Head-up display relay optical system and method

Abstract

The invention discloses a head-up display relay optical system and method, and belongs to the field of optical design. Comprising an image plane, a rectangular prism, a first positive lens, a polarization splitting prism, a 1 / 4 wave plate, a second positive lens, a half-wave plate, a third positive lens and an exit pupil which are sequentially arranged along a light path. S-line polarized light emitted by an image surface is reflected to the 1 / 4 wave plate through the rectangular prism and the polarization splitting prism, the S-line polarized light is converted into circularly polarized light through the 1 / 4 wave plate, the circularly polarized light is reflected by the reflecting surface of the second positive lens and then is converted into P-line polarized light through the 1 / 4 wave plate, and the P-line polarized light is incident to the half-wave plate through the polarization splitting prism. The P-line polarized light is converted into S-line polarized light through the half-wave plate, and then the S-line polarized light reaches an exit pupil through the third positive lens. S-linear polarized light emitted by an image surface is reflected out from an exit pupil after being turned for multiple times, so that the size of an optical system can be obviously compressed, and the problem of cracking of the wave plate in high and low temperature environments is solved.

Description

Technical Field

[0001] The present invention belongs to the field of optical design, and in particular relates to a head-up display relay optical system and method. Background Art

[0002] The layout area of ​​the HUD in the cockpit of a small civil aircraft is limited by the cabin space, and the installed HUD relay optical system is required to be small in size and resistant to high and low temperatures. At present, in order to ensure the efficiency of the HUD optical system, the HUD relay optical system installed in small civil aircraft generally uses polarization beam splitters and wave plates. However, since the thickness of the wave plate is very thin, about 1.2 microns, a substrate of a certain thickness needs to be glued to the front and back surfaces of the wave plate. The thickness of the original HUD relay optical system 1 / 4 wave plate and half wave plate plus the substrate is only 1mm, and it is glued with the polarization beam splitter prism 4 at the same time. When conducting high and low temperature tests from -55℃ to 80℃, the wave plate substrate cracked and the wave plate bonding layer debonded, which could not meet the product use requirements.

[0003] Therefore, there is an urgent need to propose a HUD relay optical system including a wave plate that can meet the requirements of use in high and low temperature environments. Summary of the invention

[0004] Technical issues to be solved:

[0005] In order to avoid the shortcomings of the prior art, the present invention provides a HUD relay optical system and method, which is a relay optical system with small size, high efficiency and good performance in high and low temperature environments. The S-linear polarized light emitted from the image plane is subjected to multiple turns and reflections through a right-angle prism, a first positive lens, a polarization beam splitter prism, a quarter wave plate, a second positive lens, a half-wave plate and a third positive lens, and then emitted from the exit pupil. The volume of the optical system can be significantly compressed, and the problem of cracking of the wave plate in high and low temperature environments is solved.

[0006] The technical solution of the present invention is: a head-up display relay optical system, comprising an image plane, a right-angle prism, a first positive lens, a polarization beam splitter prism, a quarter wave plate, a second positive lens, a half wave plate, a third positive lens, and an exit pupil arranged in sequence along an optical path; the S-linear polarized light emitted from the image plane is reflected to the quarter wave plate by the right-angle prism and the polarization beam splitter prism, the S-linear polarized light is converted into circularly polarized light by the quarter wave plate, the circularly polarized light is reflected by the reflection surface of the second positive lens and then converted into P-linear polarized light through the quarter wave plate, the P-linear polarized light is incident on the half wave plate through the polarization beam splitter prism, the P-linear polarized light is converted into S-linear polarized light by the half wave plate, and then reaches the exit pupil through the third positive lens.

[0007] A further technical solution of the present invention is: the optical parameters of the right-angle prism, the first positive lens, the polarization beam splitter prism, the quarter wave plate, the second positive lens, the half wave plate, and the third positive lens are as follows:

[0008]

[0009] A further technical solution of the present invention is that the front surface of the first positive lens, the rear surface of the second positive lens and the front surface of the third positive lens are all aspherical surfaces.

