CN103175611B - Free-form optical device used for correcting astigmatism and coma aberration in spectrograph - Google Patents
Free-form optical device used for correcting astigmatism and coma aberration in spectrograph Download PDFInfo
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Abstract
The invention relates to improvement on optical spectrum instruments and aims at providing a free-form optical device used for correcting astigmatism and coma aberration in a spectrograph. The spectrograph comprises a light source, an incident slit, a concave collimating mirror, a plane diffraction grating, a concave imaging mirror and a photoelectric detector, the free-form optical device is positioned between the concave imaging mirror and the photoelectric detector, and the upper surface of the free-form optical device is a free-form surface while the lower surface of the same is a plane and is stacked together with the photoelectric detector. The free-form optical device is arranged on the photoelectric detector (a linear CCD (charge coupled device) array) of the spectrograph, and curvature of the free-form surface of the upper surface changes respectively along and perpendicularly to the dispersion direction to respectively correct comatic aberration and astigmatism of the spectrograph, so that light collecting efficiency is improved and sensitivity of the spectrograph is increased.
Description
Technical Field
The invention relates to an improvement of a spectral instrument, in particular to a free-form surface optical device for simultaneously correcting meridional coma aberration and astigmatism of a broadband of a spectrometer system.
Background
Spectroscopic instruments are commonly used to determine the spectral composition of a light source, including spectral wavelength distribution, intensity response, and spectral bandwidth. Taking a conventional Czerny-Turner spectrometer as an example, the conventional Czerny-Turner spectrometer includes an entrance slit, a planar diffraction grating, a collimating mirror, an imaging mirror and a photodetector. The collimator collimates and reflects the incident beam to the diffraction grating, the reflector focuses and images the beam dispersed by the diffraction grating onto the detector, and the common photoelectric detector is a linear CCD array, so the light collecting efficiency and resolution of the spectrometer need to be improved.
In the Czerny-Turner spectrometer system, the light rays pass through the off-axis collimating mirror and the imaging mirror, reach different optical paths on the image surface, and have different intersection points with the main light rays, so that aberration is generated. In the meridian plane, the marginal rays on both sides are reflected by the reflector and then intersect with the principal ray at different points, so that meridional coma is generated. Meanwhile, after the light rays are reflected by the reflection system, the intersection points of the light beams in the meridian plane and the principal ray and the intersection points of the light beams in the sagittal plane and the principal ray are not coincident, so that astigmatism is obtained. Astigmatism and coma are the main factors affecting the collection efficiency and resolution of the CCD array, so both types of aberrations need to be corrected in the spectrometer.
The common method is to add a cylindrical mirror on the image plane of the spectrometer, but the cylindrical mirror can only correct the astigmatism of the spectrometer. Method for correcting coma aberration of spectrometer system: and adjusting various parameters of the optical system, namely selecting proper off-axis angle and curvature radius of the collimating mirror, off-axis angle and curvature radius of the imaging mirror, and incident angle and diffraction angle of light on the grating, so that the parameters meet Shafer formula to correct coma aberration with specific wavelength. However, this method can correct only coma aberration of the center wavelength, and coma aberration of the entire optical system is distributed in a V-shape with wavelength variation.
In order to obtain the maximum resolution and the maximum light collecting efficiency of the spectrometer, an optical device is needed to simultaneously correct astigmatism and broadband meridional coma of the spectrometer.
