Variable focal length lens device
A variable focal length lens device includes: a variable focal length optical system configured to change a focal length; a beam splitter configured to cause passing light, which is reflected off an object and passes through the variable focal length optical system, to branch into branched beams; an image-forming lens configured to condense the branched beams respectively; an image sensor configured to capture an image of the object by receiving the branched beam condensed by the image-forming lens; and an image sensor configured to capture an image of the object by receiving the branched beam condensed by the image-forming lens. An imaging distance on a first optical axis from the image sensor to the image-forming lens and an imaging distance on a second optical axis from the image sensor to the image-forming lens are different from each other.
1 . A variable focal length lens device, comprising:
a variable focal length optical system configured to change a focal length;
a beam splitter configured to cause passing light to branch into a first branched beam and a second branched beam, the passing light being reflected off an object and passing through the variable focal length optical system;
at least one image-forming lens configured to condense the passing light before being split by the beam splitter or condense each of the first branched beam and the second branched beam;
a first image sensor configured to capture an image of the object by receiving the first branched beam condensed; and
a second image sensor configured to capture an image of the object by receiving the second branched beam condensed, wherein
a first imaging distance and a second imaging distance are different from each other, the first imaging distance being a distance on a first optical axis from the first image sensor to the image-forming lens arranged just in front of the first image sensor, the second imaging distance being a distance on a second optical axis from the second image sensor to the image-forming lens arranged just in front of the second image sensor, and
wherein the beam splitter is provided between the variable focal length optical system and the first and second image sensors.
2 . The variable focal length lens device according to claim 1 , wherein a gap on the first optical axis is provided between a variable range of a first focusing position and a variable range of a second focusing position, the first focusing position being a focusing position of an image formed at the first image sensor, the second focusing position being a focusing position of an image formed at the second image sensor.
3 . The variable focal length lens device according to claim 1 , wherein a variable range of a first focusing position and a variable range of a second focusing position are mutually continuous on the first optical axis, the first focusing position being a focusing position of an image formed at the first image sensor, the second focusing position being a focusing position of an image formed at the second image sensor.
4 . The variable focal length lens device according to claim 1 , further comprising: a movement mechanism configured to move the second image sensor along an incident direction of the second branched beam.
5 . The variable focal length lens device according to claim 1 , wherein the variable focal length optical system comprises:
an objective lens;
an intermediate image-forming lens configured to form an intermediate image by condensing a beam from the objective lens;
a relay lens configured to relay the intermediate image at infinity, in combination with the image-forming lens; and
a variable focal length lens arranged between the relay lens and the at least one image-forming lens, a refractive index of the variable focal length lens being periodically changed in accordance with a drive signal input to the variable focal length lens, and
a front principal point of the variable focal length lens has a conjugate relationship with an exit pupil of the objective lens.
6 . The variable focal length lens device according to claim 5 , wherein the variable focal length optical system further comprises an aperture diaphragm arranged in a position corresponding to a rear focal point of the objective lens and a front focal point of the intermediate image-forming lens.
7 . The variable focal length lens device according to claim 5 , further comprising: an image processing section configured to make a first image and a second image uniform in size, the first image being output from the first image sensor, the second image being output from the second image sensor.
8 . The variable focal length lens device according to claim 1 , wherein a range for the variable focal length lens device includes a variable range of a first focusing position and a variable range of a second focusing position utilized as a scan range that is wider than each of the variable range of the first focusing position and the variable range of the second focusing position, the first focusing position being a focusing position of an image formed at the first image sensor, and the second focusing position being a focusing position of an image formed at the second image sensor.