[0010] A further technical solution of the present invention is that the splitting surface of the polarization splitting prism is coated with a polarization splitting film, and the requirements of the polarization splitting film are: λ0=525nm, within the wavelength range of 505nm~545nm, the incident angle range of 45°±8°, Rsavg>95%, Tpavg>95%.

[0011] A further technical solution of the present invention is: the reflective surface of the second positive lens is coated with an internal reflection film, and the requirements of the internal reflection film are: a multi-layer dielectric film, λ0=525nm, an incident angle range of 0°-20°, within the wavelength range of 490nm~570nm, Rmin is not less than 98%; within the wavelength range of 570nm~610nm, Rmin is not less than 96%.

[0012] A further technical solution of the present invention is: the 1 / 4 wave plate is glued to the second positive lens, and the half wave plate is glued to the third positive lens.

[0013] A reflection method for a head-up display relay optical system, the specific steps are as follows:

[0014] The S-polarized light emitted from the image plane is emitted to the right-angle prism, and the right-angle prism performs a first 90-degree reflection on the incident S-polarized light;

[0015] The S-polarized light after the first reflection is transmitted through the first positive lens and incident on the polarization beam splitter prism, and the beam splitter film of the polarization beam splitter prism reflects the S-polarized light for a second time at 90 degrees.

[0016] The S-linear polarized light after secondary reflection passes through the 1 / 4 wave plate, which converts the S-linear polarized light into circular polarized light.

[0017] After the circularly polarized light passes through the second positive lens, it is reflected back to the quarter wave plate by the reflection surface of the second positive lens;

[0018] The circularly polarized light is then converted into P linear polarized light by a 1 / 4 wave plate. The P linear polarized light passes through a polarizing beam splitter prism and a half-wave plate in sequence, and is converted into S linear polarized light by the half-wave plate, and then reaches the exit pupil through the third positive lens.

[0019] A further technical solution of the present invention is that the distance between the 1 / 4 wave plate and the polarization beam splitter prism is 1 mm.

[0020] A further technical solution of the present invention is that the distance between the half-wave plate and the polarization beam splitter prism is 3 mm.

[0021] A civil aircraft comprises the HUD relay optical system.

[0022] Beneficial Effects

[0023] The beneficial effects of the present invention are as follows: the present invention uses a right-angle prism and a polarization splitter prism to perform two 90-degree deflections on the incident light, converts it into reverse parallel light, and then enters the 1 / 4 wave plate for transformation. By setting a reflective surface on the rear surface of the second positive lens, the light is returned to the 1 / 4 wave plate along the original path and converted into P-linear polarized light, and then the P-linear polarized light is converted into S-linear polarized light by the half-wave plate. The overall structure is compact and the display effect is enhanced.

[0024] The relay system of the present invention designs the structural parameters and positions of the right-angle prism, the first positive lens, the polarization beam splitter prism, the quarter wave plate, the second positive lens, the half wave plate, and the third positive lens, and adopts high-transmittance optical materials, as well as the polarization beam splitter prism, the quarter wave plate and the half wave plate optical elements, so that not only the miniaturization of the optical system is achieved, but also the efficiency of the optical system is greater than 80%. By adjusting the gaps between the polarization beam splitter prism, the quarter wave plate and the half wave plate, the problem of wave plate cracking in the high and low temperature environment test of the optical system is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The HUD relay optical system of the present invention;

[0026] Explanation of the reference numerals: 10. Image plane, 11. Right-angle prism, 12. First positive lens, 13. Polarization beam splitter prism, 14. 1 / 4 wave plate, 15. Second positive lens, 16. Half-wave plate, 17. Third positive lens, 18. Exit pupil. DETAILED DESCRIPTION

