Good morning and welcome to Oxford Instruments' half-year results. Before we get started today, I'd just like to say that we were greatly saddened when Alan Thomson, our chairman, passed away in July. Alan brought a wealth of experience and wisdom to the role, and his support, guidance, and friendship have been greatly valued. The process to appoint Alan's successor is underway, and in the meantime, Steve Blair, our senior independent director, is operating as Interim Chair. In terms of the agenda for today, I will take you through the highlights, hand over to Gavin, who will cover the financial results, before returning for a progress update with Horizon, an operational review, and then closing with summary and outlook. Moving straight to the highlights. We continue to make good progress with the implementation of our Horizon strategy, whilst maintaining a sharp focus on the near-term delivery of improved performance.
The strategy is now well-embedded across the group, and we are starting to see positive results with good order and revenue growth. Our chosen end markets and their underlying growth drivers remain positive and robust. Group performance was in line with our expectations, with growth in reported revenue and adjusted operating profit before tax. Positive order intake across our three sectors resulted in reported order and orderbook growth for the period. Looking at our sectors, strong financial performance across materials and characterization was driven by the success of recently launched products and increased customer application focus and positive end markets. Good first-half performance in research and discovery was driven by growth in the healthcare and life science and quantum technologies end customer segments.
Service and healthcare had a good order and orderbook growth in the period, driven by demand for services relating to our own products and growth in service contracts within OI Healthcare. Good cash collection in the period further strengthened the balance sheet, with net debt down to GBP 12.5 million. I'll now hand over to Gavin for the financial review.
Thanks, Ian. Good morning, everyone. We'll start with the income statement. Reported revenue grew by 11.3% to GBP 147 million. On a constant currency basis, revenue growth was 12.6%. After a currency headwind of just under GBP 1 million, reported adjusted operating profit grew by 11.7% to GBP 21 million. On a constant currency basis, this was growth of 16%. Lower average debt over the period and a small reduction in pension financing charges led to a fall in net financing costs to GBP 1.2 million. Adjusted PBT grew by 21.5% to GBP 19.8 million, with margin rising from 12.3% to 13.5%. This half-year, we've adopted IFRS 15 revenue from contracts with customers, as well as IFRS 16 leases, a year ahead of when we needed to.
The main difference on the introduction of IFRS 15 is that revenue recognition on customised magnet and cryogenic systems is deferred from being primarily on transfer of rights and rewards of ownership to completion of installation. The difference at the half-year is expected to partially unwind over the remainder of the year. The net effect of these two new standards is to increase revenue by GBP 5.1 million and profit before tax by GBP 2.2 million for the half-year. Compared to the comparative period, the group was unable to satisfy incremental customer orders to the value of GBP 1.7 million following the refusal of government export licenses and compliance with US sanction legislation. In the half-year, we have engaged consultants to accelerate the operational excellence element of our Horizon strategy and incurred restructuring costs primarily on the closure of a small facility in North America.
These costs totaled GBP 1 million and have been included within adjusted operating profit. Amortization of acquired intangibles of GBP 4.7 million is a non-cash charge and is treated as an adjusted item. Non-recurring items were a net charge of GBP 0.6 million. During the period, we repaid GBP 11.6 million of the principal outstanding on loan notes as a condition of the sale of i ndustrial analysis. The make-whole cost due at the time of the repayment was GBP 0.9 million. In addition, we recognized a small net gain of GBP 0.3 million on adjustments relating to our Scienta Omicron joint venture. The mark-to-market loss in respect of derivative financial instruments was GBP 2.9 million. This reflects a movement from a net fair value asset to a small net liability position on currency derivatives that are hedging future transactional currency exposures for the group compared to the previous year-end.
Profit before tax from continuing operations was GBP 11.6 million. The improvement in adjusted profit before tax led to a rise of 22% in adjusted basic EPS. Given the good growth seen in the first half, but taking into account the second half seasonal weighting, the board has decided to increase the interim dividend to GBP 3.8, a rise of GBP 2.7. Looking at revenue by sector, reported revenue for materials and characterization grew by 20%, 21.2% at constant currency, with particularly strong growth across our imaging and analysis products, scanning probe microscopes, and semiconductor processing solutions. Reported revenue grew by 13.4%, 14.6% at constant currency for research and discovery, with growth from our optical imaging cameras and systems. A strong focus on installing a backlog of our complex customised magnet and cryogenic systems supported segment growth. Constant currency growth in this sector was 2.7% on a pre-IFRS 15 basis.
