At the start of Voyager's time in the Delta Quadrant, the medical tricorder is the same model utilised in the late 2360s aboard, say, Galaxy-class starships such as USS Enterprise NCC-1701-D, namely the medical tricorder version of the Mark VII tricorder. These were introduced in 2366 (i>(they were introduced in Season 3 of [Star Trek: The Next Generation]. This model of medical tricorder in fact consists of the standard tricorder model TR-580 mark VII to which is added a specialised medical peripheral (MP) device. This peripheral, one of a number of dedicated auxiliary computing options available to Starfleet crews, adds many powerful sensor and analysis functions to those used by sickbay personnel aboard the ship. The MP comprises two components, the computing section and separate deployable high-resolution sensor. The latter is stored slotted into the computing section until needed. When deployed it is usually held in one hand by the user and moved in front of the relevant part of the person to be scanned, while at the same time the main unit provides a detailed analytical read-out.

The Doctor uses a medical tricorder - it is a standard tricorder model TR-580 mark VII with added medical periphery (MP) at its top end. In the first screenshot the separate deployable sensor can be seen stored in the top. By the second screenshot the Doctor has removed it. [Caretaker]

The MP works with the standard tricorder user interface to access all the normal and added functions, in both shipboard and field operations. It measures 8.5 x 3.0 x 3.0 cm and masses 80 grammes, bringing the total tricorder length to 15 cm, and mass to 430 grammes. As with the standard tricorder, the case is constructed of micromilled duranium foam. The major components include an auxiliary sarium krellide power cell, sensor assemblies, peripheral processing block, and memory storage units. Power is not tapped from the main supply in the standard tricorder unless required, and cells in both sections can be recharged through the standard tricorder induction circuit. Total operation time is eighteen hours. The peripheral sensors encompass 86 electromagnetic devices mounted about the internal frame, upper and side panels of the casing, and the forward section of the hand sensor receptacle. Each maintains an FOV lower limit of ¼°. None are omnidirectional, but specialised for focused medical readings. The separate deployable hand sensor incorporates fifteen high-resolution devices for readings down to thirty seconds of arc. Active and passive scans provide detailed diagnostic readings of total body mechanical processes, organ system function, disease organism infiltration, and body electromagnetic conditions. Combined readings can synthesise images and numerical readouts to aid sickbay personnel in identifying biological antagonists and determining courses of treatment. The MP computer capabilities are contained in the medical database comparator/analysis subsection (MDC/AS) attached to 101 sensors. The MDC/AS manages incoming data, prioritises processing tasks, routes processed data, and manages control and power systems. It is rated at 1.5 x 10 calculations per second. In the field the database section draws upon an updatable file of known medical conditions for most humanoid types and 217 DNA-based non-humanoids. When operating aboard ship, the MP can draw upon the entire medical database of USS Voyager as well as the files allocated to other disciplines. A wide selection of tomographic* and micrographic scans are included in the default device settings. The function controls of the standard tricorder may be used to configure custom scan modes for the case-mounted and hand sensors, with menu choices visible on the main display screen.

A side-by-side comparison of the Mark VII general tricorder used on [TNG] and the medical tricorder used on [TNG] and Season 1 of [Star Trek: Voyager].. The medical tricorder shown retains a version of the separate scanner originally found in the first Mark VIs. The Mark VI was never seen in [Star Trek: Voyager]. Above: On the left are the models of the Mark VII gneral tricorder. The top one is a "stunt" or "breakway" model. This is just a light and inexpensive plastic shell for use in the background of a scene or to be worn by actors and stunt people in active situation where there is a chance it might be damaged. The shell does not open, has no electronic parts and its finishing details consist of simple stickers. The one below is the working model which contains lights and LEDs. On the right is the view of the top of the medical tricorder with scanner in place. Above: View of the top of the medical tricorder with the scanner removed from its storage slot.

above 4 screenshots: [#17 Projections]

Kim hands the Doctor a medical tricorder
[#17 Projections] being a flashback to events in [#1 and #2 Caretaker]

Voyager's crew have an upgrade of the standard tricorder, the TR-590 mark X. During the journey home the medical tricorder is upgraded and the upgrade is, by appearance, identical to the standard tricorder used on Voyager, thus it eliminates the MP add-on, although the deployable hand sensor continues to be stored in the top end.

[#171 and #172 Endgame]

Internally, therefore, Voyager's medical tricorder incorporates the facilities of its predecessor's MP, whilst retaining the usual sensor and analysis functions. This makes the internal workings very compact, even though the Voyager standard tricorder is rather larger than the standard tricorder used aboard USS Enterprise-D. This would at first seem to be contrary to the trend of miniaturisation (the mark VII measured 8.5x12x3 centimetres and weighed 353 grams, whereas the Voyager model measures 15.81x7.62x2.84 cm. At 298.3 grams it is slightly lighter than the mark VII), but it is more powerful and has more features. As regards Voyager's medical tricorder, the extra size is probably essential in order to incorporate the features that were previously in the MP. The Voyager model retains from the previous model the feature of a separate deployable sensor for finer sensor targeting: as with the previous model, it is held in one hand while the other hand holds the main unit.

Behind-the-scenes: For reasons of economy on production costs, the same prop is used for the medical tricorder as for the standard tricorder. The separate deployable sensor is an additional prop.

^* Tomography is any of various techniques which provide images of successive plane sections of the human(oid) body or other solid objects using X-rays or ultrasound and, by the 24th century, processed by computer to give a three-dimensional image.