GB2597748A

GB2597748A - Scanning depletion laser microscope

Info

Publication number: GB2597748A
Application number: GB2012000.2A
Authority: GB
Inventors: Huo Suguo
Original assignee: Lemon Scientific Instrument Ltd
Current assignee: Lemon Scientific Instrument Ltd
Priority date: 2020-07-31
Filing date: 2020-07-31
Publication date: 2022-02-09
Also published as: CN114063274A; GB202012000D0

Abstract

Two types of Scanning Depletion Laser (SDL) Microscope are used to obtain a depletion nanobeam composed by an Airy Disc and a reversed amplitude Doughnut. The first type of SDL (SDL-I) proposed employs an 180o phase shift lens unit composed of an Airy Disc lens 830 and a relative 180o phase shift Doughnut lens unit to form a depletion nanobeam on the sample surface after passing a laser beam. The second type of SDL (SDL-II) employs two 180o phase shift laser crossbeams 1712, 1714 to pass an Airy Disc lens and a Doughnut lens unit in a zero phase shift lens unit, respectively, to form a depletion nanobeam on the sample surface. Solutions and gases can also fill between the lens unit and the sample to further reduce the nanobeam size. A high resolution nanoscale image may be obtained and this is useful for nanoscale optical lithography and nanoscale optical information storage.

Description

BACKGROUND

Nanoscale resolution optical image has been achieved with a stimulated emission depletion (STED) fluorescence microscope that was awarded Nobel chemistry prize in 2014. This invention has brought a revolutionary in optical image resolution by breaking through the optical diffraction limit although its application is limited to image of dye molecular. Nanoscale image is also claimed with a Scanning Nearfield Microscopy (SNM) that has a very sharp tip having a nanoscale hole. The SNM has not limitation to image any particular sample, its working distance is, however, only a few of nanometers causing other issues, such as nanoscale hole contamination and overheating when light intensity increases.

Photolithography is a key process to make mass production of circus, chips and devices and a photolithography machine for making nanoscale patterns on photoresist is an essential process for the success in micro/nano-electronic industry. Now, it is claimed that the line width made by an extremely expensive photolithography machine has managed to go down to sub 10 nm. However, this kind of optical Photolithography machine is too expensive to afford by many research institutes and even in many industries. Electron Beam Lithography (EBL) is Generally used for nanoscale research in universities, institutes or even in industry R&D and small scale production because EBL is relatively affordable. However, there are a lot of limitations in EBL for making nanoscale patterns, such as no magnetic stray field from the sample and the electron charge must be earthed. Particularly, EBL is too slow to use in mass production in industry. Also, sub 10 nm resolution presents a big challenge even using EBL. Scanning Laser Direct writer machine has also been invented and used in optical photolithography, but limit to submicron line width.

Information storage presents one of the key parts in information technology and people's daily life. Currently, magnetic storage and semiconductor flush memory are still two main methods for information storage. Optical storage has been beaten down due to a wave length limit leading to a low aerial storage density. However, compare with magnetic storage and semiconductor flush memory, optical storage uses a noncontact storage method and is free of virus during data transfer. Therefore, as long as the aerial storage density can match those in magnetic storage and flush memory, optical storage can replace the removable magnetic hard drive or removable flush memory drive due to its virus free, much economic by using an optical disc and more reliable because an optical storage disc is only a recording media without any mechanical or electrical complexity.

The disclosure proposed are two types of high resolution Scanning Depletion Laser (SDL) Microscope that don't need to dye or stain sample requested in a STED microscope and can also overcome most of the issues in a SNM The first type of the SDL microscope (SDL-1) uses a proposed phase shift lens unit, composed of 0' phase shift lens and a relative 1800 phase shift lens, to produce an Airy Disc beam and a reversed amplitude Doughnut beam, respectively, after passing a laser beam on the lens unit, to compose a nanoscale beam on sample surface by overcoming the optical wave length limit. The phase shift lens unit is composed of a central sub-wave length transparency round lens surround with at least three sub-wave length transparency round lenses to a ring shape lens having relative180° phase shift compared with that in the central one. The laser beam passing through the central lens will produce an Airy Disc and the laser beam passing the other surrounding 180" phase shift lenses will produce a series Airy Disc that will form a Doughnut shape laser beam pattern having a reversed amplitude compared with that from the central Airy Disc. The overlap of the Doughnut and the central Airy Disc, similar to that in a STED fluorescence microscope, can compose a nanoscale beam spot, a nanobeam on the sample surface The second type of SDL microscope (SDL-II) employs two 180" phase shift laser crossbeams passing a 0" phase shift lens unit composed of a sub-wave length transparency round lens and a lens of at least three small transparency sub-wave length round lenses to a ring shape, respectively, to produce an Airy Disc beam and a reversed amplitude Doughnut beam, respectively, to compose a nanoscale beam at the crossbeam point on a sample surface by overcoming the optical wave length limit.

The nanobeam produced by SDL-1 microscope or SDL-II microscope can then be used to image sample by scanning either the sample (stage) or the phase shift lens unit with the beam. A small size aperture may be used to block the scattering light. A detector like that used in SNM can be used for collecting the reflect beams from the sample. One design can be a ring shape photodetector to collect the reflect nanobeam by the sample. This SDL microscope could obtain a better resolution than that of about 20 nm claimed in STED fluorescence microscope because it can use a ultralight wave length, such as the typical ArF excimer 195 nm wave laser that has doubled less wave length than that of the shortest wave length of about 400 nm in a visible light used in STED fluorescence microscope.

The proposed Scanning Depletion Laser (SDL) Microscope can have many applications, such as, nanoscale images, nanoscale photolithograph and also high aerial density optical storage. Also, a typical laser beam spot can be micron to millimeter scale and can cover a multiple of the phase-shift lens units and a multiple of phase-shift lens units can greatly speed up the process Compared with STED fluorescence nanoscope, the proposed SDL microscope can work on all the materials and doesn't need to dye or stain the sample. Compared with scanning nearfield microscopy, the nanobeam laser microscopy doesn't need to use a nanoscale of 50 nm hole that can be easily contaminated, and can have a relatively large working distance. Particularly, the nanobeam in the SDL microscope can be much smaller than 50 nin, might go down to sub 10 nm The SDL microscope can be used for nanobeam lithography. The proposed SDL microscope can also be used like a normal laser direct writer, but can go down to nanoscale resolution due to using the proposed phase shaft lens unit to produce a nanobeam probe. Compared with EBL, the SDL nanobeam laser microscope doesn't require a conductive sample and nonmagnetic sample. Also, a multiple of nanobeams can speed up the process. SDL microscope is also much cheaper than any nanoscale photolithography machine.

