WO1987005709A2 - Lens - Google Patents
Lens Download PDFInfo
- Publication number
- WO1987005709A2 WO1987005709A2 PCT/GB1987/000195 GB8700195W WO8705709A2 WO 1987005709 A2 WO1987005709 A2 WO 1987005709A2 GB 8700195 W GB8700195 W GB 8700195W WO 8705709 A2 WO8705709 A2 WO 8705709A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- lens
- coeff
- dies
- plastics material
- pair
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B3/00—Simple or compound lenses
- G02B3/02—Simple or compound lenses with non-spherical faces
- G02B3/04—Simple or compound lenses with non-spherical faces with continuous faces that are rotationally symmetrical but deviate from a true sphere, e.g. so called "aspheric" lenses
Definitions
- the present invention relates to lenses. More particularly, but not exclusively, the invention relates to small lenses adapted particularly for use with systems where information may be retrieved optically, e.g. compact disc players.
- a lens system for use in reading optical data having as one component a pick-up lens having finite or infinite conjugates, the pickup lens being biaspheric where the surfaces may have spherical, para-boloidal or general conic base curves and higher order correction terms up to 30th order when required.
- a method of making a lens of plastics material comprising diamond machining to a required shape a pair of blanks of metal which is comparatively soft, e.g. brass, taking a negative copy thereof by electro-forming a harder metal e.g. nickel, copying from said negative copy one or more pairs of dies in a hard material, e.g. nickel, and using one pair of said dies to mould the plastics material.
- a third aspect of the present invention there. is provided another method of making a lens of plastic material comprising machining comparatively roughly, e.g. to an accuracy of ⁇ 1 micron, a pair of blanks of hard material, e.g.
- the layer of electroplated metal such as nickel has a thickness in the region of 3 microns.
- a lens of plastics material comprising using hardened steel dies as in the third aspect but having inserted dies made from diamond machined ceramics such as silicon or sapphire, and using said ceramics dies in pairs to mould the plastics material.
- the preferred plastics material is polymethylmethacrylate.
- the lens may more advantageously be made from other materials such as acrylic with low water absorption, polycarbonate, derivatives of polystyrene and certain polyolefins such as TPX and derivatives thereof.
- FIGURE 1 shows diagrammatically a lens according to the prior art having two hyperboloid aspheric surfaces
- FIGURE 2 shows diagrammatically a lens embodying first surface ellipsoid and second hyperboloid
- FIGURE 3 shows another lens embodying a stronger ellipsoid and a weaker hyperboloid than Figure 2;
- FIGURE 5 is a light ray diagram of the lens of Figure 4;
- FIGURE 6 shows diagrammatically a lens embodying a finite conjugate principle;
- FIGURE 7 shows a lens incorporated higher order term mathematics
- FIGURE 8 shows a test plate for interferometric measurement of the lens seen in Figures 4 and 5.
- a lens of plastics material preferably of polymethylmethacrylate but alternatively of other materials that have lower moisture absorption, which has two different aspheric surfaces and is adapted to focus parallel light from finite or infinite conjugates accurately and without distortion onto a point.
- the lens of Figure 4 is shown moulded integrally with abutments to protect the faces of the lens and which are adapted to co-operate with a lens holder.
- registration surfaces are provided whereby the lens may be maintained at a predetermined distance, e.g. 2mm, from the disc.
- the lenses may be moulded from dies made in one of a number of ways. The simplest is to machine a pair of brass blanks by means of diamond cutting which will give nominal accuracy of 0.025 microns. These may be used as dies for subsequent moulding of plastic lenses. However, since the brass is comparatively soft, the dies have a short life.
- a development of the above method is to machine the brass blanks as described above, and then take a nickel electroform copy, known as a submaster from the blank. The submaster is then used to produce a nickel copy, known as a daughter, which may be used as a die for the moulding process.
- This has the advantage that a number of dies may be made from a single brass blank.
- a further alternative is to machine hard tool steel blanks, comparatively roughly, e.g. to a tolerance of 1 micron, into a rough outline of the desired surface.
