Wearable heads-up display with integrated eye tracker and different optical power holograms
View Patent ↗Systems, devices, and methods that integrate eye tracking capability into scanning laser projector (“SLP”)-based wearable heads-up displays are described. An infrared laser diode is added to an RGB SLP and an infrared photodetector is aligned to detect reflections of the infrared light from features of the eye. A holographic optical element (“HOE”) may be used to combine visible light, infrared light, and environmental light into the user's “field of view.” The HOE may be heterogeneous and multiplexed to apply positive optical power to the visible light and zero or negative optical power to the infrared light.
1. A wearable heads-up display (“WHUD”) with an integrated eye tracker, comprising:
a laser module including an infrared laser diode to output an infrared light and at least one visible light laser diode to output a visible light;
a scan mirror aligned with an output of the laser module to receive both the infrared light and the visible light and to controllably reflect both the infrared light and the visible light;
a wavelength-multiplexed holographic optical element (“HOE”) aligned to receive both the infrared light and the visible light reflected from the scan mirror and to redirect both the infrared light and the visible light towards an eye of a user, wherein the wavelength-multiplexed HOE includes a first hologram that is responsive to the visible light and unresponsive to the infrared light and a second hologram that is responsive to the infrared light and unresponsive to the visible light, the first hologram to apply a first optical power to the visible light and the second hologram to apply a second optical power to the infrared light, and wherein the first optical power is a positive optical power that is greater than the second optical power and wherein the first hologram is oriented to converge the visible light to a first exit pupil having a first diameter at the eye of the user and the second hologram is oriented to redirect the infrared light to a second exit pupil having a second diameter at the eye of the user, the second diameter larger than the first diameter; and
an infrared detector aligned to receive at least a portion of infrared light reflected from the eye of the user.
2. The WHUD of claim 1 wherein the wavelength-multiplexed HOE comprises at least two distinct layers of holographic material, a first layer of holographic material that includes the first hologram and a second layer of holographic material that includes the second hologram.
3. The WHUD of claim 1 wherein the wavelength-multiplexed HOE comprises a single volume of holographic material that includes both the first hologram and the second hologram.
4. The WHUD of claim 1 wherein the at least one visible light laser diode in the laser module includes at least one visible light laser diode selected from the group consisting of: a red laser diode, a green laser diode, a blue laser diode, and any combination of a red laser diode, a green laser diode, and/or a blue laser diode.
5. The WHUD of claim 1 wherein the second optical power is less than or equal to zero.
6. The WHUD of claim 1 , wherein the infrared detector is aligned to directly receive the at least a portion of infrared light reflected from the eye of the user.
7. The WHUD of claim 1 wherein the second exit pupil encompasses the first exit pupil at the eye of the user.
8. The WHUD of claim 1 wherein:
the at least one visible light laser diode includes a red laser diode, a green laser diode, and a blue laser diode, the first hologram is responsive to red light output by the red laser diode;
the wavelength-multiplexed HOE further includes a third hologram that is responsive to green light output by the green laser diode and a fourth hologram that is responsive to blue light output by the blue laser diode;
the first hologram is oriented to converge the red light to the first exit pupil having the first diameter at the eye of the user;
the third hologram is oriented to converge the green light to the first exit pupil having the first diameter at the eye of the user; and
the fourth first hologram is oriented to converge the blue light to the first exit pupil having the first diameter at the eye of the user.
9. The WHUD of claim 1 , further comprising:
a support frame that has a general shape and appearance of a pair of eyeglasses, wherein the laser module, the scan mirror, the wavelength-multiplexed HOE, and the infrared detector are all carried by the support frame, and wherein the wavelength-multiplexed HOE is substantially transparent to environmental light and positioned in a field of view of at least one eye of the user when the support frame is worn on a head of the user.
10. The WHUD of claim 9 , wherein the infrared photodetector is carried on a part of the support frame at a perimeter of the wavelength-multiplexed HOE.