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Ultra Long WD 18mm 100X Objective

Application: The current market is limited to working distance 12mm for 100X microscope objectives. Our clients require a cost effective and compact solution for 18 mm ultra long working distance 100X objective. Our newly developed ultra long working distance, three points (red, blue and yellow) achromatic design has high resolution of 0.1@1000 lp/mm. This innovative objective can enable users to study with ease a single cold atom trapped in ultra-high vacuum chamber in great detail and accuracy.

Ultra Long WD 18 mm 100 X Objective - 01

Market Opportunity: Shanghai Optics is on schedule to introducing the ultra long working distance 100X objective into the Photonics market end of 2014. We anticipate a huge interest and demand from quantum physics, biomedical research, life science research and development work area.

Impact: The availability of ultra long working distance (18mm) microscope objectives and three points (red, blue and yellow) achromatic design with high resolution @ 1000 lp/mm will allow for maintaining high N.A. and high contrast and good color reproducibility. This enables scientists and researchers to gather data in territories previously not possible.

With this breakthrough in high resolution/high magnification/Achromatic/Long working distance objective, the working distance has been increased 50% from what’s available on current market.

The availability of this special objective has huge impact in science and research market, it will enable the detail in-depth observation with greater accuracy in advanced material science and bio-medical research area.

Design Challenges:

High resolution objective system design is a rather complicated process and demand strong design disciplines, our design engineers consider all factors during our design and optimization process. Our primary concern is to fully understand optical system structure and the change of system parameters affect the imaging of the system in the manufacturing process and assembly, therefore provide theoretical guidance for future production.

Our experienced engineers went through vigorous tolerance function analysis of eac crucial parameters that having an impact on image quality parameters including the curvature of the lens, thickness and refractive index, Abbe number and positions of the lenses and the centering issues and many more.

For high-magnification microscope objective lens, even though its focal length is very short, and field of view is not very large, there is still serious field curvature, therefore the clear field of view is very limited for high magnification microscope objectives. Only in the center of a small field of view range the image is clear. For clear large view field, such as a photomicrograph, it needs to correct curvature of field of the objective lens and the astigmatism, especially need to adjust Petzval Sum. (Petzval Sum is the sum of all the optical surface curvature. If it is zero, that means there is no Petzval curvature in the system, it also complies with the flat field conditions). Such a microscope objective can make image flat and very clear in the larger field of view, known as flat field lens.

Field curvature correction method primarily can be accomplished by adding several thick meniscus lenses, which would make the internal structure of the microscope objective very complicated, adds difficulty to manufacturing and assembly process. Therefore compact size with high-precision high-magnification microscope objective has its tremendous commercial potential. Thanks to our revolutionary design, we have achieved the design and can take us to the first step of commercialization.

As a key manufacturer of microscope objectives, SO provides a wide range of objectives designed to meet the special imaging performance needs. Our design is optimized to compensate on the thickness variation of cover glass can increase the effectiveness of the objective lens. Typically, the functionality of a particular of the objective lens cannot be obtained simply by adjusting the structure of the objective lens. We also include eyepiece as a part of our design concept in order to reduce errors and changes in optical flatness field.In general of the achromatic microscope objective lens, the secondary spectrum of chromatic aberration of the objective lens is one the major players in increasing of a numerical aperture and the magnification. In high power achromatic microscope objective lens, the secondary spectrum often becomes the main factors that affect quality or the image. Because there is approximately direct proportion between corresponding geometric aberrations value of secondary spectrum and the focal length of the objective lens. With the increase of the magnification of the objective lens, the chromatic aberration on the surface of the secondary spectrum will decrease with shortened focal length, but the value of a geometrical aberration of the wavefront aberration and with corresponding to the square of the numerical aperture are approximately proportionate. Thus overall, with increased magnification and numerical aperture, the corresponding of wavefront of the secondary spectral color aberration will need to be increased. Particularly high quality microscope objectives require correcting secondary spectral color aberration.

Novelty and Innovation

Shanghai Optics are the pioneers in developing the ultra long working distance with WD 18 mm 100X microscope objective. This enables users to study in atomic level with greater accuracy than ever before. This will potentially lead to new discoveries and theories that would be possible with the current technology. Industry high magnification microscope objectives usually have a short working distance which tremendously limits the functionality of the microscope. For example, using our system for CCD pixel measurement, the CCD surface has a cover glass with thickness of 0.8 – 1mm and distance between the cover glass and the object is about 0.5 – 1mm. Due to our revolutionary design and manufacturing, we have increased the working distance to be WD 18 mm. We can accomplish measuring task under extreme circumstances along with the additional benefits of the long working distance which can effectively protect the sample being damaged from being contacted by the objective during focus adjustment. Thus improving the overall function of the high magnification microscope technology.

Design and Technology

Current off-the-shelf 100X microscope objective’s working distance is only 12 mm. The objective has a Parfocal distance of 95mm which is different from the usual 45 mm on the current market. Its extra long working distance enable customers to achieve high level diffraction limit. SO’s special optical/ mechanical design and manufacturing technique provides us with the foundation for the major breakthrough. By using optical materials such as CaF2, ED/UD glasses, we achieve excellent apochromatic performance (red, blue and yellow), through our design and manufacturing expertise. We also achieve the availability of ultra long working distance (18mm) objectives but with regular TOTR while maintaining high N.A. and high contrast and good color reproducibility.

High resolution objective system design is rather complicated and demand strong design disciplines, our design engineers consider all factors during our design process. We also need to venture out to know how the optical system structure and the change of system parameters affect the imaging of the system in the manufacturing process and assembly, therefore provide theoretical guidance for future production.

Our experienced engineers went through vigorous tolerance analysis function analysis of each crucial parameters that having an impact on image quality parameters including the curvature of the lens, thickness and refractive index, Abbe number and positions of the lenses and the centering issues and many more.

Comparison between theoretical resolution and diffraction limit (0~1000 Max Frequency)

After tolerance analysis, different MTF nominal values and tolerance values for each wavelength are shown in the table.

Objective MTF

WavelengthFOV(deg)MTFT (1000lp/mm)MTFS (1000lp/mm)
Nominal ValuesMonte Carlo 90%>Nominal ValuesMonte Carlo 90%>
399nm00.4250.1390.4310.151
20.4310.1400.4350.149
3.20.4260.1360.4350.147
532nm00.3090.1120.3280.121
20.3400.1160.3390.124
3.20.3020.1080.3240.119
556nm00.2860.1100.3040.100
20.3150.1200.3150.103
3.20.2770.1130.3000.101

In conclusion, consider manufacturing and assembling tolerances, the MTF Curve can reach 0.1 @ 1000 llp/mm.

Partial Section View

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What other technologies are essential?

The system of microscope that we designed has function of high magnification (100 times), also a long working distance (18 mm) and 399 nm, 532 nm, 556 nm apo-chromatic.

Internal Diagram of WD 18mm 100 X Objective

Internal Diagram of WD 18mm 100 X Objective

Product Schematic Diagram

Ultra Long WD 18 mm 100 X Objective Schematic Diagram