Theoretical Analysis of Surface Characteristics of Aspheric Lenses

 Abstract:

Aspheric lenses are becoming more and more important in some high-precision optical systems. And, like other optical lenses, the surface must meet the same quality standards in terms of surface shape accuracy and surface roughness. In this paper, are aspheric less studied deeply from the theory of surface characteristics, the calculation method of surface features of aspheric lenses, aspheric surface characteristics, and calculation formula are given, and the characteristics of surface fitting error of aspheric lenses are analyzed. Taking K9 glass aspheric optical lens, for example, the surface characteristic function is discussed in detail. The results show that the surface characteristic function of aspheric lenses has higher precision, and its fitting error is better than + 30nm

 

Keyword: aspheric surface, surface characteristic, fitting error

As an important optical element, aspheric lenses occupies an important position in the optical system. Aspheric lenses function in 3-4 times than spherical lenses in the optical system. Mainly because of spherical aberration of aspherical lenses in the optical system, such as lateral deviation, axis deviation and angle deviation, which limits the application of spherical lens in the optical system. The aspheric lens has the ability to eliminate spherical aberration, thus greatly improving the sphere of use of aspheric lenses in the optical system.

 

The research of aspheric lenses is mainly in two aspects. 1 using the optical design software (such as CODE V and ZEMAX) design of aspheric lenses, so as to solve the problem of light propagation and imaging in the aspheric lens; the research mainly focuses on the production process of an aspheric surface.

 

In foreign countries, the surface fitting of the aspheric surface has been studied deeply, and the fitting method of the aspheric surface is less. Hector proposed a curve algorithm suitable for conic aspheric; based on linear least squares method, ZHANG proposed aspheric parameters calculation algorithm; By changing the conic constant values of K and using the max-min value of the least squares method, G ugsa gets the surface contour standard. The above method considers only the surface of a single standard surface. When measuring the aspheric surface in the day, the estimation of the cone constant K will be biased due to the different coefficients of the polynomial. In this paper, the surface characteristic function of the aspheric surface is established by theoretical analysis. The surface characteristic function of the aspheric surface is discussed by taking K9 glass as an example, and the fitting error is analyzed.

 

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Technology Advantages and Applications of Infrared Lens

 Infrared Lens is a rising technology with a limited range of applications. However, with the trend in security, Infrared Lens will rapidly expand.

 

Infrared Lens technology

Infrared lenses uses special optical glass materials and modern optical design methods to eliminate the focus shift between visible light and infrared light, allowing both types of light to be imaged at the same focus point for a clear image. Currently, Infrared cameras on the market mainly use an infrared filter to switch between day and night modes. During the day, the filter blocks infrared light from reaching the CCD, enabling it to detect only visible light. At night or under poor lighting conditions, the filter stops working, allowing infrared light, reflected from objects, to enter the lens and be imaged by the CCD.

 

Advantages of Infrared Lens technology

However, commonly a clear daytime image becomes blurry under Infrared conditions. This is because the wavelengths of visible and infrared light differ, causing the focus point to be different which results in a blurry image. The latest optical design methods, special optical glass materials, coatings, and advanced materials eliminate the focus shift between visible and infrared light. The special optical glass material addresses the clarity issue of infrared imaging, allowing light to be focused at the same point for both visible and infrared light. Special coatings ensure that infrared light penetrates the lens while suppressing ghosting and flares in backlit conditions, providing high-quality images with high contrast, even under unfavorable backlight conditions.

 

Applications of Infrared Lens

Infrared Lens has a wide range of applications. It can be used as a specialized lens for Infrared purposes or as a regular lens. Infrared lenses can be easily synchronized with conventional color cameras, white cameras, and day-to-night switchable cameras, depending on the application. White cameras do not have an infrared stop filter, and the sunlight spectrum contains infrared light, so even under daylight conditions, white cameras can be affected by infrared light. Therefore, using an Infrared Lens can significantly improve image quality.

 

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Collimating Lenses

 Custom Collimating Lenses for Precise Optical Performance

Hyperion Optics offers economical custom design collimating lenses that can effectively correct spherical and chromatic aberrations, including singlet and chromatic lenses. Many of our clients had experiences where off-the-shelf collimators they purchased for their system do not collimate the light source perfectly, thus affecting the final system performance. To better serve clients with similar challenges when building a cost-effective system, Hyperion Optics provides free design consultation for custom collimators in both singlet and chromatic formats.

