WO2001088597A1 - Systeme d'imagerie virtuelle pour textes en petites fontes - Google Patents

Systeme d'imagerie virtuelle pour textes en petites fontes Download PDF

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Publication number
WO2001088597A1
WO2001088597A1 PCT/US2001/014634 US0114634W WO0188597A1 WO 2001088597 A1 WO2001088597 A1 WO 2001088597A1 US 0114634 W US0114634 W US 0114634W WO 0188597 A1 WO0188597 A1 WO 0188597A1
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WO
WIPO (PCT)
Prior art keywords
prism
optical system
power
recited
optical
Prior art date
Application number
PCT/US2001/014634
Other languages
English (en)
Other versions
WO2001088597A9 (fr
Inventor
Gregory L. Heacock
Original Assignee
Virtual Vision, Inc.
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
Priority claimed from US09/805,712 external-priority patent/US20010048561A1/en
Application filed by Virtual Vision, Inc. filed Critical Virtual Vision, Inc.
Publication of WO2001088597A1 publication Critical patent/WO2001088597A1/fr
Publication of WO2001088597A9 publication Critical patent/WO2001088597A9/fr

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/017—Head mounted
    • G02B27/0172—Head mounted characterised by optical features

Definitions

  • the present invention is directed to an optical system for use with an image source to provide a virtual image and more particularly to such a system including a prism having positive, balanced power to provide an enlarged virtual image of text with minimal geometric distortion so that print in small fonts such as an 8 or 10 point font can be readily discerned.
  • FIG. 539,422 assigned to the assignee of the present invention shows a prism having three optical surfaces where each of the optical surfaces with power can be formed as a spherical surface, a cylindrical surface or a toroidal surface, i.e. a rotationally asymmetric aspheric surface.
  • This prism has two transmissive surfaces and a reflective surface.
  • the prism can be used in a single reflection mode of operation in which light from a display enters a first transmissive surface and is then reflected by the reflective surface to the second transmissive surface through which the light exits the prism and is directed to a user's eye.
  • the prism In a total internal reflection mode of operation, the prism is turned slightly with respect to the display so that light entering the first transmissive surface intersects the second transmissive surface at the angle at which total internal reflection occurs such that light is reflected from the second transmissive surface to the reflective surface. The light is then reflected by the reflective surface so that it exits the prism through the second transmissive surface.
  • Examples of other prisms used in a total internal reflection mode of operation include U.S. Patent Nos. 4,563,061; 4,611,877; 4,969,724; 5,249,081 and 5,459,612.
  • U.S. Patent No. 5,701,202 is typical of these patents and shows various examples of the prism with the reflector being formed of a rotationally asymmetric aspheric surface and the two transmissive surfaces being formed of either planar, spherical or rotationally asymmetric aspheric surfaces.
  • the reflector being formed of a rotationally asymmetric aspheric surface
  • the two transmissive surfaces being formed of either planar, spherical or rotationally asymmetric aspheric surfaces.
  • the prism is formed with a rotationally symmetric aspheric entrance surface adjacent to the display, a rotationally asymmetric aspheric reflector and a spherical total internal reflection surface that also serves as an exit surface of the prism.
  • the virtual image generated by these systems has a central portion with high quality; whereas the edge or peripheral portion of the image is of a significantly lower quality.
  • prisms with free formed surfaces are extremely difficult and costly to design and manufacture.
  • these types of optics are decentered or used with other optics having aspheric surfaces, absolutely precise alignment is required or the image is substantially affected.
  • the system of the present invention includes a prism having positive power balanced among the prism surfaces and across each surface and employs a combination of surface shapes to provide an enlarged virtual image of text with minimal geometric distortion so that print in small font sizes such as an 8 or 10 point font can be readily discerned.
  • the optical system includes a prism having at least three surfaces including a transmissive entrance surface that receives light provided by an image source; a transmissive exit surface through which light passes out of the prism and a reflective surface wherein the exit surface is a rotationally asymmetric surface and the reflective surface is a rotationally symmetric surface.
  • This prism can be used in a single reflection mode of operation or in a multiple reflection mode of operation wherein one of the transmissive surfaces reflects light by total internal reflection.
  • the reflective surface may be formed as a partial reflector so as to allow the prism to be used in a see- through mode of operation wherein the virtual image is superimposed upon the user's environment which can be seen through the prism.
  • both of the transmissive surfaces are formed of a rotationally asymmetric surface whereas the reflective surface is formed of a rotationally symmetric surface.
  • the optical system includes a prism having at least three physical surfaces and at least three optical surfaces with power wherein the total prism power is divided among the optical surfaces with power such that that