Lower revenue from equipment sales in OI Healthcare resulted in a constant currency decline of service and healthcare of just under 3%. With total orders in the half-year of GBP 163 million, our book-to-bill ratio, which compares orders received to goods and services billed in the period, was 1.11. Moving to revenue by territory. In Europe, we have seen constant currency revenue growth of 10.8%, driven by strong demand for imaging and analysis products. A reduction in orders for our plasma processing solutions, which do tend to be irregular in nature, resulted in a small decline in constant currency orders of 1.4%. In North America, we saw constant currency growth of 5.3%, driven by an improvement in demand for our plasma processing solutions and optical imaging systems. For Asia, we saw strong constant currency revenue growth of 18.9%, with double-digit growth across China, Japan, and the rest of Asia.
China represents 21% of group revenue in the first half. Orders for the region were up 29% against last year at constant currency, driven by strong demand across the materials and characterization sector and our optical imaging solutions. Orderbook. The orderbook as of 31 March 2018 has been restated on an IFRS 15 basis to show a true like-for-like comparison. The orderbook has grown by 16.3% since last year on a reported basis and 12.5% at constant currency. Constant currency growth was just under 34% for materials and characterization, with strong growth for imaging and analysis products, as well as our semiconductor processing solutions. Good order growth for our imaging and optical microscopy systems led to constant currency orderbook growth of 5% for research and discovery.
An improvement in orders within our U.S. and Japan healthcare businesses led to an orderbook increase of 9.3% in constant currency within the service and healthcare segment. Turning to adjusted operating profit, constant currency adjusted operating profit in materials and characterization grew by just under 39%. The operating margin increased to 16.1%. Research and discovery constant currency operating profit grew by just under 24%. Despite the improvement in revenue, the margin for the segment was held flat due to a loss from our Scienta Omicron joint venture and a weaker performance from our x-ray technology business. We expect to see an improvement from both businesses in the second half. Fewer system upgrades and a weaker first-half performance from U.S. healthcare resulted in a decline in service and healthcare operating profit of just under 11%.
Across the group, we have invested in sales and service resources and training, operational support, and IT. We have also capitalized less R&D in the period. In addition, we are no longer receiving income and rent following the end of the transitional services agreement with Hitachi High- Technologies and the sale of two properties that were made last year. These changes have mitigated total group margin growth. Turning to the cash flow. The group made adjusted earnings before interest, tax, depreciation, and amortization of GBP 26.4 million. Cash generated from operations of GBP 21.4 million represents 91% cash conversion against 13% last year. The working capital outflow of GBP 1.2 million reflects an increase in inventories of GBP 7.9 million, a decrease in receivables of GBP 12.6 million, a decrease in payables of GBP 7.7 million, and an increase in customer deposits of GBP 1.8 million.
The increase in inventories primarily reflects an increase in work in progress and components to support our planned production schedule in the second half of the year, particularly for our deposition and etch process solutions and our optical imaging systems. The pension deficit fell from GBP 15.1 million at the end of last year to GBP 9.9 million due to an increase in bond yields and deficit recovery payments made in the period. Net debt fell to GBP 12.5 million. This represents a net debt to EBITDA leverage of 0.2 times. Our covenant is set at 3. The business has a large exposure to foreign currency fluctuations facing translational and transactional currency exposures. Our total currency exposure is detailed on this chart. In sterling equivalent, we've net exposures of $26.4 million, EUR 15.6 million, and JPY 7.9 million.
As many of the manufacturing sites are based in the U.K., we have a short sterling exposure of GBP 28.6 million. We maintain a hedging program against our net transactional exposure using internal projections of currency trading transactions expected to arise over a period extending over the next 18 months. Finally, to summarize key highlights from the first half, we have seen good reported and constant currency growth in orders and orderbook. Adjusted operating profit grew by 11.7%, with margin rising to 14.3%. This is after investments made across the group to improve capability and support sustained growth, as well as incorporating overhead previously absorbed by industrial analysis. Continued adjusted basic earnings per share grew by over 22%. We have a strong balance sheet with good cash conversion of 91%, contributing to a fall in net debt to GBP 12.5 million.
Finally, last July, we completed a refinancing of the business. We entered into a new multicurrency revolving facility agreement committed until June 2023, with uncommitted extension and accordion options. The facility comprises a EUR 50 million multicurrency facility and a $80 million U.S. dollar multicurrency facility. With that, I'll hand back to Ian.
Thank you, Gavin. Starting with an update on our strategy. We set out our Horizon strategy a year and a half ago to deliver sustainable revenue growth and margin improvement. We've made good progress with the implementation of the strategy, which is now well embedded across the group. We are starting to see positive results from our increased focus on end market applications with good underlying order and revenue growth. Our chosen end markets and their underlying growth drivers remain positive and robust.