- the tool steel is then electroplated with nickel to a depth of approximately 3 microns.
- the nickel layer can then be machined by diamond cutting to the exact shape required with an accuracy as above. This can be used directly as a production die.
- a further alternative is to machine a hard tool steel surround in which may be mounted an insert manufactured from certain ceramics of which examples are silicon or sapphire. These may be diamond machined directly and used as production dies.
- Lenses according to Figure 4 are intended to focus collimated light to a point within the material of the disc. Accordingly, it is not possible to test such lenses for quality control in the absence of the disc material.
- the lens of Figure 3 is an interim infinite conjugate design intended for easy laboratory interferometry since it focuses to a real point in space. Testing is conducted by passing parallel light through the lens and reflecting it from a common sphere reflector placed such that its centre of curvature coincides with the focal point of the lens. The returned light then forms fringes at an interferometer beam splitter and shows the double-pass perfor-mance of the lens.
- the lens of Figure 6 is a finite conjugate lens, for which testing resembles that for Figure 3 excpet that the input light of the lens must have a cone angle equal to that in actual use.
- the lens in Figures 4 and 5 cannot be directly measured in the manner of the lens shown in Figure 3, since the real focus of the light is contained within the body of the disc at a rear surface thereof.
- the preferred light source is a laser diode having a peak wavelength of 780 nm.
- the refractive index of polymethylmethacrylate is taken to be 1.4848.
- the light leaving the collimator lens and reaching the pickup lens comprises parallel rays and accordingly separation of the two lenses is comparatively unimportant.
- the pickup lens is adapted to be maintained at a predetermined distance from the disc on which is stored the data and, being made of plastics material, is sufficiently light to be moved easily.
- the geometry of the surface is calculated as follows:
- the back vertex focal length given for the embodiment of Figure 4 is calculated on the basis that the disc is not present.
- the spot diameter given in the table is calculated geometrically and takes no account of diffraction effects.
- the exact parameters of the lens may need to be changed slightly in some respects.
- coefficients for various lenses are given in the Table below.
- FIGURE 1 A first figure.
- One further lens has a first surface which is a modified paraboloid, and a second surface which is a sphere.
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8606838 | 1986-03-19 | ||
GB868606838A GB8606838D0 (en) | 1986-03-19 | 1986-03-19 | Lens |
Publications (2)
Publication Number | Publication Date |
---|---|
WO1987005709A2 true WO1987005709A2 (en) | 1987-09-24 |
WO1987005709A3 WO1987005709A3 (en) | 1987-11-05 |
Family
ID=10594900
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB1987/000195 WO1987005709A2 (en) | 1986-03-19 | 1987-03-19 | Lens |
Country Status (5)
Country | Link |
---|---|
US (1) | US5013143A (en) |
EP (1) | EP0263139A1 (en) |
JP (1) | JPH01500225A (en) |
GB (2) | GB8606838D0 (en) |
WO (1) | WO1987005709A2 (en) |
Families Citing this family (29)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2200763B (en) * | 1987-01-28 | 1991-02-13 | Combined Optical Ind Ltd | Stand magnifiers and lens |
ES2151971T3 (en) * | 1995-12-12 | 2001-01-16 | Pareto Eugeni Jordana | LENS SYSTEM WITHOUT SPHERICITY OPENING, AND STEREOSCOPIC CAMERA INCLUDING SUCH LENS SYSTEM. |