Disclosure of Invention
The invention mainly aims to overcome the defects in the prior art and provide a free-form surface optical device capable of simultaneously correcting the meridional coma aberration and astigmatism of a broadband of the existing spectrometer. In order to solve the technical problem, the solution of the invention is as follows:
the free-form surface optical device is characterized in that the free-form surface optical device is positioned between the concave surface imaging mirror and the photoelectric detector, the upper surface of the free-form surface optical device is a free-form surface, the lower surface of the free-form surface optical device is a plane, and the lower surface of the free-form surface optical device is overlapped with the photoelectric detector; the free-form surface is determined by the following method:
A. and calculating the total coma generated by the light beam passing through the concave collimating mirror, the plane diffraction grating and the concave imaging mirror: the optical path function of a light beam entering the spectrometer from the entrance slit and reflected to the planar diffraction grating by the concave collimator can be expressed as:
wherein, F1The optical path of the marginal ray from the incident slit to the concave collimating mirror and then to the plane diffraction grating, R and R 'are the optical paths of the principal ray before and after passing through the concave collimating mirror, omega is the distance between the marginal ray and the principal ray on the concave collimating mirror, alpha and alpha' are the incident angle and the emergent angle of the principal ray on the concave collimating mirror, R1The radius of curvature of the concave collimating mirror;
since the light rays behind the concave collimating mirror are parallel light, r' = ∞;
from the geometrical relationship of the light beams we can derive ω = ω '/cos α',；
where ω' is the half-width of the parallel beam after passing through the concave collimating mirror, W is the width of the planar diffraction grating, αgThe incident angle of the parallel light beam on the planar diffraction grating can be obtained, so that the formula (1) can be simplified:
according to the Fermat principle, i.e.It is possible to obtain:
α = - α' can be obtained from the reflection principle, and the first term of formula (2) is zero;
getSuch that the second term of equation (2) is also zero, equation (2) can be expressed as:
can obtainThat is, the formula (3) is ∂ alpha for the angular aberration generated by passing light through the concave collimating mirrorgExpressing coma after light passes through the concave collimating mirror;
according to the grating equation m λ = d (sin α)g+sinβg) Where m is an integer, λ is the wavelength, d is the grating constant, βgThe diffraction angle of the light with the wavelength on the plane diffraction grating is shown;
the angle aberration generated by the concave collimating mirror can be changed into the following by diffraction of the plane diffraction grating:
wherein, ∂ betagRepresenting the angular aberration of the light after passing through a concave collimating mirror and a planar diffraction grating, using ∂ betagExpressing coma after light passes through the plane diffraction grating;
in the same way, coma generated after light passes through the concave imaging mirror can be deduced;
let light reach the concave from the planar diffraction gratingThe optical path function of the surface imaging mirror to the image surface is F2Then F is2The derivation process of (2) is consistent with the derivation process of light from the entrance slit to the concave collimating mirror to the planar diffraction grating, so that:
wherein, F2The optical path of marginal ray from the plane diffraction grating to the concave imaging mirror to the image plane, beta is the incident angle of the chief ray on the concave imaging mirror, R2Is the radius of curvature of the concave imaging mirror;
so that the total coma aberration delta generated by the concave collimating mirror, the planar diffraction grating and the concave imaging mirrortCan be expressed as:
B. calculating out coma aberration generated in the spectrometer structure by each wavelength of light beam after adding the free-form surface optical device: adding free-form surface optical device above the photoelectric detector, wherein the curvature of the intersection part of the light beam and the free-form surface is R3Instead, the refractive index of the material of the free-form surface optic for the wavelength is replaced by n,
the light ray reaches the optical path function F of the image plane from the plane diffraction grating to the concave imaging lens and then to the free-form surface optical device30Can be expressed as: increasing the optical path from the plane diffraction grating to the concave imaging mirror to the original image surface of the front light of the free-form surface, subtracting the optical path from the position of the front free-form surface of the free-form surface to the original image surface, and adding the optical path from the position of the rear free-form surface of the free-form surface to the current image surface; f30Can be expressed as:
F30=F2+F3(7)
