Optical system for atomic interference raman laser self-reflection

Abstract

The application discloses an optical system for atomic interference Raman laser self-reflection, which comprises two parts of an ultrahigh vacuum cavity and a lens group I and a reflection group II arranged in sequence, the lens group I is composed of seven lenses L1-L7 arranged in sequence, the reflection group II is composed of a plane mirror M1 with a reflection-increasing film and a polarization film coated on the surface, and the image plane of the lens group I is located on the reflection plane of the reflection group II; after an incident light beam from a narrow-line-width laser is incident on the lens group I, the light beam is returned along the path through the reflection group II and finally irradiated into the ultrahigh vacuum cavity by passing through the lens group I again; the optical system only needs to pass through a conventional lens group, can greatly increase the angle range of the incident laser, increase the design space of the Raman laser layout, and promote the development and improvement of a new atomic interference device.

Description

Technical Field

[0001] This invention belongs to the field of quantum precision measurement technology, and relates to an atomic interferometer system for precise measurement of physical quantities, specifically to an optical system for self-reflection of atomic interferometric Raman lasers. Background Technology

[0002] Atomic interferometry is a technique that manipulates the transformation of atomic quantum states to study and precisely measure the physical properties of atoms. It has applications in quantum communication, atomic clocks, cold atom gravimeters, quantum computing, quantum simulation, and many other fields. Cold atom interferometers use Raman lasers to manipulate the transitions between the ground state energy levels of atoms, achieving matter wave interference from the superposition of two different quantum states. By measuring the phase shift of the interference, target physical quantities can be precisely measured.

[0003] The direction of the physical vector measured by a cold atom interferometer is determined by the propagation direction of the Raman laser beam. Atomic interferometry Raman lasers typically consist of two laser beams with opposite propagation directions and overlapping positions. A common approach is to input the two laser components of the Raman laser through the same optical path and then reflect them back along the same path using a mirror. However, this method requires the beam to be incident strictly along the normal to the mirror, limiting the input angle range of the Raman laser. Therefore, it is necessary to realize an optical system that allows for self-reflection of the Raman laser over a wider angle range.

[0004] The direction of the measurement axis vector of an atomic interferometer is directly related to the direction of the Raman laser. During atomic interferometry, the Raman laser consists of two laser beams with opposite propagation directions and overlapping positions. The common method is to input the two laser components of the Raman laser through the same optical path and then reflect them back along the same path using a mirror. This creates a laser beam with opposite propagation directions and overlapping positions. However, this method requires the beams to be incident strictly along the normal to the mirror, limiting the ability to control the direction of the Raman laser. Summary of the Invention

[0005] The present invention aims to design an optical system for self-reflection of Raman lasers with atomic interference, which can realize the original path reflection of Raman lasers incident over a wide range of angles, and also meet the requirements of good wavefront quality for precise atomic interference measurements.

[0006] To achieve the above objectives, the technical solution adopted by the present invention to solve its technical problem is as follows: an optical system for self-reflection of atomic interference Raman lasers, comprising an ultra-high vacuum cavity arranged in sequence, and two parts: a lens group I and a reflection group II; an incident beam from a narrow linewidth laser is incident on lens group I, returns along the path through reflection group II, and finally illuminates the ultra-high vacuum cavity again through lens group I; the ultra-high vacuum cavity includes a cavity shell, a cavity optical window fixed to the side wall of the cavity shell, and an atomic cluster located at the optical system aperture inside the cavity shell; lens group I consists of seven lenses L1 to L7 arranged in sequence from front to back, wherein lenses L2, L3, L5, and L6 are positive lenses, and lenses L1, L4, and L7 are negative lenses; the reflection group II consists of a plane mirror M1 with a surface coated with an anti-reflection film and a polarizing film, possessing the ability to reflect the incident beam and change the polarization of the outgoing laser; the image plane of lens group I is located on the reflecting surface of reflection group II.

[0007] The optical system described above for self-reflection of atomic interference Raman lasers has lenses L1 and L4 as meniscus negative lenses, lenses L2 and L5 as biconvex positive lenses, lenses L3 and L6 as meniscus positive lenses, and lens L7 as a biconcave negative lens.

[0008] The optical system described above for self-reflection of atomic interference Raman lasers has an image-side telecentricity θ of lens group I not exceeding 5″.

[0009] The optical system for self-reflection of atomic interference Raman lasers has a total length of lens group I ≤ 100 mm, a distance from the entrance pupil to lens group I ≥ 60 mm, an image-side working distance ≥ 10 mm, and a total length of the optical system not exceeding 162.5 mm.

