Far-infrared imaging device and far-infrared imaging method
Provided are an imaging method and device for imaging using far infrared light that make it possible to quickly image a subject without producing damage or a non-linear phenomenon in the subject. A variable-frequency coherent light source is used, illumination light from the light source is irradiated onto a linear area on an imaging subject, transmitted or reflected light is used to form an image of the imaging subject, a non-linear optical crystal is used for wavelength conversion, and a one-dimensional or two-dimensional array sensor is used to image the imaging subject while the imaging subject is moved in at least one direction.
1. A far-infrared imaging apparatus, comprising:
a wavelength-tunable far-infrared light source in which a first pump light and a first near-infrared light are incident onto a non-linear optical crystal to generate a first far-infrared light;
an illumination optical system that irradiates the first far-infrared light on a sample;
a far-infrared light imaging optical system that forms an image of the sample;
a detecting non-linear optical crystal onto which a second far-infrared light transmitting through or reflected from the sample and a second pump light are incident, thereby generating a second near-infrared light;
a sensor that detects the image; and
a detecting optical system that introduces light emitted from the detecting non-linear optical crystal onto the sensor, wherein
the second far-infrared light is incident obliquely onto an upper surface of the detecting non-linear optical crystal,
the second pump light is incident onto a side surface of the detecting non-linear optical crystal, and
the side surface of the detecting non-linear optical crystal onto which the second pump light is incident is approximately parallel to an optical axis of the second far-infrared light.
2. The far-infrared imaging apparatus according to claim 1 , wherein the second pump light in incident obliquely onto the side surface of the detecting non-linear optical crystal.
3. The far-infrared imaging apparatus according to claim 2 , wherein an optical axis of the second pump light is incident from the side surface of the detecting non-linear optical crystal, proceeds toward an longitudinal direction of the detecting non-linear optical crystal, and emits from the detecting non-linear optical crystal at another side surface opposite to the side surface.
4. The far-infrared imaging apparatus according to claim 1 , wherein a Si prism is placed on the detecting non-linear optical crystal.