Cleaning and Caring for the 40x Objective on your microscope.

The 40x :
Microscope Objective - Troubleshooting Poor Image Quality

 

1. 
   This seems simple, but it happens more often than one would imagine. Make sure the specimen slide has the cover slip side UP. If you have the specimen facing down, the working distance will not be enough to focus THROUGH the glass slide to the specimen UNDERNEATH. The typical working distance of a 40x Objective is 0.65mm on an Achromat objective Your typical class A slide is 1-1.2mm thick. 
2. 
   Make sure you are using the proper  sized cover slip. 0.17mm thick is recommended for optimal specimen viewing.
3. 
   Make sure your condenser is in the correct position. The condenser should be in the uppermost position so that your light is condensed into a point on the focal plane of the specimen.
4. 
   Make Sure your 40x:
   Microscope Objective is clean. You can use a magnifying glass to inspect the front of your 40x lens. You can remove your objective by unscrewing it from the nose piece. Examine the front of the objective under a good light source with your magnifying glass. Never go through the back of the objective, or inside the objective. If the lens appears to be scratched, you should call a
   Microscope technician for  possible repair or replacement. In the event of dirt or oil you will want to gently clean the lens using a cotton Q tip. Use a solution of warm soapy water to dip the cotton Q Tip into, then work the Q tip back and forth between your fingers as it makes contact with the lens. This will  temporarily clean your lens of  dirt. You will want to use air in a can as the second step of the cleaning procedure. You will most likely need to repeat these steps multiple times.  In the event that you have oil on your 40x lens from cross contamination with the 100x Oil objective (which happens frequently) you will need to use petroleum benzene to wipe off immersion oil using a cotton Q tip applicator as before. For optimal results, you should follow up with a cleaning using methyl alcohol using another cotton q tip applicator. Use both Petroleum Benzine and Methyl Alcohol sparingly, as the lens of your objective is held in place with a form of rubberized cement. This cement can fail over time if it is over saturated with cleaning solutions. 

 

If the above steps do not improve the quality of your vision through the 40x, you should call your micrsocope service and repair company. Google Keywork "Microscope Repair"  and narrow it down by the major city near you.

       



 

Koehler Lighting in Microscopes - What is it and is it necessary?

Q: What is Koehler Illumination? I keep hearing this term in the reference to compound microscopes.

A: Most modern compound microscopes prior to 2011 use halogen or tungsten lamps as a source of illumination in the base of the microscope. That lamp contains a tiny wire inside used to complete the electrical circuit and illuminate the lamp. That wire is referred to as a "filament". That thin wire can sometimes be seen when you look through your microscope.
Microscopes that use LED illumination do not need Koehler illumination as there is no filament in the light source. An example of this is the Nikon 55i Microscope

Koehler Illumination is a way to solve that problem by evenly distributing the light throughout the field of view. This is done by focusing and centering the filament in the back of the objective focal plane and the front of the condenser focal plane. By keeping the filament focused at the meeting of those two planes, the fllament becomes "defocused" in the plane of the image specimen.

Most high quality microscopes like Nikon come with precentered lamps as in the Nikon E 200, thus making Koehler illumination unnecessary. The use of a field diaphragm in the Olympus allows for Koehler illumination.

Numerical Aperture - N.A.

In microscopy Numerical Aperture measures the ability of an objective to gather light. The higher the numerical aperture (NA), the more light can be collected by the lens in the microscope objective. This results in a better resolution and a higher intensity image. A high numerical aperture also allows for greater field of depth and a better overall image.

Numerical Aperture in a high quality 100x Oil Objective is typicaly 1.25.


In Fluorite's that number rises to 1.30.


In Apochromat Objectives the numberical aperture is 1.40

However, don't be fooled. Just because the numerical aperture of a given microscope objective is 1.40, that does not mean it is the same quality as a high quality objective like Nikon or Olympus.

Nikon objectives are some of the highest quality objectives that you will find in the world. Their CFI60 objectives use a 200mm tube length and a wider body (25mm thread pattern) to achieve high numerical apertures and longer working distances. (*The working distance is the distance between the tip of the objective and the specimen.)

Micrometers and Reticles for the Microscope

In microscopy, micrometers (also refered to as reticles) are used to measure and or count specimens or portions of specimens. A straight line reticle is used to measure the length of a specimen under observation with microscope. There are two types of micrometers for straight line measurements. The most common type, and preferred type is an eyepiece reticle. The less common type is a stage micrometer. To overstate the obvious, the eyepiece reticle is installed in the eyepiece, where as the stage micrometer lays on the stage and is manipulated by hand.