US5757758A (en) * | 1995-12-19 | 1998-05-26 | Konica Corporation | Optical pickup apparatus objective lens and converging optical system for optical pickup and optical disk apparatus |
WO1999009446A1 (en) * | 1997-08-19 | 1999-02-25 | Koninklijke Philips Electronics N.V. | An optical system restraining aberrations within the maximum imaging volume |
US6349159B1 (en) * | 1999-09-02 | 2002-02-19 | Agilent Technologies, Inc. | Lenses that launch high bandwidth modes into a fiber optic cable while eliminating feedback to a laser |
EP1394572B1 (en) * | 2001-05-09 | 2010-04-21 | Hamamatsu Photonics K.K. | Method of producing optical lens, and optical lens |
JP4197957B2 (en) * | 2001-05-09 | 2008-12-17 | 浜松ホトニクス株式会社 | Manufacturing method of optical lens |
EP1391753B1 (en) * | 2001-05-09 | 2010-12-15 | Hamamatsu Photonics K. K. | Optical lens |
US7629941B2 (en) * | 2007-10-31 | 2009-12-08 | Searete Llc | Electromagnetic compression apparatus, methods, and systems |
US7733289B2 (en) * | 2007-10-31 | 2010-06-08 | The Invention Science Fund I, Llc | Electromagnetic compression apparatus, methods, and systems |
US20090218523A1 (en) * | 2008-02-29 | 2009-09-03 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | Electromagnetic cloaking and translation apparatus, methods, and systems |
US20090218524A1 (en) * | 2008-02-29 | 2009-09-03 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | Electromagnetic cloaking and translation apparatus, methods, and systems |
US8638504B2 (en) * | 2008-05-30 | 2014-01-28 | The Invention Science Fund I Llc | Emitting and negatively-refractive focusing apparatus, methods, and systems |
US8531782B2 (en) * | 2008-05-30 | 2013-09-10 | The Invention Science Fund I Llc | Emitting and focusing apparatus, methods, and systems |
US8817380B2 (en) * | 2008-05-30 | 2014-08-26 | The Invention Science Fund I Llc | Emitting and negatively-refractive focusing apparatus, methods, and systems |
US8493669B2 (en) * | 2008-05-30 | 2013-07-23 | The Invention Science Fund I Llc | Focusing and sensing apparatus, methods, and systems |
US8773776B2 (en) * | 2008-05-30 | 2014-07-08 | The Invention Science Fund I Llc | Emitting and negatively-refractive focusing apparatus, methods, and systems |
US7830618B1 (en) * | 2008-05-30 | 2010-11-09 | The Invention Science Fund I | Negatively-refractive focusing and sensing apparatus, methods, and systems |
US8773775B2 (en) * | 2008-05-30 | 2014-07-08 | The Invention Science Fund I Llc | Emitting and negatively-refractive focusing apparatus, methods, and systems |
US7869131B2 (en) * | 2008-05-30 | 2011-01-11 | The Invention Science Fund I | Emitting and negatively-refractive focusing apparatus, methods, and systems |
US8164837B2 (en) * | 2008-05-30 | 2012-04-24 | The Invention Science Fund I, Llc | Negatively-refractive focusing and sensing apparatus, methods, and systems |
US7872812B2 (en) * | 2008-05-30 | 2011-01-18 | The Invention Science Fund I, Llc | Emitting and focusing apparatus, methods, and systems |
US7777962B2 (en) * | 2008-05-30 | 2010-08-17 | The Invention Science Fund I, Llc | Negatively-refractive focusing and sensing apparatus, methods, and systems |
US8736982B2 (en) * | 2008-05-30 | 2014-05-27 | The Invention Science Fund I Llc | Emitting and focusing apparatus, methods, and systems |
US9019632B2 (en) * | 2008-05-30 | 2015-04-28 | The Invention Science Fund I Llc | Negatively-refractive focusing and sensing apparatus, methods, and systems |
US8638505B2 (en) * | 2008-05-30 | 2014-01-28 | The Invention Science Fund 1 Llc | Negatively-refractive focusing and sensing apparatus, methods, and systems |