We continue to embed a sharp commercial focus and build capabilities across the group with a specific emphasis on sales, marketing, and operations teams in the period. We have continued our migration to a customer-centric approach, increasingly offering solutions rather than tools. To support this, we have further invested in our customer-facing and marketing communications teams. From an operational excellence perspective, we have increased the capabilities and number of lean leaders within the business. With our cohort of internal operational champions now in place, we have increased our investment and focus on this aspect of the Horizon strategy, with a particular attention to strategic procurement, operational efficiencies, and logistics. These investments will support our future growth ambitions and contribute to margin improvement. Moving to our operational performance. As a group, we report in three sectors: materials and characterization, research and discovery, and service and healthcare.
The group delivered good underlying growth in orders, revenue, and operating profit, supported by our end market application focus and the increase in tailored products and solutions. This has provided more value to our existing customers whilst expanding the addressable market, resulting in strong growth from commercial and industrial customers, increasing their proportion of total sales to 53% compared to 45% in the previous first half. Reported orderbook, representing orders for future delivery, grew by 16% since March 2018, with growth within each of our constituent sectors. We continue to focus on creating value for our customers through enabling new scientific discoveries, accelerating their applied R&D, and increasing their manufacturing productivity. I'm encouraged by the results for the first half of the year, given the currency headwind and the increased global tensions that have impacted international trading environments.
As a consequence, we have seen a slight tightening of the grant of export licenses to certain customers, as well as the imposition of US sanctions and China tariffs, which have modestly impacted orders and revenue in the period. Now, looking at our end markets. As you can see from the breakdown on the right-hand side of the slide, we have a diverse customer base across a wide range of applications and end markets. We have seen strong order and revenue growth in advanced materials and the healthcare and life science customer segments. Revenues from customers associated with quantum technologies also increased in the period, with orders slightly down, primarily due to the phasing and high value of individual system opportunities.
Revenues associated with semiconductor and communications, which relate to both our imaging and analysis and semiconductor processing solutions, were broadly in line with the previous year, but with good order growth in the period. Moving to our individual sectors and starting with materials and characterization. This sector represents 41% of group revenue and comprises the NanoA nalysis, Asylum Research, and Plasma Technology business units. The sector provides products and solutions for the imaging and analysis of materials down to the atomic level, as well as the fabrication of semiconductor devices and structures through a range of etch and deposition processes. Now, this sector has a strong emphasis on supporting and accelerating our customers' applied R&D and improving production capabilities and productivity in high-tech manufacturing.
Orders, revenue, and profitability all achieved double-digit growth, supported by our Horizon strategy of increased customer application focus and the continued success of recently launched higher margin products. This, combined with healthy end markets, drove growth in the U.S., Europe, and Asia, and increased revenue from industrial and commercial customers, which rose to 58% of sales in the period for the sector. Looking at end markets, the sector is dominated by customers across advanced materials and semiconductor and communications segments, each representing 39% of sales. In the period, we saw strong growth in advanced materials and continued demand from customers across the mainstream silicon and specialized compound semiconductor end markets. Moving to look more closely at the growth drivers within the sector. Within advanced materials, growth was strongly supported by the continued success of recently launched analysis products.
These provide significantly more accurate information and results much faster, driving both capability and productivity for our customers across the automotive and aerospace industries, as well as those customers needing to analyze metals, ceramics, composites, and polymers. In addition, we have developed new application solutions targeted at quality assurance and quality control for the high-end additive manufacturing and 3D printing markets. Specifically, our microstructure analyzer enables the qualification of the critical material properties, performance, and quality of the manufactured metal components and the optimization of the manufacturing process. We've also built on our expertise in particle analysis to develop a tailored solution providing quality control of the raw material feedstock used in additive manufacturing, helping to avoid contamination and maintain end product performance. We also saw good growth in customers involved in development and production support across energy generation, storage, and battery applications. Looking at the semiconductor and communications segment.
Semiconductors remain a core target market for the sector, where in addition to our imaging and analysis products, we provide etch and deposition processes used across a wide range of compound semiconductor and silicon device applications. This is increasingly attractive as we enter what some call the decade of materials, whereby performance materials and specifically compound semiconductors will enable new applications and unprecedented device performance, such as higher energy efficiency and storage, longer range electric vehicles, and higher data communication rates. We are tailoring our research and applied R&D products for commercial production customers whilst developing key leading capabilities in the processing steps required for the manufacture of discrete devices and optoelectronic components. As an example, our capabilities in several processing steps in the manufacture of vertical cavity surface emitting lasers has enabled us to win a number of new production customers.