Another application of SDL microscope is in information storage. Currently, magnetic hard drive storage and semiconductor flash memory are used in most of the information storage. The laser optical storage is rarely used because of its low areal density. The proposed SDL microscope can greatly increase the areal density over 1Tb per square inch if using a 20 nm nanobeam that can match or even higher than current available storage areal density in either magnetic or flash memory storage. Moreover, the laser storage is a non-contact storage that can prevent of any virus transfer issue -a common issue in using USB. Therefore, it is expected that the nanobeam laser storage can replace the current removable USB drive because of no virus issue through storage transfer and also optical disc is much cheap.

SUMMARY

Two types of Scanning Depletion Laser (SDL) Microscope are proposed for nanoscale images, nanoscale optical lithography and high aerial density nanoscale optical storage. The first type of SDL (SDL-I) uses a phase shift lens unit composed of both a 00 phase shift lens and 180° phase shift lens unit to realize a nanoscale beam by passing over the optical wave limitation. In one embodiment, the phase shift lens unit is composed of an Airy Disc lens having a sub-wave length size round lens surrounding by a relative 180) phase shift Doughnut lens unit composed of at least three Airy Disc lenses. After a laser beam passes through the phase shift lens unit, an Airy Disc is formed by the central round lens and a Doughnut shape, having a reversed amplitude, is formed with a series of Airy Disc produced by the surrounding 180" phase shift lens to form a depletion nanobeam spot on the sample surface because the overlapped parts of Airy Disc and the reversed amplitude Doughnut can cancel each other due to their 180° phase shift in amplitudes. In a second embodiment, the two 180° phase shift lenses are made on two 180' phase shift glasses at an angle of less than, but close to, 180" to overcome the extremely complicated fabrication of the first embodiment proposed above and it can also convert the laser beam into two cross beams of a 0° phase shift Airy Disc and a 180' phase shift Doughnut to form a depletion nanobeam at the cross-point of the two beams. In a third embodiment, a kind of semi-sphere lens (or semi-sphere shell lens) composed of one nanosized lens unit on its top polar point to produce a doughnut beam and a few of nanosized relative 180') phase shift lenses, arranged symmetrically relative the top polar point on a latitude circle of the semi-sphere lens, to produce one strong amplitude 180° phase shift Airy Disc by eliminating their horizontal components at their crossbeam point and then compose with the reversed amplitude Doughnut beam to form a depletion nanobeam for nanoscale images, nanoscale photolithography and even in nanoscale optical recording. The second type of SDL (SDL-H) microscope proposed has employed two relative180° phase shift laser beams to pass an Airy Disc lens and a Doughnut lens, respectively, to produce an Airy Disc beam and a reversed amplitude Doughnut beam to form a deletion nanobeam at the cross-point of crossbeams on a sample surface. In one embodiment, the Airy Disc lens and the Doughnut lens are mode on two joined glasses at an angle of less than, but close to, 180'. In a second embodiment, a group of Airy Disc lenses and a group of Doughnut lens units are placed on a symmetry position, relative to the pole of a semi-sphere shell lens unit (or a semi-sphere lens unit) or a sphere lens, respectively. Two 180" shift polarized beams can also be used in SDLII microscope to compensate horizontal amplitudes to obtain even a sharp composed depletion nanobeam. Solutions and gases can be used to fill between the lenses and the sample surface in SDL-I and SDL-II to further reduce the nanobeam size.

A multiple of phase shift lens units and multiple of sources are also proposed to speed up the process. The source of the SDL will include both of normal and polarised visible, UV, EV light and electromagnetic waves.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig.1 shows a typical single-point scanning STED microscope work principle.

Fig.2 shows the textures for materials used in the designs.

Figs.3(a)-3(d) show the Aperture, Airy Discs and Amplitudes & Intensity on a sample for one Airy Disc, two Airy Discs without much overlapped, two Airy Discs with almost one thirds overlapped and two Airy Discs with almost two thirds overlapped, respectively.

Figs.4(a)&4(b) show Mask designs, Amplitude & Intensity for a lens without Phase Shift Mask and a Lens with 180" Phase Shift Mask, respectively.

Figs.5(a)&5(b) show the Mask design and Amplitude & Intensity for a single lens with 180' Phase Shift Mask and two lenses without Phase Shift Mask, respectively.

Fig.6(a)&6(b) show the design, Amplitude and Intensity of an 180" Phase Shift Lens unit composed of the Lenses in Fig.5(a)&5(b), respectively.

Figs.7(a)&(b) show the Phase Shift Lens designs, Airy Disc and Amplitudes of one central nanoscale lens with 1800 phase and six surrounding nanoscale lenses with 00 phase shift, respectively.

Figs.8(a)-8(c) show two types of nanobeam phase shift lens unit designs for the first kind of Scanning Depletion Laser (SDL-I) microscopy, Airy Discs and Amplitudes & Intensity of all Lenses shown in Fig.7(a)&7(b) and one central 180' phase shift lens surround by a ring shape 00 phase shift lenses, respectively.

Figs.9(a)-9(c) show a second embodiment of a SDL-I design of two 180" relative phase shift lenses joined at an angle of close to, but smaller than, 1800, the nanobeam formed at the cross point by the depletion of the Airy Disc and the reversed amplitude Doughnut and their corresponding Amplitudes, respectively.

Figs.10(a)-10(e) show a top view, a side view, a cross-section view, the beam Airy Discs and the corresponding Amplitudes of a cross beam Semi-spherical shell (or Semi-spherical) 180" phase shift lens design of SDL-I microscope, Figs.11(a)-11(c) illustrate the top views of three sub-wave length lenses of an Airy Disc lens, a Doughnut lens and a Trimer lens, their corresponding Airy Discs and the amplitudes & intensities, respectively.

