Optics: measuring and testing – Lens or reflective image former testing – For optical transfer function
Patent
1995-12-27
1998-06-02
Font, Frank G.
Optics: measuring and testing
Lens or reflective image former testing
For optical transfer function
356372, 356376, G01B 900, G01B 1100, G01B 1114
Patent
active
057608890
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to apparatus for the measurement of the curvature of a surface.
More especially although not exclusively it relates to apparatus for affording, on a production line for example, a simple but accurate indication of whether the surface curvature of a product being manufactured is within a curvature specification, together with an indication of any deviation from a required curvature specification.
SUMMARY OF THE INVENTION
One embodiment of the invention relates in particular to a measure of the radii of curvature of spectacle lenses in order that accurate lenses can be manufactured. With the requirement to measure the radius of curvature of spectacle lenses to an accuracy greater than is presently possible, a need also exists for an instrument to accurately measure the radii of curvature across zones of a lens, to measure the power of a lens and also to measure prism power. Additionally, a need has arisen for the measurement of lenses on a production line for identification prior to packaging so that the correct lens power can be printed on the package.
A further embodiment of the invention relates to a problem where the radii of curvature of contact lenses is required to be measured in order that accurate lenses could be manufactured. With the requirement to measure the radius of curvature of the contact lens with an accuracy greater than is presently possible, the need exists for an instrument to objectively, and accurately, measure the radii of curvature across the zones of the lens.
It is therefore an object of the present invention to provide apparatus which will satisfy the aforementioned needs whereby the rapid and accurate measurement of lenses is facilitated.
According to the present invention there is provided apparatus for measurement of the curvature of a surface, comprising at least one source of electromagnetic radiation, electromagnetic radiation detector means, lens means positioned and arranged to focus source radiation reflected from said surface onto said detector means, a beam splitter positioned between said detector means and the surface, via which radiation from said source is directed onto the surfaces, and means for calculating said measurement from signals detected by said detector means. The detector menus is a two dimensional detector. A scanning means is provided which causes a beam of radiation from said source to be scanned across the surface, thereby producing a multiplicity of beams which are reflected from said surface via said lens means where a reflected angle of each beam is transformed in physical displacement on said detector means.
In an embodiment, the scanning means may be in the form of a scanning mirror prism.
In an embodiment, the scanning means may be in the form of a light shutter used in combination with a further lens means.
The light shutter comprises an addressable array of light switches.
The apparatus may be used to control a cutting tool, or may be used in a sorting process.
Some embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block schematic diagram of Go/No Go lens measurement apparatus of the present invention.
FIG. 2 is a block schematic diagram of a multibeam detector system for use in the system of FIG. 1 of the present invention.
FIG. 3 is a block schematic diagram showing the parameters of a dual beam system of the present invention.
FIG. 4 is a block schematic diagram of a lens testing system using multibeams of the present invention.
FIG. 5 is a block schematic diagram showing in more detail a scanner for use in the system shown in FIG. 4 of the present invention.
FIG. 6 is a somewhat schematic block diagram showing a production line control system using an AMROC.TM. lens sorter/checker of the present invention.
FIG. 7 is a block schematic diagram showing an alternative lens measurement system
FIG. 8 is a block schematic diagram of apparatus for measuring the surfac
REFERENCES:
patent: 4495386 (1985-01-01), Brown et al.
patent: 4537373 (1985-08-01), Maschmeyer
patent: 4588270 (1986-05-01), Tamaki
patent: 4701945 (1987-10-01), Pedigo
patent: 5461412 (1995-10-01), Paoli et al.
Font Frank G.
Roke Manor Research Limited
Stafira Michael P.
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