may have characteristics of resolutions, detection bands, and sensitivities, at least one of which is different from each other so as to simultaneously acquire a plurality of characteristics from the same light. In another embodiment, the first detector154and the second detector164may use the same detector, whereby signal correction or signal-to-noise ratio characteristics may be improved.

AlthoughFIG.4shows an example of using a single reflection mirror and a single diffraction grating, it is naturally possible also to have a configuration in which the 0thorder light reflected by the reflection mirror is provided to the diffraction grating, and 0thorder light formed at this time is provided to the diffraction grating again by a second reflection mirror to be spectroscopically processed and is detected by a third detector. When an intensity of the provided light is sufficient enough, two or more reflection mirrors and detection units may be provided, so that the spectroscopic processes and analyses may be performed with the same light a plurality of times.

In the present embodiment the single diffraction grating is used, so it may be difficult to change the resolution of the first and second spectroscopic processing, but by varying a photodiode array size or pixel pitch of the first and second detectors, spectroscopic processing conditions such as resolution, sensitivity, spectroscopic area, and the like may be adjusted.

In the embodiment described above with reference to the drawings, the collimator120, the first condenser152, the second condenser162, the objective lens182, and the focusing lens184are all exemplified as convex lenses. However, such convex lenses may be used in combination with concave lenses in order to reduce an influence of non-ideal characteristics of the lens, such as chromatic aberration. In addition, the convex lens may be substituted with a concave mirror (or vice versa), and the concave lens may be substituted with a convex mirror (or vice versa).

Third Embodiment

Hereinafter, an imaging device3according to the third embodiment will be described with reference to the accompanying drawings. For a simple and clear description, a description of elements that are the same as or similar to those described in the first and second embodiments may be omitted.FIG.5is a block diagram showing an outline of the imaging device according to the third embodiment. With reference toFIG.5, the imaging device3according to the present embodiment includes: a diffraction grating130configured to spectroscopically process provided light; a condenser152configured to condense the light spectroscopically processed by the diffraction grating130, a detector154configured to detect light condensed by the condenser to output an electrical signal corresponding to detected light; and an imaging unit190configured to image 0thorder light output from the diffraction grating130, wherein the imaging unit190includes: a condensing lens (not shown) configured to condense 0thorder light and a focusing lens194configured to collect light condensed by the condenser lens.

In one embodiment, the imaging device3according to the present embodiment may further include a light delivery unit180(refer toFIG.2) configured to condense the light provided from a target T to provide the condensed light to the slit110. Here, the light delivery unit180(refer toFIG.2) may include as described above at least any one of an objective lens182(refer toFIG.2) configured to condense the light provided from the target T and a focusing lens184(refer toFIG.2) configured to provide the light condensed by the objective lens182(refer toFIG.2) to the slit110.

The condenser152is disposed to condense the light of a desired order from the diffraction grating130. The condenser152is configured to condense the light of the desired order to provide to the detector154, and the detector154is configured to output an electrical signal corresponding to provided light.

The diffraction grating130is configured to provide the 0thorder light to the imaging unit190. The imaging unit190includes a focusing lens194configured to focus the provided 0thorder light. In the one embodiment, the diffraction grating130may have non-ideal characteristics, and consequently, the 0thorder light provided by the diffraction grating130may be diffused or condensed therefrom. For the purpose of correcting such non-ideal characteristics or reducing aberration, the imaging unit190may further include a condensing lens (not shown), and the condensing lens is configured to form the 0thorder light provided by being diffused or condensed from the diffraction grating130into the parallel light.

The imaging unit190is configured to image the light provided from the diffraction grating130, thereby allowing imaged light to be provided for an ocular observation and/or photograph. In the one embodiment, the light imaged by the imaging unit190may be provided to a microscope for ocular observation of the target or may be provided to a photographing device for photographing the target. According to an embodiment not shown inFIG.5, the imaging unit190may further include a beam splitter configured to allow the light provided by the focusing lens194to be split and the split light to be provided for the ocular observation and photograph.

Similar to the above-described embodiment of the spectrometer, the wavelength region to be analyzed may be adjusted by splitting the light by adjusting the position of a detection unit150with respect to the diffraction grating130.

In the embodiment described above with reference to the drawings, the collimator120, the condenser152, the objective lens182, and the focusing lens184are all exemplified as convex lenses. However, such convex lenses may be used in combination with concave lenses in order to reduce an influence of non-ideal characteristics of the lens, such as chromatic aberration. In addition, the convex lens may be substituted with a concave mirror (or vice versa), and the concave lens may be substituted with a convex mirror (or vice versa).

Although it has been described with reference to the embodiments shown in the drawings in order to help the understanding of the present disclosure, these are embodiments for implementation and merely examples. Accordingly, it will be appreciated by those of ordinary skill in the art that other embodiments having various modifications and equivalents of the above embodiments are possible. Accordingly, the true technical protection scope of the present disclosure should be defined by the appended claims.