[0010] The optical system described above for self-reflection of atomic interference Raman laser has an entrance pupil diameter ≥14mm and an object-side field of view range ≥+ / -7.5°, which can meet the incident angle range of Raman laser; the full field-of-view wave aberration RMS of the optical system is better than 1 / 100λ.

[0011] The optical system described above for self-reflection of atomic interference Raman lasers has an angular deviation of no more than 30″ and a positional deviation of no more than 0.2mm between the incident and emitted lasers.

[0012] The beneficial effects of this invention are: 1. Compared with existing optical systems, this invention adopts a transmission optical structure and a mirror group consisting of no less than 7 objective lenses to complete an optical system design with a laser beam diameter of no less than 14mm, a beam reflection angle range of no less than + / -7.5°, and a wavelet aberration RMS better than 1 / 100λ, so that the position and angle of the incident beam and the outgoing beam are kept coincident, which meets the current requirements of advanced atomic interferometry precision measurement devices.

[0013] 2. Compared to the current method of using a single plane mirror to achieve the original path reflection of Raman laser, which can only be used for Raman laser incident at a single angle, the optical system of this invention only needs to use a conventional lens group, which can greatly increase the angle range of incident laser, increase the design space of Raman laser layout, and promote the development and improvement of new atomic interference devices.

[0014] 3. This invention uses commonly used optical materials and devices, resulting in lower production costs; it also has a larger entrance pupil distance, providing ample space for the design of subsequent atomic interferometry precision measurement equipment.

[0015] 3. The optical system of the present invention, which features large-angle Raman laser self-reflection, is applied to atomic interferometry precision measurement equipment. The total length of the lens group does not exceed 110mm; the distance from the entrance pupil to lens group I is not less than 60mm, reserving sufficient design space for the ultra-high vacuum cavity 1; the exit pupil diameter is not less than 14mm, providing the beam size and collimation required for atomic interferometry; the incident angle range is not less than + / -7.5°, the angular deviation between the incident laser and the emitted laser is not greater than 30″, and the positional deviation is not greater than 0.2mm, meeting the requirements of atomic interferometry for Raman laser coincidence; the wavefront aberration across the entire field of view is better than 1 / 100λ, meeting the accuracy requirements of atomic interferometry precision measurement. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the optical structure of the optical system of the present invention; Figure 2 This is a waveform aberration curve of the optical system of the present invention; Figure 3 This is the MTF curve of the optical system of the present invention; Figures 4-6 This is a wavefront diagram of the optical system of the present invention.

[0017] The accompanying figures are labeled as follows: 1—Ultra-high vacuum cavity, 1-1—Cavity shell, 1-2—Optical window, 1-3—Atomic cluster, L1 / L4 / L7—Negative lens, L2 / L3 / L5 / L6—Positive lens, M1—Plane mirror. Detailed Implementation

[0018] This invention aims to provide an optical system for self-reflection in atomic interference Raman lasers. The specific implementation measures of this invention are described in detail with reference to the accompanying drawings.

[0019] Reference Figure 1 As shown, the present invention discloses an optical system for self-reflection of atomic interference Raman laser, comprising an ultra-high vacuum cavity 1 arranged in sequence, and two parts: a lens group I and a reflection group II; the incident beam from the narrow linewidth laser is incident on the lens group I, returns along the path through the reflection group II, and finally irradiates the ultra-high vacuum cavity 1 through the lens group I again.

[0020] The ultra-high vacuum cavity 1 described herein comprises a cavity shell 1-1, a cavity optical window 1-2, and an atomic cluster 1-3, with the optical system's aperture located at the atomic cluster 1-3. The lens group I consists of seven lenses L1 to L7 arranged sequentially from front to back, wherein lenses L2, L3, L5, and L6 are positive lenses, and lenses L1, L4, and L7 are negative lenses. The reflection group II consists of a plane mirror M1 with an anti-reflection coating and a polarizing coating on its surface, possessing the ability to reflect the incident beam and change the polarization of the emitted laser. The image plane of the lens group I is located on the reflecting surface of the reflection group II.

[0021] The working wavelength laser of the optical system, consisting of lens group I and reflection group II, comes from a narrow linewidth laser, and the influence of chromatic aberration is negligible. The refractive index of the selected lens material at the working wavelength ranges from 1.45 to 1.72.

[0022] The optical system of this invention constructs a cat's eye structure based on the telecentric optical path of the image side to achieve the original path reflection of Raman lasers with a large incident angle range. During the original path reflection process, the reflected optical path of the beam must coincide with the incident optical path to ultimately maintain the same position of the beam interacting with the atomic cluster. Therefore, the optical system needs to be free of vignetting throughout the entire field of view.

