LumaScope Objective Lenses
The LumaScope product line uses infinity corrected, Royal Microscopy Society (RMS) threaded objectives. We have selected a family of objective lenses which fit in the price-performance realm of the LumaScope product line.
Those selected for the 400 series and Phase Contrast Accessory are from the Chinese manufacturer, Motic. Their price reflects the recommended use of bright field/phase only. Inexpensive lenses often suffer from auto-fluorescent glass at lower wavelengths. This means the lens glass itself is fluorescing and adding a large background to the image. This is more likely to occur at lower wavelengths such as the 405nm offered on the Model 600. As a result inexpensive lenses may be appropriate for some 488 or 589nm imaging but most likely not for 405nm.
A 10x EFN lens demonstrates auto-fluorescence noise.
The Model 500 lenses are from a Japanese manufacturer, Meiji, and are tailored to work with the 488nm excitation of the Model 500. You may notice these are “U Plan” meaning they are normally used in an upright scope but this has no effect on performance in the inverted configuration of the LumaScopes.
The Model 600 lenses are also from Meiji and are suggested due to their transparency at 405nm.
It should be noted that any infinity corrected, RMS objectives can be used in the LumaScopes. Often, changing lenses can have a dramatic effect on image quality.
As the magnification increases, the working distance (WD) shortens. This is the distance that the sample must be from the lens to achieve focus. You will notice that the 100x objectives have working distances of 0.2mm or less. This is microscope coverslip thickness and so one cannot focus through a standard glass slide and must invert the slide to allow the coverslip to be towards the lens.
There are long working distance versions of most lenses with an increase in cost. These are often denoted “TC” for tissue culture, indicating they are appropriate for most labware thicknesses.
Use of Oil Immersion
The 100x lenses are indicated as oil immersion. This technique increases the numerical aperture-NA (light collection efficiency) by matching the refractive index of the lens and eliminating interfacial losses.
We have had customers successfully use oil immersion in the LumaScopes just as it is used in traditional inverted microscopes.
Phase Contrast Lenses
The lens annulus in a phase contrast lens.
Phase contrast lenses have an annulus in them that matches a corresponding light annulus allowed through the illumination mask.
We have again chosen Motic for their Phase Contrast Lens/Mask combinations. Ph0 mask is used with the 4x, Ph1 with the 10 and 20x and Ph2 with the 40x. Phase contrast lenses can be used for some bright fluorescence work with the 488 and 589nm excitation. It is not recommended for use with the 405 nm excitation of the Model 600.
For automated experiments requiring both a brightfield/phase contrast image as well as a fluorescence image, it may be possible to use the phase lenses. A better choice might be to work with the brightfield illumination without phase to work with a standard fluorescence lens designed for the fluorescent wavelengths in use.
Field of View
The following table lists the FOVs of all lenses on the Model 400 and 500 LumaScopes. Data was obtained using a reticule slide and a LumaScope Model 500 with all available lenses, including those designated for Model 400, Phase Contrast, and the 600.
Model 400 Lenses
|EF-N Plan 10x objective lens, NA 0.25, WD 4.4mm
|EF-N Plan 40x objective lens, NA 0.65, WD 0.5mm
|EF-N Plan 60x objective lens, NA 0.85, WD 0.2mm
Model 500 Lenses
|MA830 2.5x objective lens, Semi Apo
|MA965 4x objective lens, NA 0.10, WD 15.3 mm,
|MA966 10x objective lens, NA 0.25, WD 7.3 mm ,
|MA833 20x objective lens, NA 0.40, WD 7.3 mm,
|MA968 40x objective lens, NA 0.65, WD 0.5 mm,
|MA823 40x LWD NA 0.65, WD 2.5 mm,
|MA969 60x NA .8, WD 2.9 mm
Model 600 Lenses
|MA1012 Apochromat F4x objective lens, NA 0.13, WD 17.5mm
|MA980 Apochromat F10x objective lens, NA 0.30, WD 8.6mm
|MA981 Apochromat F20x objective lens, NA 0.65, WD 0.7mm
|MA982 Apochromat F40x objective lens, NA 0.80, WD 0.2mm
|MA849 TC Plan F4x objective lens, NA 0.13, WD 17.5mm
|MA850 TC Plana F10x objective lens, NA 0.30, WD 7.5mm