Fundus examination apparatus

A fundus examination apparatus comprising:

• an irradiating system configured to irradiate the fundus of an examined eye with a measuring beam, said irradiating system including a deflector configured to deflect the measuring beam and change the position of the measuring beam on the fundus;
• a light receiving system configured to receive the scattered light from the fundus of the eye by said measuring beam, and to obtain a signal of the scattered light of the measuring beam necessary for examination;
• a tracking system configured to irradiate the fundus of the eye with a tracking beam, wherein said light receiving system is configured to receive a scattered tracking beam scattered from the fundus of the eye and to produce an image signal of a region illuminated by the tracking beam, wherein said tracking system is configured to control said deflector on the basis of the image signal of the region illuminated by said tracking beam;
• and
• a controller having a processor configured to evaluate the signal of the scattered light of the measuring beam obtained by said light receiving system, and to control said deflector on the basis thereof during the execution of tracking to thereby correct the irradiated position of said measuring beam, wherein said processor is configured to find the reliability of the signal necessary for examination by performing a process including the calculation of the signal-to-noise ratio of the light necessary for examination and wherein said processor is also configured to effect said evaluation.

A fundus examination apparatus comprising:

• an irradiating system for irradiating the fundus of an examined eye with a measuring beam;
• a light receiving system for receiving the scattered light from the fundus of the eye by said measuring beam, and obtaining a signal necessary for examination;
• and
• a processor for frequency-analyzing the signal obtained by said light receiving system, and calculating the velocity of blood flow in a vessel on the fundus of the eye,
• said processor executing signal processing including a first step of calculating an integrated curve in which the spectral distribution of the result of said frequency analysis is accumulated from a high frequency side, and a second step of dividing said spectral distribution into at least two areas which area noise area existing in a high frequency area and approximated to white noise, and a signal area existing more adjacent to a low frequency side than said noise area, by the use of said integrated curve.

A method of measuring flow velocity comprising the steps of:

• irradiating an examined portion with a measuring beam through a deflector, and detecting the scattered light from said examined portion by a detecting system;
• irradiating the vicinity of the examined portion with a tracking beam through said deflector to thereby obtain tracking information, and controlling said deflector on the basis of the tracking information and executing tracking;
• calculating a position at which the reliability of detected signals of said detecting system is relatively improved during the tracking using at least the signal-to-noise ratio of the detected signals, and controlling said deflector so that said measuring beam irradiates said position;
• and
• frequency-analyzing the detected signals obtained by said detecting system and calculating the flow velocity of a fluid flow through the examined portion.