LOMO Microscope Lighter OI-21

The lighter is made at LOMO in 1980. Below is translation of user manual.

1. PURPOSE

Lighter of reflected light OI-21 is purposed to work with biological microscopes "Biolam R", "Biolam S", "Biolam D", MBR, MBI-3, MBI-1. It is used for researching of opaque and semi-transparent objects in usual and polarized light in bright field and dark field.

The lighter is able to work in macroclimatic regions with temperate climate in laboratories at air temperature of +10 to +35 centigrade, or in macroclimatic regions with dry or wet tropical climate in laboratories at air temperature of +10 to +45 centigrade.

2. SPECIFICATIONS

Objectives

Max height of researched object, not more than - 60mm
Light source - lamp RN8-20
Power source of the lamp - 220V 50Hz AC through power adapter 9V 25W.
Dimensions:
   length - 270mm
   width - 70mm
   height - 90mm.
Weight - 0.9kg.

3. DELIVERY SET

4. CONSTRUCTION AND PRINCIPLES OF WORK

4.1. Optical construction

When working in bright field, beams from the light source (1) (see optical diagram) are directed by the collector (2) and the lighting lens (3) to the mirror plate (4) which directs the beams into the objective (5). The beams light researched part of the object through the objective (5) and being reflected back to it. They pass the objective (5), the mirror plate (4), and achromatic lens (6), and form an image in the focal plane of the eyepiece (7). Scatter diaphragm (8) limits the object field down to the eyepiece field of view.

To research objects in dark field, it is necessary to include special dark field diaphragm (9). In this case, light beams form a light collar on the mirror (10). To achieve best results for dark field research, it is necessary to remove the mirror plate (4) from the optical path. After reflection from the mirror (10), the beams get to inner surface of the epiobjective parabolic mirror and being focused on the researched object. It is possible to put an interchangeable light filter (11) right after collector and scatter diaphragm.

To research objects in polarized light, it is necessary to include the polarizer (12) and analyzer (13) into optical path.

4.2. Mechanical construction

The lighter consists of the lamp unit (14) and housing with optical system assembled in it. There is a lamp socket (15) and the lamp in the lamp unit. The lamp is powered by 9V 25W through adapter plugged into wall outlet 220V 50Hz. The lamp is plugged to the power adapter by means of the plug (16). The lamp can be centered by means of two thumbscrews (17). To adjust the lamp in lengthwise direction, you can slide the lamp socket inside the lamp unit. The lamp unit can be removed together with the lamp and collector by unscrewing the ring (18). The lever (19) adjusts aperture of the field diaphragm. Two slots in the lighter housing allows to insert a filter and polarizer. Dark field diaphragm is installed into the slide rails (20).

Handle (21) allows to include or remove the mirror plate (4) used to work in bright field from optical path. An objective is screwed into the bottom threaded mount of the lighter. Analyzer is put into its place in the top part of the lighter.

5. MARKING

Two first digits of the serial number means last two digits of the year of manufacturing.

6. SAFETY MEASURES

Possible danger of using the OI-21 lighter is electric shock. Construction of the lighter and power adapter excludes possibility of accident contact with alive nonisolated parts. Housing of the power adapter provides a ground terminal. Ground the power adapter before plugging it into wall outlet. Keep the lighter unplugged from the wall outlet during lamp replacement or lamp socket installation.

7. INSTALLATION

The lighter OI-21 should be installed onto a microscope with removed objective turret and eyepiece tube as pictured on the general view. Use the thumbscrew to secure it. Install the eyepiece tube into the top part of the lighter.

8. OPERATION

To work in bright field, install 7x eyepiece into the tube, screw 9x0.20 objective into bottom part of the lighter, insert the plug (16) into the power adapter. Switch the lamp on. Place an object onto microscope stage.

If the object is not high, place it onto metal plate from the lighter delivery set. The plate should be placed onto the microscope stage. Open the field diaphragm fully be means of the lever (19), set the slide rails (20) into position "C" and focus the microscope to get a clear image of the object. replace the 7x eyepiece with the scatter diaphragm and, looking through it, adjust the lamp lengthwise to achieve sharp image of the filament in the output pupil of the objective. Center the image by means of the thumbscrews (17). Replace the scatter diaphragm by the eyepiece again, close the field diaphragm down to size of the field of view, and do you research.

To work in dark field, set the lighter as for bright field first. Then, remove the mirror plate (4) from optical path by means of the handle (21), set the slide rails (20) into "T" position, open the field diaphragm fully by means of the lever (19), and research the object.

To work in polarized light, setup the lighter as for bright field. Insert the polarizer into one of the housing slots, remove the eyepiece tube, place the analyzer into its place in the top part of the lighter, put the eyepiece tube back, and do research.

If exposure for photographing with the lighter it too high, use a lamp OP-12-100 in the lamp unit of the lighter OI-24.

To do this, remove the lamp unit (14) and attach a lighter OI-24 (not included into the delivery set). To protect eyes from a bright light in this case, it is recommended to place the cone from the delivery set between the lamp and lighter housing. The cone should be installed into the housing with its narrow end.