Light-scanning apparatus and light-scanning-apparatus control method

A light-scanning-apparatus control method in which light emitted from a distal end of an optical fiber is scanned on an imaging subject in a spiraling manner, the light-scanning-apparatus control method comprising:

• generating a driving signal that has a frequency different from a resonant frequency of the optical fiber and that is for causing the distal end of the optical fiber to undergo spiral oscillations;
• and
• causing the distal end of the optical fiber to undergo spiral oscillations in accordance with the generated driving signal,
• wherein the generating of the driving signal generates the drive signal that includes, during one scanning period, a first period in which an amplitude gradually increases from substantially zero to a maximum value and a second period in which the amplitude gradually decreases from the maximum value to substantially zero, and that satisfies conditional expression (1) or conditional expression (2) below:
• {
• Eq
• .
• ⁢
• 2
• }
• 2
• ≥
• 1
• N
• ⁢
• ⁢
• 2
• 2
• ·
• 12
• (
• fd
• fr
• -
• 0.999
• )
• 2
• ⁢
• (
• ⁢
• when
• ⁢
• ⁢
• fd
• fr
• >
• 1
• )
• (
• 1
• )
• 2
• ≥
• 1
• N
• ⁢
• ⁢
• 2
• 2
• ·
• 12
• (
• 1.001
• -
• fd
• fr
• )
• 2
• ⁢
• (
• ⁢
• when
• ⁢
• ⁢
• fd
• fr
• <
• 1
• )
• (
• 2
• )
• where
• fr is the resonant frequency of the optical fiber;
• fd is the frequency of the driving signal;
• and
• N2 is number of oscillations of the driving signal in the second period.