37-550: The Twin Dilemma is the seventh and final serial of the 21st season of the British science fiction television series Doctor Who , which was first broadcast in four twice-weekly parts from 22 March to 30 March 1984. In the serial, the alien Gastropod Mestor ( Edwin Richfield ) plots to explode the sun of the planet Jaconda to scatter his eggs throughout the universe to conquer it. It
74-420: A birefringent crystalline material like calcite , but other materials like quartz and α-BBO may be necessary for UV applications, and others ( MgF 2 , YVO 4 and TiO 2 ) will extend transmission farther into the infrared spectral range. Prisms made of isotropic materials like glass will also alter polarization of light, as partial reflection under oblique angles does not maintain
111-434: A remote asteroid named Titan 3. Meanwhile, the mysterious Professor Edgeworth abducts two teenaged math geniuses, Romulus and Remus Sylvest, at the behest of Mestor, the leader of the slug-like Gastropods who have usurped Edgeworth as ruler of the planet Jaconda. Mestor orders Edgeworth to hide on Titan 3, and destroys a pursuing squad of fighters. The only survivor of the fighter squadron is Lt. Hugo Lang, who crash-lands near
148-464: Is a transparent optical element with flat, polished surfaces that are designed to refract light . At least one surface must be angled — elements with two parallel surfaces are not prisms. The most familiar type of optical prism is the triangular prism , which has a triangular base and rectangular sides. Not all optical prisms are geometric prisms , and not all geometric prisms would count as an optical prism. Prisms can be made from any material that
185-442: Is formed by polarizing prisms which use birefringence to split a beam of light into components of varying polarization . In the visible and UV regions, they have very low losses and their extinction ratio typically exceeds 10 5 : 1 {\displaystyle 10^{5}:1} , which is superior to other types of polarizers . They may or may not employ total internal reflection; These are typically made of
222-542: Is transparent to the wavelengths for which they are designed. Typical materials include glass , acrylic and fluorite . A dispersive prism can be used to break white light up into its constituent spectral colors (the colors of the rainbow ) to form a spectrum as described in the following section. Other types of prisms noted below can be used to reflect light, or to split light into components with different polarizations . Dispersive prisms are used to break up light into its constituent spectral colors because
259-507: The 200 stories produced up to that point saw the serial finish in last place again, along with finishing last in every single age group that voted (although Dimensions in Time technically scored lower, it was no longer included in the main poll due to its lack of canonicity within the series and was instead placed in a spin-off section). A similar poll in 2014 placed the story in last place once again. A novelisation of this serial, written by Saward,
296-1049: The Doctor in The Caves of Androzani . Colin Baker makes his first full appearance as the Doctor in the final serial The Twin Dilemma . Janet Fielding ( Tegan Jovanka ) and Mark Strickson ( Vislor Turlough ) continue their roles as the Fifth Doctor 's companions for their final season, Janet Fielding leaves in Resurrection of the Daleks and Mark Strickson departs in Planet of Fire . New companion Peri Brown played by Nicola Bryant makes her first appearance in Planet of Fire . The shape-shifting Android Companion Kamelion, played by Gerald Flood , makes his second and final appearance in Planet of Fire , though
333-417: The Doctor make amends before the former dies. Hugo decides to stay on Jaconda and become its new ruler, while the Doctor agrees to return Romulus and Remus to their parents. Peri still has doubts about the Doctor's new personality, but he reminds her that "I am the Doctor, whether you like it or not!" The Doctor is unusually violent at the start of this episode, even attempting to strangle Peri. The intention
370-506: The Doctor regenerates. Davros makes his first appearance since Destiny of the Daleks (1979) this time played by Terry Molloy . Episodes were broadcast twice weekly on Thursday and Friday evenings, with Resurrection of the Daleks broadcast on two consecutive Wednesday nights. Resurrection of the Daleks was planned as a standard four-parter. However, the BBC's coverage of the 1984 Winter Olympics meant that Doctor Who' s normal timeslot
407-537: The Fifth Doctor ( Peter Davison ) serial Warriors of the Deep , and ended on 30 March 1984 with Colin Baker 's first serial The Twin Dilemma . For the third time (the first being during Season 4 and second being Season 18 ), the entire TARDIS crew changed over the course of a single season. John Nathan-Turner produced the series, with Eric Saward script editing. Peter Davison makes his final regular appearance as
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#1733085840399444-517: The TARDIS. The Doctor saves Hugo at Peri's behest, and he and Peri investigate the asteroid, leading to them being captured by Edgeworth. The Doctor recognises that "Edgeworth" is actually Azmael, a fellow Time Lord and his former tutor. Azmael tries to strand the Doctor and Peri on Titan 3, but unbeknownst to Azmael, his assistant Noma arms a bomb intended to kill them both, and they narrowly escape with their lives. The Doctor, Peri, and Hugo follow Azmael to
