Heavy metal status in cocoa (Theobroma cacao L.) soils and beans: the case of Abuakwa North Municipality of Eastern Region, Ghana.

In recent times, public concerns over the potential accumulation of heavy metals in agricultural soils and crops due to the excessive use of agrochemicals are increasing. This study was conducted in the Abuakwa North Municipality of Eastern Region, Ghana, to assess the status of heavy metals in cocoa soils and beans. Cocoa farms aged between 10 and 20 years and have received agrochemicals for at least 5 years were selected, and their adjacent forests were used as controls. Soil samples and cocoa pods were collected randomly and processed for laboratory analysis. The study discovered that across the sampling sites, heavy metal concentrations in soil were below permissible limits. However, contamination factor and geo-accumulation index results revealed that Tontro cocoa farms were considerably contaminated and moderately polluted respectively with Cu, probably due to long-term fungicide application. The concentrations of Fe (39.3-47.1 mg kg-1) and Zn (54.8-70.0 mg kg-1) in the cocoa beans across the communities were below the FAO/WHO's safe limit of 99.4 mg kg-1 and 73.0 mg kg-1 respectively. Lead (0.03-0.06 mg kg-1) and Cd (0.12-0.20 mg kg-1) concentrations were below the EU's maximum allowable level and Codex Alimentarius Commission's limit of 1.0 mg kg-1 respectively. However, bean Cu content in the Tontro farm (51.5 mg kg-1) was slightly above the EU's recommended maximum limit of 50.0 mg kg-1, possibly due to the continuous application of copper-based fungicides. The study showed that, overall, agrochemicals used for cocoa farming in Abuakwa North Municipality of Ghana did not cause serious harm to the soils and beans, since the mean metal concentrations were not alarming and guarantee public health safety.

Postharvest Quality Improvement of Bell Pepper (Capsicum annuum L. cv Nagano) with Forced-Air Precooling and Modified Atmosphere Packaging.

Optimum postharvest storage conditions increase the postharvest quality and shelf life of horticultural crops. The effects of forced-air precooling (FAP) and modified atmosphere packaging (MAP) on shelf life, physicochemical quality, and health-promoting properties of bell pepper (Capsicum annuum L. cv. Nagano) harvested at 90 and 50% coloring stages in May and July respectively, stored at 11 °C, 95% relative humidity were assessed. Fruits were subjected to four treatments: FAP + 30 µm polyethylene liner (FOLO); FAP-only (FOLX); 30 µm polyethylene liner-only (FXLO); and control (FXLX). The quality attributes, viz. weight loss, firmness, color, soluble solids content (SSC), soluble sugars, total phenolic content (TPC), total flavonoid content (TFC), 2,2-dephenyl-1-picrylhydrazyl (DPPH), and 2,2'-azino-bis-3-ethylbenzo-thiazoline-6-sulfonic acid (ABTS) were evaluated. The investigated parameters differed significantly (p < 0.05) among treatments except for soluble sugars. FOLO maintained sensory quality (weight loss, firmness, and color), physicochemical (SSC and soluble sugars), and health-promoting properties compared to other treatments during storage. The 50% coloring fruits had a huge variation between treatments than 90% coloring. The results revealed more TPC and antioxidant capacity in the 50% than in the 90% coloring fruits. The study highlights the need to consider the ideal fruit coloring stage at harvest under the effect of FAP and MAP treatments in preserving bell pepper's postharvest quality and shelf life.

Effect of landuse on floristic composition and diversity of medicinal plants in the Guinea Savanna zone of Ghana.