US8837058B2 (en) * | 2008-07-25 | 2014-09-16 | The Invention Science Fund I Llc | Emitting and negatively-refractive focusing apparatus, methods, and systems |
US8730591B2 (en) * | 2008-08-07 | 2014-05-20 | The Invention Science Fund I Llc | Negatively-refractive focusing and sensing apparatus, methods, and systems |
KR20100076784A (en) | 2008-12-26 | 2010-07-06 | 삼성전자주식회사 | Aspheric lens and optical pickup employing the same as objective lens |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2088273A (en) * | 1980-12-03 | 1982-06-09 | Philips Electronic Associated | Method of making biaspherical optical elements |
EP0011331B1 (en) * | 1978-11-06 | 1983-01-26 | Philips Electronics Uk Limited | Method of making a master replicating tool |
Family Cites Families (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB558657A (en) * | 1942-05-08 | 1944-01-14 | Cecil Reginald Burch | Improvements in lenses |
NL127036C (en) * | 1959-06-02 | 1900-01-01 | ||
GB1176659A (en) * | 1966-01-04 | 1970-01-07 | Hans-Joachim Gasa | An Optical Lens. |
FR2271585B1 (en) * | 1974-05-14 | 1976-10-15 | Philips Nv | |
US3944337A (en) * | 1974-10-18 | 1976-03-16 | Eastman Kodak Company | Three element objective lens with ellipsoidal, hyperbolic, and parabolic surfaces |
US3912379A (en) * | 1974-11-05 | 1975-10-14 | Eastman Kodak Co | Three element objective lens having asphoric surfaces on the middle element |
JPS5776512A (en) * | 1980-10-31 | 1982-05-13 | Konishiroku Photo Ind Co Ltd | Large-aperture aspheric single lens |
JPS5880601A (en) * | 1981-11-09 | 1983-05-14 | Sony Corp | Generator for parallel luminous fluxes |
JPS5926714A (en) * | 1982-08-05 | 1984-02-13 | Olympus Optical Co Ltd | Lens for optical disc |
US4561730A (en) * | 1982-09-30 | 1985-12-31 | Coulter Systems Corporation | Synthetic resin lens system for imaging apparatus |
US4542961A (en) * | 1983-03-03 | 1985-09-24 | Canon Kabushiki Kaisha | Triplet type objective |
NL8403198A (en) * | 1984-10-22 | 1986-05-16 | Philips Nv | SIMPLE BIASPHERIC LENS. |
-
1986
- 1986-03-19 GB GB868606838A patent/GB8606838D0/en active Pending
-
1987
- 1987-03-19 JP JP62501841A patent/JPH01500225A/en active Pending
- 1987-03-19 WO PCT/GB1987/000195 patent/WO1987005709A2/en not_active Application Discontinuation
- 1987-03-19 EP EP87902118A patent/EP0263139A1/en not_active Withdrawn
- 1987-03-19 GB GB08706524A patent/GB2188167A/en not_active Withdrawn
-
1989
- 1989-12-21 US US07/456,631 patent/US5013143A/en not_active Expired - Fee Related
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0011331B1 (en) * | 1978-11-06 | 1983-01-26 | Philips Electronics Uk Limited | Method of making a master replicating tool |
GB2088273A (en) * | 1980-12-03 | 1982-06-09 | Philips Electronic Associated | Method of making biaspherical optical elements |
Non-Patent Citations (2)
Title |
---|
Applied Optics, Vol. 22, No. 16, August 1983 (New York, US) R.O. MASCHMEYER et al.: "Optical Performance of a Diffraction-Limited Molded-Glass Biaspheric Lens", pages 2413-2415, see the entier document * |
Applies Optics, Vol. 24, No. 12, June 1985 (New York, US), J.J.M. BRAAT et al.: "Design and Production Technology of Replicated Aspheric Objective Lenses for Optical Disk Systems", pages 1853-185k, see pages 1853-1854 * |
Also Published As
Publication number | Publication date |
---|---|
GB2188167A (en) | 1987-09-23 |
GB8706524D0 (en) | 1987-04-23 |
WO1987005709A3 (en) | 1987-11-05 |
GB8606838D0 (en) | 1986-04-23 |
US5013143A (en) | 1991-05-07 |
EP0263139A1 (en) | 1988-04-13 |
JPH01500225A (en) | 1989-01-26 |
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