Patent ID: 11879839
Assignee: TOKYO ELECTRON LIMITED
Field: Measurement (Instruments)
Classification: CPC G  H | IPC G

Claim 7:
8. The substrate processing apparatus of claim 7,
wherein the light projector selectively radiates first light and second light to the flow path forming unit, the first light and the second light having different wavelengths from each other and at least one of the first light or the second light being the near-infrared light,
the light receiving-side light path forming unit configured to guide the light emitted from the flow path forming unit to the light receiver is provided,
the light receiving-side light path forming unit includes a first band pass filter and a second band pass filter, pass bands of the first band pass filter and the second band pass filter including a peak wavelength of the first light and a peak wavelength of the second light, respectively, and being different from each other, and
a first relative position changing mechanism configured to change a relative position of the light receiving-side light path forming unit with respect to the flow path forming unit such that one of the first band pass filter and the second band pass filter is located on a light path of the light emitted from the flow path forming unit depending on the light radiated from the light projector to the flow path forming unit is provided.