The use of medicinal plants is the most accessible primary health care approach in rural communities with limited infrastructure for western medicine. Medicinal plants are therefore an integral component of traditional medicine in Ghana, but wild bushes where medicinal plants regenerate naturally are being converted to alternative landuse. Although most landuse changes are destructive to biodiversity, some indigenous land use systems are known to be environmentally friendly. The present study examined the diversity and abundance of medicinal plants in three landuse types (Protected Area, Fallow land and Farmland) of northern Ghana. Twenty-five quadrates of 30 × 30 m were randomly laid in each landuse and replicated in three communities. Leguminosae, Combretaceae and Rubiaceae occurred as the most dominant medicinal plant families in all landuse but woody plants were significantly abundant in protected areas (p = 0.001). Species richness, Shannon diversity index, alpha and gamma diversities were all higher in the protected areas. Species composition also varied between landuse in beta diversity (p = 0.005, r2 = 0.33). Medicinal plant population have reduced significantly in farmlands, farmers should therefore adopt agroforestry practices to help conserve medicinal plant biodiversity.

Two new sphingolipids from the stem bark of Synsepalum msolo (Sapotaceae).

Synsepalum msolo commonly known as Bang Bali in Bali-Nguemba, Cameroon is used in traditional medicine against various diseases. The leaves and stem bark extracts were subjected to silica gel and Sephadex LH20 column chromatography to yield pure compounds. The structures of the compounds were determined by detail analysis of NMR and Mass spectroscopic data and by comparison with data reported in the literature. Amongst the isolates, were two new sphingolipids: synsepaloside B (1), synsepaloside C (2), and five known compounds: (+)-catechin (3), (-)-epicatechin (4), myricitrin (5), triacontanol (6), and aurantiamide acetate (7). Compounds 1-5 were screened for their antibacterial and anti-yeast activities on several microorganisms. All the tested compounds exhibited weak antibacterial (MIC ≥ 200 µg/mL) and anti-yeast (MIC > 200 µg/mL) activities as compared to standard: ciprofloxacin 0.468 < MIC >0.234 µg/mL and fluconazole MIC = 0.05 µg/mL, respectively.

Cytotoxic phytochemicals from the crude extract of Tetrapleura tetraptera fruits towards multi-factorial drug resistant cancer cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Tetrapleura tetraptera is an African medicinal spice used in traditional medicine to treat several ailments including cancer. AIM OF THE STUDY: The present study was designed to evaluate the cytotoxicity of the dichloromethane-methanol (1:1) extract of the fruits of Tetrapleura tetraptera (TTF) and its constituents: (3R, 4S)-3,4-dimethyloxetan-2-one (1), luteolin (2), stigmasterol (4), 3-O-[6'-O-undecanoyl-ß-D-glucopyranosyl]stigmasterol (6), olean-12-en-3-ß-O-D-glucopyranoside (7), 3-O-ß-D-glucopyranosyl-(1 â†’ 6)-ß-D-glucopyranosylurs-12-en-28-oic acid (8), 3-O-ß-D-glucopyranosyl-(1 â†’ 3)-ß-D-glucopyranosyl-27-hydroxyolean-12-ene-28-oic acid (9), methyl-O-ß-D-glucopyranoside (10), ß-D-fructofuranosyl-(2 â†’ 1)-ß-D-glucopyranoside (11) towards a panel of cancer cell lines including MDR phenotypes. The cellular mode of induction of apoptosis by TTF and compound 7 was further investigated. MATERIALS AND METHODS: The resazurin reduction assay (RRA) was applied to determine the cytotoxicity of the studied samples. The cell cycle (PI staining), apoptosis (annexin V/PI staining), mitochondrial membrane potential (MMP; JC-1) and reactive oxygen species (ROS; H2DCFH-DA) were measured by flow cytometry. Column chromatography was used for the purification of TTF, whilst nuclear magnetic resonance (NMR) spectroscopic analysis was applied for structural elucidation. RESULTS: The botanical, TTF and the phytochemicals, 2, 7, 8 and 9 as well as doxorubicin exerted cytotoxicity against 9 cancer cell lines including drug-sensitive and drug resistant phenotypes. TTF, compound 7 and doxorubicin were the most active samples, and displayed IC50 values ranging from 10.27 µg/mL (in CCRF-CEM leukemia cells) to 23.61 µg/mL (against HCT116 p53-/- colon adenocarcinoma cells) for TTF, from 4.76 µM (against CCRF-CEM cells) to 12.92 µM (against HepG2 hepatocarcinoma cells) for compound 7, and from 0.02 µM (against CCRF-CEM cells) to 122.96 µM (against CEM/ADR5000 cells) for doxorubicin. TTF induced apoptosis in CCRF-CEM cells through MMP alteration and increased ROS production while compound 7 induced apoptosis mediated by caspases activation, MMP alteration and increased ROS production. CONCLUSION: Tetrapleura tetraptera and some of its constituents, mostly compound 7 are good cytotoxic natural products that should be explored in depth to develop new drugs to fight cancers.