Figs.12(a)-12(d) show the top views, cross sectional views of the three embodiment SDL-II microscopes of combined two sub-wave length lenses of an Airy Disc lens with a Doughnut lens, an Airy Disc lens with a Trimer lens and a compact Trimer lens with a Trimer beam lens, their corresponding Amplitudes & Intensity and the Airy Discs including the composed nanobeam at the cross point of the two 180' phase shift cross beams on the two sub-wave lenses in each embodiment, respectively.

Figs.13(a)-13(c) show the top views, cross-sectional view and Airy Discs of two SDL-II microscope embodiments of a group of Airy Disc beam lenses with a group of Doughnut beam lenses and a group of a Trimer lens plus a central Airy Disc beam lenses with a group of Trimer beam lenses, symmetrically relative to the top polar point of a semi-spherical shell (or semi-spherical) lens and a spherical lens, respectively.

Figs.14(a)&14(b) show the top view and cross-sectional view of the two embodiments of SDLII lenses shown in Fig.13 attached on a probe cantilever frame, respectively.

Figs.15(a)-15(c) show a top view of a cantilever having a hole near the end of the cantilever, a top view and a side view of a spherical lens (or a semi-spherical shell lens) on a cantilever, respectively.

Figs.16(a)&16(b) show a top view of a 2/2 lens units on a frame and the corresponding 2/2 composed depletion nanobeams on a sample surface Fig.17 shows the lens unit in an SDL-II microscope with two polarized 180' phase shift crossbeams.

Fig.18 shows the lens unit composed of a separate an Airy Disc beam lens and a Doughnut beam (or a Trimer) lens, respectively.

DETAILED DESCRIPTION

Fig.1 100 is a typical single-point scanning S 1ED microscope where a focused excitation beam (left) is overlapped by a doughnut-shaped STED beam (middle) that instantly quenches excited molecules at the periphery of the excitation spot and meanwhile confines fluorescence emission to the doughnut zero. Saturated quenching results in a fluorescent spot of about 20 nm, far below diffraction (right), whose scanning across the sample yields a subdiffraction-resolution image.

Figs.2(a)-2(h) 200 show the textures for Opaque materials 210, Glass Lens materials 220, partially opaque materials 230, Lens with 180' phase shift 240, Lens with 0° phase shift 250, 1800 phase shift beam intensity 260, 00 phase shift beam intensity 270 and cantilever material 280, respectively. All of the materials will be used in the designs of this disclosure.

Fig.3 300 shows four kinds of lenses of 310, 320, 330, 340 and their corresponding Airy Disc and Amplitude & Intensity, respectively.

Fig.3(a) shows the top view & cross section view of a single sub-wave length hole lens design 310, the corresponding Airy Disc 316 and its amplitude & intensity 318. The lens design of 310 is actually like an aperture composed of 314, a sub-wave length diameter D hole, opened on an opaque material 312. The lens of top view and cross-sectional view through a to b are shown, respectively. The 314 diameter D is less than the laser wave length, A, and hence an Airy Disc, 316, is obtained. The Radius of Airy Disc, 316, can be expressed as 1.22 (1) R = Ah Where R is radius of Airy Disc;.!) is the diameter of the hole; A is the light wavelength and h is the working distance of the lens to the object.

Therefore, in order to obtain a small Airy Disc spot, small light wave length A, small working distance h and a relatively large hole D are required in the condition that the D must be smaller than the wave length A in order to obtain a light diffraction pattern.

Fig.3(b) shows the lens design of 320 composed of two identical (or almost identical) sub-wave length holes of same diameter D, 322 & 324, also made on an opaque material 312; the cross-sectional view through a to b of the lens; the two Airy Discs 326, just starting overlapped in their adjacent tails and the two corresponding beam Amplitudes in solid lines where each shows a Gauss distribution and the composed intensity of dot line in 328 The composed intensity shows a deep hump shape of dot line in 328.

Fig.3(c) shows the lens design of 330 composed of two even closer sub-wave length holes of same diameter D, 332 & 334, also made on the opaque material 312, the cross-sectional view through a to b of the lens; the two Airy Discs 336 of about 1/3 overlapped and their amplitudes of solid line & combined intensity of dot line in 338. The composed intensity shows a shallow hump shape Fig.3(d) shows the lens design of 340 composed of also two further closer sub-wave length holes of same diameter D, 342 & 344, made on the opaque material, 312. The lens top view

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and a cross-sectional view through a to b, the two Airy Discs 346 overlapped of about 2/3 and the two corresponding light Amplitudes in solid lines where each shows a Gauss distribution and also a more or less one peak Gauss distribution of composed Intensity in dot line of 348 With this further closing of the two holes, the hump composed intensity is disappeared and one peak composed intensity is obtained although there are still two peaks of amplitudes. Therefore, it is not possible to distinguish of two beams from the intensity if the two holes are too close.

Fig.4 400 illustrate the designs of two dual beam mask lenses of 410, a 0° phase shift lens, and 420, an 180" phase shift lens, and their corresponding amplitude and intensity, respectively.

Fig.4(a) shows the dual beam Mask lens design, 410, 0" phase shift lens and its corresponding amplitude & intensity of the two beams on the sample surface. 410 is composed of a glass 412 coated with an opaque material 320, such as chrome (Cr) widely used in an optical mask, and two open holes of 322 & 324 made on 320. The amplitudes of the two beams have a same phase and a bit of overlapped in the adjacent tails. The combined intensity shows a hump shape leading to an almost doubled size pattern instead of two separated patterns.

Fig.4(b) shows a dual beam Mask design 420, composed of a 0" phase shift lens and an 180° phase shift lens and their corresponding amplitudes & combined intensity on the sample surface. 420 is composed of a glass of 422 made by a 0° phase shift glass 412, an 180° phase shift glass 424 and also two holes of 322 & 324 made on 320 where 322 & 324 are underneath 412 and 424, respectively. Therefore, 322 plus 412 formed a 0° phase shift lens and 324 plus 424 formed an 180' phase shift lens. The beam Amplitude from 0° phase shift lens 322 & 412 is still same to that in Fig.4(a), but the beam Amplitude from the 180° phase shift lens 324 & 424 has been reversed. Then, their combined intensity shows a two well separated beam distributions because the overlapped parts of two reversed amplitudes are quenched each other. This kind of phase shift mask has been widely used in commercial photolithography processes to obtain well separated adjacent lines. This disclosure will employ this shift lens technique to obtain a narrow beam.