VCSELs, as they are called, are increasingly being used across a wide range of applications, including facial recognition on smartphones. Moving to our second sector, research and discovery. This sector represents 37% of group revenue, comprises Andor Technology, nanoscience, magnetic resonance, x-ray technology, and our 47% share of the Scienta Omicron joint venture. The sector provides advanced solutions that create unique environments and enable the imaging and analytical measurements down to the molecular and the atomic level. Products in the sector are predominantly used to support fundamental research and accelerate applied R&D, with a higher proportion of customers with academic and government funding representing 65% of sales. The sector had improved orders, revenue, and profitability driven by strong performance from our scientific cameras, optical microscopy, and cryogenic systems and research magnets.
These products provide growth into the healthcare and life science and quantum technology segments, which represent 40% and 25% of revenue, respectively. Research and fundamental science also remains a significant customer segment at 18% of sector revenue. Within healthcare and life science, our Dragonfly optical microscopy portfolio continues to gain customer recognition and market share, with our leading image quality improving research capabilities and productivity within neuroscience, developmental biology, and advanced medicines and therapies. Moving to performance within the sector. Growth and enhanced financial performance was driven by Andor Technology and the Nanoscience business units, partially offset by first-half headwinds within the rest of the sector. The improvement plan within our Nanoscience business is progressing well under a new leadership team, with stronger commercial focus improving the quality of current and future orders, whilst working through the historic orderbook of complex, low-margin, specialized systems.
Despite a softer first half, our benchtop magnetic resonance analyzers continue to have a good pipeline of opportunities across a range of food, industrial applications, as well as oil exploration. The market for our scientific x-ray tubes remains buoyant, with order growth in the period, although delayed shipments and timing of orders has negatively impacted revenue and profitability in the half year. We expect to see improvement in the second half. The relatively high value of later phasing of orders within Scienta Omicron impacted financial performance in the period. With more positive order intake, we expect improved trading in the second half. Looking at growth drivers within this segment, we have built on our leadership in scientific cameras by focusing on the key market drivers, which include cell biology, personalized medicine, astronomy, and physical science.
In the period, we launched new application-specific cameras, delivering the advanced set of performance features without compromise. Sonar, which in Gaelic means to be full of life, is tailored specifically for life science applications with high sensitivity, improving cell imaging and the understanding of cellular processes. Marana, which in Gaelic means to think, is optimized for astronomy and high-speed physical science applications such as quantum optics and the search for near-Earth objects and space debris. Moving to quantum technologies. The quantum technology market remains attractive with strong global research funding due to the potential for significant market and technology disruption. Activity is driven by investment from large corporates and across the wider academic community through significant government funding in the E.U., U.S., and China.
Now, quantum is making progress from the fundamental science to applied research targeting commercial applications with end market drivers, including quantum computing, secure communications, and advanced sensors and imaging. Our cryogenic systems, high-field magnets, and scientific cameras provide the fundamental capabilities and platforms to enable both the research and the development of viable commercial applications. We saw good revenue growth in the half year with a healthy pipeline for future orders. However, the market remains irregular in frequency due to the value of individual customer opportunities. Looking at research and fundamental science, this remains an attractive segment for the group, with our range of optical components, cryogenics, and magnets providing customers with a broad range of platforms and solutions used predominantly across the physical sciences.
Customers in the period included the recent BepiColombo European space mission to Mercury, which has incorporated our x-ray detector technology to measure the nature and composition of the planet. Moving to our final sector, service and healthcare. The sector comprises the group's support services related to our own products under the OI Service brand and the sales, service, and rental of refurbished third-party imaging systems under the OI Healthcare brand. Whilst revenue in the period slightly declined due to the reduced sales of refurbished healthcare imaging systems, customer demand for our other services increased both orders and order book by 15%. Within OI Service, we continue to provide a broad range of products, training, and services increasingly tailored to our customers' specific needs, whilst improving our efficiency and response time through the utilization of technology.
We have increased the number of application-specific seminars and have completed a very successful second summer school in collaboration with the Chinese Academy of Sciences. Within OI Healthcare, we have seen good strategic progress in our service contracts to new customers, as well as an improved utilization of our leasing fleet. The market for refurbished imaging equipment remains soft, impacting revenue in the period. Within Japan, we have won a new contract to start the servicing of some of Hitachi healthcare's magnet-based imaging systems. Finally, moving to our summary and outlook. We've continued to make good progress in the implementation of our horizon strategy. Our end markets and their underlying drivers remain positive, with strong growth from commercial and industrial customers resulting in good financial performance in the first half.
Our expectations for the current financial year remain unchanged, supported by growth in constant currency orders and order book, along with our anticipated second-half seasonal bias. Thank you very much for your attention.