Cytotoxicity of seputhecarpan D, thonningiol and 12 other phytochemicals from African flora towards human carcinoma cells.

BACKGROUND: Despite the remarkable progress in cancer therapy in recent years, this disease still remains a serious public health concern. The use of natural products has been and continues to be one of the most effective ways to fight malignancies. The cytotoxicity of 14 compounds from African medicinal plants was evaluated in four human carcinoma cell lines and normal fibroblasts. The tested samples included: ß-spinasterol (1), friedelanone (2), 16ß-hydroxylupeol (3), ß-amyrin acetate (4), lupeol acetate (5), sequoyitol (6), rhamnitrin (7), europetin 3-O-rhamnoside (8), thonningiol (9), glyasperin F (10), seputhecarpan B (11), seputhecarpan C (12), seputhecarpan D (13) and rheediaxanthone A (14). METHODS: The neutral red uptake (NR) assay was used to evaluate the cytotoxicity of samples; caspase-Glo assay, flow cytometry for cell cycle analysis and mitochondrial membrane potential (MMP) as well as spectrophotometry to measure levels of reactive oxygen species (ROS) were performed to detect the mode of action of compounds 9 and 13 in MCF-7 breast adenocarcinoma cells. RESULTS: Compounds 3, 9-13 displayed cytotoxic effects against the four tested cancer cell lines with IC50 values below 85 µM. Compounds 9 and 13 had IC50 values below 10 µM in 4/4 and 3/4 tested cell lines respectively. The IC50 values varied from 0.36 µM (against MCF7 cells) to 5.65 µM (towards colon carcinoma DLD-1 cells) for 9, from 9.78 µM (against MCF7 cells) to 67.68 µM (against HepG2 cells) for 13 and 0.18 µM (towards HepG2 cells) to 72 µM (towards Caco-2 cells) for the reference drug, doxorubicin. Compounds 9 and 13 induced cell cycle arrest in Go/G1 whilst doxorubicin induced arrest in G2/M. The two molecules (9 and 13) also induced apoptosis in MCF-7 cells through activation of caspases 3/7 and 9 as well as enhanced ROS production. CONCLUSION: Compounds 9 and 13 are good cytotoxic phytochemicals that should be explored more in future to develop a cytotoxic drug to fight human carcinoma.

Potential of Zanthoxylum leprieurii as a source of active compounds against drug resistant Mycobacterium tuberculosis.

