WO2021156148A1 - Lentille de moiré modifiée - Google Patents

Lentille de moiré modifiée Download PDF

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Publication number
WO2021156148A1
WO2021156148A1 PCT/EP2021/052119 EP2021052119W WO2021156148A1 WO 2021156148 A1 WO2021156148 A1 WO 2021156148A1 EP 2021052119 W EP2021052119 W EP 2021052119W WO 2021156148 A1 WO2021156148 A1 WO 2021156148A1
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WO
WIPO (PCT)
Prior art keywords
phase modulating
optical system
optical
light
light reflecting
Prior art date
Application number
PCT/EP2021/052119
Other languages
English (en)
Inventor
Martin BAWART
Stefan Bernet
Alexander Jesacher
Original Assignee
Medizinische Universität Innsbruck
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Medizinische Universität Innsbruck filed Critical Medizinische Universität Innsbruck
Publication of WO2021156148A1 publication Critical patent/WO2021156148A1/fr

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G02B3/0081—Simple or compound lenses having one or more elements with analytic function to create variable power
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/06—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the phase of light
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/12—Reflex reflectors
    • G02B5/122—Reflex reflectors cube corner, trihedral or triple reflector type

Definitions

  • the development of the Moire lens has lead to notable improvements in optical system capabilities as it allows for a smooth and continuous adjustment of focal length or related optical parameters.
  • a Moire optical system two Moire lenses are placed adjacent one another. One of the lenses is then rotated with respect to the other lens and due to the specific phase profile of a Moire lens, the combination of the two images allows for the resulting emitted light to have an adjustable focal length which depends on the angle of the lens rotation.
  • EP 2 174 168 B1 describes such an optical device comprising a pair of specifically designed plate-like diffractive optical elements successively arranged in parallel to each other. Placing the two diffractive optical elements in succession and in parallel to each other in a certain distance, the combination optically corresponds to a single diffractive optical element, and it can perform similar tasks, acting as a lens, an axicon, a phase shifter, or a spiral phase plate. If one of the diffractive optical elements is rotated with respect to the other around a common central axis, the property of the optical device, like the focal length, the refractive power, helical index, or phase shift changes continuously.
  • the invention relates to an optical system comprising a phase modulating element wherein the phase modulating element has a phase function F(GRM, QRM) expressed in polar coordinates GRM, QRM, which is an odd function with regard to the polar angle QRM, and a light reflecting element defining an optical axis, wherein light impinging on the light reflecting element parallel to said optical axis at any point of the optically active surface of the light reflecting element with polar coordinate 0LR is reflected from the light reflecting element parallel to said optical axis with the polar coordinate -0LR.
  • F(GRM, QRM) expressed in polar coordinates GRM, QRM, which is an odd function with regard to the polar angle QRM
  • a light reflecting element defining an optical axis
  • the phase modulating element, the optical arrangement and the light reflecting element are arranged and configured such that light interacting with the phase modulating element and passing through the optical arrangement is reflected by the light reflecting element back through the optical arrangement onto the phase modulating element.
  • the light reflecting element not only light impinging on the light reflecting element parallel to said optical axis at any point of the optically active surface of the light reflecting element with polar coordinate 0LR is reflected from the light reflecting element parallel to said optical axis with the polar coordinate -0LR, but light which impinges upon the light reflecting element with any angle (within a certain angular cone) relative to the optical axis at any point of the optically active surface of the light reflecting element with polar coordinate 0LR is reflected from the light reflecting element parallel to said angle with the polar coordinate - 0LR.
  • the angular cone for which this relation is true depends on the light reflecting element and may have an opening angle of 30°, 45° or even 60°.
  • the optical arrangement comprises a number of focusing elements N, wherein N is preferably equal to any of 1 , 2, or 3 and a distance between the phase modulating element and the first focusing element along the optical axis is equal to the focal length of the first focusing element.
  • the phase modulating element is one of a (higher order-) diffractive optical element, a refractive element, a meta lens, a holographic optical element or a gradient index optics element. While each of these lenses can fulfill the requirements of the system, each may prove advantageous or desirable for certain imaging circumstances. For example, diffractive lenses and meta lenses require much less space for implementation, while refractive lenses may be lower in cost.
  • phase modulating element is light transmissive.
  • phase modulating element may be light reflective.
  • the optical system may include a half-wave plate, and/or a polarizing or non polarizing beam splitter.
  • the optical system may be configured to direct light through the half-wave plate and the beam splitter before interacting with the phase modulating element and wherein the optical system is configured to emit light from the beam splitter into a different direction than the incident light is coming from, after reflecting off of the light reflecting element.
  • a polarizing beam splitter is used such arrangements can help to improve light efficiency in the optical system.
  • the half-wave plate, the beam splitter, and the phase modulating element are positioned along a first optical axis and the phase modulating element, the optical arrangement, and the light reflecting element are positioned along a second optical axis.
  • the first optical axis and the second optical axis are aligned.
  • the phase modulating element may be a transmissive element and the entire optical system may be positioned along a single axis.
  • the first optical axis and the second optical axis form an angle of between 1° and 179°, preferably wherein the angle is between 1° and 90°, more preferably wherein the angle is between 1° and 60°.
  • the phase modulating element may be a reflective element.
  • the mount comprises an actuator or motor for enabling the relative polar rotation between the phase modulating element and the light reflecting element.
  • the actuator or motor may comprise a galvo scanner, a stepper motor, a voice coil motor, a piezo motor, a DC motor, a servo motor, and/or a MEMS based micro motor.
  • a motor would promote rapid adjustment times of the optical system and a reliable orientation between the phase modulating element and the light reflecting element.
