Fluorescein fluorescent fundus angiography device employing polarizing beam splitter and linear polarizing filter
Disclosed is a fluorescent fundus camera which is one kind of ophthalmological diagnostic equipment, using a blue excitation light beam when a contrast medium appears in the retinal vessels. When an abnormal blood vessel is present, the contrast medium leaks into the retina or appears as color in tissues surrounding the retina, and the presence of damage to the retina and the appearance of abnormal neovascularization can be found.
1. A fundus angiography device employing a polarizing beam splitter and a linear polarizing filter, comprising:
a light source ( 10 ) which is a blue light source having a center wavelength ranging from 470 nm to 490 nm;
a diffusion lens ( 20 ) configured to diffuse the light incident from the light source ( 10 );
an illumination lens ( 30 ) configured to irradiate the light incident from the diffusion lens ( 20 ) at a predetermined exit angle;
a mirror ( 40 ) configured to reflect the light incident from the illumination lens ( 30 );
a polarizing beam splitter ( 50 ) configured to allow P-polarized light of the light incident from the mirror ( 40 ) to pass therethrough and reflect S-polarized light among light incident from the mirror ( 40 );
an objective lens ( 60 ) configured to enlarge an image of the fundus which is formed by the light incident from the polarizing beam splitter ( 50 );
a short-distance ocular lens ( 70 ) configured to reduce or enlarge the image of the fundus which is enlarged by the objective lens ( 60 );
a linear polarizing filter ( 80 ) configured to allow only the P-polarized light to pass therethrough;
a light blocking filter ( 90 ) configured to filter light having a center wavelength ranging from 520 nm to 530 nm or block light having a wavelength that is shorter than 500 nm among the light passing through the linear polarizing filter ( 80 );
an excitation filter ( 110 ) provided between the light source ( 10 ) and the polarizing beam splitter ( 50 ) and having a center wavelength of 480 nm; and
an imaging element ( 100 ) configured to convert the light passing through the light blocking filter ( 90 ) into an electrical signal,
wherein the linear polarizing filter ( 80 ) includes a first linear polarizing filter ( 81 ) provided between the light source ( 10 ) and the polarizing beam splitter ( 50 ), and a second linear polarizing filter ( 82 ) provided between the polarizing beam splitter ( 50 ) and the short-distance ocular lens ( 70 ).
2. The fundus angiography device of claim 1 , wherein the linear polarizing filter ( 90 ) includes one or more among a first light blocking filter ( 91 ) provided between the polarizing beam splitter ( 50 ) and the second linear polarizing filter ( 82 ), a second light blocking filter ( 92 ) provided between the second linear polarizing filter ( 82 ) and the short-distance ocular lens ( 70 ), and a third light blocking filter ( 93 ) provided between the short-distance ocular lens ( 70 ) and the imaging element ( 100 ).
3. The fundus angiography device of claim 1 , wherein the linear polarizing filter ( 90 ) has a full width at half maximum (FWHM) ranging from 40 nm to 50 nm.
4. The fundus angiography device of claim 1 , wherein the excitation filter has a full width at half maximum (FWHM) of 40 nm or less.
5. The fundus angiography device of claim 1 , wherein the excitation filter is a bandpass optical filter.