in which increasing the free-curved front light from a planar diffraction grating to concave imagingOptical path F from mirror to original image plane2The remaining part of the optical path F, which has been derived previously3Can be expressed as:
wherein, F3The change of the optical path of the edge light from the free-form surface optical device to the image surface after the free-form surface is added and before the free-form surface is added is shown, omega3Distance r of marginal ray from principal ray of light beam on free-form surface optical device3And r'3The optical paths from the position to the image plane of the chief ray when the free-form surface optical device is not added and the chief ray after the free-form surface optical device is added are respectively beta3And beta'3The incident angle and the refraction angle of the chief ray on the free-form surface optical device are respectively;
the width omega of the light beam on the concave collimating mirror is calculated by the formula (8), and sin beta is obtained according to the refraction principle3=nsinβ′3The optical path difference can be expressed as:
selection of r3，r3'，R3，β3With the proviso that the first term in equation (9) is 0, and combining the geometric relationship, the relationship of equation (10) is obtained:
coma aberration Δ generated by the free curved surfacecCan be expressed as:
in summary, the coma aberration Δ generated in the spectrometer structure by the light beam with each wavelength after the free-form surface optical device is added is:
Δ=Δt+Δc(12)
C. determining a free-form surface: the sum of the meridional coma aberrations of the spectrometer in a certain waveband range is reduced to the minimum by utilizing an evaluation function so as to correct the coma aberration of a wide waveband;
in the formula (11) < beta >, < beta >3、r3、R3N four variables are changed along with the wavelength, and the variable value corresponding to a certain wavelength is calculated as beta3λ,、r3λ、R3λ、nλWherein n isλA refractive index at the current wavelength; firstly, get the appropriate r30The intersection point position of the central wavelength principal ray and the free-form surface is shown; and that the radius and centre of curvature of each point on the curve formed by the intersection of the free-form surface with the meridian plane may be different, but the centre of curvature must lie on the line on which the central wavelength principal ray lies, then for each selected R3λFrom the geometric relationship, a certain beta can be obtained3λAnd r3λTherefore, the optimization process is to find R corresponding to each wavelength within a certain range3λMinimizing the merit function of equation (13);
the intersection point position and curvature of the free-form surface and the principal ray of each wavelength in the meridian plane can be determined according to the optimized variable values, the values are fitted into a curve, the curve is formed by the intersection of the free-form surface and the meridian plane, and the curvature of the curve which is perpendicular to the meridian plane and intersects with the curve is selected to correct astigmatism, namely the free-form surface required by people is determined.
In the present invention, the center thickness of the free-form optical device is 9.4 mm.
In the present invention, the free-form surface optical device is an optical device made of optical glass.
In the present invention, the radius of curvature of the free-form surface perpendicular to the dispersion direction is between 4.5mm and 5.5 mm.
Compared with the prior art, the invention has the beneficial effects that:
a free-form surface optical device is added on a photoelectric detector (a linear CCD array) of the spectrometer, the free-form surface curvature of the free-form surface optical device is respectively changed along the dispersion direction and the direction vertical to the dispersion direction, the meridional coma aberration and astigmatism of the spectrometer are respectively corrected, the light collecting efficiency is improved, and the sensitivity of the spectrometer is increased.
Drawings
FIG. 1 is a block diagram of the present invention.
Fig. 2 is a cross-sectional view of the present invention.
Fig. 3 is a side view of the present invention.
Fig. 4 is a schematic bottom view of the present invention.
FIG. 5 is a diagram of a spectrometer system incorporating the present invention.
Fig. 6 is a meridional view of a section of free-form surface corresponding to a certain wavelength.
FIG. 7 is an optical path diagram of a concave collimating mirror in a spectrometer.
The reference numbers in the figures are: 1, a light source; 2 an entrance slit; 3, a concave collimating mirror; 4 a planar diffraction grating; 5 a concave imaging mirror; 6 an upper surface of the free-form surface optical device; 7 a lower surface of the free-form surface optic; 8, a photoelectric detector; 9 incident light beam; 10 collimating the light beam; 11 image the light beam.
Detailed Description
The invention is described in further detail below with reference to the following detailed description and accompanying drawings:
the spectrometer comprises a light source 1, an incident slit 2, a concave collimating mirror 3, a plane diffraction grating 4, a concave imaging mirror 5 and a photoelectric detector 8, and is a Czerny-Turner spectrometer.