Figs.5(a)&(b) 500 show the design and corresponding Amplitude & Intensity for an 180° phase shift one sub-wave length hole aperture lens in 510 and 512 in Fig.5(a) and for a 0° phase shift two sub-wave length hole aperture in 520 and 524 in Fig.5(b), respectively.

The 180° phase shift one small hole aperture lens 510 is composed of both a zero-phase shift glass lens 412 and an 180° phase shift glass lens 424 and an opaque coating layer 310 with a sub-wave length hole aperture 314, just underneath 424. A laser beam on 424 lenses will pass through the small open hole of 314 to form a Gauss distribution of light amplitude 512.

The two 0° phase shift sub-wave length hole aperture lens 520 is also made on the same glass of 412 & 424, but the opaque coating layer 330 opens two sub-wave length holes of 332 & 334 underneath the 0' phase shift glass 412. 522 is a thin coating layer to reduce the passing beam amplitude to the two 0" phase shift lenses. 524 shows the corresponding two amplitudes from 332 & 324 in solid lines, respectively and their composed amplitude in hump dot lines is similar to 338 in Fig.3(c). The intensifies shown in 512 and 524 were reversed due to a 180' phase shift in 510 & 520. A reduced amplitude in 524 is obtained compared with that in 512 due to using 522.

Figs.6(a)&6(b) show a lens design 610 by combined of the two lenses in Fig.5 and the corresponding amplitudes & intensity 620 in 600, respectively. 610 is composed of 0° phase shift glass 412 coated with 522 to reduce light amplitude, 180" phase shift glass 424 and a coating opaque layer of 320 having three opening sub-wave length holes 332 and 334 with 314 in the middle. The 314 is underneath the 180° phase shift glass 424 to form an 180" phase shift lens and its corresponding amplitude is shown in A of 512. The 332 & 334 are underneath the 0" phase shift glass 422 to form a 0" phase shift lens whose corresponding amplitudes are shown in B of 524 Because the 314 hole is in the middle of the two holes 332 8z 334, the two amplitudes of 512 and 524 will be aligned and the combined Intensity of A & B will result in a narrow beam, C, shown in 622 after carefully engineering design. To obtain a desired beam amplitude of 524, as mentioned above, a coating layer 522 is used to reduce the hump amplitude to the right value. Clearly, the combined beam 622, shown in C, has a much fine probe shape.

However, three-hole phase shift lens design 610 in Fig.6 cannot produce a circle beam spot In order to obtain a symmetry nanobeam spot, at least four nanoscale holes are required where one central sub-wave length hole is surround by other three sub-wavelength holes on each vertex of a equilateral triangle.

Figs.7(a)&7(b) show two lenses of an 180° phase shift lens 710 and 0° phase shift lens 720, their corresponding Airy Discs and the amplitude & intensity distributions, respectively in 700. 710 shows the top view of the 180' phase shift lens and has one sub-wave length open hole 712. 714 is the illustration of the Airy disc on the sample surface after passing a laser beam through 712. 716 shows the corresponding Amplitude distributions cross a & b in 714. 720 is the top view of the zero-degree phase shift lens and it is composed of six same sub-wavelength holes 722 along a ring with equal space between any two adjacent holes. 724 shows the illustration of the airy disc assembly having a doughnut shape where each hole in 722 has its own Airy Disc and six Airy Discs along the ring can form a doughnut shape of 724 and 726 is the corresponding Amplitude distribution cross c & din 724, showing a zero-degree phase shift hump shape intensity. The amplitude in 726 is lower than that in 716 that can be achieved by using a coating layer 522 on the lens of 720 to reduce the light amplitude. ab and cd can be made to about same size.

Figs.8(a)-8(c) show two types of lens designs of 810 and 820 proposed to produce a nanobeam spot, their airy discs 830 and the corresponding amplitudes & Intensity 840 in 800. 810 shows the top view of the lens design of 812, composed of one 180' phase shift central sub-wave length hole lens surrounding by six sub-wave length hole 0" phase shift lenses. 820 shows the top view of the lens design of 822, composed of one 180° phase shift central sub-wave length hole lens surrounding by a 00 phase shift ring lens that can be considered as an infinite numbers of sub-wave length round lenses along a ring circle. The functions of 810 & 820 are similar and 810 is taken as an example to illustrate. 810 is actually a combination of the two lenses of 710 & 720 in Fig.7. As discussed in Fig.7, after passing a laser beam, 710 will produce an 180" phase shift Airy disc and 720 will produce a zero-phase shift doughnut shape. After 710 & 720 are aligned, the Airy Disc 832 and the reversed amplitude Doughnut 834 will overlap to compose a nanobeam spot 836 as shown in 830. 840 shows the amplitudes & intensity in solid line of ab cross section in the 180° phase shift Airy Disc 832 produced by 710, the amplitude in dash line and intensity in dot line of cd cross section in the 0" phase shift doughnut 834 produced by 720 and the composed nanobeam 842 by 716 and 726 intensity lines. Obviously, 842 is much narrower than that of the original Airy Disc beam 716 although the amplitude is reduced.

In the design, the central lens and its surround lenses will have a 1800 phase difference and they can be in the same plane or two different planes where the central lens will be on the top plane, far from the sample surface, and the surrounding lenses will be the low plane, near the sample surface in order to obtain a fine composed nanobeam spot by braking through the light wave limit The above phase shift lens unit design will require a very complicated fabrication process to make. In order to overcome this, a second embodiment of phase shift lens unit 900 where the 0" phase shift lens and the 180" phase shift lens unit are made on two 180° phase shift different glasses at an angle less than, but close to, 1800 angle is proposed and shown in Fig.9. The laser beam, 910, and the cross section, 920, of the 900 are shown in Fig.9(a), respectively. 920 is composed of two 180° phase shift glasses of 922 and 924 at an angle of a, close to, but smaller than 180" to convert the incident laser beam 910 into two cross beams of 912 and 914 at a small angle of at of (180°-a) through the lenses of 922 and 924, respectively, and then meet at the beam cross-point 916 to depletion into a nanobeam. The corresponding Airy Discs of the two crossbeams are shown in 930 of Fig.9(b) where 932 is the 1800 phase shift reversed amplitude Airy Disc of the beam 912, 934 is the 0° phase shift Doughnut of the beam 914 and the 936 is the depletion nanobeam formed at the beam cross-point of 916. The corresponding Amplitudes & Intensity of 932, 934 and 936 in 930 are shown as 944, 942 and 946, respectively, in 940 of Fig.8(c). Clearly, 940 in Fig.9(c) is also a nanosized beam probe, similar to the 840 in Fig.8(c).