 

Advantages of Hyperion's Custom Collimating Lenses

 

Hyperion's custom collimator lenses help parallelize the entrance light rays into your optical system setup, enabling you to control the field of view, collection efficiency, and spatial resolution. Our existing collimator design is responsive at UV-VIS, or VIS-NIR spectrum.

 

Affordable Aspherical Collimator Lenses for Volume Production

Aspherical collimator lens is another hot product that we offer as a cost-effective replacement for volume production. Unfortunately, brand-name aspherical lenses are not the most budget-friendly. Hyperion Optics provides reverse engineering services to help you maintain a competitive edge in the global market, oftentimes with even better system performance since our redesign aimed at optimizing the aspherical lens for your specific application. Please refer to our reverse engineering and aspherical surface production pages for more information.

 

How to Design Your Custom Laser Collimating Lens

To start with your customized collimator lens design, please verify the expected spot size and focal length of your setup:

 

For a point source, near collimation can be assumed so that the beam will be the “clear” aperture of the laser collimating lens. If a fiber is attached to the lens, the divergence angle can be calculated depending on the height of the thread. This information allows you to calculate the spot size at a distance.

 

Tan(Theta) = (Height of fiber)/(Focal Length)

Focal Length = Height of fiber = (1/2)*core diameter

Theta = divergence angle

 

Should I choose a chromatic or singlet collimator lens?

 

For applications such as absolute irradiance, the use of achromatic lenses can offer the maximum benefits. An achromatic lens helps to eliminate the unexpected “contamination” of the spectrum caused by wavelength outside of the optimal FOV.

 

Further, Hyperion Optics offers free consultation on your mechanical design, including lens mount, barrel, and, assembly housing. Contact our technical sales team today to find out the best collimating solution for your optical system.

 

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Beam Expander

 Beam expansion or reduction is a common application requirement in most labs using lasers or light sources and optics. Users always find there are so many off-the-shelf laser beam expander, however, hard to find one exactly fit their needs in terms of spectral range or expansion ratio. In most cases, the plug and play solution may not be the answer.

 

Hyperion Optics helps customers with their unique expander development project, from optical design, mechanical design and responsible for the application performance. It is critical to communicate with our engineers your input and output beam diameter ratio requirement. For simple laser expander, such as telescopes, consists of two lenses, the magnification of a 2 lens system is equal to the ratio of the focal lengths of the lenses, which is also equal to the ratio of the radii of curvatures of the lenses.

 

M= the magnification of the beam expander

F2= effective focal length of exit lens

F1= effective focal length of entry lens

R2= radius of curvature of exit lens

H2=radius of exit spot (image height)

H1=radius of entry spot (object height)

 

At Hyperion Optics, we offer rapid optical design and prototyping, in most expander cases, we offer 6 weeks delivery, means when we study your application, expansion ratio and input output parameters, we are able to deliver assembled expander within 6 weeks. Or we can work on your existing off-the-shelf solution to improve your application’s performance.

 

We also offer off-the-shelf expanders, please refer to following products for your requirement, or contact our engineer for further information.

 

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Anamorphic Lenses

 Hyperion Optics specializes in custom anamorphic projection lens design and production. We are experienced in creating custom solutions for unique applications such as projection and anamorphic photography. Generally speaking, these lenses are special systems that effectively change the aspect ratios when projecting the image onto the camera sensor.

 

Compared to a more common type spherical lenses, which project images onto the sensor without causing an aspect ratio change, anamorphic lenses for dslr compress along the longer dimension and require subsequent stretching in post-production or at the projector for the output image to be properly displayed.

 

With our high quality achromatic cylindrical lenses production capability, we are able to meet the challenging and demanding anamorphic lens design performance, please refer to our cylindrical lens fabrication capability. Note that in some cases, custom achromatic cylindrical lenses are extremely thick in CT, and oftentimes material availability would be a manufacturing obstacle. Hyperion’s production team is able to cement singlet parts on a real-time alignment device to avoid thickness unavailability of certain materials.

 

We begin with a cinemascope screen. Here we’re displaying a 2.35 or 2.40 film, notice the top and bottom black bars.

 

The first step is to electronically stretch the image vertically. This process is either called ‘vertical stretch’ or ‘zoom’ or ‘anamorphic mode’. The vertical stretch feature can be found in many projectors and Blu-Ray players. We have taken the active illuminated pixels in the black bars and scaled them back into the image. This process increases the overall on-screen luminance or brightness. Once vertically stretched, everything on screen looks tall and skinny - compare the image below with the image above.