[0027] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0028] Based on the existing HUD relay optical system, the thickness of the quarter wave plate and the half wave plate plus the substrate is only 1mm, and they are glued with the polarization beam splitter prism 4. When performing a high and low temperature test at -55°C to 80°C, the wave plate has substrate cracking, the wave plate glue layer is debonded, and the product use requirements cannot be met. The present invention provides a HUD relay optical system, which is characterized by comprising an image plane, a right angle prism, a first positive lens, a polarization beam splitter prism, a quarter wave plate, a second positive lens, a half wave plate, a third positive lens, and an exit pupil arranged in sequence along an optical path; the S linear polarized light emitted from the image plane is reflected to the quarter wave plate by the right angle prism and the polarization beam splitter prism, the S linear polarized light is converted into circular polarized light by the quarter wave plate, the circular polarized light is reflected by the reflection surface of the second positive lens and then converted into P linear polarized light through the quarter wave plate, the P linear polarized light is incident on the half wave plate through the polarization beam splitter prism, the P linear polarized light is converted into S linear polarized light by the half wave plate, and then reaches the exit pupil through the third positive lens.

[0029] Specifically, the optical parameters of the right-angle prism, the first positive lens, the polarization beam splitter, the quarter wave plate, the second positive lens, the half wave plate, and the third positive lens are as follows:

[0030]

[0031]

[0032] The present invention provides a reflection method for a HUD relay optical system, and the specific steps are as follows:

[0033] Step 1: The S-polarized light emitted from the image plane is emitted to a right-angle prism, and the right-angle prism performs a first 90-degree reflection on the incident S-polarized light;

[0034] Step 2: The S-polarized light after the first reflection is transmitted through the first positive lens and incident on the polarization beam splitter prism, and the beam splitter film of the polarization beam splitter prism reflects the S-polarized light for a second time at 90 degrees;

[0035] Step 3: The S-linear polarized light after secondary reflection passes through the 1 / 4 wave plate, and the 1 / 4 wave plate converts the S-linear polarized light into circular polarized light;

[0036] Step 4: After the circularly polarized light passes through the second positive lens, it is reflected back to the 1 / 4 wave plate by the reflection surface of the second positive lens;

[0037] Step 5: The circularly polarized light is then converted into P linear polarized light by the 1 / 4 wave plate. The P linear polarized light passes through the polarization beam splitter prism and the half-wave plate in sequence. The half-wave plate converts the P linear polarized light into S linear polarized light, and then reaches the exit pupil through the third positive lens.

[0038] The invention discloses a head-up display relay optical system which is applied to civil aircraft.

[0039] The above technical solution is further described below in conjunction with the accompanying drawings:

[0040] The present embodiment is a HUD relay optical system, which includes an image plane 10, a right angle prism 11, a first positive lens 12, a polarization beam splitter prism 13, a quarter wave plate 14, a second positive lens 15, a half wave plate 16, a third positive lens 17, and an exit pupil 18 in sequence along the optical path. The S linear polarized light emitted from the image plane 10 is totally reflected by the S11 surface of the right angle prism 11, and is reflected by the first positive lens 12 and the beam splitting film surface S13 of the polarization beam splitter prism 13 in sequence, and then passes through the quarter wave plate 14 to become circular polarized light, and is reflected by the reflection surface S15 of the second positive lens 15, and then passes through the quarter wave plate 14 to become P light, and then passes through the polarization beam splitter prism 13, the half wave plate 16, and the third positive lens 17 in sequence to reach the exit pupil 18.

[0041] The incident light of the image plane 10 and the outgoing light of the exit pupil 18 are S-polarized lights.

[0042] The S12 surface of the first positive lens 12 , the S15 surface of the second positive lens 15 , and the S17 surface of the third positive lens 17 are aspherical surfaces.

[0043] The 1 / 4 wave plate 14 is glued to the positive lens 15, and the half wave plate 16 is glued to the positive lens 17. The total thickness of the 1 / 4 wave plate 14 and the half wave plate 16 is 2.8 mm. The gaps between the 1 / 4 wave plate 14, the half wave plate 16 and the polarization beam splitter prism 13 are 1 mm and 3 mm respectively.