  • the relative polar rotation angle between the phase modulating element and the light reflecting element alters the focal length, and/or the beam mode and/or the resulting global phase of the optical system. Consequently, using relatively few optical elements an optical system can be used to rapidly modify characteristics of light transmission.
  • the phase modulating element has a circular effective area, preferably the effective area has a diameter A of 50 mm or less, preferably 25 mm or less, more preferably 10 mm or less.
  • the focal length of the optical system may be altered between -100*A and +100*A preferably between -10* A and +10* A, more preferably between -1*A and 1*A.
  • Such a range of focal lengths attainable with a simple and effective optical system promotes a highly flexible and versatile optical system.
  • Fig. 1 schematically shows an exemplary optical system with a transmissive phase modulating element in a 4f arrangement
  • Fig. 2 schematically shows an exemplary optical system with a transmissive phase modulating element in an 8f arrangement
  • Fig. 3 schematically shows an exemplary optical system with a reflective phase modulating element in a 4f arrangement
  • Fig. 4 schematically shows an exemplary optical system with a reflective phase modulating element in an 8f arrangement
  • Fig. 5 schematically shows a perspective view of an exemplary refractive phase modulating element.
  • Fig. 1 depicts one possible configuration of a modified Moire lens in which the optical system 100 includes a phase modulating element 110, a light reflecting element 120, an optical arrangement 130, which consists of a single lens in this embodiment, interposed between the phase modulating element 110 and the light reflecting element 120, and a mount 140 for supporting the phase modulating element 110.
  • the same or another mount could support the light reflecting element 120.
  • the phase modulating element 110 is characterized by a phase function F(GRM, QRM), which is expressed in polar coordinates and which is an odd function with regard to the polar angle QRM.
  • the phase function F(GRM, QRM) of the phase modulating element 110 may take on any form from a very large range of different usable phase functions.
  • Fo 1 the values are not symmetric about the value zero, but instead symmetric about some other constant value.
  • phase function may also be expressed as either a “wrapped” function, wherein apparent discontinuities are present at points where the function flips from a minimum to a maximum or vice-versa.
  • phase function may be expressed as an “unwrapped” function, wherein the discontinuities are detected and compensated for by either adding or subtracting integer multiples of 2p.
  • F(TPM) and G(rpM) may be chosen such that the transmission function is rotationally symmetric.
  • the phase function may take on the form of one of the lenses described in EP 2 174 168 B1 and specifically within the claims detailed therewithin.
  • the phase modulating element 110 may be of any size or shape useful for the optical system, but may comprise a circular effective area of use through which light passes and which is utilized for light modulation. This effective area can have a diameter of 50 mm or less, preferably 25 mm or less, or more preferably 10 mm or less, based on the requirements of the optical system.
  • the phase modulating element 110 may also consist of numerous individual elements which, when working together, satisfy the before-stated requirements. Many different types of optical elements have been developed that satisfy this requirement and one example of such a phase altering element may also be referred to as a Moire lens.
  • the phase modulating element 110 can be a (higher order-) diffractive optical element, a refractive optical element, a meta lens, a holographic optical element or a gradient index optics element.
  • phase modulating element 110 may be a diffractive optical element
  • the phase function F(GRM, QRM) may be subject to a modulo h*2p operation (where n is an integer) applied to one of the phase functions as previously described.
  • the modulo h*2p operation may not be necessary for a phase modulating element 110 which is a refractive optical element.
  • phase modulating element 110 may also fulfill the required function of the phase modulating element 110.
  • a coefficient may be present for each of the components of the possible phase functions, wherein the coefficient ranges between -10% and +10%.
  • Fig. 5 schematically shows a perspective view of an exemplary refractive phase modulating element.
  • This optical arrangement may comprise any number of lenses and/or diffractive elements, in order to control the orientation of the light emerging from the phase modulating element 110.
  • the optical arrangement may also serve to align each point of the phase modulating element with another point on the phase modulating element after the image has been reflected.
  • the light reflecting element 120 which defines an axis, satisfies the requirement that light impinging upon the light reflecting element at a point with polar coordinate OLR is emitted from the light reflecting element with the polar coordinate -OLR.
  • Such a light reflecting element may be realized, for example, by means of two planar reflecting surfaces being arranged perpendicularly with respect to each other as schematically shown in Fig. 1.
  • each of the two planar reflecting surfaces defines an angle of 45° with the optical axis of the optical system.
  • the two planar reflecting surfaces are arranged symmetrically with respect to the optical axis of the optical system.
  • Light focused by the optical arrangement 130 is consequently reflected by the light reflecting element 120 back through the optical arrangement 130 to arrive at the phase modulating element 110 for a second time.
  • the light reflecting element 120 and the optical arrangement 130 cooperate such that a light passing through the phase modulating element 110 is imaged back onto the phase modulating element 110 preferably with a perfectly aligned effective area.
  • the optical system 100 further includes a mount 140 which may support the phase modulating element 110 as shown, for example, in Fig. 1, but may alternatively support the light reflecting element 120 or both the phase modulating element 110 and the light reflecting element 120.
  • the mount may also optionally support other components of the optical system 100 as well.
  • the mount 140 is configured to enable a relative rotation between the phase modulating element 110 and the light reflecting element 120.
  • a phase modulating element 110 such as a Moire lens
  • the combination of both modulation functions results in the Moire-effect, wherein through a relative polar rotation, the focal length, beam mode, and/or resulting global phase of the optical system can be continuously readjusted. Due to the nature of the light reflecting element 120 in combination with the optical arrangement 130, any rotation of the phase modulating element 110 will cause the light arriving at the phase modulating element 110 for the second time to rotate in the opposite direction.
  • the focal length of the optical system may be rapidly altered.
  • the focal length of the optical system may be altered between -100*A and +100*A preferably between -10* A and +10* A, more preferably between -1*A and 1*A.
  • the degree of change is dependent on the phase profile of the phase modulating element 110.