In 900, the opaque layer in both lenses of 922 and 924 are coated in the bottom surface and the sub-wavelength holes are opened on the opaque layer. The opaque layer can also be coated on the glass top surface or coated on a top and bottom surface glasses and the sub-wavelength holes will be opened on the corresponding opaque layer to for the phase shift lens, respectively.

Clearly, the two 180' phase shift lenses in 910 fabricated on two glasses that can make the fabrication much easier, but the amplitude of either in Airy Disc or the Doughnut on the cross-point is not quite uniform on the horizontal plane that could result in some remain weak light in the depletion area around the depletion nanobeam at the cross-point of the two crossbeams. Also, the phase shift lens unit to obtain a Doughnut beam is composed of several sub-wavelength holes and then the amplitude of Doughnut is a much larger than that in an Airy Disc from a one sub-wavelength hole. As mentioned before, a semi-opaque coating on the Doughnut lens unit will be required to reduce the amplitude of Doughnut to that in Airy Disc and this will result in a weak depletion nanobeam.

Fig.10 1000 shows a third embodiment of semi-spherical shell (or semi-spherical) phase shift lens. The top view 1010 of the 1000 is shown in Fig.10(a) where a semi-spherical shell (or semi-spherical) lens of 1014 is placed on a holder of 1012. A 0° phase shift Doughnut lens unit of 1018 is at the center polar position of 1014 and the four 180° phase shift Airy Disc lenses of 1016 are symmetrically on a circle relative to the top polar position, also a center of the 1014. Fig.10(b) shows the side view of the 1010 where the semi-spherical shell lens 1014 sits on the hold of 1012 and 1018 is on the top polar point and all the four 1016 are located symmetrically on the latitude circle relative to the top polar point. 1020 in Fig.10(e) shows the cross-sectional view of the lens 1010 through A and B in Fig.10(a) and the glass lens is a semi-spherical shell glass 1022 where the glass thickness under the 1018 Doughnut lens is a half of the thickness of the glass in the other area of the 1014. Hence the 1018 lens unit and the four 1016 lenses on the semi-spherical shell lens will have 1800 phase shift. A laser beam of 910 will be converted into a Doughnut beam after 1018 lens unit and an 1800 phase shift Airy Disc after each 1016 lens. A Doughnut beam of 1028 having vertical beam amplitude component only is obtained because the 1018 is located at the top polar point of the Semi-spherical shell (or Semi-spherical) lens and a strong Airy Disc beam also having vertical amplitude component only is obtained at the crossbeam point because any two symmetric 1016 lenses, such as 1024 & 1026, will cancel their horizontal components and all four Airy Discs from the four 1016 lenses will form a much strong Airy Disc at the cross point of beams and then a much strong and vertical beam component only depletion nanobeam is obtained at the crossbeam point. 1030 in Fig.10(d) shows the corresponding Doughnut beam 1034 from 1028 after 1018 at the crossbeam point, the relative 1800 phase shift Airy Disc 1032 at the beam cross-point formed by all four Airy Discs after all 1016 lenses and the depletion nanobeam 1036 formed by 1032 and 1034 at the beam cross-point. 1040 in Fig.10(e) shows the Amplitude and Intensity corresponding to 1030 where the dot line in 1042 is the intensity of the Doughnut beam 1032, 1044 is the reversed Amplitude & Intensity of the Airy Disc 1034 and the 1046, obtained by the depletion of 1042 & 1044, is the depletion nanobeam 1036 by 1032 and 1034.

The height of the Semi-spherical shell (or Semi-spherical) lens, h, should be just a bit of less than the sphere radius r and then the nanobeam formed at the crossbeam point (center of the sphere lens) is on the photoresist surface for photolithograph or sample surface for image and optical storage application The above Scanning Depletion Laser (SDL) Microscope employing an 180° phase shift lens unit that is composed of an Airy Disc lens and a relative 180" phase shift Doughnut lens to compose a depletion nanobeam is called first type of SDL (SDL-I) Microscope. In the SDL-I, 1800 phase shift is realized by using the 1800 phase shift lens that is difficult in the fabrication. A second type of SDL (SDL-II) microscope proposed is employing two 1800 phase shift laser cross beams to pass through an Airy Disc lens and a same phase Doughnut lens, respectively, to obtain an Airy Disc beam and a reversed amplitude Doughnut beam to compose a depletion nanobeam at the beam cross-point. Clearly, in an SDL-I1 microscope, the 1800 phase shift and lens fabrication are separated to make the lens unit fabrication much less complicated. The two 180" phase shift crossbeams can be two laser sources or can come from a same laser source and then one beam can pass an additional 1800 phase shift lens to change the laser phase 1800 before passing through the SDL-II microscope. There are also other methods to change laser beam phase.

Fig.11 1100 shows a Trimer lens in additional to the Airy Disc lens and Doughnut lens. As mentioned before, A trimer lens unit has three sub-wave length Airy Disc beam lenses, the minimum numbers for a Doughnut lens unit, located at the equilateral triangle vertices to form an Airy Disc beam having a Trimer shape. Fig.11(a)-11(c) show the top view, Airy Disc beam and the Amplitude & Intensity of an Airy Disc lens 1110, a Doughnut lens 1120 and a Trimer lens 1130, respectively. In Fig.11(a), after a laser beam passes through an Airy Disc lens 1110 having a sub-wave length hole, an Airy Disc beam 1112 is obtained and 1114 is the Amplitude & Intensity of the Airy Disc beam. In Fig.11(b), after a laser beam passes through a Doughnut beam lens 1120, a Doughnut beam 1122 is obtained and 1124 is the Amplitude & Intensity of the Airy Disc beam where the composed intensity is a hump shape at dot lines. In Fig.11(c), after a laser beam passes through a Trimer lens 1130, a Trimer beam 1132 is obtained and 1134 is the Amplitude & Intensity of the Trimer beam where the composed intensity is a deep hump shape at dot lines. Compared the composed intensity line of 1124 from a Doughnut beam lens 1122 with the composed intensity line of 1134 from a Trimer beam lens 1132, the Trimer beam lens can produce a composed intensity having much deep hump shape, shown in 1134 as dot line that can be used to depletion an Airy Disc beam to obtain a sharp composed nanobeam probe. The deep hump shape of a Trimer has also got more room to obtain an even fine composed nanobeam.

