• Current Optics and Photonics
• /
• v.6 no.1
• /
• pp.23-31
• /
• 2022

Heterodyne efficiency is an indicator to evaluate the performance of space coherent laser communication systems. It is affected by signal light and local oscillator (LO) light amplitude, phase and polarization state. In this paper, based on the common heterodyne efficiency, a heterodyne efficiency model that can reflect polarization aberration of optical system is proposed. The heterodyne efficiency is analyzed when the signal light and the LO light are linearly polarized or circularly polarized. For a coherent communication optical system, when the incident signal light is right-circularly polarized light and the incident LO light is 45° linear polarized light. Based on the three-dimensional ray tracing theory and the heterodyne efficiency proposed in this paper, the change of polarization states and the distribution of heterodyne efficiency of the signal light and LO light influenced by the optical system's polarization aberration are analyzed. Analysis shows that the heterodyne efficiency model proposed in this paper can be used to evaluate coherent communication systems and reflect the influence of optical system polarization aberration.

• Korean Journal of Optics and Photonics
• /
• v.16 no.5
• /
• pp.423-427
• /
• 2005

In this paper, we propose easily tooling method for Seidel third order aberration, which are not well utilized in actual design process due to the complication of mathematical operation and the difficulty of understanding Seidel third order aberration theory, even though most insightful and systematic means in pre-designing for the initial data of optimization. First, using paraxial ray tracing and Seidel third order aberration theory, spherical aberration coefficient is derived for a two-mirror system with a finite object distance. The coefficient, which is expressed as a higher-order nonlinear equation, consists of design parameters(object distance, two curvatures, and inter-mirror distance) and effective focal length(EFL). Then, the expressed analytical equation is solved by using a computer with numerical analysis method. From the obtained numerical solutions satisfying the nearly zero coefficient condition($<10^{-6}$), linear fitting process offers a linear relationship called the curvature linear equation between two mirrors. Consequently, this linear equation has two worthy meanings: the equation gives a possibility to obtain initial design data for optimization easily. And the equation shows linear relationship to a two-mirror system with a finite object distance under the condition of corrected third order spherical aberration.

• Journal of the Optical Society of Korea
• /
• v.20 no.1
• /
• pp.64-69
• /
• 2016

A new compact conformal dome optical system was established, and the aberration characteristics of the dome were investigated using Zernike aberration theory. The aberrations induced by the dome at different fields of regard (FORs) from 30° to 100° were effectively balanced by a rotating cylindrical lens. This kind of optical system can be widely used in top-view optical searching devices. A design method was introduced and the optimization results analyzed in detail. The results showed that the Zernike aberrations produced by the conformal dome were decreased dramatically. Also, a complete conformal optical system was designed, to further illustrate the aberration correction effect of the rotating cylindrical lens. Using a cylindrical lens not only provided a large FOR, but also simplified enormously the structure of the conformal optical system.

• Korean Journal of Optics and Photonics
• /
• v.11 no.4
• /
• pp.239-245
• /
• 2000

In this paper, the fundamental properties of diffractive optical element were investigated. Also, this work deals with theoretical approaches for achromatization in DOE's optical system based on thin lens theory. It is found that achromatization could be satisfied by one hybrid lens only, which is composed of a diffractive and a refractive element. In order to have compact optical system, we used the tele-photo type lens composed of a positive and a negative power elements instead of retro-focus lens. From the Gaussian brackets and Seidel aberration theory, the initial design was numerically obtained. The aberration properties of an initial design was aplanat and flat field. In order to correct the chromatic aberrations, refractive and diffractive elements were used on front element. This hybrid lens is also useful for correction of higher order aberrations. Compared to conventional design composed of refractive lenses only, this approach dramatically improved the compactness of the optical system. Finally, residual aberration balancing results in a lens with focal length of 3.89 mm and overall length of 5.19 mm, which has enough performance over an f-number of 4.0. Also, it is expected to fulfill all the requirements of a digital still camera lens. This optical system is superior to the current refractive lens system in the number of elements, weight, and aberration properties. rties.

• Journal of the Optical Society of Korea
• /
• v.19 no.6
• /
• pp.604-613
• /
• 2015

An unobstructed off-axis two-mirror system is presented in this paper. First a suitable initial configuration is established based on third-order aberration theory. In order to achieve a wide field of view (FOV) with high image quality , the diffractive mirror is adopted in the two-mirror system to increase the optimization freedom and the aberration relationship between diffractive phase coefficients and Zernike coefficients is derived. Furthermore, a complete comparison design example with a focal length of 1200 mm, F-number of 12, and FOV of 40° × 2° is given to verify the aberration correction ability of the diffractive mirror. The system average wavefront error is 0.007 λ (λ=0.6328 μm) developed from 0.061 λ when the system didn’t adopt the diffractive mirror. In this system the phase modulation function of the diffractive mirror is established as an even function of x, so we could obtain a symmetrical imaging quality about the tangential plane, and the symmetric aberration performance also brings considerable convenience to alignment and testing for the system.