BACKGROUND: Tuberculosis (TB) is still a global health problem mainly due to development of resistance and co-infection with the Human immune Virus (HIV). Treatment of multi and extensively drug resistant TB requires use of second line drugs which are less efficacious, expensive and very toxic. This has necessitated a need to search for new treatment regimens especially from medicinal plants. Zanthoxylum leprieurii, a plant species from Rutaceae is used locally in the treatment of tuberculosis in Uganda. The aim of the study was to isolate, identify and characterize bio active compounds from Z. leprieurii stem bark with antimycobacterial activity. METHODS: Crude extracts, fractions and compounds from air dried stem bark of Z. leprieurii were tested against pan sensitive (H37rv), isoniazid resistant (TMC 301) and rifampicin resistant (TMC 331) strains of M. tuberculosis using micro plate alamar blue assay. Isolation of active compounds was done by using column chromatography and thin layer chromatography. They were analysed using nuclear magnetic resonance spectroscopy and mass spectroscopy. RESULTS: The methanol extract had minimum inhibitory concentrations (MIC) of 47.5, 75.3 and 125.0 µg/ml on the pan sensitive strain, rifampicin resistant and isozianid resistant strains of M. tuberculosis respectively. The chloroform extract had MIC values of 260 µg/ml agnaist the pan sensitive strain and 156 µg/ml on the rifampicin resistant strain. Of the sixteen fractions from the methanol extract, fraction Za4 (MIC = 6.3 µg/mL, 23.0 µg/mL, 11.7 µg/mL) and Za6 (MIC = 11.7 µg/mL 31.2 µg/ml, 31.2 µg/ml) were the most active. Three acridone alkaloids; hydroxy-1, 3-dimethoxy-10-methyl-9-acridone (1), 1-hydroxy-3-methoxy-10-methyl-9-acridone (2) and 3-hydroxy-1, 5, 6-trimethoxy-9-acridone (3) were isolated from Za4 and Za6. The MIC of compound 3 was found to be 5.1 µg/ml, 4.5 µg/ml and 3.9 µg/ml on H37rv, TMC 331 and TMC 301 while that of 1 was found to be 1.5 µg/ml, 8.3 µg/ml and 3.5 µg/ml respectively. CONCLUSION: The results of this study suggest that Z. leprieurii is active on resistant strains of M. tuberculosis and could be a potential source of new leads against resistant tuberculosis. It also verifies the local use of the plant in treatment of tuberculosis.

Secondary metabolites with antiproliferative effects from Albizia glaberrima var glabrescens Oliv. (Mimosoideae).

A new 5-dehydroxyflavan, namely Albiziaflavan B or (+)-(2R, 3S, 4R)-3',4', 7-trihydroxy-4-methoxy-2,3-trans-flavan-3,4-trans-diol (1) was isolated from the root bark of Albizia glaberrima, together with six known compounds including three flavans: (+)-mollisacacidin (2), (+)-fustin (3) and butin (4); two steroids: chondrillasterol (5) and chondrillasterone (6), and a triterpenoid: lupeol (7). The structure of 1 was established by detailed analysis of its spectroscopic data, especially 1D and 2D NMR spectra, HRESIMS and CD data. Compounds 1-6 were assayed for their antiproliferative effects on two human cancer cells, HeLa at 50 µM (n = 2) and HL60 at 20 µM (n = 2). Compound 3 and 4 were the most active on HL60 with IC50 of 8.1 and 8.3 µM, respectively. Compound 6 was the most active with an IC50 of 4.6 µM on HeLa.

Thonningiiflavanonol A and thonningiiflavanonol B, two novel flavonoids, and other constituents of Ficus thonningii Blume (Moraceae).

A phytochemical study of Ficus thonningii has led to the isolation of two previously unreported compounds, thonningiiflavanonol A and thonningiiflavanonol B together with 16 known compounds: shuterin, naringenin, syringic acid, p-hydroxybenzoic acid, genistein, 5,7,3',4',5'-pentahydroxyflavanone, luteolin, methylparaben, aromadendrin, garbanzol, dihydroquercetin, 5,7,3'-trihydroxyflavanone, ß-sitosterol, sitosterolglucoside, lupeol acetate, and taraxerol. Their structures were elucidated on the basis of spectroscopic data. The new compounds and extracts displayed potent antioxidant activity.

Challenges and predictors of exclusive breastfeeding among mothers attending the child welfare clinic at a regional hospital in Ghana: a descriptive cross-sectional study.

