RU214866U1 - Wide spectrum fluid lens - Google Patents

Abstract

The utility model relates to the field of optical instrumentation and can be used in wide-spectrum television and photographic cameras, as well as active-pulse surveillance and location devices. The required technical result, which consists in expanding the spectral range and expanding the arsenal of technical means that can be used to create wide-spectrum lenses, is achieved in a device containing the first group of lenses placed in series on one optical axis and separated by an air gap, consisting of a liquid lens of the first group , placed between the first shell lens of the first group and the second shell lens of the first group, and the second lens group, consisting of a liquid lens of the second group, placed between the first shell lens of the second group and the second shell lens of the second group, and the liquid in the liquid lens the first group has a refractive index N _D =1.2950 and a dispersion coefficient ν _D =101, and the liquid in the liquid lens of the second group has a refractive index N _D =1.4580 and a dispersion coefficient ν _D =57. 3 ill.

Description

The utility model relates to the field of optical instrumentation and can be used in wide-spectrum television and photographic cameras, as well as active-pulse surveillance and location devices.

The operation of hyperspectral and panspectral optical devices using silicon television matrices requires, as a rule, the provision of a high-quality image in the spectral range of 0.4–1 μm.

Petzval lenses are known (https://radojuva.com/2020/11/petzval-180-mm-f-4-5-darlot-paris-1862/), consisting of two positive achromatized components separated by an air gap corrected in a wide spectral range.

Such lenses provide a high relative aperture with small fields of view and are convenient for use in television cameras, long-focus photographic cameras and night vision devices.

The disadvantage of this technical solution is the relatively narrow corrected spectral range of 0.43-0.61 μm and the low degree of correction of chromatic aberrations.

Also known wide-spectrum lens company Lockheed Missiles & Space Company (US 4929071, G02B 13/02, 9/28, 9/12, 009/00, 09/29/1990), which is a modified Petzval optical lens, the constructive form of which has a large focal length (up to 1000 mm) with a large relative aperture ( f/2) in a field of view of 4.2 without vignetting, which is well corrected for both monochromatic and chromatic aberrations, and which has color correction at four wavelengths in the spectral range extending from the visible to the near infrared regions of the electromagnetic spectrum, moreover, the optical lens is made of two different optical glasses, the design shape can be enlarged or reduced from the focal length of 1000mm using the appropriate zoom factor, the position chromatism of the 9-lens lens is corrected at 4 wavelengths in the range of 0.5-1μm, which can be attributed lens for superapochromats.

The disadvantage of this technical solution is the relatively large complexity, since the lens has a significant number of lenses with numerous close radii separated by small air gaps, requiring extremely tight tolerances for the location and decentration of the lenses, which usually entails a serious deterioration in the actual performance of the lens in comparison with calculated expectations.

Closest to the proposed lens is a wide-spectrum lens from Lockheed Missiles & Space Company. (US 5731907, G02B 3/12, 001/06, 009/00, 009/00, 03/24/1998), using a liquid lens and consisting of four solid lenses in two groups of lenses, in the first group of which two optical glass lenses are separated by an air gap, in the second group, two optical glass lenses are filled with an optical liquid with a refractive index of 1.62 and a dispersion coefficient of 13.5.

In the closest technical solution, a special course of the dispersion of the refractive index of the liquid provides correction at three wavelengths in the spectral range of 0.43-0.61 μm, where the position chromatism reaches 250 μm, while the focal length is 1519 mm, and the relative aperture is 1:10. In addition, in this lens, the ratio of the optical powers of the lens components to the optical power of the first component is 1, -0.5638, -1.6644, 0.5436, 1.1275, the lens materials have refractive indices N _D 1.516800, 1.620041, 1.805182, 1.642690, 1.744002, respectively, and the coefficient variances ν _D 64.16, 36.36, 25.43, 13.49, 44.71, respectively.

The disadvantage of the closest technical solution is a relatively narrow corrected spectral range of 0.43-0.61 μm and a low degree of correction of chromatic aberrations.

The problem solved in the utility model is to create a lens with a wider spectral range, providing a high-quality image in the spectral range from 0.4 to 1 µm, acceptable for a photodetector matrix with a step of about 3.5 µm.

The required technical result is to expand the spectral range.

To solve this problem and achieve the required technical result, it is necessary to provide such a combination of optical powers, refractive indices, dispersion coefficients and partial dispersions so that the total optical powers of the lens at all calculated wavelengths within the required spectral range do not differ significantly. At the same time, the chromatic shift of the focal plane can serve as a criterion for the chromatic difference in the optical power of the lens, reaching 250 μm in the prototype lens in the range of 0.43-0.61 μm, and the task of expanding the spectral range should be solved provided that the modulation transfer function at the main wavelength, which is the main criterion for image quality is not degraded.

The problem is solved, and the required technical result is achieved in a device containing the first group of lenses placed in series on the same optical axis and separated by an air gap, consisting of a liquid lens of the first group, placed between the first lens-shell of the first group and the second lens-shell of the first group, and a second group of lenses, consisting of a liquid lens of the second group, placed between the first shell lens of the second group and the second shell lens of the second group, moreover, the liquid in the liquid lens of the first group has a refractive index N _D = 1.2950 and a dispersion coefficient ν _D = 101, and the liquid in the liquid lens of the second group has a refractive index N _D = 1.4580 and a dispersion coefficient ν _D = 57.