  • Power t is the power of the z th optical surface having power
  • Power ⁇ is the total power of the prism and N equals the number of optical surfaces with power.
  • the optical system includes a prism having at least three optical surfaces including a rotationally asymmetric surface with a ratio of CJC y that satisfies the equation
  • the optical system includes a prism having positive optical power to enlarge an image, the prism having at least three surfaces including two transmissive surfaces and one reflective surface and the optical system also includes a corrector lens having a rotationally asymmetric aspheric surface disposed in an optical path between the prism and a user's eye wherein the optical power of the corrector lens is less than or equal to 30% of the prism' s optical power.
  • the corrector lens is extremely thin, having a center thickness that is less than or equal to 3mm.
  • the surface of the corrector lens opposite to the aspheric surface of the lens may be planar or have positive power. However, this surface preferably has negative power and can be used in conjunction with a prism whose reflective surface is a partial reflector so as to provide a see-through virtual imaging system wherein the virtual image is superimposed upon the user's environment.
  • the optical system includes a prism and a lens disposed between the prism and the user's eye wherein both the lens and the prism are decentered relative to the central visual axis and wherein the distance between the lens and prism is fixed and the distance between the image source and the prism is variable so as to provide focus adjustment.
  • it is the image source that is movable along a central axis of the source, while the decentered optical system remains stationary.
  • Fig. 1 is a cross-sectional view of an image source and the optical system of the present invention with the prism operating in a total internal reflection mode;
  • Fig. 2 is a cross-sectional view of the optical system of Fig. 1 wherein the prism is operating in a single reflection mode;
  • Fig. 3 is a cross-sectional view of another embodiment of the present invention wherein the prism has five optical surfaces.
  • An optical system 10 used with an image source 12 in accordance with the present invention includes a prism 14 having positive power to provide an enlarged virtual image.
  • the prism 14 may be used alone or in combination with a thin corrector lens 16.
  • the configurations of the prism and corrector lens are described below in detail.
  • the image source 12 may be any type of image source including a display such as a liquid crystal display, a scanned image source, etc.
  • the image source 12 is a micro-display such as an OLED (Organic Light Emitting Device).
  • the surfaces of the prism 14 are formed so that the virtual image produced by the optical system 10 has minimal geometric distortion such as on the order of 5% or less.
  • the prism surfaces are also selected to ensure that the optical system 10 delivers information with a sufficiently high MTF
  • the optical system 10 has a Modulation Transfer Function of 0.10 or higher at 20 Une pairs with respect to a horizontal field of view greater than or equal to 25°.
  • the prism 14 preferably has balanced optical power with respect to each of the optical surfaces as well as with respect to the tangential and the sagittal ray propagation throughout the system as discussed in detail below.
  • optical surface refers to a surface that intersects a ray once. Therefore, a physical surface that intersects a ray, for example, twice is considered as two optical surfaces.
  • the prism 14 has two transmissive surfaces 18 and 20 and a reflective surface 22.
  • the term reflective surface refers to a surface that is fully reflective or partially reflective as obtained by reflective coatings and partially reflective coatings respectfully.
  • the prism 14 can operate in a single reflection mode as shown in Fig. 2. In this mode, light from the display 12 enters the prism via the entrance surface 18 and is reflected by the reflective surface 22 so that the light exits through the transmissive exit surface 20 where it is thereafter directed to the user's eye 24.
  • the prism 14 is used in a total internal reflection mode of operation as shown in Fig. 1.
  • light from the display 12 enters the prism 14 through an entrance surface 18 and intersects the transmissive surface 20 at the angle at which total internal reflection occurs for the material of the prism.
  • the material of the prism 14 can be formed of a homogeneous material having an index of refraction n that is greater than or equal to 1 or the prism may be formed of different materials so as to comprise an achromat.
  • the prism 14 is a homogeneous material, such as plastic, having an index of refraction in the range of
  • the entrance surface 18 is shaped as a rotationally asymmetric asphere so as to pre-distort the image in a manner that is more easily corrected than if the entrance surface of the prism was planar.
  • the reflective surface 22 is a rotationally symmetric aspheric surface and the exit surface 20 is a rotationally asymmetric aspheric surface.
  • each of the rotationally asymmetric aspheric surfaces 18 and 20 are anamorphic aspheric surfaces, other rotationally asymmetric aspheric surfaces may be employed as well such as a toroidal surface, a biconic surface, etc.
  • the anamorphic aspheric surfaces 18 and 20 are defined by the following equation:
  • R y is the radius with respect to the y axis.