BACKGROUND: The challenges and predictors of exclusive breastfeeding (EBF) have been examined in many parts of the world. Considering the socio-cultural dynamics and the few research studies in Ghana, the factors that hinder and predict EBF practice in other countries may be different in the Ghanaian setting. The study therefore sought to assess the challenges and predictors of EBF among mothers attending a child welfare clinic at a regional hospital in Ghana. METHODS: A descriptive cross-sectional study was carried out between January and March, 2015 to elicit information from 240 mothers who were sampled using simple random sampling technique. A validated structured questionnaire was used in collecting data on participants' socio-demographic characteristics and reported breastfeeding practices. Participants' breastfeeding challenges were rated on a Likert scale from 1 (not at all), 2 (mild), 3 (moderate), 4 (severe) to 5 (unbearable). In this study, EBF refers to birth of the infants up to six months. RESULTS: The top three breastfeeding challenges of mothers were: belief that breast milk alone was not sufficient in meeting their babies' nutritional needs [mean 3.43 (standard deviation {SD} 1.35)], short maternity leave period [mean 3.41 (SD 1.29)], and socio-cultural pressure to introduce water and artificial feeds [mean 3.39 (SD 1.28)]. Independent predictors of EBF were: infant's age [Adjusted Odds Ratio (AOR) 0.82 (95% Confidence Interval [CI] 0.71, 0.95)], and self-employment [AOR 2.67 (95% CI 1.11, 6.41)]. CONCLUSION: Mothers are confronted with numerous EBF challenges both at the individual and societal levels, and stakeholders need to consider these in order to support breastfeeding mothers to maximize outcomes. Reviewing the labour laws on Ghana's maternity leave to accommodate an extended maternity leave in addition to the employee's annual leave could further improve EBF practice rates.

Examining the association between musculoskeletal injuries and carpal tunnel syndrome in manual laborers.

INTRODUCTION: The association between musculoskeletal injuries and carpal tunnel syndrome (CTS) has not been investigated in a large, population-based study. METHODS: Latino manual laborers were recruited as part of a study of work-related health conditions. Each had a clinical examination, completed a hand diagram, and had nerve conduction studies. RESULTS: A total of 512 individuals completed all testing. An association was found between rotator cuff syndrome and CTS, with an adjusted odds ratio of 2.25 (P = 0.01) for the right arm, 2.08 (P = 0.03) for the left arm, and 1.84 (P = 0.03) for all individuals. Associations between epicondylitis and CTS did not reach statistical significance. CONCLUSIONS: Individuals with rotator cuff syndrome have a higher prevalence of CTS. Further investigations will be needed to examine for causation and to determine if 1 condition typically occurs first and leads to the other. Muscle Nerve 54: 31-35, 2016.

Antrocarines A-F, antiplasmodial ergostane steroids from the stem bark of Antrocaryon klaineanum.

During a study on the chemistry and biological activity of Antrocaryon klaineanum Pierre, six new sterols including 4,24(28)-ergostadiene-6α,7α-diol (1), 6α-methoxy-4,24(28)-ergostadiene-7α,20S-diol (2), 6α-methoxy-4,24(28)-ergostadien-7α-ol (3), 20S-hydroxy-24(28)-ergosten-3-one (4), 7α-hydroxy-4,24(28)-ergostadien-3-one (5), and 24(28)-ergostene-3ß,6α-diol (6) were characterized by physical and spectroscopic means. The known steroids 7 and 8 were also isolated. The crude extract and the isolated compounds were evaluated for their ability to inhibit the 3D7 strain of Plasmodium falciparum. Compounds 2, 3, and 8 showed potent activity while that of the crude extract was moderate.

Two New Triterpenoidal Saponins from Roots of Pachystela msolo.

