The multiple objectives with parcentered optics allow users to quickly switch between lenses and magnifications to obtain just the right view. This facilitates efficient and intuitive workflows.

The set of 3 objective lenses on most compound microscopes elegantly fulfills the range of observational needs in microscopy, from scanning the big picture to examining the most minute details. Their differing optical properties and fields of view provide efficient and flexible viewing capabilities not possible with a single objective lens. The specific numbers and powers may be tailored for particular applications, but the core triad arrangement remains ubiquitous out of logical necessity.

A question commonly asked about compound microscopes is: What’s the purpose of having 3 objective lenses attached to it? The answer is quite simple.

Fischer, C., and I. Kakoulli. "Multispectral and hyperspectral imaging technologies in conservation: current research and potential applications," Reviews in Conservation 7 (2006): 3-16.

Image

Types ofmicroscopeobjectives

Phase contrast and fluorescence microscopy require specialized objectives with matched condenser optics to image transparent specimens. These are often incorporated as a fourth objective or replace one of the standard ones.

The provision of 3 objective lenses with differing optical properties confers important complementary advantages that enhance the microscopy user experience and workflow efficiency.

Objectivelensmicroscopefunction

With the availability of low cost hyperspectral cameras, hyperspectral imaging is starting to be used as a nondestructive technique that can help with material identification in cultural heritage objects. The complex 3D datasets that are generated through hyperspectral imaging are similar in form, if not in content, to the astrophysical datasets studied at SAO.

The lowest magnification objective is typically a 4x or 10x lens. Its primary purpose is to provide a wide field of view of the overall specimen on the slide for initial orientation and scanning. The low magnification reduces aberrations from optical imperfections.

Microscopeparts

Image

While the basic 3 objective arrangement still dominates today, some microscopes incorporate additional objectives or special enhancements for increased performance and capabilities.

The same camera, lighting and filters can be used for multispectral imaging. MCI will need to incorporate additional steps for the proper acquisition and calibration of images and a software solution for visualization and analysis.

Ricciardi, P., J.K. Delaney, M. Facini, and L. Glinsman. 2013. "Use of Imaging Spectroscopy and in situ analytical methods for the characterization of the materials and techniques of 15th century illuminated manuscripts." Journal of the American Institute for Conservation 52(1): 13-29.

Multiband, multispectral and hyperspectral imaging can carry a range of definitions depending on the project and application. These techniques presented on this website are defined here, along with reflectance imaging spectroscopy, to clarify the differences between them. Multispectral and hyperspectral imaging are both types of reflectance imaging spectroscopy, which Ricciardi et al. (2013, 13) define as the "collection of images at many different wavelengths to obtain reflectance spectra over a large spatial area." Reflectance refers to the light reflected or scattered by a material relative to the incident light, and reflectance spectra is a curve illustrating the amount of reflectance at each wavelength over a defined spectral range (Fischer and Kakoulli 2006). Ricciardi et al. (2013) define multispectral imaging in the context of reflectance imaging spectroscopy as the acquisition of calibrated images with bandwidths of tens to hundreds of nanometers and hyperspectral as the collection of images with bandwidths of a few nanometers or less. Multiband imaging is similar to these techniques, however it refers to the acquisition of uncalibrated images with bandwidths of 100's nm that are captured using a modified digital SLR camera and bandpass filters. Similar to hyperspectral and multispectral imaging, multiband imaging captures characteristic spectral information about objects, however the uncalibrated image sets cannot produce reflectance spectra.

You may use these html tags and attributes:

Aalderink, B.J., Klein, M.E., Padoan, R., Bruin G., & Steemers, T.A.G. (May 2009). Clearing the Image: A Quantitative Analysis of Historical Documents Using Hyperspectral Measurements. Poster presented at the Book and Paper Group of the AIC 37th Annual Meeting, Los Angeles, CA.

The compound light microscope is an indispensable tool used ubiquitously in science disciplines to visualize small objects in fine detail. Unlike simple magnifying glasses, the compound microscope uses two lens systems to enlarge specimens up to 1000x their actual size.

The 40x or 100x high power objective produces the highest magnification and resolution to reveal subcellular structures and other intricate details not discernable with the lower powered lenses but has an extremely narrow field of view. It is used for critical inspection of key areas after initial surveys with lower-powered objectives.

What arethe3objectivelenseson a microscope

Some microscopes include extra low power 1x or 2x objectives for an even wider field of view to help orient the largest samples. These have become more common on inverted microscopes.

High-performance objectives may have adjustable correction collars to optimize the optical correction for viewing specimen slides with different coverslip thicknesses, allowing the best possible image.

Lenses with lower power and larger fields of view can have optics optimized for brightness whereas high magnification lenses with narrow fields are optimized for resolution at the expense of brightness.

Practically, low magnification facilitates efficient scanning of the overall specimen to find areas of interest to study further, saving significant time compared to searching blindly at high power. It provides necessary contextual orientation.

The 10x or 20x medium power objective delivers comfortable viewing magnification and reasonably high resolution to see some finer details in the context of the larger specimen structure. It is commonly used for routine examination, counting cells, measuring proportions, and making sketches.