In FIG. 1 - optical scheme of a wide-spectrum objective with liquid lenses;

in fig. 2 - calculated position chromatism (focal plane shift) as a function of wavelength in the spectral range 0.4-0.1 µm, for a lens with a focal length of 100 mm and a relative aperture of 1:5, for a zonal beam (0.7 of the maximum aperture);

in fig. 3 is a calculated graph of the rms point spread spot over the linear field of view corresponding to a photodetector matrix of 2400×1920 elements, with a step of 3.5 μm, with a lens focal length of 100 mm and a relative aperture of 1:5.

In the drawing of FIG. 1 marked

a liquid lens of the first group placed between the first shell lens of the first group and the second shell lens of the first group, and a second lens group consisting of a liquid lens of the second group placed between the first shell lens of the second group and the second shell lens of the second group,

1 - the first lens-shell of the first group (for example, a lens made of Schott SF59 glass);

2 - liquid lens of the first group (for example, liquid 296244);

3 - the second lens-shell of the first group (for example, a lens made of Schott LAKN13 glass;

4 - the first lens-shell of the second group (for example, a lens made of Schott SF59 glass);

5 - liquid lens of the second group (for example, liquid 458582);

6 - the second shell lens of the second group (for example, a lens made of Schott LAFN23 glass).

Wide spectrum fluid lens contains the first group of lenses placed sequentially on one optical axis and separated by an air gap, consisting of a liquid lens of the first group, placed between the first lens-shell of the first group and the second lens-shell of the first group, and the second group of lenses, consisting of a liquid lens of the second group, placed between the first shell lens of the second group and the second shell lens of the second group, moreover, the liquid in the liquid lens of the first group has a refractive index N_D= 1.2950 and dispersion coefficient ν_D = 101, and the liquid in the liquid lens of the second group has a refractive index N_D= 1.4580 and dispersion coefficient ν_D = 57.

Liquid 296244 liquid lens of the first group has a refractive index N _D = 1.2950, a dispersion coefficient ν _D = 101 and the following spectral refractive indices:

λ, nm 365 486.1 589.3 656.3 1064.8 _Nλ 1.3010 1.2970 1.2950 1.2941 1.2920

Liquid 458582 liquid lens of the second group has a refractive index N _D = 1.4580, a dispersion coefficient N _D = 57 and the following spectral refractive indices:

λ, nm 365 404.7 4861 589.3 656.3 1064.8 _Nλ 1.4780 1.4719 1.4637 1.4580 1.4557 1.4500

The ratio of the optical powers of lenses 1-6 to the optical power of the lens is (successively, along the beam): -0.00015, 0.0011, -0.00043, -0.0017, 0.0058, -0.005.

The lens materials have refractive indices of 1.95, 1.30, 1.69, 1.95, 1.46, 1.69 and dispersion coefficients of 20, 124, 53, 20, 58, 50, respectively.

The table shows an example of the implementation of the lens on glasses from the Schott catalog and liquids 296244, 458582, corresponding to the indicated combinations of refractive indices and dispersion coefficients.

N Relates strength Refractive index coefficient of dispersion Optic
material one -0.00015 1.952 twenty Schott SF59 2 0.00106 1.295 124 Liquid 296244 3 -0.00043 1.693 53 Schott LAKN13 four -0.00169 1.952 twenty Schott SF59 5 0.00581 1.458 58 Liquid 458582 6 -0.00495 1.689 fifty Schott LAFN23

In FIG. Figure 2 shows the calculated position chromatism (focal plane shift) as a function of wavelength in the spectral range 0.4-0.1 µm, for a lens with a focal length of 100 mm and a relative aperture of 1:5, for a zonal beam (0.7 of the maximum aperture).

The position chromatism is corrected for five wavelengths and does not exceed ±1 µm. This value is negligibly small for a photodetector matrix with a step of photosensitive elements of 3.5 µm.

With a lens focal length of 1500 mm, the calculated position chromatism does not exceed ±13 µm. Twenty times less than the chromatism of the position of the prototype lens in a narrower spectral range.

In FIG. Figure 3 shows the calculated graph of the root-mean-square point spread spot over the linear field of view corresponding to a photodetector matrix of 2400 × 1920 elements, with a step of 3.5 μm, with a lens focal length of 100 mm and a relative aperture of 1:5.

Over the entire field, the radius of the polychromatic scattering spot does not exceed the diffraction resolution limit of 4.3 μm.

This combination of optical power ratios, refractive indices and dispersion coefficients, in combination with the liquid optical materials used, provides correction of position chromatism at five wavelengths (a higher degree compared to superapochromat), limiting the chromatic shift of the focal plane position to within 0.005% in a wide spectral range 0.4 - 1 µm.

Compared with the closest technical solution, the position chromatism is an order of magnitude smaller with the same focal length, the same number of solid lenses and a three times larger spectral range, which confirms the achievement of the required technical result.

Claims (1)

A wide-spectrum objective with liquid lenses, comprising a first group of lenses placed sequentially on one optical axis and separated by an air gap, consisting of a liquid lens of the first group placed between the first lens-shell of the first group and the second lens-shell of the first group, and the second group of lenses consisting of from a liquid lens of the second group, placed between the first lens-shell of the second group and the second lens-shell of the second group, and the liquid in the liquid lens of the first group has a refractive index N _D =1.2950 and a dispersion coefficient ν _D =101, and the liquid in the liquid lens the lens of the second group has a refractive index N _D =1.4580 and a dispersion coefficient ν _D =57.

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