 

The first step is to electronically stretch the image vertically. This is either called ‘vertical stretch’ or ‘zoom’ or ‘anamorphic mode’. This feature can be found many projectors and Blu Ray players. We have taken the active illuminated pixels in the black bars and scaled them back into the image. This process increases the overall on screen luminance or brightness. Once vertically stretched, everything on screen looks tall and skinny- compare the image below with the image above.

 

Finally, we take the optical expansion of the vertically stretched image to restore the geometry and to fill the entire cinemascope screen with the active image. The result below is an image that is 78% larger than the original. Now compare the top and bottom images.

 

Highlights of Hyperion Optics’ anamorphic design

Expected aspect ratio control

Sharp image quality, tested and verified MTF according to system requirements

Excellent achromatic feature

Design fit for 2.35, 2.39 and 2.4 aspect ratio

Theatrical cinema projection design available

 

ADVANTAGES OF ANAMORPHIC LENSES:

 

Anamorphic lenses takes full advantage of the performance of the projector to show a broader view and to bring about a more comfortable viewing effect.

 

Why use anamorphic lenses:

Anamorphic lenses can deform the projection image through the lens to meet the need of a wider screen. It allows for a wide range of scenes to be compressed into the standard frame area.

 

How the anamorphic lens works:

Add a set of oval compression lenses to the lens, and the film will be vertically stretched to fit the size of 35 mm. At the time of the screening, all we need to do is to use the opposite oval to magnify the lens, and we could recover the original film of 2.35:1.

 

The difference between spherical and anamorphic lenses:

1. The curvature radius of the spherical lens is the same everywhere, but the curvature radius of the anamorphic lens is different from the center to the edge of the lens; and the curvature radius of the edge is usually longer.

 

2. A zoom lens of multi-slice spherical lens combination can easily produce barrel distortion at the wide angle end, and pillow distortion can be easily generated at long focus end.

 

For more information about anamorphic optics and optical design manufacturing, please feel free to contact us!

 

Multichannel Filter

 Multichannel filters differ from conventional bandpass filters by allowing only one continuous band of light to pass through it, allowing two or more bands of light to pass through.

 

 

Multi-channel filters can be achieved on a filter to achieve the need for multiple general filter stack to achieve the effect, making the design more compact, and can reduce costs.

 

This filter in the optical communications, infrared and medical applications have a wide range.

 

As one of optical component manufacturers, we will do our best to meet all the needs of customers.

 

Fluorescence Filters

 Fluorescence microscopy filters are a class of filters classified by application type.

 

Fluorescence filter is a fluorescence imaging filter for biomedical and life science instruments, the key components, the main role is in the biomedical fluorescence analysis system for the separation and selection of substances in the excitation and emission fluorescence Of the spectral characteristics of the band. It is usually required that the filter cut-off depth be greater than OD5 (optical density, OD = -lgT). The core requirements for filters used in fluorescence detection systems are high cut-off steepness, high transmittance, high positioning accuracy, high cut-off depth, and excellent environmental stability.

 

Fluorescent filter is a combination of three, three are excitation filters, emission filters and dichroic filters.

 

Excitation Filter (Exciter Filter, Excitation Filter, Excitation Filter): In the fluorescence microscope, only the excitation wavelength of the filter can pass through the fluorescence. In the past, a short-pass filter was used, and now a band-pass filter is basically used. The housing is marked with arrows indicating the direction of propagation of the recommended light.

 

Emission Filter (Emitter Filter, Emitter): Select and transmit the fluorescence emitted by the sample, the other range of light cut-off. The wavelength of the emitted light is longer than the wavelength of the excitation light (closer to red). A band-pass filter or a long-wave-pass filter may be selected as the emission filter. The housing is marked with arrows indicating the direction of propagation of the recommended light.

 

Dichroic Mirror (Dichromic Beamsplitter, Dichromatic Beamsplitter): also known as dichroic mirrors or dichroic mirrors. And placed at an angle of 45 ° to the optical path of the microscope. This filter reflects one color of light (excitation light) and transmits another color of light (emitted light), the reflectivity of the excitation light is greater than 90% and the transmittance of the emitted light is greater than 90%. The impervious portion of the spectrum is reflected rather than absorbed. Filter in the transmitted light and reflected light color complement each other, and thus also known as dichroic filters.

 

Our fluorescence filters are designed for fluorescence imaging applications, with durability in mind and high-performance optical specifications in manufacturing. The filter substrate is made of quartz, which can achieve 1/10 lambda surface accuracy, while the thermal expansion coefficient of quartz is relatively small, can obtain higher image quality.

 

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