The eyepiece reticle is made from glass and has minute etchings used for measurements. The most common straightline reticle is 10mm in 100 divisions ( No. 0 thru 10 ) which is common in clincal laboratories.

Eyepiece micrometers can also be used to count portions of specimens within specimens. Take for instance the Howard Counting Reticle used in food processing (typically tomato paste and fruit juices). The pattern on the Howard Counting Reticle is a 13.82 diameter circle encompassing an evenly distributed network of squares in a grid pattern. As the specimen is viewed under the 10x objective, a count of mold fibers takes place for each square in the grid. If the number exceeds recommended amounts as set by the USDA, a secondary check using the 20x objective is used to confirm the existence of mold in the process.

Other counting reticles and micrometers such as the Miller Disc or Walton Beckett micrometer are available from most microscope dealers.

* How to determine the size of the eyepiece micrometer you need.

1)If you are sure that the eyepieces that you have on your microscope are the original ones, you can look at your owner's manual which will give you the size of the micrometer/reticle shelf. This number is typically between 18mm and 29mm, but not always.

2)If you do not have the instruction booklet or the original eyepieces have been changed out, you will need to take an accurate measurement.

3)High quality micrometers are custom cut, so your measurement should be exact. In order to measure, you need to remove one of the eyepieces and flip it upside down. (taking special care not to get the eyepiece lens dirty). I use a caliper to measure the inside diameter of the eyepiece. This is where the micrometer enters the eyepiece. You also need to determine if the bottom of the eyepiece srews off at this point. If the bottom of the eyepiece screws off, it usually means that they reticle will sit on a reticle shelf and be held in place by the plastic part of the eyepiece when it is screwed back in.


If the bottom of the eyepiece does not screw off, it will be necessary to order a retaining clip with your micrometer in order to lock it into place. Clips are relatively cheap costing less than $3.00 in most cases.

So, for a microscope like a Nikon Eclipse 200, the reticle/micrometer size is 27mm which is the inside diameter of the bottom of the invoice. Do not be confused by the field number printed on the side of the eyepiece. This is the field number, not the measurement of the inside diameter of the eyepiece. You will NOT find the micrometer size printed on the eyepiece

There is a company that allows you to send your existing eyepiece to them for sizing and installation of micrometers. This is nice becuase they make sure the reticle is clean, right side up, and seated properly when installed. Installing a micrometer sounds simple, but it can be a really excercise in patience, when trying to keep it clean and get the numbers facing right side up.

Reticles

Veterinary Microscope - Best in Class?

Veterinary Microscope of the Year....and the winner is....

The Labomed LX400 is a surprisingly popular choice amongst veterinary clinics due to its affordable pricing and high quality features geared towards veterinarians. The Labomed uses infinity objectives, which allows it to be fully upgradeable.

The durable stand and construction make it a favorable choice for high volume multi user labs. It's ergonomic design makes for comfortable, stable specimen viewing. The rackless stage allows for precision manipulation of the specimen through the field of view. To be blunt, it's one of the more sturdy microscopes currently available in the clinical microscopy market.

While most laboratory level microscopes on the market meet the basic qualifications of veterinary technicians for fecal analysis, urinalysis, and differential counts, the Labomed has additional features that make it stand out above some of the other microscopes in its class such as the Nikon E 200 and Olympus CX 31.

BENEFITS:

1) LED Illumination Source:

The Labomed LX 400 employs a variable Light Emitting Diode (LED) illumination system. The light output of the LED light source is a bright, crisp, white light which remains even across the entire field of view. This removes the need for blue filters for color compensation as employed by the standard halogen illumination systems on other microscopes. The LED illumination is much softer on the users eyes when looking through the microscope. This is because LED illumination does not emit any UV lighting. The energy efficient LED lamp light cluster lasts for 100,000 hours as opposed to the standard 2,000 hours of halogen lamp life. Overall, it's a greener environmentally friendly choice than a halogen microscope, while producing a higher quality of light.
The LED illumination system also produces far less heat than the halogen alternative.
Input voltage is universal which makes it ideal for use in countries with different voltage standards.

2) Plan Objectives:

The Labomed LX 400 comes standard with PLAN anti fungal objectives. 4x, 10x, 40x, and 100x Oil objectives sit parfocally in the reverse facing quadruple nosepiece and provide amazing clarity and picture throughout the entire field of view. The 40x and 100x oil objectives both have retractable tips to prevent specimen damage. The lens coatings have been engineered to correct for chromatic aberration. The quality of these objectives is similar to that of Nikon and Olympus and there is no decrease in image quality as the viewpoint approaches the outer edges.