Fig.12(a)-(d) show the top views, the cross-sectional view, the Amplitude & Intensity and the corresponding Airy Disc beams of the first embodiment SDL-II microscope lens unit 1210 composed of an Airy Disc beam lens of 1110 joined at an angle of a, smaller than and close to 180", with a Doughnut beam lens of 1120, a second embodiment of a SDL-II microscope lens unit 1220 composed of an Airy Disc beam lens of 1110 joined at an angle of a, smaller than and close to 180", with a Trimer beam lens 1130 and a third embodiment of a SDL-II microscope lens unit 1230 composed of a compact Trimer lens of 1232 joined at an angle of a, smaller than and close to 180", with a Trimer beam lens of 1130, respectively, in 1000.

Fig.12(b) 1240 shows the cross-sectional view of the three lens units in Fig.12(a), respectively, where the two lenses in each lens unit are joined at an angle of a, smaller than and close to 180" and the two 180' phase shift cross-beams of 1242 and 1244, at an angle of (180" -a), pass perpendicularly through the two flat lenses at each lens unit and compose into a nanobeam of 1246 at beam cross-point. The corresponding amplitudes and intensities, at the cross-beam point, of Airy Disc beam 1242, Doughnut beam 1244 and the composed nanobeam 1246 are shown in 1250 of Fig.12(c), respectively. The three kinds of nanobeams of 1262, 1272 and 1282 obtained from Lens unit 1210, Lens unit 1220 and lens unit 1230 after two 180" phase shift cross-beams pass through their corresponding two lenses are shown in 1260, 1270 and 1280, respectively, in Fig.12(d). Compared with the composed nanobeam 1262 from an Airy Disc beam 1112 and a Doughnut beam 1122, obtained from lens unit 1210, the composed nanobeam 1272 from an Airy Disc beam 1112 and a Trimer beam 1132, obtained from lens unit 1220 is even fine as discussed before. However, the composed nanobeam 1272 shows some uncompensated shadow beam around the edge in additional to the nanobeam and this shadow beam around the edge can cause some issues in both image and fabrication. This shadow beam issue can be fixed in the lens unit design 1230 composed of a compact Trimer lens 1232 to produce a solid Trimer beam and a Trimer beam lens 1130 to produce a dump shape Trimer beam. After two 180" phase shift crossbeams pass trough the 1232 compact Trimer lens and 1130 a normal Trimer lens, a solid Trimer beam 1232 and a reversed amplitude dump Trimer beam 1132 can be obtained and they will compose to a nanobeam 1282 at the crossbeam point without the shadow beam issue.

However, all three lens units in Fig.12 have not maximumly employed the laser power because the laser spot is much large than the size of sub-wave length lens. A semi-spherical shell lens (or a semi-spherical lens) and a spherical lens, shown in 1300 of Fig.13, are proposed to fix this issue by maximumly employing the laser beam power to produce a high amplitude composed nanobeam. 1310 and 1320 in Fig.13(a) show the top views of a semi-spherical shell lens unit (or spherical lens unit) or spherical lens units of 1312 and 1322, respectively. The 1312 lens unit is composed of a group of Airy Disc lens 1110 and a group of Doughnut beam lens 1120. 1322 lens unit is composed of a group of compact Trimer lens 1324 and a group of Trimer beam lens 1130 in order to obtain an even sharp composed nanobeam probe as illustrated in 1280 of Fig.12. The semi-spherical shell lens (or semi-spherical lens) or spherical lens can focus on all the beams from either a group of Airy Disc lenses and a group of Doughnut lenses in design of 1310 or a group of compact Trimer lenses and a group of Trimer lenses in design of 1320 into the beam cross-point. 1330 and 1340 in Fig.13(b) show the cross-sectional views of a Semi-spherical shell lens having 1312 lens unit (or 1322 lens unit) and a spherical lens having 1312 lens unit (or 1322 unit), respectively. In a Semi-spherical shell lens of 1330 and a spherical lens of 1340, two 180" phase shift crossbeams of 1242 and 1244 will pass through lens unit of 1312 (or 1322) and focus at the beam cross-point 1332 and 1342, to compose into a nanobeam, respectively. A semi-spherical shell lens and a spherical lens will focus all beams on the beam cross-point to increase the beam amplitude by fully employed the laser spot power.

1350 and 1360 in Fig.13(c) show the corresponding Airy discs at the beam cross-point 1332 (or 1342) after two 180" phase shift crossbeams pass through the lens unit of 1312 and 1322 on a semi-spherical shell lens (or a spherical lens), respectively. 1350 shows that An Airy Disc beam 1112 obtained after the laser beam 1242 passes through a group of Airy Disc beam lens 1110 in 1312 lens unit and a reversed amplitude Doughnut beam 1122 obtained after the 180) laser phase shift beam 1244 passes through a group of Doughnut beam lens 1120 in 1312 lens unit will compose into a nanobeam 1352 at 1332 and 1342 for a semi-spherical shell lens 1330 and a spherical lens 1340, respectively. The composed depletion nanobeam 1352 in Fig.13(c) is similar to the 1262 in Fig.12(c), but has a much high amplitude due to using a group of sub-wave length lenses of 1110 and 1120 to fully use the laser beam spot and also a focus lens, such as a semi-spherical shell lens, a semi-spherical lens and a spherical lens, is used to focus the Airy Disc beams and Doughnut beams on the beam cross-point. 1360 shows that a solid Trimer beam 1326 obtained after the laser beam 1242 passes through a group of compact Trimer beam lens 1324 in 1322 lens unit and a reversed amplitude Trimer hump beam 1132 obtained after the 180" laser phase shift beam 1244 passes through a group of Trimer beam lens 1130 in 1322 lens unit will compose into a high amplitude nanobeam 1362 at 1332 and 1342 for a semi-spherical shell lens 1330 and a spherical lens 1340, respectively.

