Optical measurement method and appartus
An objective of the present invention is to provide a technique for reducing measurement errors when measuring specimen using light. An aspect of an optical measurement method according to the present invention: acquires relationship data that describes a relationship between an intensity of reflection light when irradiating light onto a specimen and a size of the specimen; and acquires the size of the specimen using the relationship data and the intensity of the reflection light. Another aspect of an optical measurement method according to the present invention subtracts a component due to an inclination of a vessel of a specimen from a detection signal representing an intensity of reflection light when irradiating light onto the specimen, thereby correcting the inclination of the vessel.
1. An optical measurement method to measure a specimen having a size equal to or less than three times a size of an optical spot, comprising:
focusing light at a plurality of predetermined focus points in an optical axis direction to generate the optical spot on the specimen;
detecting, at each of the focus points, reflection light reflected from the specimen while scanning the optical spot across the specimen perpendicular to the optical axis direction; and
acquiring a size of the specimen by referring to relationship data that describes a relationship between an intensity of the reflection light and the size of the specimen.
2. The optical measurement method according to claim 1 ,
wherein a maximum signal value of the intensity of the reflection light is acquired at each of the focus points, and
wherein the size of the specimen is acquired by referring to the relationship data using a half width of the maximum signal value of the intensity of the reflection light.
3. The optical measurement method according to claim 1 ,
wherein the relationship data describes a relationship among: a shifted amount representing an amount by which the focus point is shifted from a center of the specimen, an amount by which the intensity of the reflection light attenuates depending on the shifted amount, and the size of the specimen,
wherein an attenuation amount is acquired that represents an amount by which the intensity of the reflection light attenuates by shifting between the focus points in the optical axis direction, and
wherein the size of the specimen is acquired by referring to the relationship data using the attenuation amount and the amount by which each of the focus points is shifted when acquiring the attenuation amount.
4. An optical measurement apparatus that measures a specimen using an optical spot, the specimen having a size equal to or less than three times a size of the optical spot, comprising:
an optical source that irradiates laser light;
a lens that focuses the laser light onto a specimen;
a detector that detects reflection light reflected from the specimen; and
a processor that is programmed to:
control the lens to focus the laser light at a plurality of predetermined focus points in an optical axis direction to generate the optical spot on the specimen,
control the detector to detect, at each of the focus points, the reflection light reflected from the specimen while scanning the optical spot across the specimen perpendicular to the optical axis direction, and
acquire a size of the specimen by referring to relationship data that describes a relationship between an intensity of the reflection light and the size of the specimen.