3) Wide field of View:

The Labomed Lx 400 has a number 20 field of view which allows for a wider scan of the specimen as compared with the Nikon E 100 or the Olympus CX 21 which have an 18mm field number. This is helpful when doing differential cell counts using the 40x and 100x objectives. A wider field makes for more efficient work.

4) Cordless Rechargeable:

A big BONUS FEATURE on the Labomed Lx 400 for Veterinarians and Breeders is the fact that it is rechargeable and cordless. You can use this microscope in the field without a power source for up to 4 hours. This is convenient for trips to ranches, farms, and other facilities where power may not be available. It's a popular option for mobile vets. There is also a handsome carrying case available for the Lx 400 as well.

5) Pricing:

The list price for the Labomed Lx 400 is $1,040.00 and can be found on the internet at discounted prices from Labomed authorized dealers. Compared with the Nikon E 200 MSRP of $1,966.00 and the Olympus CX 31 MSRP $2,022.00, you can see that the bang for your buck is substantial. Upgrades and options include digital image capturing for case documentation and internet collaboration, teaching heads for veterinary schools, and even a fluorescent attachment for labs who want to keep their future options open with regards to microbiological specimen evaluation are available for an additional price.

So, if there were an award for Veterinary Microscope of the year, you can see why I would give it to the Labomed LX 400 Binocular LED microscope

* As with all equipment purchases, shop around to find the best price from an AUTHORIZED reputable dealer who not only offers the standard LABOMED factory warranty but also backs the microscope through their own service center.

Labomed is based in California and you can learn more about that company at the following link: Labomed Microscopes

SEO Enterprises Inc is an Authorized Labomed dealer out of Florida who stocks the LX 400 Binocular Microscope. You can visit their website at the following link: Microscope

Optical Abberations in Microscopy with regards to Objectives.

What is an aberration?

In microscopy we often hear that engineering has been used to correct for "aberrations". To understand this, we must first understand what an aberration is as it relates to optics.

An optical aberration is any disturbance of the rays of a pencil of light such that they can no longer be brought to a sharp focus or form a clear image at the tip of that cone shaped pencil of light. The finer the tip of the cone or pencil, the clearer and sharper the image.

ACHROMAT OBJECTIVES have best optical performance in the center of the view field, and correct effectively for many kinds of aberrations. C (red) and F (blue) chromatic aberrations are removed. As the image approaches the outer diameter the field becomes less flat and the image becomes less than perfect. Achromat objectives are low quality and are typically used by primary schools, where image quality comes second to teaching students how to use microscopes for the first time.

PLAN OBJECTIVES produce flat, sharp images throughout the filed of view from center to edges. Plan objectives are acceptable for clinical use in high quality brands like Nikon and Olympus.

InAPOCHROMAT OBJECTIVES not only C (red) and F (blue) chromatic aberrations, but also G (violet) aberrations are corrected in these objectives to cover the full spectrum of visible light. These top-of-the-line lenses combine a large numerical aperture and ideal correction of aberrations all the way to the edges of the field view.

FLUORITE OBJECTIVES can be used for brightfield, Nomarski DIC, or epi-fluorescence microscopy. These lenses have a particularly high ultraviolet transmittance rate and low autofluorescence, enabling high contrast fluorescence images to be obtained.

Many different engineering methods are used to correct for aberrations of light all across the visible spectrum. In microscopy, depending on how much money you're willing to spend and how precise of an image you need to get in most cases there's an objective available to you that will get the job done. Optical leaders like NIKON, OLYMPUS, and LEICA have put in many years or research and development to be at the forefront of microscopy optics.

Microscope Objectives

10 Steps to Using your Microscope in the Lab

10 Steps for Lab Microscope Personel

These ten steps allow for lab technicians to achieve the perfect image each time.


1) Turn the power to your microscope
on so that the lamp illuminates.
2) Raise the condenser to the uppermost position
3) Open the field diaphragm and aperture diaphragm.
4) Move the 10x objective into the optical path.
5) Move your stage to bring your prepared specimen into view.
6) Focus the specimen so that you have a clear picture.
7) Adjust the eyepiece diopters and the interpupillary distance to fit your face.

8) Focus and center the condenser
9) Switch to the desired objective and view the specimen.
* Adjust the field diaphragm and aperture diaphragm each time you change objectives
10) Turn off the power after completing the observation.