Two new triterpenoidal saponins, pachystelanosides A (1) and B (2), and six known compounds have been isolated from the roots of Pachystela msolo. Their structures were elucidated on the basis of extensive ID and 2D NMR studies ('H, "C, DEPT, COSY, TOCSY, NOESY, HSQC, HMBC), and ESI-MS as 3-O-(ß-D-glucopyranosyl-(1-->2)-ß-D-apiofuranosyl-(1-->6)-ß-D-glucopyranosyl)-28-O-(ß-D-xylopyranosyl-(1--4)[α-L-rhamnopyranosyl-(1-->2)}-α-L-arabino- pyranosyl)-hydroxyprotobassic acid (1) and 3-O-(ß-D-glucopyranosyl-(1-->2)-ß-D-apiofuranosyl-(1-->6)-ß-D-glucopyranosyl)-28-O-(ß-D-xylopyranosyl- (1-->4)[α-L-rhamnopyranosyl-(1-->2)]-α-L-arabinopyranosyl)-7α-hydroxyprotobassic acid (2).

Widefield two laser interferometry.

A novel system has been developed that can capture the wide-field interference pattern generated by interfering two independent and incoherent laser sources. The interferograms are captured using a custom CMOS modulated light camera (MLC) which is capable of demodulating light in the megahertz region. Two stabilised HeNe lasers were constructed in order to keep the optical frequency difference (beat frequency) between the beams within the operational range of the camera.This system is based on previously reported work of an ultrastable heterodyne interferometer [Opt. Express 20, 17722 (2012)]. The system used an electronic feedback system to mix down the heterodyne signal captured at each pixel on the camera to cancel out the effects of time varying piston phase changes observed across the array. In this paper, a similar technique is used to track and negate the effects of beat frequency variations across the two laser pattern. This technique makes it possible to capture the full field interferogram caused by interfering two independent lasers even though the beat frequency is effectively random.As a demonstration of the system's widefield interferogram capture capability, an image of a phase shifting object is taken using a very simple two laser interferometer.

Excelsoside: a new benzylic diglycoside from the leaves of Milicia excelsa.

A new benzylic diglycoside was isolated from the leaves of Milicia excelsa and identified as 3,4-dimethoxybenzyl beta-D-xylopyranosyl (1 --> 2)-beta-D-glucopyranoside (1). It was obtained together with four known secondary metabolites including lupeol acetate (2), ursolic acid (3), triacontyl (E)-ferulate (4), and 2-(3,5-dihydroxyphenyl)benzofuran-5,6-diol (5). Their structures were determined based on their spectroscopic data and by comparison with those reported in the literature.

Elatumic acid: a new ursolic acid congener from Omphalocarpum elatum Miers (Sapotaceae).

A new triterpene diastereomer, 1, of the previously reported 3beta,6beta,19alpha-trihydroxy-urs-12-en-28-oic acid-24-carboxylic acid methyl ester was obtained from the stem bark of Omphalocarpum elatum Miers (Sapotaceae) along with a-amyrin acetate (2), spinasterol (3), spinasterol 3-O-beta-D-glucopyranoside (4), and tormentic acid (5). The structures of the isolates were established on the basis of NMR and mass spectrometric data and by comparison with those previously reported in the literature. Compound 1 showed weak antibacterial activity against E. aerogenes ATCC13048 and EA3, K. pneumoniae ATCC29916, and P aeruginosa; it also displayed moderate cytotoxicity against CCRF-CEM, CEM/ADR5000, and MDA-MB231 cells.

Cytotoxicity of four Aframomum species (A. arundinaceum, A. alboviolaceum, A. kayserianum and A. polyanthum) towards multi-factorial drug resistant cancer cell lines.

