Optical system for a virtual retinal scan display

An optical system for a virtual retinal scan display, comprising:

• an illumination device including a projector unit, wherein the illumination device includes at least one first laser diode configured to emit a first light beam within a first wavelength range, wherein the first wavelength range shifts toward a second wavelength range depending on a temperature of at least one first laser cavity of the first laser diode, and
• a first controllable deflection unit for the first light beam configured for scanning projection of image content;
• and
• a holographic optical element configured to deflect the first light beam incident on the holographic optical element from the first controllable deflection unit onto an eye of a user of the optical system, wherein the holographic optical element is made of liquid crystals, and the holographic optical element includes a first holographic function with a first diffraction efficiency range and a second holographic function with a second diffraction efficiency range, wherein the first wavelength range at least partly overlaps the first diffraction efficiency range and the second wavelength range at least partly overlaps the second diffraction efficiency range;
• a sensor configured to acquire at least one item of information about a current first or second wavelength range of the emitted first light beam;
• and:
• (i) a control unit, and/or (ii) a polarization switch for switching the first light beam to a first or a second polarization direction, wherein the first light beam with the first polarization direction is assigned to the first diffraction efficiency range and the first light beam with the second polarization direction is assigned to the second diffraction efficiency range of the holographic optical element;
• wherein the control unit is configured to control the holographic optical element or the polarization switch depending on the acquired information about the current first or second wavelength range of the emitted first light beam in such a way that the first light beam with a first wavelength within the first wavelength range, which is incident on the holographic optical element at a first time with a first angle of incidence, and the first light beam with a second wavelength within the second wavelength range, which is incident at a second time following the first time with the first angle of incidence, are deflected toward the same positions of the eye.

A method for controlling a holographic optical element or a polarization switch of an optical system for a virtual retinal scan display, the optical system including:

• an illumination device including a projector unit of the optical system, wherein the illumination device includes at least one first laser diode configured to emit a first light beam within a first wavelength range, wherein the first wavelength range shifts toward a second wavelength range depending on a temperature of at least one first laser cavity of the first laser diode;
• a first controllable deflection unit or the first light beam for a scanning projection of image content;
• the holographic optical element configured to deflect the first light beam incident on the holographic optical element from the controllable deflection unit onto an eye of a user of the optical system, wherein the holographic optical element is made of liquid crystals, and the holographic optical element includes a first holographic function with a first diffraction efficiency range and a second holographic function with a second diffraction efficiency range, wherein the first wavelength range at least partly overlaps the first diffraction efficiency range and the second wavelength range at least partly overlaps the second diffraction efficiency range;
• a sensor configured to acquire at least one item of information about a current first or second wavelength range of the emitted first light beam;
• and:
• (i) a control unit, and/or
• (ii) the polarization switch for switching the first light beam to a first or a second polarization direction, wherein the first light beam with the first polarization direction is assigned to the first diffraction efficiency range and the first light beam with the second polarization direction is assigned to the second diffraction efficiency range of the holographic optical element;
• wherein the method comprises the following steps:
• emitting the first light beam using the first laser diode;
• acquiring the information about the current first or second wavelength range of the emitted first light beam using the control unit;
• and
• controlling the holographic optical element or the polarization filter of the optical system depending on the acquired information about the current first or second wavelength range of the emitted first light beam using the control unit in such a way that the first light beam with a first wavelength within the first wavelength range, which is incident on the holographic optical element at a first time with a first angle of incidence, and the first light beam with a second wavelength within the second wavelength range, which is incident at a second time following the first time with the first angle of incidence, are deflected toward the same positions of the eye.