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The LS Microscope (Lumascope) product line uses infinity corrected, Royal Microscopy Society (RMS) threaded objectives with a 45 mm parfocal distance. We offer a family of objectives that provides a range of price-performance (see Objectives Offered Table below). You may also be able to use your own objectives, including those typically used in upright microscopes. If RMS threaded, they can be installed directly, or they may work with an objective adapter (inquire at Etaluma). However, they should always be infinity-corrected in order to achieve high resolution.

Tila stem auto-fluorescence on LS620 3-color fluorescence microscope
Tila stem auto-fluorescence on LS620 3-color fluorescence microscope

Coverglass Correction

Objectives are corrected for different thicknesses of material between the objective and sample (referred to as cover glass thickness or CGT) and thus should be considered when choosing objectives. If the material is a coverslip or bottom of a glass bottom microplate, the thickness is 0.17 mm. If a microscope slide or plastic microplate well bottom, the thickness will likely be 1 mm but should always be confirmed. The material thickness correction (often referred to as coverglass correction) is typically shown on the objective body and listed for each objective in the Objectives Offered Table below. It may also be possible to adjust the material thickness in order to use a certain objective, e.g., by inverting a microscope slide with mounted coverslip so that a higher magnification objective corrected for 0.17 mm can be used, or by switching to a glass bottom microplate from a plastic bottom microplate.

 

Important Objective Characteristics    
Plan AchromatObjective type corrected for spherical and chromatic (red & blue) aberrations
Plan ApochromatObjective type with highest degree of correction for spherical and chromatic (red, green and blue) aberrations
Plan Semi ApochromatObjective type with spherical and chromatic aberrations close to Plan Apochromats
Numerical Aperture (NA)A measure of the amount of highly diffracted image-forming light rays captured by the objective; objectives with higher NAs produce a more highly resolved image
Working Distance (WD)Distance from the objective front lens to the closest surface of a coverslip when specimen is in sharp focus; in general, WD decreases as magnification and NA both increase
Infinity corrected objectivesFocus at infinity; offer long working distances and allow placement of optical components such as optical lenses or optical filters into the optical path
Field of View (FOV)Area of the specimen captured by the image
ParfocalDistance between the objective mounting plane and the specimen

 

Fluorescence and Brightfield

The objectives optimal for your application depend on your samples, labware and resolution desired. In general, the better the objective, the better the resolution. With regard to fluorescence, high resolution images can be obtained using the Meiji Plan Apochromat objectives. However, the Olympus collared objectives are the most versatile because the cover glass thickness (CGT) correction can be adjusted from 0 mm to 2 mm, allowing imaging through a full range of labware including coverslips, slides, glass and plastic bottom slides, flasks, and Petri dishes.

If you do not see objectives below that meet your needs, inquire at Etaluma. For example, some objectives are available in long working distance (LWD) versions (typically with an increase in price). These may be denoted “TC” for tissue culture, indicating they are appropriate for most labware thicknesses.

Human buccal cells on LS620 using Phase Contrast Accessory and 20x Motic objective
Human buccal cells on LS620 using Phase Contrast Accessory and 20x objective

We do not recommend using very inexpensive objectives because they can auto-fluoresce at lower wavelengths, adding significantly to image background.

Use of Oil Immersion

As with most 100x objectives, our 100x objectives require oil immersion. Microscopy oil increases the numerical aperature (light collection efficiency) by matching the refractive index of the lens and eliminating interfacial losses. Oil immersion objectives work well on LS Microscopes. Because 100x objectives typically have a coverslip correction of 0.17 mm, microscope slides should be inverted so the coverslip is toward the objective.

Phase Contrast

Phase contrast objectives have a phase plate with a ring shaped phase shifter at the rear focal plane. This ring is matched to a ring annulus at the front focal plane of the phase condenser. With Etaluma’s Phase Contrast Accessory, the appropriate annulus (mask) is contained within a slider. The slider also contains an open position (no mask) so that phase objectives can be used for fluorescence and brightfield as well.

 

Objectives Offered by Etaluma for LS Microscopes  
Etaluma Part #MagnificationTypeNA*WD^, mmCover Glass Thickness, mmMFR & Part #
ELL0025MA8302.5xPlan Semi Apochromat0.075.70.17Meiji MA830
ELL0004FPLN44xPlan Achromat0.111.90.17FPLN
ELL000F4MA10124xPlan Apochromat0.1317.20.17Meiji MA1012
ELL000F4MA8494xTC Plan Achromat0.1317.51Meiji MA849
ELL0004B5224xU Plan Fluorite0.1317Olympus UPLFLN4x
ELL0010MA96610xPlan Achromat0.257.30.17Meiji MA966
ELL00F10MA98010xPlan Apochromat0.38.60.17Meiji MA980
ELL00F10MA85010xTC Plan Achromat0.37.51Meiji MA850
ELL0010B52410xU Plan Fluorite0.310Olympus UPLFLN10X2
ELL0020MA83320xPlan Semi Apochromat0.47.290.17Meiji MA833
ELL00F20MA98120xPlan Apochromat0.650.70.17Meiji MA981
ELL00F20MA85120xTC Plan Achromat0.47.51Meiji MA851
ELL0020B52520xLWD U Plan Fl0.52.10.17Olympus UPLFLN20X
ELL0020B375 20x w/c-collarLWD U Plan Fl0.456.4-7.60-2Olympus LUCPLFLN20X
ELL0040MA96840xPlan Achromat0.650.50.17Meiji MA968
ELL00F40MA98240xPlan Apochromat0.80.20.17Meiji MA982
ELL00F40MA85240xTC Plan Achromat0.62.91Meiji MA852
ELL0040B37740x w/c-collarLWD U Plan Fl0.62.7-4.00-2Olympus LUCPLFLN40X
ELL0060MA96960xPlan Achromat0.80.290.17Meiji MA969
ELL0100MA970100xPlan Achromat1.250.14-0 w/oil0.17Meiji MA970
ELL0F100MA983100xPlan Apochromat1.250.20.17Meiji MA983
*NA, numerical aperature;
^WD, working distance
Phase Objectives Offered by Etaluma for LS Microscopes 
Etaluma Part #MagnificationTypeNA*WD^, mmCover Glass Thickness, mmMFR & Part #
ELL0004C522IPC
4xU Plan Fluorite Phase IPC0.13171Olympus UPLFLN4XIPC
ELL0010C144IPC
10xAchromat Phase IPC0.258.81Olympus CACHN10XIPC
ELL0020C145IPC
20xLWD Achromat Phase IPC0.43.21Olympus LCACHN20XIPC
ELL0040C147IPC
40xLWD Achromat Phase IPC0.552.21Olympus LCACHN40XIPC
ELL0010C524PH10xU Plan Fluorite Phase PH0.310Olympus UPLFLN10X2PH
ELL0020C375PH20xLWD U Plan Fluorite Phase PH0.456.4-7.60-2Olympus LUCPLFLN20XPH
ELL0040C377PH40xLWD U Plan Fluorite Phase PH0.62.7-4.00-2Olympus LUCPLFLN40XPH
ELL0060C381PH60xLWD U Plan Fluorite Phase PH0.71.5-2.20.1-1.3Olympus LUCPLFLN60XPH
*NA, numerical aperature
^WD, working distance