An optical detection device comprising: a light source section that generates a first pulsed light; a filter section that transmits a second pulsed light formed from a portion of a frequency spectrum exhibited by the first pulsed light, and that reflects a third pulsed light formed from another portion of the frequency spectrum exhibited by the first pulsed light; a phase modulation section that phase modulates the second pulsed light at a plurality of phases comprising at least three phases; a multiplexing section that produces a fourth pulsed light by multiplexing the third pulsed light with the second pulsed light phase modulated by the phase modulation section; a detector (16, 18) that spectrally disperses and detects scattered light generated by radiating the fourth pulsed light onto a target object; and an extraction section that uses calculation processing of or to synchronize with the phase modulation in the phase modulation section, so as to extract coherent anti-Stokes Raman scattering, CARS, spectrum components of scattered light that are synchronous with the phase modulation from the frequency spectrum of the scattered light detected by the detector, wherein and are as follows: the plurality of phases are φ, φ + 2π/3, and φ + 4π/3 (where φ is a fixed phase), and the extraction section extracts a CARS frequency spectrum in which the value of the intensity I is 0 or a value within an acceptable range of 0, where I is expressed by the equation below where the intensities I(φ), I(φ + 2π / 3), and I(φ + 4π / 3) are the intensities at the plurality of phases of the scattered light detected by the detector (16, 18): I = I Ø + 2 π 3 − I Ø + 4 π 3 3 2 + I Ø + 2 π 3 + I Ø + 4 π 3 − 2 I Ø 3 2 the plurality of phases are φ, φ + π/2, φ + π, and φ + 3π/2 (where φ is a fixed phase), and the extraction section extracts a CARS frequency spectrum in which the value of the intensity I is 0 or a value within an acceptable range of 0, where I is expressed by the equation below where the intensities I(φ), I(φ + π/2), I(φ + π), and I(φ + 3π/2) are the intensities at the plurality of phases of the scattered light detected by the detector (16, 18): I = I Ø − I Ø + π 2 + I Ø + π 2 − I Ø + 3 π 2 2 a light source section that generates a first pulsed light; a filter section that transmits a second pulsed light formed from a portion of a frequency spectrum exhibited by the first pulsed light, and that reflects a third pulsed light formed from another portion of the frequency spectrum exhibited by the first pulsed light; a phase modulation section that phase modulates the second pulsed light at a plurality of phases comprising at least three phases; a multiplexing section that produces a fourth pulsed light by multiplexing the third pulsed light with the second pulsed light phase modulated by the phase modulation section; a detector (16, 18) that spectrally disperses and detects scattered light generated by radiating the fourth pulsed light onto a target object; and an extraction section that uses calculation processing of or to synchronize with the phase modulation in the phase modulation section, so as to extract coherent anti-Stokes Raman scattering, CARS, spectrum components of scattered light that are synchronous with the phase modulation from the frequency spectrum of the scattered light detected by the detector, wherein and are as follows: the plurality of phases are φ, φ + 2π/3, and φ + 4π/3 (where φ is a fixed phase), and the extraction section extracts a CARS frequency spectrum in which the value of the intensity I is 0 or a value within an acceptable range of 0, where I is expressed by the equation below where the intensities I(φ), I(φ + 2π / 3), and I(φ + 4π / 3) are the intensities at the plurality of phases of the scattered light detected by the detector (16, 18): I = I Ø + 2 π 3 − I Ø + 4 π 3 3 2 + I Ø + 2 π 3 + I Ø + 4 π 3 − 2 I Ø 3 2 the plurality of phases are φ, φ + π/2, φ + π, and φ + 3π/2 (where φ is a fixed phase), and the extraction section extracts a CARS frequency spectrum in which the value of the intensity I is 0 or a value within an acceptable range of 0, where I is expressed by the equation below where the intensities I(φ), I(φ + π/2), I(φ + π), and I(φ + 3π/2) are the intensities at the plurality of phases of the scattered light detected by the detector (16, 18): I = I Ø − I Ø + π 2 + I Ø + π 2 − I Ø + 3 π 2 2 the plurality of phases are φ, φ + 2π/3, and φ + 4π/3 (where φ is a fixed phase), and the extraction section extracts a CARS frequency spectrum in which the value of the intensity I is 0 or a value within an acceptable range of 0, where I is expressed by the equation below where the intensities I(φ), I(φ + 2π / 3), and I(φ + 4π / 3) are the intensities at the plurality of phases of the scattered light detected by the detector (16, 18): I = I Ø + 2 π 3 − I Ø + 4 π 3 3 2 + I Ø + 2 π 3 + I Ø + 4 π 3 − 2 I Ø 3 2 the plurality of phases are φ, φ + π/2, φ + π, and φ + 3π/2 (where φ is a fixed phase), and the extraction section extracts a CARS frequency spectrum in which the value of the intensity I is 0 or a value within an acceptable range of 0, where I is expressed by the equation below where the intensities I(φ), I(φ + π/2), I(φ + π), and I(φ + 3π/2) are the intensities at the plurality of phases of the scattered light detected by the detector (16, 18): I = I Ø − I Ø + π 2 + I Ø + π 2 − I Ø + 3 π 2 2