481-433: The amplitude ratio (nor phase) of the s- and p-polarized components of the light, leading to general elliptical polarization . This is generally an unwanted effect of dispersive prisms. In some cases this can be avoided by choosing prism geometry which light enters and exits under perpendicular angle, by compensation through non-planar light trajectory, or by use of p-polarized light. Total internal reflection alters only
518-669: The audio play Spider's Shadow , and Professor Eustacius Jericho in the Jodie Whittaker episodes " Village of the Angels ", " Survivors of the Flux " and " The Vanquishers ". Seymour Green had previously played Hargreaves in The Seeds of Doom . Helen Blatch had earlier been a voice artist in The Deadly Assassin . Where the previous serial, The Caves of Androzani , is frequently cast among
555-506: The beam into decoherence of its polarization components. Total internal reflection in prisms finds numerous uses through optics, plasmonics and microscopy. In particular: Other uses of prisms are based on their beam-deviating refraction: By shifting corrective lenses off axis , images seen through them can be displaced in the same way that a prism displaces images. Eye care professionals use prisms, as well as lenses off axis, to treat various orthoptics problems: Prism spectacles with
592-462: The character itself – along with other Fifth Doctor companions who left by this story (Tegan, Nyssa, Adric, and Turlough) – all make illusionary cameos as the Doctor regenerates at the climax of The Caves of Androzani . Anthony Ainley returns in Planet of Fire as the Master, which was intended to be his final appearance. Ainley, like other departed fifth Doctor companions make illusionary cameos as
629-513: The era. How did Nathan-Turner and Saward think that this approach might be in any way acceptable?" A 1998 poll by Doctor Who Magazine ranked the serial the second worst of all time (the Children in Need special Dimensions in Time was ranked lowest), while a 2003 poll by fansite Outpost Gallifrey ranked it worst of all, below even Dimensions in Time . In 2009, another Doctor Who Magazine poll of
666-456: The fourth episode without resolution to the plot, with the final battle taking place in another dimension against a being called Azlan who was controlling Mestor all along. The cat badge worn by the Sixth Doctor on his lapel for this story was handmade and painted by Suzie Trevor and purchased for the programme from a specialist badge shop in central London. For each subsequent story, the Doctor
703-436: The galaxy. After the Doctor tries and fails to kill him, Mestor announces that he will take over the Doctor's body. The Doctor tries to goad Mestor into doing this, but he instead takes over Azmael. The more experienced Azmael manages to briefly retake control of his body and initiates a regeneration, but since he has used up his entire regeneration cycle, this has the effect of killing both himself and Mestor, though Azmael and
740-442: The hypotenuse of one right-angled prism, and cemented to another prism to form a beam-splitter cube. Overall optical performance of such a cube is determined by the thin layer. In comparison with a usual glass substrate, the glass cube provides protection of the thin-film layer from both sides and better mechanical stability. The cube can also eliminate etalon effects , back-side reflection and slight beam deflection. Another class
777-563: The light beam. They are typically used to erect the image in binoculars or single-lens reflex cameras – without the prisms the image would be upside down for the user. Reflective prisms use total internal reflection to achieve near-perfect reflection of light that strikes the facets at a sufficiently oblique angle. Prisms are usually made of optical glass which, combined with anti-reflective coating of input and output facets, leads to significantly lower light loss than metallic mirrors. Various thin-film optical layers can be deposited on
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#1733085840399814-468: The mutual phase between s- and p-polarized light. Under well chosen angle of incidence, this phase is close to π / 4 {\displaystyle \pi /4} . Birefringent crystals can be assembled in a way that leads to apparent depolarization of the light. Depolarization would not be observed for an ideal monochromatic plane wave , as actually both devices turn reduced temporal coherence or spatial coherence , respectively, of
851-930: The novelisation was released, read by Colin Baker. The Twin Dilemma was released on VHS in May 1992. The tape was available exclusively through branches of Woolworths as part of a special promotion. A general release followed in February 1993. It was released on DVD on 7 September 2009 in the United Kingdom and on 5 January 2010 in the United States. This serial was released as part of the Doctor Who DVD Files in Issue 127 on 13 November 2013. Doctor Who (season 21) The twenty-first season of British science fiction television series Doctor Who began on 5 January 1984 with
888-504: The now-desolate Jaconda, where Azmael makes it clear he never intended for them to be harmed, and reveals that Mestor is forcing him to have Romulus and Remus create calculations which will terraform two nearby planets that the Gastropods can settle on. The Doctor, however, realizes that Mestor has lied to Azmael about the nature of his plan, and the calculations will actually cause Jaconda's sun to go supernova, allowing Gastropod eggs to infest
925-785: The opening sequence for the Seventh Doctor . Colin Baker also provides, uncredited, the voice of a Jacondan at Freighter Control in part three. Dennis Chinnery had previously appeared as Albert C. Richardson in the William Hartnell story The Chase and as Gharman in the Tom Baker story Genesis of the Daleks . Edwin Richfield had previously appeared as Captain Hart alongside Jon Pertwee's Doctor in The Sea Devils . Kevin McNally later played Henry in
