Opthalmologic Apparatus

• US 20070236661A1
• Filed: 04/05/2007
• Published: 10/11/2007
• Est. Priority Date: 04/07/2006
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Topcon
• Original Assignee: Kabushiki Kaisha Topcon
• Inventors: Fukuma, Yasufumi, Otsuka, Hiroyuki, Yumikake, Kazuhiko
• Granted Patent: US 7,370,966 B2
• Time in Patent Office: Days
• US Class Current: 351/205
• CPC Class Codes: A61B 3/102 for optical coherence tomography [OCT]
• CPC Class Codes: G01B 11/14 for measuring distance or clearance between spaced objects or spaced apertures G01B11/26 takes precedence; rangefinders G01C3/00
• CPC Class Codes: G01B 9/0203 With imaging systems
• CPC Class Codes: G01B 9/02068 Auto-alignment of optical elements
• CPC Class Codes: G01B 9/02091 Tomographic interferometers, e.g. based on optical coherence

Abstract

The ophthalmologic apparatus 1 splits low coherence light LO into a signal light LS and a reference light LR, the interference light LC being generated by having the signal light LS overlap with the reference light LR, and detects this interference light LC. In addition, the apparatus comprises an optical alignment system 190A for performing the alignment of an optical system forming the signal light path to the eye EL. An intraocular distance calculator 214 determines the distance between the position where the signal light LS has been introduced onto the eye E and the position where the signal light LS has been reflected by the fundus oculi E based on length of the optical path of the signal light, the length of the optical path of the reference signal light, the working distance after alignment, and the detection signal output by the CCD 184 (or signal intensity data).

Claims

1. An ophthalmologic apparatus comprising:

a light source configured to emit a low coherence light;

an interference light generator configured to split the emitted low coherence light into the signal light directed toward the fundus oculi of an eye and the reference light directed toward the reference object, and to overlap the signal light irradiated onto the eye via a signal light path and reflected by the fundus oculi and the reference light reflected by said reference object via a reference light path, so as to generate interference light;

a detector configured to receive the generated interference light and to output a detection signal;

an alignment part configured to align an optical system forming said signal light path to the eye; and

an intraocular distance calculator operable to determine the intraocular distance based on the optical path length of said signal light path, the optical path length of said reference light path, said aligned distance between the eye and said optical system, and said output detection signal, the intraocular distance being between the incident position of said signal light onto the eye and the reflection position of said signal light at the fundus oculi.

2. An ophthalmologic apparatus according to claim 1, wherein said intraocular distance calculator determines said intraocular distance by subtracting the optical length of said signal light path and said aligned distance from the optical path of the reference light path, where intensity of the corresponding component of the portion of said signal light reflected by the surface of the fundus oculi is the greatest among the portions included in said detection signal.

3. An ophthalmologic apparatus according to claim 2, wherein:

the incident position of said signal light is a position at the top of the cornea of the eye, and

said intraocular distance calculator determines the axial length between the position at the top of the cornea and the center position on the surface of the fundus oculi.

4. An ophthalmologic apparatus according to claim 1, wherein:

said alignment part projects an alignment indicator onto the position half of the radius of curvature away from the center of the corneal curvature,

said aligned distance is the distance between the projection points of said alignment indicator and said optical system, and

said intraocular distance calculator determines the axial length of the eye by subtracting the optical length of said signal light path and said aligned distance from the optical path of the reference light path and adding half of the distance of said radius of curvature to the results of the subtraction, where the intensity of the corresponding component of portion of said signal light reflected by the surface of the fundus oculi is the greatest among the portions included in said detection signal.