[0023] Specifically, in the optical system described in this invention: the image-side telecentricity θ of lens group I does not exceed 5″. The total length of lens group I is ≤100mm, the distance from the entrance pupil to lens group I is ≥60mm, the image-side working distance is ≥10mm, and the total length of the optical system does not exceed 162.5mm.

[0024] Furthermore, lenses L1 and L4 are meniscus negative lenses, lenses L2 and L5 are biconvex positive lenses, lenses L3 and L6 are meniscus positive lenses, and lens L7 is a biconcave negative lens. Specific parameters for each component are shown in the table below.

[0025] .

[0026] The optical system has an entrance pupil diameter ≥14mm and an object-side field of view range ≥+ / -7.5°, which meets the incident angle range of Raman lasers; the full-field-of-view wavelet aberration RMS of the optical system is better than 1 / 100λ. The angular deviation between the incident laser and the emitted laser in the optical system is no greater than 30″, and the positional deviation is no greater than 0.2mm.

[0027] Wavelength aberration curves of the optical system of this invention are shown below. Figure 2 As shown; the MTF curve of the optical system of the present invention is as follows. Figure 3 As shown, the wavefront aberration RMS is better than 1 / 100λ, and the wavefront aberration PV is better than 1 / 25λ; the wavefront shape of the optical system of this invention is shown in the figure. Figures 4-6 As shown. Based on the requirements of the Raman laser in the atomic interferometer, the optical specifications of this embodiment are as follows.

[0028] Operating wavelength: 780.2nm + / -2pm; entrance pupil diameter: 14mm; object half field of view: 7.5°; entrance pupil distance: 62.5mm; total lens length: 110mm; exit pupil diameter: 14mm.

[0029] Here, the object plane represents the object plane of the optical system, located at infinity, indicating that the incident laser is collimated; the image plane is located on the reflecting mirror. INF represents infinity, indicating that the radius of the sphere is infinite, i.e., a plane.

[0030] The positional deviation between the emitted beam and the incident beam after mirror reflection is no more than 0.001 mm and the angular deviation is no more than 1″, obtained by beam tracing.

[0031] Overall, the optical system described in this invention exhibits excellent outgoing wave aberrations, meeting the requirements for atomic interference Raman laser manipulation. The detailed design examples described in this invention are merely illustrative of its advantages and rationality; all projection lens examples optimized based on the technical solutions of this invention fall within the scope of this invention. Techniques and principles not elaborated in detail in this invention are within the scope of this invention and are well-known to those skilled in the art.

Claims

1. An optical system for self-reflection of atomic interference Raman lasers, characterized in that: The system includes an ultra-high vacuum cavity (1) arranged in sequence, a lens group I, and a reflection group II. An incident beam from a narrow-linewidth laser is incident on the lens group I, then returns along the path through the reflection group II, and finally illuminates the ultra-high vacuum cavity (1) again through the lens group I. The ultra-high vacuum cavity (1) includes a cavity shell (1-1), a cavity optical window (1-2) fixed to the side wall of the cavity shell (1-1), and an atomic cluster (1-3) located at the optical system aperture inside the cavity shell (1-1). The lens group I consists of lenses L1 to L7 arranged in sequence, wherein lenses L2, L3, L5, and L6 are positive lenses, and lenses L1, L4, and L7 are negative lenses. The reflection group II consists of a plane mirror M1 with an anti-reflection coating and a polarizing coating on its surface. The image plane of the lens group I is located on the reflecting surface of the reflection group II.

2. The optical system for self-reflection of atomic interference Raman lasers according to claim 1, characterized in that, Lens L1 and L4 are meniscus negative lenses, lens L2 and L5 are biconvex positive lenses, lens L3 and L6 are meniscus positive lenses, and lens L7 is a biconcave negative lens.

3. The optical system for self-reflection of atomic interference Raman lasers according to claim 2, characterized in that, The image-side telecentricity θ of the lens group I does not exceed 5″.

4. An optical system for self-reflection of atomic interference Raman lasers according to claim 1, 2, or 3, characterized in that, The total length of the lens group I is ≤100mm, the distance from the entrance pupil to the lens group I is ≥60mm, the image-side working distance is ≥10mm, and the total length of the optical system does not exceed 162.5mm.

5. An optical system for self-reflection of atomic interference Raman lasers according to claim 1, 2, or 3, characterized in that, The optical system has an entrance pupil diameter ≥14mm and an object-side field of view range ≥+ / -7.5°; the full-field wave aberration RMS of the optical system is better than 1 / 100λ.

6. An optical system for self-reflection of an atomic interference Raman laser according to claim 1, 2, or 3, characterized in that, The angular deviation between the incident laser and the emitted laser in the optical system is no greater than 30″, and the positional deviation is no greater than 0.2mm.

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