Patent ID: 7826325

Claim:
A recording and reproducing apparatus for recording data to and reproducing data from a hologram recording medium, comprising: light emitting means for emitting light to be directed to the recording medium set at a predetermined position; spatial light modulation means for performing spatial light modulation on incident light by pixels; an image sensor for receiving incident light by pixels and converting the incident light into an electrical signal; an optical system for guiding the light emitted by the light emitting means to the recording medium via the spatial light modulation means while guiding, to the image sensor, light reflected from the recording medium in response to the light emitted by the light emitting means; and determination means for controlling the spatial light modulation means so that each pixel within the spatial light modulation means modulates the light incident thereon with a high/low intensity modulation in light intensity with the light emitting means remaining switched on, and for determining the presence or absence of a defect in an optical path based on a determination as to whether a value indicative of high/low light intensity is obtained as a value detected on each pixel in the image sensor in response to the high/low intensity modulation, wherein the determination means determines, as being defective, pixels that provide the detected values, arising from the high/low light intensity modulation, failing to be values representing the high/low light intensity values, acquires, with the light emitting means switched off, values of the defective pixels that provide at least the values responsive to the high/low light intensity, and determines whether a detected pattern of high/high/low light intensity inclusive of the detected value is obtained in order to determine that a defect occurring in a collinear optical axis with the defective pixel is a pixel defect in the spatial light modulation means.