Testing and calibrating device for optical eye length...

Details Testing and calibrating device for optical eye length... Testing and calibrating device for optical eye length...

2000-08-03

2002-11-19

Manuel, George (Department: 3737)

Optics: eye examining, vision testing and correcting

Eye examining or testing instrument

Reexamination Certificate

active

06481847

ABSTRACT:

BACKGROUND OF THE INVENTION
a) Field of the Invention
The present invention relates to a testing and calibrating device for optical eye length measurement devices.
b) Description of the Related Art
A spherical transparent test body which is preferably made of glass, has coatings and a refractive index of approximately 2 is known as a testing and calibrating device for optical eye length measurement instruments (EP-A 509903, U.S. Pat. No. 5,347,327, U.S. Pat. No. 5,347,328) from DE 19504465 A1 by the present Applicant. The coating, chiefly of the back of the test body, involves a costly technique and difficult technology.
OBJECT AND SUMMARY OF THE INVENTION
Therefore, the primary object of the present invention is a test body for optical eye length measurement devices that is simple to produce but is universally applicable.
In accordance with the invention, a testing and calibrating device for optical eye length measurement devices comprises two plano-convex lenses which are arranged in the illumination beam path so as to be oppositely oriented. A neutral filter with a defined transmission is located between these two plano-convex lenses.


REFERENCES:
patent: 5535743 (1996-07-01), Backhaus et al.
patent: 6042785 (2000-03-01), Harju
patent: 43 13 031 (1994-10-01), None
patent: 195 04 465 (1996-08-01), None
*English Abstract of DE 195 04 465 A1.
*English Abstract of DE 43 13 031 A1.

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