For multiband imaging, we use a modified DSLR. Most DSLRs have IR-cut filters on the sensors that increase the quality of the visible light image by blocking any infrared radiation from the sensor. The modification of the camera we use included the removal of the IR-cut filter and the color filter array (CFA) allowing the camera to have a maximum sensitive of around 330nm to 1200nm and to acquire monochrome images.¹ The spatial resolution of this camera, 5616 x 3744 pixels, allows an entire object to be captured at a fairly high resolution in a single image. Generally the camera is mounted on a studio stand and the filters are changed manually, without changing the focus or position of the camera. Movement of the camera or focus while changing the filters manually could affect the alignment of the images. A filter wheel could be useful to avoid these small shifts, however this increases setup costs and manual changing has been adequate so far. Nine filters are used, producing nine monochrome images for each filter. The transmission curve for the filters can be seen below.

Each monochrome image records the interaction of light (reflection and absorption) with the material of the textile and pigment at the specific bandwidth of the filter. The variation of the interaction of the light with the different bandwidths can reveal and distinguish materials. Image subtraction with image processing software such as Adobe Photoshop or ImageJ can be used to process images to better reveal some of the pigments used. Image subtraction is a simple, powerful process that can be applied for visualizing the difference or changes between two images (Jain 1986). The pixel values of two images are subtracted resulting in an image that reveals the differences between the pixel values of two images.

Image

Where is the objective on a microscopediagram

The standard compound microscope contains 3 objective lenses with different powers, resolutions, and fields of view to provide a tiered viewing experience.

Low powerobjective microscopefunction

The level of microscope magnification depends on the optical properties of both the ocular and objective lenses. The ocular lens magnifies the primary image 10x. The objectives provide progressively higher magnifying power of 4x, 10x, 40x, and sometimes 100x.

The range of magnifications enables users to choose the appropriate level for their particular application, whether surveying tissue architecture or examining subcellular organelles. No single objective lens can provide optimal performance across this wide range of viewing needs.

What doesthestage doon a microscope

Higher magnification requires higher resolution to realize the full benefit. The higher-powered objectives have correspondingly greater resolving power to take advantage of the increased magnification whereas the lower-power lenses have comparatively less resolution which is ample for their magnification level.

Warda, Jeffrey, Franziska Frey, Dawn Heller, Dan Kushel, Timothy Vitale, and Gawain Weaver. The AIC Guide to Digital Photography and Conservation Documentation. 2nd ed. Washington: American Institute for Conservation of Historic and Artistic Works, 2011. Print.

The standard compound light microscope has 3 objective lenses to provide different magnification powers, resolving abilities, and fields of view to visualize specimens in increasing detail.

Proper illumination from below is vital for viewing clarity. The maximum resolution or resolving power is limited by the wavelength of light and optics. Higher quality objectives provide greater usable resolution to see fine details.

Having a continuum of magnifications allows the microscope to accommodate samples of vastly different sizes from whole insect bodies down to single cells. A single high-power objective cannot cover this entire range.

Certain instruments are designed to accommodate additional high-power 60x or 100x objective lenses when extremely high magnification and resolution are critical, such as for cytology or microbiology applications.

Dyer, Joanne, Giovanni Verri, and John Cupitt. "Multispectral Imaging in Reflectance and Photo-induced Luminescence Modes: A User Manual.". The British Museum. The British Musem, Oct. 2013. Web. 25 June 2014.

The major components of a compound microscope are the ocular lens in the eyepiece, the objective turret housing multiple objective lenses, the condenser lens below the stage, the illumination system, and the mechanical arm. Each part plays a critical optical or functional role.

Whatis objectivelens inmicroscope

Ricciardi, P., J.K. Delaney, L. Glinsman, M. Thoury, M. Facini, and E.R. de la Rie. 2009. "Use of visible and infrared reflectance and luminescence imaging spectroscopy to study illuminated manuscripts: pigment identification and visualization of underdrawings." Proceedings of O3A: Optics for Arts, Architecture, and Archaeology II: 7391(July 2, 2009): 739106-1-12.

As stated above, hyperspectral imaging is a reflectance imaging spectroscopy technique that involves collecting images with bandwiths of a few nanometers or less. The system used at MCI utilizes a CCD censor and has a spectral sensitivity from 400-1000nm. The camera acquires 128 images between 400nm to 1000nm creating a data cube that can provide reflectance spectra for pixels or areas of interest, as well as images of the area analyzed at a particular wavelength. The reflectance spectra helps researchers, conservators and scientist with material identification.

The Smithsonian Astrophysical Observatory (SAO) and MCI received a 2013 Smithsonian Grand Challenge Level One Grant from the Consortium for Unlocking the Mysteries of the Universe to fund Adapting SAOImage DS9 for General Purpose Hyperspectral Imaging. Members of SAO have developed extensive expertise in the visualization and analysis of complex astrophysical datasets. SAOImage DS9 is a software application developed at SAO specifically for this task and is widely used world wide by the astrophysical community. In particular, SAOImage DS9 has enhanced support for the visualization of large complex 3D datasets without the need for advanced or specialized computer hardware.

Delaney, J. K., E. Walmsley, B. H. Berrie, and C.F. Fletcher. 2005. Multispectral Imaging of Paintings in the Infrared to Detect and Map Blue Pigments. Proceedings of the National Academy of Sciences Scientific Examination of Art: Modern Techniques in Conservation and Analysis Washington, DC March 2003, 120-136.

To fully exploit the information obtained by the hyperspectral imaging camera at MCI requires a sophisticated visualization and analysis software package. The work between SAO and MCI involves investigating the possibility of adapting SAOImage DS9 to support general purpose hyperspectral visualization and analysis. Bill Joye (SAO developer) and E. Keats Webb are working closely to determine the requirements for visualization and analysis, to identify which of these functions already exist within SAOImage DS9, and to determine the effort required to provide MCI (and others with similar needs) the full functionality that is required.