• Korean Journal of Optics and Photonics
• /
• v.12 no.4
• /
• pp.270-275
• /
• 2001

We have studied effects of annular phase apodizer and bump shapes on the read-out signal in an optical disc system, using scalar diffraction theory. In order to detennine the optimum parameters of annular phase apodizer which will minimize the influence of spherical aberration, we defined WR as the ratio between the maximum wavefront aberration and some absolute value of wavefront aberration at any position r in the pupil. A cylindric bump, a semi-conic bump and a conic bump were$.$ also considered as different types of bump shape. As the radius and shape of bump varies, the read-out signal from an optical disc system with an annular phase apodizer was similar to that from an optical disc system without apodizer. When spherical aberration increases, the maximum read-out signal of an optical disc system with an annular phase apodizer and minimum bump radii giving read-out signal higher than 0.6 rarely varied. Especially, the optimum parameters at $W_R$ = 0.4 , 0.6 gave the most compensated effect of a spherical aberration.ration.

• Journal of the Korean Data and Information Science Society
• /
• v.14 no.3
• /
• pp.707-714
• /
• 2003

Because of complex aliasing, nonregular designs have traditionally been used for screening only main effects. However, complex aliasing actually may allow some interactions entertained and estimated without making additional runs. According to hierarchical principle, the minimum aberration has been used as an important criterion for selecting regular fractional factorial designs. The criterion is not applicable to nonregular designs. In this paper, we give a criterion for choosing fractional factorial designs based on the fan theory. The criterion is focused on the partial ordering given by set inclusion on estimable sets which is called leaves.

• 정보저장시스템학회:학술대회논문집
• /
• 2005.10a
• /
• pp.14-15
• /
• 2005

In near-field recording (NFR) optics using solid immersion lens (SIL), near-field air gap induces unwanted spherical aberration, defocus and astigmatism. This phenomenon can be explained with the apodization of phase and amplitude between each linearly polarized light. In this paper, we analyzed the effect of phase and amplitude apodization with the fundamental multiple beam interference theory, and we compared resultant diffracted patterns on the image plane for the Si-disk first surface media structure and cover-layer incident media structure.

• Korean Journal of Optics and Photonics
• /
• v.18 no.1
• /
• pp.19-23
• /
• 2007

We derived analytically the generalized curvature linear equation useful in the initial optical design of a two-mirror system with finite object distance, including an infinite object distance from paraxial ray tracing and Seidel third order aberration theory for coma coefficient. These aberration coefficients for finite object distance were described by the curvature, the inter-mirror distance, and the effective focal length. The analytical equations were solved by using a computer with a numerical analysis method. Two useful linear relationships, determined by the generalized curvature linear equations relating the curvatures of the two mirrors, for the cancellation of each aberration were shown in the numerical solutions satisfying the nearly zero condition ($<10^{-10}$) for each aberration coefficient. These equations can be utilized easily and efficiently at the step of initial optical design of a two-mirror system with finite object distance.

• Korean Journal of Optics and Photonics
• /
• v.3 no.2
• /
• pp.77-85
• /
• 1992

The design of a flat-field XUV spectrograph is optimized for a high throughput, aberration-corrected spectral image in the wavelength region of 50-300 $\AA$ The varied-line spacing (VLS) concave grating theory for an XUV spectrograph with a toroidal mirror in front of an entrance slit is derived. Since the derived theory includes the arbitrary shaped source, it is able to correct the limit of the simple optimization theory which considers only a point source at the center of the entrance slit. The reflection matrix at the toroidal mirror and the diffraction matrix at VLS grating are derived and compared with those of a holographic grating. The absolute energy efficiency of a flat-field spectrograph is calculated by considering the reflectivities of the toroidal mirror and the Au coated concave grating and the grating efficiency. The alignment sensitivity of the toroidal mirror and the concave grating is investigated, and the method to achieve the best imaging of XUV spectrum is discussed. The calculated resolving power of the flat-field XUV spectrograph is more than 4000 in the aberration-corrected wavelength range. The focused spot size at the dispersion plane is less than $20\mu \textrm m\times \mu \textrm m$at the wavelength 100$\AA$ It is shown that a high throughput characteristic can also be achieved through a careful adjustment of alignment parameters.