Long Working Distance Microscope Objectives are designed around 426 to 656 nm to provide a chromatic aberration-free image with flat field correction. The objectives are called “Plan” because they produce the flat image across the field of view. The “apochromat” objectives provide chromatic correction for three wavelengths and spherical correction for two wavelengths. In the case of white light, plan apochromatic objectives offer superior images for color photomicrography than achromatic objectives can provide.

In general, the focal length and working distance of objective lens varies very little with wavelength and is usually not specified at a particular wavelength. At most, over a specified wavelength range, one could potentially see only microns of deviation, and this amount would be even smaller for apochromatic objectives.

Infinity corrected objectives are used in a wide variety of imaging and laser focusing applications. Light rays leaving the objective’s rear aperture are collimated, so that for imaging applications, a secondary lens (usually called a tube lens) is needed in order to focus the collected light from the specimen onto the sensor. The labeled magnification is calculated, assuming the objective is being used with a tube lens of a particular focal length by design. When a tube lens of a different focal length is used, the magnification will need to be adjusted accordingly. As an advantage over finite conjugate objective lenses, a variety of auxiliary optical components, such as optical filters and polarizers can be inserted between the infinity objective lens and the tube lens without altering how the beam propagates and forms the image down the optical path. In laser applications such as optical tweezers and laser cutting, laser beams entering the rear aperture of an infinity objective can be tightly focused to a diffraction-limited spot, providing concentrated optical power and excellent resolution.

Many times microscope objectives with high magnifications will have very short working distances to the focused spot. Because of this short distance, if one is not careful while focusing in on the targeted specimen, the end of the microscope objective may "crash" into the object under study. These Long Working Distance Objectives are ideal to use when the application requires there be room between the objective and the target for other equipment like pipettes or syringes. These objectives have some of the world's longest working distances.

The thread on the long working distance objectives are M26, so the M26-RMS adapter is required to step down to standard RMS threads.  Please make sure to purchase one for use with any RMS mount such as the LH-OBJ microscope objective holder.