  • R x is the radius with respect to the x axis and R y is the radius with respect to they axis.
  • the power of the prism 14 is preferably balanced so that the total prism power is divided among the optical surfaces of the prism such that
  • Power t is the power of the i jth optical surface having power
  • Power ⁇ is the total power of the prism
  • N is the number of optical surfaces with power
  • each of the rotationally asymmetric aspheric surfaces 18 and 20 has a ratio of CJC y that satisfies
  • R y the radius of curvature of the rotationally asymmetric aspheric surface with respect to the y axis.
  • a thin corrector lens 16 is positioned between the prism 14 and the user's eye 24.
  • the corrector lens 16 protects the total internal reflection surface 20 from contaminants and further provides subtle distortion correction.
  • the corrector lens 16 has a surface 26 facing the prism 14 which is a rotationally asymmetric aspheric surface such as described above.
  • the opposite surface 28 of the corrector lens 16 may be a planar surface or a surface with positive power. However, in a preferred embodiment, the surface 28 has negative power.
  • the corrector lens 16 is formed with a total negative power that is equal and opposite to the power of the surface 22 so that the user's view of his environment through the optical system 10 is not distorted.
  • the optical power of the corrector lens is less than or equal to 30% of the optical power of the prism 14.
  • the corrector lens has a center thickness that is less than or equal to 3mm.
  • the corrector lens can be formed of a material having an index of refraction and dispersion qualities that are different from the index of refraction and dispersion qualities of the material forming the prism 14 so as to correct for chromatic aberrations.
  • the corrector lens 16 may also include a liquid crystal material that modulates the brightness of the virtual image so as to accommodate variations in the ambient light so that the optical system can be used both indoors and outside. In accordance with a preferred embodiment, both the corrector lens 16 and the prism 14 are decentered with respect to the central visual axis.
  • the optical surfaces are preferably described as follows.
  • the surface 28 of the corrector lens 16 is spherical having a radius of -.0033.
  • the surface 26 of the lens 16 is an anamorphic asphere with the following terms:
  • the physical surface 20 which forms two optical surfaces, the first and third optical surfaces of the prism 14 is an anamorphic asphere defined with the following terms
  • the second optical surface of the prism 14, reflective surface 22, is a rotationally symmetric aspheric surface with the following coefficients.
  • the next optical surface in the ray trace is again the physical surface 20 which is as described above.
  • the fourth optical surface is the entrance surface 18 which is an anamorphic aspheric surface defined with the following terms.
  • both of the corrector lens 16 and the prism 14 are decentered relative to the central visual axis, it is desirable to have these elements fixed with respect to each other.
  • the distance between the prism 14 and the image source 12 is made variable.
  • the prism and lens can be moved together with respect to the image source 12, in a preferred embodiment, it is the image source 12 that is moved relative to the prism 14 to provide for focus adjustment.
  • the image source or display 12 is moved along the central axis of the display towards and away from the entrance surface 18 of the prism.
  • the optical system 10 of the present invention can be used in a monocular head mounted display system or a pair of optical systems 10 can be provided, one system 10 for each of the user's right eye and left eye so as to provide a binocular head mounted system.
  • the corrector lens 16 can include the user's optometric prescription so that the user can use the binocular system without his, or her eyeglasses.
  • the optical system of the present invention may be used as a virtual imaging system incorporated into any portable device.
  • the optical system 10 is extremely well suited for hand held devices such as cellular telephones, PDAs etc., because it is small, compact and lightweight.
  • the prism 14 is not limited to three physical surfaces or three optical surfaces as depicted in Figs. 1 and 2.
  • An example of a prism having more surfaces is depicted in Fig. 3 for a prism 30.
  • light from the display 12 enters the prism 30 through a transmissive entrance surface 32.
  • the light from the entrance surface 32 is reflected by the opposite reflective surface 34 which reflects the light to an adjacent transmissive surface 36 at the angle that is necessary for total internal reflection.
  • the transmissive surface 36 After being reflected by the transmissive surface 36, the light is reflected by a reflector 38 back to the transmissive surface 36 so that the light exits the prism 30 therethrough.
  • the light After exiting the prism, the light passes through the corrector lens 16 to the user's eye.
  • the path segments of the optical path through the prism 30 extend between opposite optical surfaces except for the path segment between adjacent optical surfaces 34 and 36. Because the path of a given ray of Ught through the prism 30 has a greater number of segments extending between opposite optical surfaces than extending between adjacent optical surfaces, the optical element 14 has minimal complex optical distortions that must be corrected.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Lenses (AREA)

