System and method to illuminate and image the inside diameter of a stent
View Patent ↗An optical system is effective to illuminate and scan an interior wall of an object having an interior bore, such as a stent. The system includes a light source, an object support having a light conducting portion, an image taking lens, and a line scan camera. The interior bore and the light conducting portion of the object support are in axial alignment with a center optical axis of the image taking lens. A drive mechanism engages the object without impacting the axial alignment. Various aspect of this optical system include a rotating wheel or transparent plate as the drive mechanism. The object support may be an opaque rod having a light conducting portion or a transparent rod. Electronics associated with this optical system include a rotary encoder engaging the drive system to drive an electric circuit capable of triggering the line scan camera in response to rotation of the object, thereby building a line by line image of the interior bore and the line scan camera connected to a computer-based imaging system effective to identify cosmetic and functional manufacturing defects.
1. An optical system effective to illuminate and scan an interior wall of an object having an interior bore, comprising:
a light source;
an object support disposed between said light source and an image taking lens, said object support being a rod having a first light conducting portion extending therethrough with a beam splitter effective to reflect light from said light source to said interior wall disposed within said first light conducting portion, said object support further having a second light conducting portion disposed generally perpendicularly to said first light conducting portion that is effective to transmit light to said beam splitter for reflection to said interior wall on to said image taking lens;
said image taking lens disposed between said object support and a line scan camera, said image taking lens having a depth of focus sufficiently shallow that an exterior wall of said object is out of focus when an opposing interior wall of said object is in focus, and wherein said interior bore and said light conducting portion are in axial alignment with a center optical axis of said image taking lens; and
a drive mechanism engaging said object without impacting said axial alignment with a rotary encoder engaging said drive mechanism and driving an electric circuit capable of triggering said line scan camera in response to rotation of the object, thereby building a line by line image of said interior bore.
2. The optical system of claim 1 wherein said drive mechanism is a rotating wheel that contacts said object.
3. The optical system of claim 2 wherein said rotating wheel includes a light conducting through hole in axial alignment with said interior bore.
4. The optical system of claim 2 wherein said rotating wheel has a diameter greater than a diameter of said object.
5. The optical system of claim 1 wherein said object is a stent.
6. The optical system of claim 1 wherein said rod is at least partially transparent.
7. The optical system of claim 1 wherein said rod is formed from a material selected from the group consisting of ceramic and quartz.