resolving eyesight ability
V.V. Rozhentsov, Т.А. Lezhnina
Visual system has a certain persistence owing to which critical flicker frequency is observed, that is to say flicker frequency in a second with which subjective perception of flickers confluence realizes. The disadvantage of critical flicker frequency (CFF) method is its low accuracy which is caused by lack of clear transition from flicker visibility to its confluence. It is explained by visual system inability to discern flicker close frequency.
There were examined several well-known ways of definition of the resolving eyesight ability to the flicker frequency with use of one light-emitting diode: with uninterruptedly variable frequency, with alternate presentation of starting and incremental/decremental frequency, with alternate presentation of incremental and decremental frequency.
It is offered a way of the resolving eyesight ability definition to the flicker frequency with use of two light-emitting diodes, starting frequency is presented on both of them. Then incremental frequency is presented on the first light-emitting diode, decremental frequency is presented on the second light-emitting diode. The difference between two presented frequencies is being increased till definition of the threshold of flicker frequency discerning.
Ten beforehand instructed 19–23-year old probationers with normal and corrected eyesight were selected for ex-perimental researches. They fulfilled two series of 10 dimensions of the resolving eyesight ability to the flicker fre-quency at a starting frequency 15 Hz each. In the first series of measurement incremental and decremental flicker frequencies were presented alternately with a period 1 sec on the first light-emitting diode for 5 probationers. In the second series of measurement it was used simultaneous presentation on two light-emitting diodes. It was chosen an inverse order of fulfillment of measurement for five other probationers.
A yellow-colored light-emitting diode in diameter of 5 mm and light intensity of 3 mcd was applied as a source of light impulses. The light-emitting diode was placed in the area of the nearest point of clear vision.
Measurement results analysis showed that differences between arithmetic means, which were got as a result of 2 series of measurement for each probationer, are not statistically reliable. Diminution of random component of measurement error, determined by diminution of standard deviation, in fulfillment of measurement with use of two light-emitting diodes in comparison with measurement, fulfilled with use of one light-emitting diode, is observed for all probationers. It composed 15 – 29 % in the group.