Optical unit, fluorescence detection device, and fluorescence detection method
A first lens configured to convert light from the objective lens into parallel light includes a concave lens part having a concave curved face in a center portion of a flat face, and a convex lens part having a convex curved face around a flat face. Further, the first lens includes first and second regions configured to diverge light through the flat face and the concave curved face and a third region configured to collect light through the convex curved face and the concave curved face. When the sample is on a sample table and sealed in a two-dimensional electrophoresis substrate, light totally reflected by a side surface of the objective lens enters the second region. In contrast, when the sample is directly on the sample table, the light enters the third region.
1. An optical unit comprising:
an objective lens element that collects light from a measuring object; and
a conversion lens that converts the light collected by the objective lens element into substantially parallel light,
wherein the objective lens element includes a total reflection part that is located in a peripheral portion to collect light by total reflection on a side surface,
wherein the conversion lens includes a plurality of regions on which the light from the total reflection part of the objective lens element is to be incident, the plurality of regions being provided in accordance with a distance between the objective lens element and the measuring object, and
wherein the conversion lens converts light from the objective lens element incident on all portions including the plurality of regions into the parallel light substantially parallel to an optical axis.
2. The optical unit according to claim 1 ,
wherein the light entering the plurality of regions of the conversion lens from the total reflection part of the objective lens element has different spread angles in accordance with the distance between the objective lens element and the measuring object, and
wherein each of the plurality of regions of the conversion lens converts the incident light having the different spread angles into light whose spread angle is substantially 0 degrees.
3. The optical unit according to claim 2 , wherein, in each of the plurality of regions of the conversion lens, the sum of a curvature of an incident surface and a curvature of an emission surface is a curvature to diverge the incident light when the spread angle of the incident light is an angle that represents convergence, and the sum of the curvature of the incident surface and the curvature of the emission surface is a curvature to converge the incident light when the spread angle of the incident light is an angle that represents divergence.
4. The optical unit according to claim 1 ,
wherein the objective lens element has a refraction part located in a center portion to collect light by refraction, and
wherein the conversion lens has, in a peripheral portion, the region on which the light is to be incident from the total reflection part of the objective lens element.
5. The optical unit according to claim 1 ,
wherein the total reflection part of the objective lens element has a concentric shape with the optical axis, and
wherein the plurality of regions of the conversion lens have concentric shapes with the optical axis.
6. The optical unit according to claim 1 ,
wherein the measuring object is placed on a sample table having a light transmissive property,
wherein the objective lens element and the conversion lens are disposed opposed to a surface of the sample table opposite from a surface on which the measuring object is placed, and
wherein the objective lens element collects the light emitted from the measuring object via the sample table.
7. A fluorescence detection device comprising:
a light source unit that irradiates a measuring object with excitation light that excites fluorescence;
the optical unit according to claim 1 on which the fluorescence emitted from the measuring object by the irradiation of the excitation light is to be incident, the optical unit converting the incident fluorescence into substantially parallel fluorescence;
a wavelength filter on which the substantially parallel fluorescence from the optical unit is to be incident, the wavelength filter reducing a light component with a wavelength equal to a wavelength of the excitation light; and
a photodetection element that detects the fluorescence from the wavelength filter,
wherein the objective lens element in the optical unit has, in a center portion, an excitation-light transmitting part that transmits the excitation light from the light source unit, irradiates the measuring object with the excitation light from the light source unit via the excitation-light transmitting part, and collects the fluorescence from the measuring object.
8. A fluorescence detection method comprising:
emitting, from a light source unit, excitation light that excites fluorescence;
applying the excitation light from the light source unit to a measuring object through a center portion of the objective lens element in the optical unit according to claim 1 ;
collecting the fluorescence emitted from the measuring object by the application of the excitation light by the objective lens element;
converting the fluorescence collected by the objective lens element into substantially parallel light by the conversion lens in the optical unit;
subtracting, by a wavelength filter, a light component having a wavelength equal to a wavelength of the excitation light from the substantially parallel fluorescence converted by the conversion lens; and
detecting the fluorescence from the wavelength filter by a photodetection element.