In order to correct the meridian coma aberration of the broadband of the spectrometer system, a free-form optical device is arranged between the concave imaging mirror 5 and the photoelectric detector 8. As shown in fig. 1, the upper surface 6 of the free-form optical device is a free-form surface, and the curvature of the free-form surface along the dispersion direction varies depending on the wavelength intersecting it to correct the meridional coma aberration for each wavelength. Perpendicular to the dispersion direction, the curved surface also has a curvature for correcting astigmatism. The lower surface 7 of the free-form optical device is flat because it is bonded to the photodetector 8. The center thickness of the free-form surface optical device is 9.4mm, the curvature radius of the free-form surface vertical to the dispersion direction is between 4.5mm and 5.5mm, the free-form surface optical device is made of optical glass, and common glass such as K9 can be selected.
The free-form surface is determined by the following method:
A. and calculating the total coma aberration generated by the light beam passing through the concave collimating mirror 3, the plane diffraction grating 4 and the concave imaging mirror 5: the optical path function of the light beam entering the spectrometer from the entrance slit 2 and reflected to the planar diffraction grating 4 by the concave collimating mirror 3 can be expressed as:
wherein, F1The light path of the marginal ray from the incident slit 2 to the concave collimating mirror 3 and then to the plane diffraction grating 4, R and R 'are the light paths of the principal ray before and after passing through the concave collimating mirror 3, omega is the distance between the marginal ray and the principal ray on the concave collimating mirror 3, alpha and alpha' are the incident angle and the emergent angle of the principal ray on the concave collimating mirror 3, R is the angle of incidence and the emergent angle of the principal1Being half the curvature of the concave collimating mirror 3And (4) diameter.
Since the light rays after the concave collimator lens 3 are parallel light, r' = ∞;
from the geometrical relationship of the light beams we can derive ω = ω '/cos α',；
where ω' is the half width of the parallel beam after passing through the concave collimating mirror 3, W is the width of the planar diffraction grating 4, αgThe incident angle of the parallel light beam on the planar diffraction grating 4 is shown, so equation (1) can be simplified:
according to the Fermat principle, i.e.It is possible to obtain:
α = - α' can be obtained from the reflection principle, and the first term of formula (2) is zero;
getSuch that the second term of equation (2) is also zero, equation (2) can be expressed as:
can obtainThat is, the formula (3) is ∂ α for the angular aberration generated by the light passing through the concave collimator lens 3gIndicating coma after the light passes through the concave collimating mirror 3.
According to the grating equation m λ = d (sin α)g+sinβg) Where m is an integer, λ is the wavelength, d is the grating constant, βgThe diffraction angle of the light with the wavelength on the plane diffraction grating 4;
the angle aberration generated by the concave collimating mirror 3 can be obtained to be changed into:
wherein, ∂ betagRepresenting the angular aberration of the light after passing through the concave collimator lens 3 and the planar diffraction grating 4, using ∂ betagIndicating coma aberration of the light after passing through the planar diffraction grating 4.
In the same way, coma aberration generated after the light passes through the concave imaging mirror 5 can be deduced;
let the optical path function of the light from the plane diffraction grating 4 to the concave imaging mirror 5 and then to the image plane be F2Then F is2The derivation process of (2) is consistent with the derivation process of the light from the entrance slit 2 to the concave collimator lens 3 to the planar diffraction grating 4, so that:
wherein, F2The optical path of the marginal ray from the plane diffraction grating 4 to the concave imaging mirror 5 to the image plane, beta is the incident angle of the chief ray on the concave imaging mirror 5, R2The radius of curvature of the concave imaging mirror 5.
So that the total coma aberration delta generated by the concave collimating mirror 3, the planar diffraction grating 4 and the concave imaging mirror 5tCan be expressed as:
B. calculating the spectrum of each wavelength of light beam after adding the free-form surface optical deviceComa generated in the structure: adding free-form surface optics above the photodetector 8, the curvature of the intersection of the beam and the free-form surface using R3Instead, the refractive index of the material of the free-form surface optical device corresponding to the wavelength is replaced with n.