BACKGROUND: The search for natural products as potential cytotoxic agents has yielded promising candidates. However multidrug resistance (MDR) is still a major hurdle for patients receiving chemotherapy. In the present study, we evaluated the cytotoxicity of the methanol extracts of four dietary Aframomum plant species (A. arundinaceum, A. alboviolaceum, A. kayserianum and A. polyanthum) against nine sensitive and MDR cancer cell lines. We have also identified the bioactive constituents of A. arundinaceum. METHODS: The cytotoxicity of the methanol extracts of the above plants was determined using a resazurin reduction assay. Chromatographic techniques were used to isolate the constituents of A. arundinaceum. RESULTS: A preliminary experiment on leukemia CCRF-CEM cells at 40 µg/mL showed that the extracts from A. kayserianum and A. alboviolaceum as well as the isolated compounds namely compounds aframodial (1), 8(17),12-labdadien-15,16-dial (2), galanolactone (3), 1-p-menthene-3,6-diol (6) and 1,4-dimethoxybenzene (7) were less active, inducing more than 50% growth of this cell line contrary to A. polyanthum and A. arundinaceum extracts, galanals A (4) and B (5), naringenin (8) and kaempferol-3,7,4'-trimethylether (9). The IC50 values below or around 30 µg/mL were recorded with A. arundinaceum extract against eight of the nine tested cancer cell lines. This extract as well as compound 8 displayed IC50 values below 40 µg/mL towards the nine tested cancer cell lines whilst A. polyanthum extract, compounds 4, 5 and 9 showed selective activities. Collateral sensitivity (hypersensitivity) was observed with A. arundinaceum extract towards leukemia CEM/ADR5000 cells and glioblastoma U87MG.ΔEGFR compared to their respective sensitive counterparts CEM/CEM and U87MG. CONCLUSION: The results of this study provide evidence of the cytotoxicity selected Aframomum species as well as a baseline information for the potential use of Aframomum arundinaceum in the fight against drug sensitive and otherwise drug-resistant cancers.

Chemical constituents of Croton oligandrum (Euphorbiaceae).

A new clerodane diterpene derivative named crotonoligaketone was obtained from the stem bark of Croton oligandrum along with eight known compounds including crotonadiol, imbricatadiol, crotonzambefuran B, 7-acetoxytrachiloban-18-oic acid, 3-O-acetylaleuritolic acid, lupeol, beta-sitosterol, and stigmasterol. The structures of the isolated compounds were established on the basis of their spectral data and by comparison with those reported in the literature.

Ultrastable heterodyne interferometer system using a CMOS modulated light camera.

A novel ultrastable widefield interferometer is presented. This uses a modulated light camera (MLC) to capture and stabilise the interferogram in the widefield heterodyne interferometer. This system eliminates the contribution of piston phase to the interferogram without the need for common path optics and results in a highly stable widefield interferometer. The MLC uses quadrature demodulation circuitry built into each pixel to demodulate the light signal and extract phase information using an electronic reference signal. In contrast to the work previously presented [Opt. Express 19, 24546 (2011)], the reference signal is derived from one of the pixels on board the MLC rather than an external source. This local reference signal tracks the instantaneous modulation frequency detected by the other pixels and eliminates the contribution of piston phase to the interferogram, substantially removing the contributions of unwanted vibrations and microphonics to the interferogram. Interferograms taken using the ultrastable system are presented with one of the interferometer mirrors moving at up to 85 mm s(-1) over a variety of frequencies from 18 Hz to 20 kHz (giving a variation in optical path length of 220 µm, or 350 wavelengths at 62 Hz). This limit was the result of complex motion in the mirror mount rather than the stability limit of the system. The system is shown to be insensitive to pure piston phase variations equivalent to an object velocity of over 3 m s(-1).

Widefield heterodyne interferometry using a custom CMOS modulated light camera.

In this paper a method of taking widefield heterodyne interferograms using a prototype modulated light camera is described. This custom CMOS modulated light camera (MLC) uses analogue quadrature demodulation at each pixel to output the phase and amplitude of the modulated light as DC voltages. The heterodyne interference fringe patterns are generated using an acousto-optical frequency shifter (AOFS) in an arm of a Mach-Zehnder interferometer. Widefield images of fringe patterns acquired using the prototype MLC are presented. The phase can be measured to an accuracy of ±6.6°. The added value of this method to acquire widefield images are discussed along with the advantages.