Abstract

L'invention porte sur un système optique (10) s'utilisant avec une source d'images (12) et produisant un image virtuelle agrandie présentant un minimum de distorsions. Ledit système, qui permet de produire des images virtuelles de textes en petites fontes, par exemple de 8 ou 10 points qui deviennent ainsi facilement lisibles comporte un prisme (14) à pouvoir positif dont la totalité du pouvoir est répartie entre les surfaces optiques du prisme et à l'intérieur desdites surfaces de manière équilibrée. Ledit prisme utilise une combinaison de surfaces (18, 20) asphériques asymétriques tournantes et d'un réflecteur (22) asphérique symétrique tournant produisant une image virtuelle présentant une très haute qualité sur toute sa largeur aussi bien sur le bord ou la périphérie qu'au centre. Ledit prisme peut être utilisé seul ou associé à une lentille correctrice mince qui non seulement corrige les distorsions minimes, mais également protège le prisme des éléments contaminants.
PCT/US2001/014634 2000-05-12 2001-05-07 Systeme d'imagerie virtuelle pour textes en petites fontes WO2001088597A1 (fr)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
US20371400P 2000-05-12 2000-05-12
US60/203,714 2000-05-12
US64521900A 2000-08-24 2000-08-24
US09/645,219 2000-08-24
US09/805,712 2001-03-13
US09/805,712 US20010048561A1 (en) 2000-08-24 2001-03-13 Virtual imaging system for small font text

Publications (2)

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WO2001088597A1 true WO2001088597A1 (fr) 2001-11-22
WO2001088597A9 WO2001088597A9 (fr) 2002-12-19

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102008005006A1 (de) 2007-01-17 2008-07-24 Carl Zeiss Smt Ag Projektionsoptik für die Mikrolithographie, Projektionsbelichtungsanlage mit einer derartigen Projektionsoptik, Verfahren zur Herstellung eines mikrostrukturierten Bauteils mit einer derartigen Projektionsbelichtungsanlage sowie durch das Herstellungsverfahren gefertigtes mikrostrukturiertes Bauelement
US7929114B2 (en) 2007-01-17 2011-04-19 Carl Zeiss Smt Gmbh Projection optics for microlithography
US8018650B2 (en) 2007-01-17 2011-09-13 Carl Zeiss Smt Gmbh Imaging optical system
US8194230B2 (en) 2006-12-04 2012-06-05 Carl Zeiss Smt Gmbh Projection objectives having mirror elements with reflective coatings
US8902406B2 (en) 2009-11-26 2014-12-02 Carl Zeiss Smt Gmbh Projection objective

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5701202A (en) * 1995-05-18 1997-12-23 Olympus Optical Co., Ltd. Head or face mounted image display apparatus
US5745295A (en) * 1995-11-28 1998-04-28 Olympus Optical Co., Ltd. Image display apparatus
US6134051A (en) * 1997-11-06 2000-10-17 Olympus Optical Co., Ltd. Optical system for image observation

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5701202A (en) * 1995-05-18 1997-12-23 Olympus Optical Co., Ltd. Head or face mounted image display apparatus
US5745295A (en) * 1995-11-28 1998-04-28 Olympus Optical Co., Ltd. Image display apparatus
US6134051A (en) * 1997-11-06 2000-10-17 Olympus Optical Co., Ltd. Optical system for image observation

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8967817B2 (en) 2001-05-25 2015-03-03 Carl Zeiss Smt Gmbh Imaging optical system with at most 11.6% of the illuminated surfaces of the pupil plane being obscured
US8194230B2 (en) 2006-12-04 2012-06-05 Carl Zeiss Smt Gmbh Projection objectives having mirror elements with reflective coatings
DE102008005006A1 (de) 2007-01-17 2008-07-24 Carl Zeiss Smt Ag Projektionsoptik für die Mikrolithographie, Projektionsbelichtungsanlage mit einer derartigen Projektionsoptik, Verfahren zur Herstellung eines mikrostrukturierten Bauteils mit einer derartigen Projektionsbelichtungsanlage sowie durch das Herstellungsverfahren gefertigtes mikrostrukturiertes Bauelement
US7929114B2 (en) 2007-01-17 2011-04-19 Carl Zeiss Smt Gmbh Projection optics for microlithography
US8018650B2 (en) 2007-01-17 2011-09-13 Carl Zeiss Smt Gmbh Imaging optical system
US8208200B2 (en) 2007-01-17 2012-06-26 Carl Zeiss Smt Gmbh Imaging optical system
US8643824B2 (en) 2007-01-17 2014-02-04 Carl Zeiss Smt Gmbh Projection optics for microlithography
US8810903B2 (en) 2007-01-17 2014-08-19 Carl Zeiss Smt Gmbh Imaging optical system
US9239521B2 (en) 2007-01-17 2016-01-19 Carl Zeiss Smt Gmbh Projection optics for microlithography
US9298100B2 (en) 2007-01-17 2016-03-29 Carl Zeiss Smt Gmbh Imaging optical system
US8902406B2 (en) 2009-11-26 2014-12-02 Carl Zeiss Smt Gmbh Projection objective

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