  • the mount 140 may in some implementations further comprise an actuator or motor (not shown) for performing the relative polar rotation action. In some configurations this actuator or motor may be controlled by a processor or computer. Many different types of actuators and motors are contemplated for use in the optical system 100 including a galvo scanner, a stepper motor, a voice coil motor, a piezo motor, a DC motor, a servo motor, and/or a MEMS based micro motor. Each of these types of actuators and/or motors provides advantages and disadvantages and must be carefully selected for use with the system 100. One advantageous arrangement includes the use of a galvo scanner, which enables the mount 140 to perform a rotation very quickly.
  • the optical system 100 shown in Fig. 1 is placed in a 4f arrangement. This describes a distance of two focal lengths (of an element of the optical arrangement 130) between the phase modulating element 110 and the light reflecting element 120, thus giving a total of four focal lengths (4f) for light leaving the phase modulating element 110, reflecting off the light reflecting element 120 and returning to the phase modulating element 110.
  • a further component of the system includes a further optical arrangement 150 which is positioned to receive light input before the phase modulating element 110.
  • the optical arrangement 150 is configured to emit light into a different direction than the incident light is coming from, after reflecting off of the light reflecting element. It may also serve to attain a high absolute efficiency of the optical system 100 in the case where polarized light is used with the optical system 100.
  • the optical arrangement 150 may include a half-wave plate 156, and/or a polarizing or non-polarizing beam splitter 154. In some configurations the system may also include further half-wave plate 152. In some configurations it may be beneficial to pass light first through the beam splitter then the half-wave plate.
  • the light may initially pass through the further half-wave plate 152 before passing through the beam splitter 154. Subsequently the light can encounter the phase modulating element 110, reflect off the light reflecting element 120, interact again with the phase modulating element 110, then reenter the further optical arrangement 150, first through the half-wave plate 156 and then the beam splitter 154.
  • the beam splitter 154 may be configured in this instance to emit light in a different direction, for example at a 90° angle, with respect to the original angle of light incidence. Thus light input can be efficiently separated from light output of the optical system 100.
  • the further half wave plate 152 can be omitted. Furthermore, in the case where the light entering the optical system 100 is circularly polarized, then a quarter wave plate may be substituted for the half-wave plate 152.
  • Another way to improve the light efficiency for any of the described configurations is to orientate the light reflecting element to a polar angle of 45° relative to the polarizing direction of the polarizing beam splitter.
  • Fig. 2 illustrates another embodiment of the optical system 200 with a transmissive phase modulating element 210 being positioned in an 8f arrangement. While the phase modulating element 210 and light reflecting element 220 are substantially similar to those described in connection with Fig. 1, the optical arrangement 230 positioned between them is instead configured to provide an 8f arrangement.
  • the 8f arrangement includes at a minimum two focal elements 232, 234 having the same focal length f.
  • the phase modulating element 210 and the light reflecting element 220 are positioned to have four focal lengths f distance between them with first and second focal elements 232, 234 having a two focal length distance between them.
  • the optical arrangements may also be asymmetric.
  • the 8f arrangement corresponds to two consecutive 4f arrangements
  • the axial distance may assume any value between zero and two times the focal length.
  • the 8f arrangement might also correspond to two asymmetric 4f arrangements where the focal length of the second focusing element is different from the first focusing element and therefore also the distance between the focusing elements and accordingly also between the second focusing element and the light reflecting element.
  • the optical arrangement may also comprise a 12f arrangement, for which the aforementioned options might be useful as well.
  • the optical arrangements may also include other lens arrangements in which the individual elements have different focal lengths. In such a configuration the distance along the optical axis between the phase modulating element and the first focusing element is equal to the focal length of the first focusing element. Distances between other focusing elements within the optical arrangement may be dependent on the focal lengths of the subsequent focusing elements.
  • the optical system 200 of Fig. 2 may also include the further optical arrangement 250, which is substantially similar to the further optical arrangement 150 discussed in connection with Fig. 1.
  • Fig. 3 illustrates another configuration of the optical system 300, which is substantially similar to the optical system 100.
  • the phase modulating element 310 of optical system 300 is not a transmissive element, but a reflective element.
  • light first reflects off of the phase modulating element 310 before passing through the optical arrangement 330 and reflecting off of the light reflecting element 320 as previously described.
  • the optical system 300 comprises a 4f arrangement, wherein the phase modulating element 310 is spaced a two-focal length distance from the light reflecting element 320 with the optical element 330 interposed in the middle.
  • an optional further half-wave plate 352, beam splitter 354, and the half-wave plate 356 are positioned along a first axis with the phase modulating element 310.
  • a second axis is aligned with the phase modulating element 310, the optical arrangement 330 and the light reflecting element 320.
  • an angle may be formed between the first axis and the second axis. This angle may have a value anywhere between 1° and 179°, preferably wherein the angle is between 1° and 90°, more preferably wherein the angle is between 1° and 60°.
  • the exact angle between the first and second axis may be dependent on the requirements of the imaging system. As shown in Fig.
  • the mount 340 is supporting the phase modulating element 310, however in practice the light reflecting element may be supported instead or additionally.
  • the mount 340 may encompass the entire back side, i.e. non-functional side of the phase modulating element 310.
  • the mount 340 is configured to enable a relative polar rotation of the phase modulating element 310 with respect to the light reflecting element 320.
  • Fig. 4 depicts a configuration of the optical system 400 substantially similar to that shown in Fig. 3.
  • the phase modulating element 410, the optical arrangement 430, and the light reflecting element 420 are positioned in an 8f arrangement. Consequently the optical arrangement 430 may include two lenses 432, 434, which are spaced a distance of 2f from one another.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Mechanical Light Control Or Optical Switches (AREA)

