LED LIGHT SOURCE FOR MEDICAL OPTICAL COHERENCE TOMOGRAPHY WITH HIGH AXIAL RESOLUTION
This specification discloses spinel-type phosphors that may be advantageously employed in light sources for medical optical coherence tomography (OCT), light sources for medical OCT comprising such phosphors, and OCT systems comprising such light sources.
1 . A light source for an OCT system, the light source comprising:
a light emitting diode; and
a wavelength converting structure comprising a spinel-type luminescent material having peak emission in the range 1100-1300 nm with a FWHM in the range 170-240 nm.
2 . The light source of claim 1 , wherein the spinel-type luminescent material has peak emission in the range 1200-1250 nm.
3 . The light source of claim 1 , wherein the spinel-type luminescent material has the formula AE 1-x-z A z+0.5(x-y) D 2+0.5(x-y)-z-u E z O 4 :Ni y ,Cr u ; where
AE=Mg, Zn, Co, Be or mixtures thereof;
A=Li, Na, Cu, Ag or mixtures thereof;
D=Ga, Al, B, In, Sc or mixtures thereof;
E=Si, Ge, Sn, Ti, Zr, Hf or mixtures thereof; and
0≤x≤1, 0<y≤0.1, 0≤z≤1, 0≤u≤0.2.
4 . The light source of claim 3 , wherein the spinel-type luminescent material has the formula Li 0.5-0.5y D 2.5-0.5y-u O 4 :Ni y ,Cr u with 0<y≤0.1, 0≤u≤0.2.
5 . The light source of claim 4 , wherein the spinel-type luminescent material has the formula Li 0.49 Al 0.05 Ga 2.384 O 4 :Ni 0.013 ,Cr 0.05 .
6 . The light source of claim 1 , wherein the wavelength converting structure comprises the spinel-type luminescent material dispersed in a binder.
7 . The light source of claim 6 , wherein the binder comprises a methyl polysiloxane resin.
8 . The light source of claim 6 , wherein the binder comprises a dimethyl polysiloxane resin.
9 . The light source of claim 1 , wherein the wavelength converting structure comprises the spinel-type luminescent material in ceramic form.
10 . The light source of claim 1 , wherein the light emitting diode is an InGaN light emitting diode configured to emit light in the 420-450 nm range and the spinel-type luminescent material is arranged to absorb the blue light and in response emit with the peak emission in the range 1100-1300 nm with a FWHM in the range 170-240 nm.
11 . The light source of claim 10 , wherein the wavelength converting structure comprises the spinel-type luminescent material in ceramic form.
12 . The light source of claim 11 wherein the spinel-type luminescent material has the formula AE 1-x-z A z+0.5(x-y) D 2+0.5(x-y)-z-u E z O 4 :Ni y ,Cr u ; where
AE=Mg, Zn, Co, Be or mixtures thereof;
A=Li, Na, Cu, Ag or mixtures thereof;
D=Ga, Al, B, In, Sc or mixtures thereof;
E=Si, Ge, Sn, Ti, Zr, Hf or mixtures thereof; and
0≤x≤1, 0<y≤0.1, 0≤z≤1, 0≤u≤0.2.
13 . The light source of claim 12 , wherein the spinel-type luminescent material has the formula Li 0.5-0.5y D 2.5-0.5y-u O 4 :Ni y ,Cr u with 0<y≤0.1, 0≤u≤0.2.
14 . The light source of claim 13 wherein the spinel-type luminescent material has the formula Li 0.49 Al 0.05 Ga 2.384 O 4 :Ni 0.013 ,Cr 0.05 .
15 . The light source of claim 14 , wherein the spinel-type luminescent material has peak emission in the range 1200-1250 nm.
16 . An OCT system comprising:
the light source of claim 1 ;
a sample arm;
a reference arm; and
a detector arranged to produce an interference signal from light emitted by the light source and coupled into the sample arm and light emitted from the light source and coupled into the reference arm.
17 . The OCT system of claim 16 , wherein the light source provides an axial resolution of less than 4 microns.