[0044] The surface of the polarization beam splitting prism 13 beam splitting film surface S13 is coated with a polarization beam splitting film, and the polarization beam splitting film requirements are: A0 = 525nm, in the wavelength range of 505nm to 545nm, within the incident angle of 45°±8°, Rsavg>95%, Tpavg>95%;

[0045] The surface of the reflection surface S15 of the positive lens 15 is coated with an internal reflection film. The requirements of the internal reflection film are: multi-layer dielectric film, incident angle range 0°-20°, within the wavelength range of 490nm to 570nm, Rmin is not less than 98%, within the wavelength range of 570nm to 610nm, Rmin is not less than 96%

[0046] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A head-up display relay optical system, Features: The invention comprises an image plane, a right-angle prism, a first positive lens, a polarization beam splitter prism, a quarter wave plate, a second positive lens, a half wave plate, a third positive lens and an exit pupil which are arranged in sequence along the optical path; the S-linear polarized light emitted from the image plane is reflected to the quarter wave plate by the right-angle prism and the polarization beam splitter prism, the S-linear polarized light is converted to circularly polarized light by the quarter wave plate, the circularly polarized light is reflected by the reflection surface of the second positive lens and then converted to P-linear polarized light by the quarter wave plate, the P-linear polarized light is incident on the half wave plate by the polarization beam splitter prism, the P-linear polarized light is converted to S-linear polarized light by the half wave plate, and then reaches the exit pupil through the third positive lens.

2. A head-up display relay optical system according to claim 1, Features: The optical parameters of the right-angle prism, the first positive lens, the polarization beam splitter prism, the quarter wave plate, the second positive lens, the half wave plate, and the third positive lens are as follows:

3. A head-up display relay optical system according to claim 2, Features: The front surface of the first positive lens, the rear surface of the second positive lens and the front surface of the third positive lens are all aspherical surfaces.

4. A head-up display relay optical system according to claim 3, Features: The splitting surface of the polarization splitting prism is coated with a polarization splitting film, and the requirements of the polarization splitting film are: 0 =525nm, within the wavelength range of 505nm~545nm, within the incident angle range of 45°±8°, Rsavg>95%, Tpavg>95%.

5. A head-up display relay optical system according to claim 4, Features: The reflective surface of the second positive lens is coated with an internal reflection film, and the internal reflection film is required to be coated with a multi-layer dielectric film, λ 0 =525nm, in the range of incident angle 0°-20°, in the wavelength range of 490nm~570nm, Rmin is not less than 98%; in the wavelength range of 570nm~610nm, Rmin is not less than 96%.

6. The head-up display relay optical system according to claim 1, Features: The 1 / 4 wave plate is glued to the second positive lens, and the half wave plate is glued to the third positive lens.

7. A reflection method for the HUD relay optical system according to any one of claims 1 to 6, Features The specific steps are as follows: The S-polarized light emitted from the image plane is emitted to the right-angle prism, and the right-angle prism performs a first 90-degree reflection on the incident S-polarized light; The S-polarized light after the first reflection is transmitted through the first positive lens and incident on the polarization beam splitter prism, and the beam splitter film of the polarization beam splitter prism reflects the S-polarized light for a second time at 90 degrees. The S-linear polarized light after secondary reflection passes through the 1 / 4 wave plate, which converts the S-linear polarized light into circular polarized light. After the circularly polarized light passes through the second positive lens, it is reflected back to the quarter wave plate by the reflection surface of the second positive lens; The circularly polarized light is then converted into P linear polarized light by a 1 / 4 wave plate. The P linear polarized light passes through a polarizing beam splitter prism and a half-wave plate in sequence, and is converted into S linear polarized light by the half-wave plate, and then reaches the exit pupil through the third positive lens.

8. The reflection method of the HUD relay optical system according to claim 7, Features: The distance between the 1 / 4 wave plate and the polarization beam splitter prism is 1 mm.

9. The reflection method of the HUD relay optical system according to claim 7, Features: The distance between the half-wave plate and the polarization beam splitter prism is 3 mm.

10. A civil aircraft, Features: Includes the head-up display relay optical system.

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