A tour around the 'Micro-Microscope' Model MM02

A field / compact model  with medium to high magnification
originally designed for Indian students.


 
by David Walker, UK

 

The Micro-Microscope Model MM02 made by Micro Instruments (Howrah, West Bengal) was recently drawn to Micscape's attention (see Acknowledgements). The original design brief was intriguing; see the two The Times of India article links below for the background to its design and inventor's details. A cheap locally made usable microscope was required for Indian students who may not have access to expensive compound microscopes.

The microscope is being made more widely available as a compact / field microscope. As standard it offers 100x and 450x magnification with built in variable LED lighting and standard WF 10x eyepiece. Below is a 'tour' of the microscope and how it performs.

 

The outfit includes eyepiece tube, microscope base, eyepiece (10x WF standard option), instructions and warranty card. (Also a 9V battery if locally purchased).


 

When dismantled the microscope is very compact and could readily be put in the pocket in a plastic bag to keep dust and dirt off for field use. With battery it weighs less than 250g.

A sturdy plastic box forms the base. The metal eyepiece tube takes standard size eyepieces which screws onto a rigid metal plate supported on two metal pillars. Two spring clips securely hold microscope slides.
Base size ca. 9 x 7 x 2.5cm. Total height 15.7 cm

The rotary knob nearest camera is a switch and intensity control for the lamp. A red LED shows when it's on. The rear knob is the focus.

Optics

The two objectives are an interesting design and described on the maker's box; 'Completely new and very special objectives have been used. Patent (Pending) technology'. They are mounted on a stiff springy plate 'P' which is securely fixed at mount 'M'. A black stub 'S' extends down a hole into the base which is the focus mechanism. The optics swing in a small arc relative to the eyepiece, but the author couldn't see any deleterious affects in viewing and focussing. See next section for how the focus works.


Detail of focus plate and objective support.
A spring stage clip is removed for clarity.

The 10x objective is housed in the small black casing which has a thin glass plate as dust cover. The 45x mag is achieved by swinging in the small element, a black stop aligns it optically. The bottom element by inspection appears to be a single element plano-convex lens. The side view shows the typical working distance of the focussed 10x objective. This decreases when the 45x objective is swung in and focussed.

With the standard 10x WF eyepiece supplied useful mags of 100x and 450x are available. A 15x is available but don't think a higher mag eyepiece is justified. A 5x eyepiece option offered would give 50x and 225x which may be better for suitable subjects and for younger students as less demanding slide manipulation.

The 10x gives a field of view of ca. 1.1 mm and the 45x ca. 0.22 mm. Test slides aren't really appropriate for a microscope with its original design brief. In practical use with real subjects such as insect parts and plant / histology sections, the images are competent to the edges, contrasty and look flat. The 10x does show increasing chromatic aberration towards field edge. The lamp is plenty bright enough for the 450x.

Detail of 10x objective and auxiliary optic for 45x from above and below.
Right, side view of focussed 10x.

Inside the box - focus and lighting


Underside with internal case exposed.

The battery compartment is accessible via two screws and takes a standard PP9 (UK code) 9V battery. For this 'tour' the glued lefthand compartment was exposed to show the construction but shouldn't need acccessing as LED's usually have a very long life. Note that the screw holes are brass bushed to give long term secure fittings.

The LED seen centre is firmly held in a metal bush immediately below a small aperture in the plastic box top i.e. there's no condenser. A potentiometer with dropping resistors supplies power to the LED.

The focus is a very simple but effective design. The focus knob turns a fine pitched brass screw whose end acts on a vertical black rod (actually a screw) with a half flat to accept it.  This neatly translates horizontal travel to the vertical focus because the black rod is attached to the spring clip on which the lenses are mounted (see above).

In use

The component parts are simply engineered for ease of manufacture and to keep cost down but work together to give a cleverly designed and pleasing little scope. It can be used in the hand or on a bench and feels stable. I had a lot of fun with it and would imagine students without normal access to microscopes would be thrilled with this tool for exploring the microscopic world. Coupled with the even bright white light that the LED offers, as the typical images below show, the optics are of sufficient quality to show what is needed for most biology courses e.g. in botany and histology. As well as revealing many aspects of live organisms in temporary mounts e.g. in pond water. I particularly liked the standard slide layout so slide manipulation is intuitive e.g. for students, compared with the more awkward inverted slide requirement for some field microscopes.

The focus works well and feels tight. The swing-in element is probably best left in when not in use to keep clean. A simple optics cleaning method is given on the maker's website. The website also gives one suggestion for photomicrography with a 35 mm SLR body but the standard eyepieces should allow other possibilities for imaging e.g. with a suitable low cost digicam (or mobile phone camera?) that could fit or be held against the eyepiece.

I believe that the Micro Microscope is being offered as a portable / field microscope for a wider market. The reviewer isn't familiar with all available alternatives and pricing; the only model in production that I'm aware of that can offer similar mags in the field is the very expensive Swift FM-31. For potential users requiring such mags in the field at lower cost and not requiring the optical quality of advanced field or compound microscopes, the Micro-Microscope could be of interest. The retail price is $75 (source NG Global).

 

 The images below were taken with a Moticam 1000 with its relay lens above the supplied eyepiece.
See links below for examples using a 35mm SLR on the Micro Instruments website.

 
Fly wing detail, prepared slide.
LOMO 7x eyepiece, 10x objective.


Mexican orange, T/S stained leaf, Biosil slide.
Baker 5x eyepiece, 10x objective.

 
Rat colon, iron haematoxylin and eosin stain,
NBS slide. 10x eyepiece, 10x objective.


Rat colon, iron haematoxylin and eosin stain,
NBS slide. 10x eyepiece, 45x objective. 

 
Draparnaldia algae, preserved fluid mount, NBS slide.
10x eyepiece, 10x objective.


Live daphnia, Baker 5x eyepiece, 10x objective.

 
Live daphnia, tail detail, Baker 5x eyepiece, 10x objective. 

The waterflea was mounted in a 0.4mm ring cell slide; there is enough room to focus and move such slides with the 10x objective thus pond life life studies of some larger invertebrates are doable.

 

Comments to the author David Walker are welcomed.

Acknowledgement: The author would like to thank Bikash Ghosh of NG Global, Texas, USA for drawing this interesting microscope to our attention and for sending a review example which will be duly donated to a good cause locally.

Links:
'The Times of India' articles.
(Note that articles may not be referring to this exact model.)
'Tiny microscope at microscopic price'. June 2002.

'CM bowled over by mini-microscope, praises inventor'.  September 2003.


Maker's Micro Instruments website links:
Please note: There is javascript on the maker's 'Home' page which gives a (hopefully) false positive with some virus checking software and which may prevent access. The web site owner assures me it is benign script but visitors may wish to avoid clicking the 'Home' button. Other pages on the website don't have this script and direct links are given below.
Product details.
Example images from 35 mm SLR camera.
Maker's and stockist contact details.

  

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