Abstract

La présente invention concerne un système optique comprenant un élément de modulation de phase et un élément réfléchissant la lumière.
PCT/EP2021/052119 2020-02-07 2021-01-29 Lentille de moiré modifiée WO2021156148A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP20156241 2020-02-07
EP20156241.0 2020-02-07

Publications (1)

Publication Number Publication Date
WO2021156148A1 true WO2021156148A1 (fr) 2021-08-12

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US354080A (en) * 1886-12-07 Chaeles gulath
EP2174168A1 (fr) 2007-07-20 2010-04-14 Medizinische Universität Innsbruck Dispositif optique avec une paire d'éléments optiques de diffraction
US9280000B2 (en) * 2010-02-17 2016-03-08 Akkolens International B.V. Adjustable chiral ophthalmic lens
WO2018115102A1 (fr) * 2016-12-21 2018-06-28 Carl Zeiss Jena Gmbh Microscope avec manipulateur de front d'onde

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US354080A (en) * 1886-12-07 Chaeles gulath
EP2174168A1 (fr) 2007-07-20 2010-04-14 Medizinische Universität Innsbruck Dispositif optique avec une paire d'éléments optiques de diffraction
EP2174168B1 (fr) * 2007-07-20 2017-10-25 Medizinische Universität Innsbruck Dispositif optique avec une paire d'éléments optiques de diffraction
US9280000B2 (en) * 2010-02-17 2016-03-08 Akkolens International B.V. Adjustable chiral ophthalmic lens
WO2018115102A1 (fr) * 2016-12-21 2018-06-28 Carl Zeiss Jena Gmbh Microscope avec manipulateur de front d'onde

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