Fig.14(a)&(b) show the top view, 1410, and a cross-sectional view, 1420, of a spherical lens (or a semi-spherical shell lens) on a cantilever probe in 1400, respectively. The top view of the cantilever frame of 1410 shows two holes of 1414 and 1416 on the cantilever of 1412 to pass through the two 180' phase shift crossbeams and AB line passes through the center of 1414 and the center of 1416. The cross-sectional view through AB of 1420 shows the spherical lens unit (or a semi-spherical shell lens unit) attached to the probe of 1421, at an angle of 13 that is also the angle of two 180" phase shift crossbeams. The two 180" phase shift crossbeams pass through the two hollow legs of 1414 and 1416 of probe 1421 and then through the semi-spherical shell lens 1330 (or spherical lens 1340) to compose into a depletion nanobeam for nanosized lithography or image.

The spherical lens unit (or semi-spherical shell lens unit) can also be placed on a cantilever only and this is shown in 1500 in Fig.15. Fig.15(a) shows a cantilever top view without placed a spherical lens unit (or a semi-spherical lens unit) where a cantilever 1512 has got a hole of 1514 to place a spherical lens unit (or a semi-spherical shell lens unit) in 1510. The AB is a cross line through the middle of the hole of 1514. Fig.15(b) 1520 shows the top view of the cantilever after placed a spherical lens unit 1320 (or a semi-spherical shell lens 1310) in 1514 on the cantilever 1512. Fig.15(c) shows the corresponding cross-sectional view of the 1520 through AB where 1330 and 1340 are the cross-sectional view of a semi-spherical shell lens unit and a spherical lens unit, respectively.

A multiple of 1-D N or even a 2-D N/N lens units can be employed to speed up the process in imaging or fabrication. Figs.16(a)&(b) show a top view of 2x2 lens units on a frame in 1610 and the corresponding 2/2 composed depletion nanobeams on a sample surface in 1620, respectively, in 1600 to illustrate. The 2x2 lens units can be 2/2 180) degree phase shift 812, 920 and 1010 lenses in SDL-I microscope, respectively. The 2/2 lens units can also be 1210, 1220, 1230, 1310 and 1320 lens units in SDL-II microscope, respectively. The distances between the two lens unit along X and Y are D, and Dv, respectively. Then, 2/2 nanobeams of 1622 are formed at (0,0), (0, DO, ,0) and (Dv, DO, shown in 1620 of Fig.16(b). The beams can be fixed while the sample stage scans. For a/V/N lens matrix design, if the distance between two adjacent lenses is d along X and Y direction, respectively, each lens needs to process an area of d>< d and then, a total of area of (1\2 x GO can be processed and the process will be N2 faster than a single lens unit. This also includes the case of multiple of laser sources of n where one laser source can cover a N/A1 lens matrix and then the process can be n/(V//V) faster than a single lens unit under a single source.

Fig.17 1700 illustrates an SDL-II microscope using two polarized 180° phase shift crossbeams of 1712 and 1714 to compose a further sharp depletion nanobeam 1716 at the beam cross-point. Two 180" phase shift polarized beams of 1712 and 1714 at a crossbeam angle of13 pass through the lens unit of 1240 to compose a depletion nanobeam 1716. Clearly, both the horizontal and vertical components of two beams will be depleted in the overlapped area to leave an even fine composed nanobeam Fig.18 1800 illustrates an SDL-II microscope similar to that in 1700 of Fig.17, but the Airy disc beam lens 1812 and the Doughnut beam lens 1814 are not joined and can be move independently. After a laser beam passes a Doughnut lens (or a Trimer lens), the Doughnut beam (or a Trimer) will be a Doughnut beam (or a hollow Trimer) initially, then will mix into a solid Airy Disc beam (or a solid Trimer) with increasing working distance and it is very critical for the beam to maintain as a fine Doughnut beam (or a fine hollow Trimer) at the cross-point of the crossbeams. An independent cantilever frame movement for the Doughnut lens (or Trimer lens) can make sure that a Doughnut beam (or a hollow Trimer) is obtained at the cross-point of two crossbeam by changing its working distance to deplete with the reversed amplitude Airy Disk to form a nanobeam probe in either a SDL-II microscope or in a SDL-I microscope having two separate Airy Disc lens and 180° relative phase shift Doughnut lens. Fig.18 1800 shows two polarized crossbeam case, but can also apply to two normal crossbeams The solutions and gases can be filled between the lens unit and substrate to further increase the image and photolithograph resolution.

The embodiments of SDL microscope devices mentioned above are illustrated only to achieve the features and advantages of the disclosure, but not limiting and may not be drawn in scale. This disclosure is intended to include any and all subsequent adapti on s, combined or variations of various embodiments that may be utilized and derived after this disclosure, but without departing from the spirit and scope of this disclosure