The light reaches the optical path function F of the image plane from the plane diffraction grating 4 to the concave imaging mirror 5 and then to the free-form surface optical device30Can be expressed as: increasing the optical path from the plane diffraction grating 4 to the concave imaging mirror 5 to the original image surface of the front light of the free-form surface, subtracting the optical path from the position of the front free-form surface of the free-form surface to the original image surface, and adding the optical path from the position of the rear free-form surface of the free-form surface to the current image surface; f30Can be expressed as:
F30=F2+F3(7)
wherein the optical path F of the free-curved front light from the planar diffraction grating 4 to the concave imaging mirror 5 to the original image surface is increased2The remaining part of the optical path F, which has been derived previously3Can be expressed as:
wherein, F3The change of the optical path of the edge light from the free-form surface optical device to the image surface after the free-form surface is added and before the free-form surface is added is shown, omega3Distance r of marginal ray from principal ray of light beam on free-form surface optical device3And r'3The optical paths from the position to the image plane of the chief ray when the free-form surface optical device is not added and the chief ray after the free-form surface optical device is added are respectively beta3And beta'3The incident angle and the refraction angle of the chief ray on the free-form optical device, respectively.
The width omega of the light beam on the concave collimating mirror 3 is calculated by the formula (8) and is subjected to the refraction principle sin beta3=nsinβ′3The optical path difference can be expressed as:
selection of r3，r3'，R3，β3With the proviso that the first term in equation (9) is 0, and combining the geometric relationship, the relationship of equation (10) is obtained:
coma aberration Δ generated by the free curved surfacecCan be expressed as:
in summary, the coma aberration Δ generated in the spectrometer structure by the light beam with each wavelength after the free-form surface optical device is added is:
Δ=Δt+Δc(12)
C. determining a free-form surface: the sum of the meridional coma aberrations of the spectrometer in a certain waveband range is reduced to the minimum by utilizing an evaluation function so as to correct the coma aberration of a wide waveband;
in the formula (11) < beta >, < beta >3、r3、R3N four variables are changed along with the wavelength, and the variable value corresponding to a certain wavelength is calculated as beta3λ,、r3λ、R3λ、nλWherein n isλA refractive index at the current wavelength; firstly, get the appropriate r30The intersection point position of the central wavelength principal ray and the free-form surface is shown; and that the radius and centre of curvature of each point on a curve formed by the intersection of the free-form surface with a meridian plane may be different, but of courseThe center must be on the line on which the central wavelength principal ray lies, then for each selected R3λFrom the geometric relationship, a certain beta can be obtained3λAnd r3λTherefore, the optimization process is to find R corresponding to each wavelength within a certain range3λThe evaluation function of equation (13) is minimized.
The intersection point position and curvature of the free-form surface and the principal ray of each wavelength in the meridian plane can be determined according to the optimized variable values, the values are fitted into a curve, the curve is formed by the intersection of the free-form surface and the meridian plane, and the curvature of the curve which is perpendicular to the meridian plane and intersects with the curve is selected to correct astigmatism, namely the free-form surface required by people is determined.
The free-form optical device made of the determined free-form surface on the upper surface is arranged on the photoelectric detector 8, and the device can be used for simultaneously correcting the meridional coma aberration and astigmatism of the broadband of the existing spectrometer.
