Optical apparatus
A signal is amplified by making a CARS beam from an observed body and a reference beam which is a portion of a super continuum beam and has a frequency of ω AS =2ω P −ω ST interfere with each other and taking out the signal from an interference beam of the CARS beam and the reference beam.
1. An optical apparatus comprising:
a first beam having a frequency ω P ;
a unit for generating a super continuum beam;
a split unit for dividing the super continuum beam into a second beam and a third beam with the frequency ω P as a boundary;
the second beam having a frequency lower than the frequency ω P maintaining a relationship of being coherent with the first beam;
the third beam which is a reference beam having a frequency of ω AS =2ω P -ω ST , the frequency being higher than the frequency ω P and which is a beam that does not irradiate an observed sample;
an optical system configured to make the first beam and the second beam coincide with each other substantially coaxially;
a mechanism configured to adjust phases of the first beam or the second beam;
an object lens configured to focus the first beam and the second beam;
an object lens configured to detect a CARS beam generated from an observed sample;
an interference optical system configured to make the CARS beam and the third beam interfere with each other coaxially;
a photo-detector configured to detect an interference beam; and
an arithmetic unit configured to process a signal from the optical detector.
2. The optical apparatus according to claim 1 , wherein the second beam is a laser beam of a broadband, and an interference beam is directed to a spectroscope are used.
3. The optical apparatus according to claim 2 , wherein the interference beam is formed by making use of the second beam transmitted through the observed sample.
4. The optical apparatus according to claim 1 , further comprising:
an image display unit configured to display an image based on the arithmetic unit.
5. The optical apparatus according to claim 1 , wherein an optical filter is installed at an optical path of the reference beam.
6. The optical apparatus according to claim 5 , wherein the optical filter mainly shields the third beam at a vicinity of an optical axis of the optical filter, and transmits the third beam at a surrounding of the optical filter remote from the optical axis.
7. The optical apparatus according to claim 1 , wherein the object lens of focusing the first beam and the second beam and the object lens of detecting the CARS beam is the same lens.