Optical coherence tomographic device comprising dual correction beams of different path lengths

An optical coherence tomographic device comprising:

• a light source;
• a measurement light generator configured to generate measurement light by using light from the light source, and generate reflected light from a subject by irradiating the subject with the generated measurement light;
• a reference light generator configured to generate reference light by using the light from the light source;
• an interference light generator configured to generate interference light by combining the reflected light from the subject generated by the measurement light generator and the reference light generated by the reference light generator;
• an interference light detector configured to detect interference signals from the interference light generated by the interference light generator;
• a processor;
• and
• a memory storing computer-readable instructions,
• wherein the interference light detector comprises:
• a first detector and a second detector configured to convert the interference light to the interference signals;
• a first signal processing unit configured to sample the interference signal outputted from the first detector;
• and
• a second signal processing unit configured to sample the interference signal outputted from the second detector,
• wherein each of the first and second signal processing units is configured to sample the interference signal at a timing that is inputted to the signal processing unit from outside,
• wherein the reflected light generated by the measurement light generator at least includes first correction light having a first optical path length and second correction light having a second optical path length that is different from the first optical path length,
• wherein the computer-readable instructions, when executed by the processor, cause the processor to:
• generate a tomographic image by using the interference signals sampled respectively by the first and second signal processing units;
• and
• correct a time lag in synchronization between sampling timings of the first and second signal processing units by using a first correction signal converted from the first correction light and a second correction signal converted from the second correction light, the first and second correction signals being included in the interference signals sampled respectively in the first and second signal processing units,
• wherein the measurement light generator comprises:
• a splitter configured to split an optical path of the light from the light source into a correction light and the measurement light;
• and
• an optical path length adjuster disposed on a first optical path split by the splitter,
• wherein the measurement light is generated by the light from the light source on a second optical path split by the splitter,
• wherein the correction light comprises the first correction light and the second correction light, both being generated by light from the light source on the first optical path, and
• wherein at least one of the first optical path length of the first correction light and the second optical path length of the second correction light is adjusted by the optical path length adjuster,
• the optical path length adjuster comprises a
• glass block that is disposed on the first optical path split by the splitter, the glass block being configured to allow a part of the measurement light to pass through, and
• the measurement light generator is configured to generate the first correction light by using light that passes through the glass block for a first number of times, and generate the second correction light by using light that passes through the glass block for a second number of times which is different from the first number of times.