EP-4737886-A1 - OPTICAL MEASUREMENT DEVICE AND OPTICAL MEASUREMENT METHOD

EP4737886A1EP 4737886 A1EP4737886 A1EP 4737886A1EP-4737886-A1

Abstract

An optical measurement device 1 includes a timing generator 70, a light source 11, a detection optical system 20 that detects detection light including fluorescence and scattered light and outputs a detection signal, a frequency conversion circuit 45 that generates a difference frequency signal that is a signal of a frequency of a difference between a frequency related to the first frequency signal and a frequency related to the second frequency signal by multiplying the detection signal by the second frequency signal input from the timing generator 70, and a cancel circuit 60 that removes a signal component corresponding to the scattered light from the difference frequency signal based on the difference frequency signal and a third frequency signal. The third frequency signal is a signal of a frequency corresponding to the frequency related to the difference frequency signal.

Inventors

TAKESHITA TERUO
KONDO Fusanori
MATSUMURA Tomokazu
ONODA Hirohisa
MORISHITA NAOKAZU
EJIRI Natsuki
IWATA NAOKI

Assignees

Hamamatsu Photonics K.K.

Dates

Publication Date: 20260506
Application Date: 20240424

Claims (5)

An optical measurement device, comprising: a timing generator configured to output a frequency signal; a light source unit configured to irradiate a sample with first light; a light source drive circuit configured to modulate and drive the light source unit based on a first frequency signal input from the timing generator; a light detection unit configured to detect detection light including second light generated from the sample irradiated with the first light and third light caused by the first light and having a phase equal to that of the first light, and output a detection signal; a frequency conversion circuit configured to calculate the detection signal and a second frequency signal input from the timing generator to generate a difference frequency signal that is a signal of a frequency of a difference between a frequency related to the first frequency signal and a frequency related to the second frequency signal; and a signal processing unit configured to remove a signal component corresponding to the third light from the difference frequency signal based on the difference frequency signal and a third frequency signal input from the timing generator, wherein the third frequency signal is a signal having a frequency corresponding to a frequency related to the difference frequency signal.
The optical measurement device according to claim 1, wherein the first light is excitation light for exciting the sample, the second light is fluorescence emitted by the sample in response to the excitation light, and the third light includes at least one of the excitation light and scattered light of the excitation light.
The optical measurement device according to claim 1, wherein a frequency related to the difference frequency signal is a frequency within a range of 10 Hz to 1 MHz.
The optical measurement device according to claim 1, further comprising: a first frequency filter provided on an input side of the frequency conversion circuit; and a second frequency filter provided on an output side of the frequency conversion circuit, wherein the first frequency filter and the second frequency filter are band pass filters.
An optical measurement method, comprising: irradiating a sample with first light based on a first frequency signal; detecting detection light including second light generated from the sample irradiated with the first light and third light caused by the first light and having a phase equal to that of the first light, and outputting a detection signal; generating a difference frequency signal that is a signal of a frequency of a difference between a frequency related to the first frequency signal and a frequency related to the second frequency signal by calculating the detection signal and the second frequency signal; and removing a signal component corresponding to the third light from the difference frequency signal based on the difference frequency signal and a third frequency signal, wherein the third frequency signal is a signal having a frequency corresponding to a frequency related to the difference frequency signal.

Description

Technical Field One aspect of the present invention relates to an optical measurement device and an optical measurement method. Background Art Patent Literature 1 discloses a technique of irradiating a fluorescence sample placed on a substrate with excitation light and generating and subtracting an attenuation signal in order to remove a fluorescence noise component (a fluorescence component from the substrate) included when fluorescence is measured. Specifically, in Patent Literature 1, an attenuation signal having a phase equal to the fluorescence of the substrate is generated, and the fluorescence noise component is removed by subtracting the attenuation signal from the measured fluorescence signal. Citation List Patent Literature Patent Literature 1: Japanese Unexamined Patent Publication No. 2010-518394 Summary of Invention Technical Problem As described above, in Patent Literature 1, a fluorescence noise component generated from a portion other than a measurement target portion of a sample is removed from fluorescence generated by irradiating the sample with excitation light. Here, as a noise component included when the sample is irradiated with light and light from the sample is detected, not only light (for example, fluorescence) generated from the sample (irradiated object) but also light (for example, scattered light) generated from the irradiation light (for example, excitation light) itself may be considered as a noise component. In the technique of Patent Literature 1, a case where the irradiation light itself becomes a noise component is not considered, and the noise component cannot be removed. In addition, even in a case where the noise component of the irradiation light itself is removed by some method, for example, when the light emission time (light emission duration time) of the light from the sample is shortened to the nanosecond level, a circuit for processing the removal is also required to cope with a high-speed signal. For a high-speed signal of, for example, 10 MHz or more, it may be difficult to remove the noise component depending on the processing capability of the circuit to be used. An aspect of the present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical measurement device and an optical measurement method capable of appropriately removing a noise component caused by irradiation light itself even when light emission time of light to be measured is short. Solution to Problem An optical measurement device according to one aspect of the present invention includes: a timing generator configured to output a frequency signal; a light source unit configured to irradiate a sample with first light; a light source drive circuit configured to modulate and drive the light source unit based on a first frequency signal input from the timing generator; a light detection unit configured to detect detection light including second light generated from the sample irradiated with the first light and third light caused by the first light and having a phase equal to that of the first light, and output a detection signal; a frequency conversion circuit configured to calculate the detection signal and a second frequency signal input from the timing generator to generate a difference frequency signal that is a signal of a frequency of a difference between a frequency related to the first frequency signal and a frequency related to the second frequency signal; and a signal processing unit configured to remove a signal component corresponding to the third light from the difference frequency signal based on the difference frequency signal and a third frequency signal input from the timing generator, in which the third frequency signal is a signal having a frequency corresponding to a frequency related to the difference frequency signal. In an optical measurement device according to an aspect of the present invention, detection light including second light and third light is detected, and a detection signal corresponding to the detection light and a second frequency signal are calculated to generate a difference frequency signal between the first frequency signal and the second frequency signal. Conventionally, there is known a method of removing a noise component caused by irradiation light (first light) itself by removing a phase component of third light from a detection signal of detection light including second light and the third light. Here, as a result of shortening the light emission time of light to be measured, in a case where the speed of the signal processed by the circuit is increased, for example, in a case where the signal becomes a high speed signal of 10 MHz or more, the noise component may not be appropriately removed only by the above-described method depending on the processing capability of the circuit to be used. In this regard, in the optical measurement device according to one aspect of the present inventio