Near infrared imaging
Endoscopes and wands, useful for near infrared imaging, particularly for medical purposes, have transmitting members that transmit between about 95% and 99.5% of the energy at a wavelength within the infrared spectrum. The wands and endoscopes have at least one channel for transmitting and receiving light in the visible spectrum and at least one channel for transmitting and receiving light in the infrared spectrum.
1. An elongated lens system in an endoscope or wand for fluorescence and visible light imaging, comprising:
a first lens group comprising an objective assembly;
a second lens group comprising a relay lens group; and
an ocular lens group,
wherein the relay lens group comprises a plurality of light transmitting members each comprising a transmitting glass surface facing an air space and an optical coating on the transmitting glass surface, wherein each coated light transmitting member is configured to reflect between 0.5% and 5% of first and second wavelengths of interest, wherein the first wavelength of interest is in the infrared spectrum and the second wavelength of interest is in the visible spectrum.
2. The elongated lens system of claim 1 , where the relay lens group comprises at least 30 air glass surfaces.
3. The elongated lens system of claim 1 , wherein the first wavelength of interest is between 825 nm and 835 nm.
4. The elongated lens system of claim 1 , wherein the plurality of light transmitting members comprise glasses with an index of refraction ranging from 1.5 to 1.65.
5. The elongated lens system of claim 1 , wherein the plurality of light transmitting members comprise glasses with an index of refraction ranging from 1.65 to 1.7.
6. The elongated lens system of claim 1 , further comprising a filter configured to block light at an excitation wavelength.
7. The elongated lens system of claim 1 , wherein the optical coating comprises layers of a high index coating material and a low index coating material.
8. The elongated lens system of claim 1 , wherein the optical coating comprises layers of TiO 2 and MgF 2 .
9. The elongated lens system of claim 1 , wherein the optical coating comprises layers of TiO 2 and SiO 2 .
10. The elongated lens system of claim 1 , wherein the optical coating comprises layers of ZrO 2 and MgF 2 .
11. The elongated lens system of claim 1 , wherein the optical coating comprises layers of Ta 2 O 5 and SiO 2 .