Claims (4)
1. A free-form surface optical device for correcting astigmatism and coma aberration of a spectrograph comprises a light source, an incident slit, a concave collimating mirror, a planar diffraction grating, a concave imaging mirror and a photoelectric detector, and is characterized in that the free-form surface optical device is positioned between the concave imaging mirror and the photoelectric detector, the upper surface of the free-form surface optical device is a free-form surface, the lower surface of the free-form surface optical device is a plane, and the lower surface of the free-form surface optical device is overlapped with the photoelectric detector; the free-form surface is determined by the following method:
A. and calculating the total coma generated by the light beam passing through the concave collimating mirror, the plane diffraction grating and the concave imaging mirror: the optical path function of a light beam entering the spectrometer from the entrance slit and reflected to the planar diffraction grating by the concave collimator can be expressed as:
wherein,the light path of the marginal ray from the entrance slit to the concave collimating mirror and then to the planar diffraction gratingRepresenting the optical path of the light from the point where it begins to diverge to the concave collimating mirror,representing the optical path of the light from the concave collimating mirror to the light converging point;the distance between the marginal ray and the principal ray on the concave collimating mirror,the incident angle and the exit angle of the chief ray on the concave collimating mirror respectively,the radius of curvature of the concave collimating mirror;
because the light rays are emitted from the slit and become parallel light after passing through the concave collimating lens, namely, the parallel light is converged at infinity, the light rays are emitted from the slit and become parallel light after passing through the concave collimating lens, and therefore, the light rays are emitted from the slit and become parallel light after passing through the concave collimating lensIs a finite number, and
from the geometrical relationship of the beams
Wherein,is the half width of the parallel light beam after passing through the concave collimating mirror,the width of the plane diffraction grating is related to the beam width or cone angle of the light when the light propagates in the spectrometer, and the beam width or cone angle influences the aberration; the width of the grating refers to the width capable of passing light;the incident angle of the parallel light beam on the grating;
thus, equation (1) can be simplified:
according to the Fermat principle, the light path is extreme from one point to another, so that the light reaches the receiving surface from the point of emission, if this is sufficientThere is no aberration; i.e. here looking forThe conditions of (1):
according to the principle of reflection, can obtainThe first term of formula (2) is zero;
getSuch that the second term of equation (2) is also zero, equation (2) can be expressed as:
can obtainThat is, the formula (3) is the angular aberration generated by the light passing through the concave collimating mirrorExpressing coma after light passes through the concave collimating mirror;
according to the grating equationWherein,is an integer which is the number of the whole,is a function of the wavelength of the light,is a constant of the grating, and is,the diffraction angle of the wavelength light on the grating;
the angle aberration generated by the concave collimating mirror can be changed into the following by diffraction of the plane diffraction grating:
wherein,the optical system represents the angular aberration of light after passing through the concave collimating mirror and the planar diffraction grating, the angular aberration is in proportional relation with the coma aberration, and the coma aberration is reduced along with the angular aberration; so can useTo express the amount of coma after the light passes through the plane diffraction grating;
in the same way, the coma quantity generated after the light passes through the concave imaging mirror can be deduced;
the optical path function of the light from the grating to the concave imaging lens and then to the image plane is set asThe light ray refers to any light ray in the light beam, including marginal light rays; thenThe derivation process of (2) is consistent with the derivation process of light from the slit to the concave collimating mirror to the grating, so that:
wherein,the incident angle of the chief ray on the concave imaging mirror,is the radius of curvature of the concave imaging mirror;
so that the total coma generated by the concave collimating mirror, the planar diffraction grating and the concave imaging mirrorCan be expressed as:
B. calculating out coma aberration generated in the spectrometer structure by each wavelength of light beam after adding the free-form surface optical device: adding free-form surface optical device above the photoelectric detector, and using the curvature of the intersection part of the light beam and the free-form surfaceInstead, the material of the free-form surface optic has a refractive index corresponding to the wavelengthInstead of this, the user can,
the light path function from the plane diffraction grating to the concave imaging lens and then to the free-form surface optical device to the image planeCan be expressed as: increasing the optical path from the plane diffraction grating to the concave imaging mirror to the original image surface of the front light of the free-form surface, subtracting the optical path from the position of the front free-form surface of the free-form surface to the original image surface, and adding the optical path from the position of the rear free-form surface of the free-form surface to the current image surface;can be expressed as:
