Improvements in or connected with Lenses and their Manufacture.
Year: 1894

page_text: Date of Application, 28th Apr., 1894
Complete Specification Left, 2:th Jan., 1895-Accepted, 13th Apr., 1895
PROVISIONAL SPECIFICATION.
Improvements in or connected with Lenses and their Manufacture.
We, Dr. HEINRICH LUDWIG HUGO SCHRÖDER of Whetstone House, Balham
in the County of Surrey, Optician and JOHN STUART of The Hollies, Clapham
Common in the County of Surrey, Gentleman do hereby declare the nature of this
invention to be as follows:-
This invention has for its object to provide a new system or combination of lenses
suitable for photography, lantern or microscope projection or other like purpose
whereby great facility, or control can be obtained in adjusting the aberrations by
correcting separately the spherical and chromatic defects, the spherical aberration
being corrected in one component and the chromatic aberration being corrected in
the other component.
The said system or combination consists of components each composed of two or
more lenses preferably cemented.
In one of the said components the dispersive powers or "relative dispersions" of
the glasses or materials of the constituent lenses are equal or as nearly equal as is
practicable and there is as great a difference between their refractions as is
practicable.
In the other of the said components the refractive powers of the glasses or
materials of the constituent lenses are equal or as nearly equal as is practicable and
there is as great a difference as is practicable between their dispersive powers. By
this means the burden of correcting the aberrations or optical defects, is divided
between the components as by the one of the said components the whole or nearly
the whole of the chromatic error can be corrected whilst by the other of the said
components nearly the whole of the correction for spherical aberration can be
compensated or adjusted. By these means 'the optical defects can be practically
eliminated and a combination formed suitably achromatised for the purpose
required.
Doted this n0th dow of Amil 100
Improvements in or connected with Lenses and their Manufacture.
We Dr. HEINRICH LUDWIG Hugo SchrōDER of Whetstone House Balham
in the County of Surrey Optician and JOHN STUART of The Hollies; Clapham
Common in the County of Surrey, Gentleman, do hereby declare the nature of this
invention and in what manner the same is to be performed³ to be particularly
described and ascertained in and by the following statement:-
This invention has for its object to provide a new system, or combination, of lenses
suitable for photography, lantern, or microscope, projection, or other like purpose,
D

page_text: whereby great facility, or control, can be obtained in adjusting the aberrations by
correcting, separately, the spherical and chromatic defects, the spherical aberration
being correctable in one component, and the chromatic aberration being correctable
in the other component.
The said system, or combination, consists of components each composed of two,
or more, lenses, preferably cemented. In one of the said components the dispersive
powers, or
"relative dispersions" of the glasses, or materials, of the constituent
lenses, are equal, or as nearly equal as is practicable, and there is as great a
difference between their refractions as is practicable.
In the other of the said components the refractive powers of the glasses, or
materials, of the constituent lenses, are equal or as nearly equal as is practicable,
and there is as great a difference as is practicable between their dispersive powers.
By this means the burden of correcting the aberrations, or optical defects, is divided
between the components as by the one of the said components, the whole, or nearly
the whole, of the chromatic error can be corrected, whilst, by the other of the said
components, nearly the whole of the correction for spherical aberration can be
compensated; or adjusted. By these means the optical defects can be practically
eliminated with great facility and a combination formed suitably achromatised for
the purpose required.
By employing elements as described not only are the colours of the spectra
suitably balanced, but the chromatic difference of the spherical aberration may be
compensated. This, as well as correction for astigmatism and roundness of field, is
effected by the selection of suitable curvatures and thicknesses according to the
material employed in the lenses, the only constants being the similarity of dis-
persions in the elements of one component, and the similarity of refractions in the
other component; for example, glasses may be used in the one component possessing
the following optical properties:
-

page_text: This system, or combination, consists of components, A, and B, each component
being shewn as consisting of two lenses, but there may be more than two, in each
component, if desired.
the
The component A, consists of a flint glass a and a crown glass 1,
dispersive powers, or relative dispersions, of these lenses a, and a being equal;
or as nearly equal as is practicable, and the difference between their refrac-
tions being as great as is practicable. The component B consists of a flint
glass b and a crown glass b₁, the refractive powers of these lenses 6 and b₁ being
equal, or as nearly equal as is practicable, and the difference between their
dispersive powers being as great as is practicable. The chromatic error, in the
component A, is compensated by the dissimilarity of the dispersive powers of the
two glasses in the component B, while the spherical aberration of component B, is
compensated by the dissimilarity of the refractions of the two glasses in the
component A, the necessary curvatures and thicknesses at the centre of the lenses
in this particular combination being set forth below the sections.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
A lens-system, or combination, consisting of components, each consisting of lenses
having the respective characteristics herein before described, so that the one
component can be corrected, or adjusted, to remedy chromatic errors only, and the
other component can be corrected or adjusted to correct spherical aberrations only,
substantially as hereinbefore described.
ليود
1005
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents for the Applicants.