Claims

What is claimed is 1. A first type of Scanning Depletion Laser (SDL-I) microscope comprising: a laser source and a focus lens; an 180° phase shift lens unit comprising a 0° phase shift Airy Disc lens made by opening a hole, smaller than the laser wave length X, in the opaque chromium (Cr) layer coated on the 0° phase shift glass, to produce an Airy Disc beam; an 180° phase shift Doughnut beam lens composed of at least three 180° phase shift Airy Disc lenses arranged with an equal space of any two adjacent 180° phase shift Airy Disc lenses along a circle and each is made by opening a hole, smaller than the laser wave length X., in the opaque Cr layer coated on a relative 180" phase shift glass, to produce an 180" phase shift Doughnut beam; the glass thickness in the 0° phase shift Airy Disc lens is either a double or a half of the glass thickness of the 180° phase shift Doughnut beam lens; the 0" phase shift Airy Disc beam lens and the 180" phase shift Doughnut beam lens share a same center on a flat glass wherein the central Airy Disc lens I surrounded by the relative 180° phase shift Doughnut beam lens unit.a frame to hold the phase shift lens unit; a detector; a stage; a beam blank.
2. The SDL-I microscope of claim 1 and wherein the laser is a visible light, UV, EUV light or electromagnetic waves.
3. The SDL-I microscope of claim 1 and wherein the glass for making the 180° phase shift Doughnut lens is coated with partially penetrated light thin layer on the clear surface of the I SO° phase shift glass in order to reduce the Doughnut beam Amplitudes to the right value to quench the overlapped reversed amplitude Airy Disc from the central lens to compose a nanobeam.
4. The SDL-I microscope of claim 1 and wherein the phase shift unit further comprising a 0° phase shift Airy Disc lens and an 180" phase shift Doughnut lens unit made on two separate flat glass lenses joined at an angle of close to 180° to obtain two cross-beams, at a small angle, of the Airy Disc from the 0° phase shift lens and the reversed amplitude Doughnut from the 1800 phase shift lens unit to form a depletion nanobeam spot at the beam cross-point.
S. The SDL-I microscope of claim 4 and wherein the phase shift unit further comprising a group of 0" phase shift Airy Disc lenses and a group of 180" phase shift Doughnut lens units made on two separate focus lenses joined at an angle of close to 1800 to form a high amplitude depletion nanobeam spot at the crossbeam focus cross-point.
6. The SDL-1 microscope of claim 1 and wherein the phase shit unit further comprising a 180° phase shift Doughnut beam lens unit and a few of 0° phase shift Airy Disc beam lens on a semi-spherical shell lens (or a semi-spherical lens) where the 180" phase shift Doughnut beam lens is on the top polar point and the 0" phase shift Airy Disc beam lenses are arranged symmetrically on a latitude circle relative to the top polar point of the semi-sphere shell lens to focus all the cross beams on the cross point to form a depletion nanobeam by all the Airy Disc from the 00 phase shift Airy Disc lenses and the reversed amplitude Doughnut from the 180' phase shift Doughnut lens unit.
7. A second type of Scanning Depletion Laser (SDL-II) microscope comprising.two 180" phase shift laser crossbeams and their focus lens; a zero phase shift lens unit comprising an Airy Disc lens made by opening a hole, smaller than the laser wave length X, on the opaque chromium (Cr) layer coated on a 0° phase shift glass, to produce an Airy Disc beam; a Doughnut beam lens composed of at least three Airy Disc lenses arranged with an equal space of any two adjacent Airy Disc beam lenses along a circle and each is made by opening a hole, smaller than the laser wave length k, on the opaque Cr layer coated on a 0' phase shift glass, to produce a Doughnut beam, the Airy Disc beam lens having a flat glass and the Doughnut beam lens unit having a flat glass are joined at an angle of close to 1800 to allow the two 180" phase shift laser crossbeams passing through them, respectively, to deplete the Airy Disc beam and the reversed amplitude Doughnut beam to a nanobeam at the beam cross-point.a frame to hold the phase shift lens unit; a detector; a stage; a beam blank.
8. The SDL-II microscope of claim 7 and wherein the two laser crossbeams are 1800 phase shift visible light laser beams, UV beams, EUV beams or electromagnetic waves
9. The SDL-11 microscope of claim 8 and wherein the laser further comprising two 180' phase shift polarised crossbeams from a visible light laser beams, UV beams, EUV beams or electromagnetic waves.
10. The SDL-11 microscope of claim 7 and wherein the glass for making the Doughnut beam lens unit is coated with partially penetrated light thin layer on the clear surface of the180° phase shift glass in order to reduce the Doughnut beam Amplitudes to the right value to quench the overlapped Airy Disc from the central lens to form a nanobeam.
11. The SDL-II microscope of claim 7 and wherein the lens unit further comprising a group of Airy Disc lenses within the laser beam spot and a group of Doughnut lenses within the laser beam spot located on symmetrically relative to the top polar point of a semi-sphere shell lens to focus the cross beams on the cross point to form a depletion nanobeam by the Airy Disc from all the Airy Disc beam lenses and the reversed amplitude Doughnut beam from all the Doughnut Beam lenses.
12. The SDL-II microscope of claim 11 and wherein the lens unit further comprising a group of Airy Disc lenses and a group of Doughnut lenses located on symmetrically relative to the top polar point of a semi-sphere lens or a sphere lens.
13. The SDL-II microscope of claim 11 and wherein the lens unit further comprising a group of Airy Disc lenses and a group of Doughnut lenses located on symmetrically relative to the top polar point of a spherical segment symmetrically relative to the longitude of a semi-spherical segment lens or a semi-spherical segment shell lens.
14. The SDL-II microscope of claim 12 and wherein the lens unit further comprising a nanosized metal tip attached to the bottom of the sphere lens or a spherical segment lens.
15. The SDL-II microscope of claim 7 (or the SDL-I microscope of claim 4) and wherein the lens unit further comprising a separate Airy Disc lens on a first cantilever frame having its own movement control in and the Doughnut lens unit on a second cantilever frame that having its own movement control.
16. The SDL-I microscope of claim t (or the SDL-II microscope of claim 7) and wherein the lens unit further composing of a 1-D of N identical lens units having an equal interval along X or a 2-D of NxN identical lens units made on one platform holder equally intervals along X and Y, respectively.
17. The SDL-I microscope of claim 1 (or the SDL-II microscope of claim 7) and further composing of a 1-D of N identical (or almost identical) SDL-1 (or SDL-II) having an equal interval along X or a 2-D of Arx/V identical SDL-I (or SDL-II) having equally intervals along X and Y, respectively, but they still share one frame and one stage.
18. The SDL-I microscope (or the SDL-II microscope) of claim 17 and wherein each lens unit has its own laser beam.
19. The SDL-I microscope (or the SDL-II microscope) of claim 18 and further comprising at least one lens unit (a couple of lens units) having a detector for positioning in photolithography.
20. The SDL-I microscope of claim 1 (or the SDL-I1 microscope of claim 7) and wherein the stage is a laser interference stage scanning along X & Y direction and can also move up & down along Z direction.
21. The SDL-I microscope of claim 1 (or the SDL-II microscope of claim 7) and wherein the lens unit cantilever frame further comprising cantilever frame scanning along X & Y direction and can also move up & down along Z direction.
22. The SDL-I microscope of claim 1 (or the SDL-I1 microscope of claim 7) and wherein the lens unit further comprising the work environment of a gas or liquid solution filled between the lens unit and the sample to further improve resolution.
23. The SDL-I microscope of claim 1 (or the SDL-II microscope of claim 7) and wherein the lens units and laser beams are fixed while the stage scans
24. The SDL-I microscope of claim 1 (or the SDL-II microscope of claim 7) and wherein stage is fixed while the lens units and laser beams scan.
25. The SDL-I microscope of claim 1 (or the SDL-II microscope of claim 7) and wherein the coating opaque layer further comprising plasmonic metal material of gold (Au), silver (Ag) or metal-like materials.