962-503: The refractive index depends on wavelength ; the white light entering the prism is a mixture of different wavelengths, each of which gets bent slightly differently. Blue light is slowed more than red light and will therefore be bent more than red light. Spectral dispersion is the best known property of optical prisms, although not the most frequent purpose of using optical prisms in practice. Reflective prisms are used to reflect light, in order to flip, invert, rotate, deviate or displace
999-452: The same version as that introduced in 1980. Prior to this, the opening sequences of the Second , Third , Fourth , and Fifth Doctor eras had incorporated a still photograph of the lead actor. For the Sixth Doctor opening this was changed to using two photographs – one of the Doctor with a smile which changes to a second image showing the Doctor grinning. This limited animation would continue with
1036-580: The time, and still feels wrong now". They also asked "How could anyone have thought that this story, of juvenile space monsters, meaningless plans and never-ending cop-outs, was ever workable?". In his review for Radio Times, Patrick Mulkern gave the serial a negative reception, stating: "If The Twin Dilemma is individually a disaster, it also establishes the opening titles, the Doctor’s clothes, his behaviour and sniping banter with Peri – all part of an unpleasant shift in tone that would permeate and eventually poleaxe
1073-481: The very best of all Doctor Who stories, the fandom often holds this serial the polar opposite, commonly regarding it as one of the very worst serials in the history of the series. The review of the story in Doctor Who: The Television Companion describes The Twin Dilemma as "painful to watch", describing the Doctor's erratic behaviour as "forced and artificial, and succeed[s] only in alienating
1110-484: The viewer." The review also argues the script "leaves much to be desired" and that the direction is uninteresting, giving the whole story "a rather tacky, B-movie feel to it". In SFX #150 new series producer Russell T Davies cites this story as "the beginning of the end" of Doctor Who . Tat Wood and Lawrence Miles , reviewing the story in the book About Time , noted that the divide in quality between The Caves of Androzani and The Twin Dilemma "felt wrong at
1147-466: Was during the Fifth Doctor's début story Castrovalva . Colin Baker said during a 2003 documentary celebrating the series' 40th anniversary that "the idea was that over the many, many years I would be playing the part, the outer layers would gradually peel away, revealing the kind-hearted soul." At least one aspect of Steven's original script featured the Jaconda and Gastropods being dropped totally early in
The Twin Dilemma - Misplaced Pages Continue
1184-545: Was published in hardback by Target Books in October 1985, and in paperback in March 1986. The cover illustration originally featured Colin Baker; however, when Baker's agent enquired about a royalty, the decision was taken to not feature him on the cover and a replacement was commissioned. This adaptation is notable for Saward's convoluted attempt at explaining in detail how the regeneration process works. In January 2012, an audiobook of
1221-551: Was slightly modified for the final serial The Twin Dilemma , and continued during Colin Baker 's reign as the Sixth Doctor until the end of the season 23 14 episode epic The Trial of a Time Lord . The entire season was broadcast from 5 January to 30 March 1984. Transmission moved to Thursdays and Fridays, except for Resurrection of the Daleks which was aired in two double-length episodes on Wednesdays. All releases are for DVD Prism (optics) An optical prism
1258-414: Was the first to star Colin Baker as the Sixth Doctor uniquely being the final story of the season. As a result of his recent regeneration, the Sixth Doctor suffers from mood swings and violent delusions, culminating in his attempt to strangle his companion, Peri Brown . Realising the threat he could pose to the universe in this state, the Doctor decides to exile himself (and Peri, over her protests), to
1295-454: Was to create a Doctor that was initially unlikeable, but would gradually reveal a kind-hearted soul (glimpsed in Revelation of the Daleks ). This was also intended to be a contrast to the instantly likeable Tom Baker and Peter Davison Doctors. However, in later interviews, director Peter Moffatt said that the original idea was merely to have the Doctor in a much more energetic state than he
1332-443: Was to wear a different cat badge to symbolise that he was a "travelling cat of different walks." Besides being adjusted for the new Doctor, the opening credits underwent additional modifications with this episode. A prism -colour effect is added and the series logo takes on a somewhat bluish hue (which also results in it appearing slightly curved in comparison to the version introduced during Tom Baker 's era). The theme music remains
1369-402: Was unavailable. Rather than delay broadcasting the story, the decision was taken to produce it as a pair of double length episodes and broadcast it in the unfamiliar Wednesday timeslot. The Caves of Androzani was the first time since Season 4's The Tenth Planet that the introduction of a new Doctor had taken place before the final serial of the season. During this season, the title card
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