wherein the optical path of the light in front of the free curved surface from the plane grating to the concave imaging mirror to the original image surface is increasedThe remaining part of the optical path, which has been deduced beforeCan be expressed as:
wherein,the change of the optical path of the marginal ray from the free-form surface optical device to the image surface after the free-form surface is added and before the free-form surface is added is shown,the distance of the marginal ray of the beam from the chief ray on the free-form optical device,andthe optical paths from the position to the image plane of the chief ray are respectively when the free-form surface optical device is not added and after the free-form surface optical device is added,andthe incident angle and the refraction angle of the chief ray on the free-form surface optical device are respectively;
since the optical system is based on the law of refraction,and deriving from the geometric relationship:
thereby finishing to obtainIn relation to (2)；
Is substituted by formula (8) andto pairCalculating the partial derivatives, the optical path difference can be expressed as:
selectingWith the proviso that the first term in equation (9) is 0, and combining the geometric relationship, the relationship of equation (10) is obtained:
coma generated by the free curved surfaceCan be expressed as:
in summary, the coma aberration Δ generated in the spectrometer structure by the light beam with each wavelength after the free-form surface optical device is added is:
C. determining a free-form surface: the sum of the meridional coma aberrations of the spectrometer in a certain waveband range is reduced to the minimum by utilizing an evaluation function so as to correct the coma aberration of a wide waveband;
in the formula (11)The four variables are varied with the wavelength, and the variable value corresponding to a certain wavelength is calculated asWherein,a refractive index at the current wavelength; get the right firstThe intersection point position of the central wavelength principal ray and the free-form surface is shown; and that the radius and centre of curvature of each point on the curve formed by the intersection of the free-form surface with the meridian plane may be different, but the centre of curvature must lie on the line on which the central wavelength principal ray lies, then for each selected pointDetermined by geometric relationshipsAndso the optimization process is to find the corresponding wavelength in a certain rangeMinimizing the merit function of equation (13);
the intersection point position and curvature of the free-form surface and the principal ray of each wavelength in the meridian plane can be determined according to the optimized variable values, the values are fitted into a curve, the curve is formed by the intersection of the free-form surface and the meridian plane, and the curvature of the curve which is perpendicular to the meridian plane and intersects with the curve is selected to correct astigmatism, namely the free-form surface required by people is determined.
2. The free-form optical device of claim 1, wherein the free-form optical device has a center thickness of 9.4 mm.
3. The free-form optical device of claim 1, wherein the free-form optical device is an optical device made of optical glass.
4. The free-form optical device of claim 1, wherein a radius of curvature of the free-form surface perpendicular to the dispersion direction is between 4.5mm and 5.5 mm.
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Cited By (3)
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| US9964444B2 (en) | 2015-05-28 | 2018-05-08 | University Of Rochester | Imaging spectrometer design tool for evaluating freeform optics |
| WO2018147731A1 (en) * | 2017-02-08 | 2018-08-16 | Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno | Correction of curved projection of a spectrometer slit line |
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| WO2016200816A1 (en) | 2015-06-07 | 2016-12-15 | University Of Rochester | Imaging spectrometer with freeform surfaces |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5384656A (en) * | 1991-10-16 | 1995-01-24 | Hyperfine, Inc. | Astigmatism corrected gratings for plane grating and spherical mirror spectrographs |
| CN101498606B (en) * | 2009-01-15 | 2010-11-10 | 清华大学 | Cheney-turner spectrometer |
| CN101634591A (en) * | 2009-08-21 | 2010-01-27 | 南开大学 | Spectrometer using cylindrical lens for astigmatism correction |
| CN101916044B (en) * | 2010-07-27 | 2011-12-21 | 浙江大学 | Free-form surface lens for double-quadrupole uniform illumination |
| CN101916047B (en) * | 2010-07-27 | 2011-12-21 | 浙江大学 | Photolithography exposure device for implementing off-axis illumination by using free-form surface lens |
| CN102932583B (en) * | 2012-07-19 | 2015-05-06 | 湖南源信光电科技有限公司 | Refraction-reflection whole-focusing imaging method |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9964444B2 (en) | 2015-05-28 | 2018-05-08 | University Of Rochester | Imaging spectrometer design tool for evaluating freeform optics |
| DE102016124980A1 (en) | 2016-01-14 | 2017-08-03 | Analytik Jena Ag | Spectrometer with two-dimensional spectrum |
| WO2018147731A1 (en) * | 2017-02-08 | 2018-08-16 | Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno | Correction of curved projection of a spectrometer slit line |
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| CN103175611A (en) | 2013-06-26 |
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